# Dual Battery Set up.



## GeoffD (Dec 21, 1999)

When you guys do your dual battery set ups on picks ups how do you do it. Do you connect the two + terminals together, and ground the - on the second battery. Or do you Connect the two + terminals together, and also connect the two - terminals together? 

Kinda going back and forth on which way is the correct way.

Geoff


----------



## CT18fireman (Nov 30, 2000)

I ground the second battery. Running the ground cable is really uneccessary because the steel of the truck will provide a route just as well as the biggest power cable. Make sure that you use good clean connectors and clean grounds.


----------



## Rooster (Dec 13, 1999)

GeoffD, 

I connect postive to postive and only run 1 ground.

Rick


----------



## DaveK (Jul 9, 2001)

I have been thinking about installing a second battery. But not just wired together. The trouble with that is that both batteries must be the same identical batteries of the same age. If not, the weaker battery will actually drain from the stronger one. 
The best way is to use some form of battery isolation.

A simple method is to install a constant duty solenoid between the 2 batteries. So that when the engine is running, both batteries are connected, system will draw off both, and both will be charged. When engine is not running, solenoid cuts out and connection between both batteries is cut. Another advantage is that if the main battery goes dead (leave lights on) you can power the solenoid from the good battery and jump start yourself , with a cab mounted push button switch wired from the secondary battery to the solenoid you wouldn't even have to open the hood.

Then there are true battery isolators that send the charging current to the battery that needs it most when engine is running, and isolates them when not.

Then I found this, (haven't actually ordered it yet, still considering the simplicity of the solenoid setup, see the bottom of this post) a review of a product from Hellroaring Technologies, Inc. You can get an optional remote module to put the switch right in the cab. You would simply turn the system to ON when you are plowing or need a self-jump, or AUTO when not plowing, or OFF when you plan on using power for an extended time with the engine off (so that you won't drain the second battery. The system is $129.95 The remote module is $39.95 So together it's $169.90 with only $5.00 shipping to anywhere in the U.S. and only $10 to our canadian friends.
The best thing about this setup is that you can use different size batteries. Maybe one optima and one regular? One deep cycle?

This quote is from Hellroaring's website, Hellroaring.com


> Some people have used simple diode isolators. But, for those who recognize the detrimental effects that diode isolators have on their battery's performance and life expectancy, they have opted for solenoid or relay type systems. Neither system offers the ideal automatic operation with protection even from alternator failure, yet still provide full cranking performance all in one package.


Here is a good solenoid setup wiring diagram


----------



## DaveO (Dec 21, 1999)

DaveK,

Good info on the dual battery setup. Isolators are a good idea, used commonly in marine applications.

It is preferred to have the same type/size of batteries, but not necessary. It is correct that if one of the batteries is weaker, it will charge off the stronger when the charging system is off. When the two batteries equalize(voltage wise), that will stop.

Two different capacity batteries will not do this unless one is weak. The static voltage difference is the only concern, not the available current capacity(cranking amps).

Geoff,

Neg to Neg is preferred, providing the existing battery has a good ground cable. Especially for electric/hydro packs. They almost always connect to the battery negative, not chassis ground. In fact Fisher has seen some problems when customers connected the negative to the frame instead of the battery. This may create a poor ground to the electric motor in the SEHP, resulting in poor operation, and arching of the motor shaft(trying to get to ground).

Dave


----------



## John Allin (Sep 18, 2000)

You guys make me glad I have a full time mechanic..... I get confused easily.


----------



## jason2 (Dec 22, 1999)

Another company to offer dual battery setups is Painless wiring. They offer different multi-battery solutions. One neat product they have is a battery manager. It allows use of: Main only, normal, main + aux 1, main + aux 2, maintainer, main + aux1 + aux2. They have marine grade 250 amp dual battery kits. Plus lot's of other goodies. all controllable from in the cab.

I will be buying from them in the future. Lot's of the 4x4 crowd swears by their products.
http://www.painlesswiring.com/battacc.htm


----------



## DaveK (Jul 9, 2001)

In reply to DaveO


> Two different capacity batteries will not do this unless one is weak.


 I don't think that is entirely correct, it has something to do with the charging of two different capacity batteries. I think the lower capacity batt can be overcharged (I'm not an electrical engineer, so don't hang me if I'm wrong) I am just going by what I have read in the following two quotes.


> Having two batteries sounds great, but can cause problems unless thought is given to the wiring of them. You need a battery management system to stop one from getting all the charge, and the other going flat, leaving you with no power at all. I've seen this happen on other trucks "...but I just installed a second battery..."


and 


> The addition of a second battery may sound logical at first. You have several choices for wiring it up. The most basic is by connecting both positive terminals (+ to +) together. This almost adds the 2 capacities together. *The disadvantage is that you need 2 identical batteries of the same age.* But no 2 batteries are identical in fact and the weaker one always pulls the stronger one down. So after a while you may have 2 dead batteries.


In reply to jason2


> Another company to offer dual battery setups is Painless wiring. They offer different multi-battery solutions. One neat product they have is a battery manager. It allows use of: Main only, normal, main + aux 1, main + aux 2, maintainer, main + aux1 + aux2. They have marine grade 250 amp dual battery kits. Plus lot's of other goodies. all controllable from in the cab.


 Hellroaring has the same (can have three batts) but I didn't think many people here would actually want or need three. I'm suprised to see their (Painless wiring's) website up. Back when I was researching this I found information reffering them (including the website address) but could not get to the website. ( I bookmarked it and tried every few days to see if it was just a server problem, but after about 2 weeks, I gave up.


----------



## DaveO (Dec 21, 1999)

*Dual Batteries*

DaveK,

There is no hanging on this site. Just goes to show you that you can't always believe what you read, especially from someone trying to sell you something.

Without getting into the electronics in detail.....If one battery is ALMOST dead it will load down the alternator, and the other battery. It will not stop the other battery from charging. A battery is like a transformer, as it charges up, it draws less current from the source(impedance changes). Provided the charging system does not exceed 15VDC, the battery will not overcharge. FYI common car/truck/bike batteries have 6 cells. Each cell is capable of charging to 2.2VDC, thus totaling 13.2VDC when fully charged. If you measure a fully charged battery, it will be closer to 12.8VDC, because the "surface charge" drains off fast. If you charge it OVER ~15VDC, it willl "boil out" and end up damaged.

I install a second battery in many of my customers "bikes" without any problems. And I don't usually use the same size/capacity either due to space considerations. Done this for years.

BTW...I am an electrical engineer working for a leading audio manufacturer. In case you were wondering....

Dave


----------



## CT18fireman (Nov 30, 2000)

I have used different size battery connected without isolators in my boats and trucks. Now I have gone all Optima Yellow tops (blue for the boat) so they are all the same. When I ran differents I never had a problem. I always recommend to put the most powerful (amps) battery that you can run.


----------



## GeoffD (Dec 21, 1999)

Even with full time mechanics, they still come to the boss with the electronics degree some days.

And its been a while from my last visit to school.

Geoff


----------



## DaveK (Jul 9, 2001)

> If one battery is ALMOST dead it will load down the alternator, and the other battery. It will not stop the other battery from charging.


 That is assuming that the engine is running and charging.



> Provided the charging system does not exceed 15VDC, the battery will not overcharge.


 See INFO #2 below. Why would they recommend using relays to cut charging of the string when the voltage reaches to an adjusted voltage if they cannot be overcharged?



> FYI common car/truck/bike batteries have 6 cells. Each cell is capable of charging to 2.2VDC, thus totaling 13.2VDC when fully charged. If you measure a fully charged battery, it will be closer to 12.8VDC


 Yes, I knew this.



> Just goes to show you that you can't always believe what you read, especially from someone trying to sell you something.


 I have read that you should use batteries of the same capacity from sources that are not trying to sell anything.

INFO #1 "In the PARALLEL CONNECTION, batteries of *like voltages and capacities* are connected to increase the capacity of the bank. The positive terminals of all batteries are connected together, or to a common conductor, and all negative terminals are connected in the same manner. The final voltage remains unchanged while the capacity of the bank is the sum of the capacities of the individual batteries of this connection. Amp-Hours Cranking Performance and Reserve Capacity increases while Voltage does not."

AND

INFO #2 "*you should never connect non homogeneous (same capacity) batteries in parallel. Batteries connected in parallel must be even of the same age (as the sulfating occurs a resistance as well) The smaller in capacity batteries, are charged quicker.* During charging you can disconnect the strings with relays and charge the strings simultaneously separated by diodes. Then each string will need a voltage control unit to cut charging of the string when the voltage reaches to an adjusted voltage. When all strings reach to the adjusted voltage then charging is stopped automatically or manually and relays will close to reconnect the batteries' strings." The last quote was from a discussion group at http://csf.colorado.edu

Some info about over discharging here. "OVERDISCHARGING is a problem which originates from insufficient battery capacity causing the batteries to be overworked. Discharges deeper than 50% (in reality well below 12.0 Volts or 1.200 Specific Gravity) significantly shorten the Cycle Life of a battery without increasing the usable depth of cycle. *Infrequent or inadequate complete recharging can also cause overdischarging symptoms called SULFATION.* Despite that charging equipment is regulating back properly, overdischarging symptoms are displayed as loss of battery capacity and lower than normal specific gravity. Sulfation occurs when sulfur from the electrolyte combines with the lead on the plates and forms lead-sulfate. Once this condition becomes chronic, battery chargers will not remove the hardened sulfate. Sulfation can usually be removed by a proper desulfation or equalization charge with external manual battery chargers. To accomplish this task, the flooded plate batteries must be charged at 6 to 10 amps. at 2.4 to 2.5 volts per cell until all cells are gassing freely and their specific gravity returns to their full charge concentration. Sealed AGM batteries should be brought to 2.35 volts per cell and then discharged to 1.75 volts per cell and their this process must be repeated until the capacity returns to the battery. *Gel batteries may not recover.* In most cases, the battery may be returned to complete its service life after performing this."

I am not saying that you must use an isolator on a dual battery system. They don't put them on at the factory for trucks with dual batteries, but then they have identical batteries don't they. From all the information I have found, you are the only one who claims that you can use different capacity batteries without an isolator. All the others say they must be the same capacity and often say they must be the same age. Sure it will work, but not for as long, especially with gel batteries (see proper desulfation above) unless you want to perform proper desulfation on your batteries when the capacity is reduced. And who wants to spend their free time doing that.

Besides using different capacity batteries, the isolators (either from Hellroaring or Painless or many others ) offer other great benefits. Self jump for when you drain the main battery. You can even run your vehicle electrical system off one battery, and your plow off the other. Those are MAJOR benefits. They have been using these on RVs (for extended power use ) and off-road 4x4s (winches, lights etc.) for years.

CT18fireman "When I ran differents I never had a problem" So are you still using the same batteries, or was their useful life used up? Perhaps prematurely?

BTW...I am an not an electrical engineer. I'm not a computer programmer either, although I do have a degree in computer programming. In case you were wondering.... But when I have an interest in anything, I do in depth research till I find the facts and understand them fully.


----------



## wolfie (Aug 14, 2001)

Chevy has an isolated dual battery option available. It use 600 CCA & a 770 CCA batteries. the RPO code is 8BO I found out about it too late to get it on my new truck. I'm going to see how it goes with the standard 600 CCA battery this year and then decide what to do next.


----------



## CT18fireman (Nov 30, 2000)

No the reason I switched was that I put a single Optima into my 4runner which has a stereo system. Worked well. So I swapped all my batteries that year to Optimas (Expensive but worth it IMO) I have done different size batteries in other people's trucks and they are still running strong today.


----------



## DaveK (Jul 9, 2001)

> Chevy has an isolated dual battery option available. It use 600 CCA & a 770 CCA batteries. the RPO code is 8BO


 Well, look at that. Even the factory uses an isolator when there are two different capacity batteries. That must mean _something._ I am sure that GM has a large team of electrical engineers that know what they are doing. I don't think they would use an isolator if it wasn't needed. (somebody would eventually file a class action lawsuit claiming that their batteries didn't last as long as they could have)



> I have done different size batteries in other people's trucks and they are still running strong today.


 I don't doubt that. You can also mix alkaline and nicad batteries in your flashlight and it will work, but it isn't recommended. And certainly doesn't give the optimum performance or optimum battery life.

I am already convinced that with different capacity batteries, you shuold have an isolator. But I will continue to research it to find undisputable evidence that will convince the non-beleivers, if needed. If anyone else can find undisputable evidence from a credible source, please post it.


----------



## CT18fireman (Nov 30, 2000)

Their pumps and accessories work better than with one battery and the truck starts every morning. What more could they want in terms of battery performance?


----------



## DaveO (Dec 21, 1999)

DaveK,


Obviously you have read a fair amount on this subject. I would have guessed on the degree in Computers, based on your proficiency(sp) with the keyboard. I really don't want to get into a pissin contest on this issue. So......

Yes a parallel circuit will increase current with NO increase in voltage. Electronics 101. Two batteries of the same voltage and SIMILIAR capacity(i.e. 400 vs 500 CCA) will function perfectly, with no decreased lifespan. Yes the smaller capacity will charge up faster, but this creates no problems. When the smaller battery is charged fully it will stop drawing current, and the other battery will draw the rest as needed. On the same note, the smaller battery will discharge quicker also due to it's reduced current capacity. Again this is not normally a problem. REMEMBER, THAT NO TWO BATTERIES ARE EXACTLY THE SAME IN CAPACITY, there will always be production variances. The batteries will always split the load requirement in half, providing each can supply 1/2 of the current demand.

About sulfation....Everything you stated is correct. The most common cause of sulfation is a heavily discharged battery(low S.G.) exposed to freezing temperatures. This causes the sulfation to occur on the plates. As you stated, you have to "shock" this coating off the plates to recover the battery's performance by a high current, high voltage cycle. This is VERY common in vehicles unused for extended periods in the winter months. This method is usually only utilized on lead/acid batteries. And they average about an 80-90% recovery of performance. We have never seen 100% recovery. And I have NEVER performed this on GEL cells, only lead/acids. Sulfation is the leading failure mechanism on lead/acids. 

The whole point of having two batteries in a plow truck is to have DOUBLE the current reserve to supply power to the electric/hydro pump. Isolating one will just leave you with a one battery supply. Yes there are many other benefits to isolation, but we are more concerned with the current available during a "surge", just like a stater motor concern. This is why diesels have dual batteries, to ensure starting after glow plug/grid heater operation, and then a high torque starter demanding current. 

I find it ironic that I am the ONLY person who has these beliefs. I do NOT argue that two identical batteries of the same age is preferred. But my experience and education supports my belief that it is not NECESSARY. You seem to be relying TOTALLY on verbage aquired from a couple of different sources. Like I said, don't always believe what you read(including my advice...LOL). There is always a difference between the textbook and the lab(real world) also. My best advice to you would be to use experience to assist your knowledge gained by research. I have found this to be VERY beneficial to me in the past.

Just FYI....REAL world example, not copied from an educational site....LOL. I installed a Fisher E Force harness on a customers F250 powerstroke. It was fairly involved, took a few hours. Required disconnecting both batteries. After finishing I connected up only one battery to test it. The truck refused to start, and the pump perated erratically. Appeared to have inadequate current suppply. So I connected the 2nd battery up. Truck started, ran fine, electric/hydro worked fine. I checked the S.G. on both batteries, and one was basically dead, the other 90%+ charged. I mentioned it to the customer when he picked it up. He said "yea, I know that battery is N/G, " he had replaced ONLY ONE battery TWO YEARS AGO. The truck runs/plows OK. Is he going to reduce the life of the new battery? Maybe, but it hasn't killed it in 2 years. Definitely not suggested IMO.


GM electrical engineers that know what they are doing? No wonder they pay me to design/test audio equipment for their "high end" vehicles. I suppose they save $$ by paying me to do it. 


Good job on the homework BTW.


Dave


----------



## DaveK (Jul 9, 2001)

> Isolating one will just leave you with a one battery supply.


 But in this application (snow plowing) they are not isolated during use, only when the key is turned off, or when not plowing. We aren't talking about "bikes" here, at least I'm not.



> I do NOT argue that two identical batteries of the same age is preferred. But my experience and education supports my belief that it is not NECESSARY.


 Perhaps you should re-read my posts, I don't think I ever stated that it was NECESSARY. I said that it "is preferred" and "the best way." For those that will accept less than the best, mix your batteries however you want. But for me, and I am sure others, that DO want the best preferred method, it will be two identical (in age AND capacity) OR battery isolation. And I think that being able to give my truck a self-jump, when needed is a worth a few extra bucks. Will it save me money in the long run, who knows, but when you are stranded or your truck won't start on a cold morning when you really need it, money isn't my first concern.



> I find it ironic that I am the ONLY person who has these beliefs.


 I don't find it ironic, I find it questionable. Since I am not an electrical engineer, my credibility is not at stake. I am not relying on my experience or education as you are, therefor I can only rely on *multiple outside sources* (you are ONLY relying on your education and experience). Then when I feel that I have adequate information, I simply believe the most prevalent facts. Which in this case, is that *an isolator while not NECESSARY, is certainly the BEST way to combine batteries of differing capacities.* I put it in bold so that Dave0 won't miss my point this time.



> I checked the S.G. on both batteries, and one was basically dead, the other 90%+ charged. I mentioned it to the customer when he picked it up. He said "yea, I know that battery is N/G, " he had replaced ONLY ONE battery TWO YEARS AGO. The truck runs/plows OK. Is he going to reduce the life of the new battery? Maybe....


 I think I would have then disconnected the "dead" battery so that the reduction of life for the good battery wouldn't be "Maybe..." common sense 101.



> Just FYI....REAL world example, not copied from an educational site....LOL.


 I don't know why you were LOL. Is there something wrong with educational sites that I am not aware of. No matter how intelligent a person is or thinks they are, education should be a life-long commitment. Learning shouldn't stop after achieving any degree.



> GM electrical engineers that know what they are doing? No wonder they pay me to design/test audio equipment for their "high end" vehicles. I suppose they save $$ by paying me to do it.


 Perhaps they are busy designing battery isolators and leaving the easy stuff to the less fortunate electrical engineers. LOL (I finally saw some humor in this topic)



> I install a second battery in many of my customers "bikes" without any problems. And I don't usually use the same size/capacity either due to space considerations. Done this for years.


 Do you tell your customers that you aren't doing it the preferred or best way?

One quick question for Dave0.... Do they use many dual battery setups in "high end" car audio these days? Never mind, I'll ask my brother-in-law, he doesn't have a degree in anything but he does work for Siemens testing anti-lock brake systems and compass/GPS systems.

Both Dave0 and I have said that using an isolator is the best preferred method to connect differing capacity and/or age batteries, although not necessary. That is what I have said throughout this thread. I have never claimed that is was necessary, and in fact I stated that it was not necessary. It appears that Dave0 has somehow reached the conclusion that I said it was necessary. And it also seems that Dave0 is discouraging the use of isolators. (why, I don't know) At least that is how I see it since we have both said virtually the same thing. I on the other hand am encouraging the use of them when it is the best way. That is the only real difference of opinion that I can see.



> Good job on the homework BTW.


 Don't try to patronize me. And I never did homework when I was in school.

FYI... I have NEVER competed in a pissin contest. Debates are another story.


----------



## CT18fireman (Nov 30, 2000)

Easy guys! 

Actually many competition car stereos may use 5-6 batteries to handle the power going to the amps. Add to this capacitors and you are talking about a lot of amps.

While you may decrease the life of the batteries I think the obverall benefit outweighs this. Installing the biggest batteries you can fit will lead to your accessories getting the most current they need. Total amps is what is important.


----------



## DaveK (Jul 9, 2001)

CT18fireman, I am going easy.  Neither of us mentioned competition car stereos. And the stereo itself doesn't require multiple batteries. Certainly not the ones used in "high end" automobiles.



> While you may decrease the life of the batteries I think the obverall benefit outweighs this.


 I am not sure what you mean by that. It sounds as if you are saying either
1) having 2 batteries will decrease the life but having more power is worth it. 
OR
2)you think one of us is saying that simply having two batteries will decrease their life, but it is worth it.

You didn't mention "with or without an isolator" or "same size or differing size batteries" which is what is being discussed.


----------



## CT18fireman (Nov 30, 2000)

I realize that I did not mention that. My original post told Geoff to use two batteries without an isolator in order to give his pump and other accessories more current. My whole point is that even if it does decrease battery life in theory (I have not found this to be true) that it would still be worth it in being able to run all equipment when plowing and not risk cooking an alternator or the truck dying out.

My whole point about stereos was to say that it is not just people with big motors and snowplows that run multiple batteries. It is the kids driving the little imports with small alternators that want big sound.

There are clear benefits to running dual batteries. Like I said when running elsectrical accessories it is best to have the most available amps you can fit into the truck. 

This is all my opinion. I am not an electrical engineer. However I am an mechanic and a landscaper, and have worked as an installer of both car stereos and snowplows. I also have experimented on my own vehicles. I am not trying to get in a pissing contest but I will say that what the "manufacturers experts" and others say and print is not always accurate in the real world.


----------



## DaveO (Dec 21, 1999)

DaveK,

From your last post:

"Perhaps you should re-read my posts, I don't think I ever stated that it was NECESSARY. I said that it "is preferred" and "the best way." "

And from your 1st post:

"The trouble with that is that both batteries *must* be the same identical batteries of the same age. "

So which is it?

Dave

"Don't ask the question if you can't understand the answer"


----------



## DaveK (Jul 9, 2001)

Do not attempt to twist the truth to you liking. Here is the actual complete first paragraph that you used to quote one part of:


> I have been thinking about installing a second battery. But not just wired together. The trouble with that is that both batteries must be the same identical batteries of the same age. If not, the weaker battery will actually drain from the stronger one. The best way is to use some form of battery isolation.


Pay attention to the 4th sentence that begins with "If not." And then the last sentence, which sums up what I have said throughout this thread.

Just because sentences are terminated with periods, you cannot take one sentence out and convey the message of the complete paragraph. The period does not terminate the message, it is just punctuation. Being an electrical engineer, I would have thought that they taught you basic english and composition as well.

Dave

"It is better to remain silent and be thought a fool, than to speak and remove all doubt"


----------



## plowking35 (Dec 21, 1999)

Now Now Daves, play nice.
Must be some Dave envy going one.
Dino


----------



## DaveK (Jul 9, 2001)

Dino, I am playing nice.  And having fun.


----------



## DaveO (Dec 21, 1999)

*Back to Dual Batteries*

For those interested in installing a dual battery setup:

If you have the extra $$, and do not mind the additional cables, utilizing an isolator is not a bad idea. I still stand by my opinion that it is not necessary for proper operation. The chances of the isolator failing and leaving you stranded are slim. If the benefits justify the cost to you, by all means feel free.

In my professional opinion, not using an isolator will NOT decrease battery life, PROVIDING one of the two batteries is not dead or shorted internally.

For DaveK:

GM employs thousands of engineers, many of them EE's. They outsource many electronic devices for various reasons. They learned back in the mid 80's that PCB design/manufacture was NOT their forte'. This is probably why Delphi exists. They contract us to design/build their audio systems simply because that is what we do well. Nissan, Audi, Porsche, and others also contract us. We also design/manufacture communication headsets for the military(US and others). These use dual battery setups(with no isolators), but I cannot comment more on those(confidentiality requirements). GM has many excellent engineers that I have dealt with.

Education is never taken lightly by me. Although education is NO replacement for experience, the combination of the two is the best way to learn. One of my most satisfying positions was a night instructor at a local college. I taught electronics for almost 3 years(microprocessor architecture, MC68000 series). This was very rewarding to me, and I may do it again in the future. I try to learn something new everyday if possible, and am always open to new ideas.

About the debate on isolators. You have still not proven to me how/why not using them causes a decrease in battery life. The post on sulfation only explains how a battery can weaken in current sourcing ability. Having two batteries does NOT cause sulfation.

To explain to me how/why not having an isolator decreases battery life, you will have to use electron theory(or quantum mechanics if you prefer), to explain that theory. The only reason I can conclude, is if one of the two batteries is shorted internally, which will kill the system regardless. If you are interested, I can explain to you why I believe different, using electron theory. I will not do this on this forum, as it will be rather long. But if you can explain different to me, I'm all "ears".

And don't confuse patronizing with respect. I try to maintain professionalism/integrity in everything I do.

Dave


----------



## TLS (Jan 31, 2000)

Hey Daves, and all other readers. My 1990 (see sig) I ordered with dual batteries. This came with an isolation Solinoid mounted to the drivers side fender. Only problem with this was the wire going between the two was only like 10 gauge. Last year I got some 4 gauge and wired the batteries directly together + to + (on the top posts). The negatives are going to the Block AND Frame on each battery. The batteries are withen 2 months of each other and are the same brand and type. The truck never started this good in its life! I now use the old battery isolation solinoid for my rear back up lights (a little overkill, but thats just me!). Plowing last year was great. I dont know how GM had the isolation solinoid activated, but it was on some sort of delay, as it never seemed to activate at startup. The days of having another battery to "jumpstart myself" are over, but I am enjoying much better performance overall.

Now if I could just have better luck with batteries! Cant seem to find ones that last longer than 3 years!


----------



## DaveK (Jul 9, 2001)

For those interested in installing a dual battery setup:

If you have the extra $$, and do not mind the additional cables, utilizing an isolator is a *very good* idea. I still stand by my opinion that it is not necessary for operation. I also stand by my opinion that the benefits justify the cost.

In my honest opinion, not using an isolator will NOT decrease battery life, PROVIDING one of the two batteries is not dead or shorted internally AND that both batteries are of the same capacity and age. If they are not of the same capacity and age, they obviously will not discharge at the same rate. I have given evidence supporting my opinions from multiple outside sources. Some of the evidence may be difficult to understand, but I quoted it the way I found it rather than attempting to put it in my own words or try to simplify it.

Feel free to do your own research to determine if my statement that "an isolator while not NECESSARY, is certainly the BEST way to combine batteries of differing capacities" is somehow flawed.

For Dave0:
There are a few questions/statements in this post that you failed to reply to. I don't see it as necessary to point them out now. So I won't.

I don't understand why this became such a debate in the first place when you yourself said "If you have the extra $$, and do not mind the additional cables, utilizing an isolator is *not a bad idea.*" Which when translated, means it's a good idea. And if it is a good idea, there must be a reason that it is a good idea. I have never claimed it was necessary, either with or without different batteries. I simply offered my own personal opinion that "using an isolator is the best preferred method when using different batteries." Which is not much different than you now stating that it is "not a bad" idea.

I then also claimed additional benefits such as in cab control of the isolation and self-jump. I honestly see those as very useful benefits. Maybe you do not see them as benefits, but that is whole new debate that I do not care to get into, since everyone is entitled to their own opinion as to what they want, need or view as important.

As for this topic, I think Dave0 and I have both made our closing arguments, so I rest my case. We both have certainly added valuable viewpoints on this subject that can only benefit plowsite. One might even say that plowsite now has the most in-depth discussion on dual batteries and isolators anywhere on the web.

For Dave0 and anyone else that cares to read it.
(has nothing to do with dual batteries, I promise)

Since Dave0 gave us a more broad view of his background, I will as well. I am very mechanically inclined and have been since early childhood. My grandfather was an engineer for GM and my father was an auto mechanic. My father passed away when I was 13 years old. Wanting to carry on in my father's footsteps, my first occupation was as an auto mechanic at the age of 17. I was state certified in tune-ups, brakes, engine rebuilding, and vehicle electrical systems. I am capable of transmission rebuilding, both manual and auto, as well as front end alignments and all other areas but was not certified to perform these since the only requirements to receive a final grade in vocational school was two take 4 state tests and pass at least two. We had to pay for the tests, and at age 17 I would rather spend my money on a date than on some state tests. After working as an auto mechanic for a few years, I grew bored and really hated it when standing under a hoist in the winter and having the snow and ice melt and drip on me, or leaning under the hood of a car in the summer. I have utmost respect for auto/truck mechanics that do this day in and day out. I was living my father's life, not mine. I then was fortunate enough to be at the right place at the right time, and ended up as the manager of a garden center - nursery. Who would have thought that botany would have paid off? I would have done my botany homework if I only had known. About six years later, I found that computers fascinated me. I went to college and studied computers. It seemed too easy. After an internship in the job placement office of the college I attended, I found myself working for EDS (Electronic Data Systems) at a GM assembly plant in Flint Michigan training engineers how to effectively use their new computers and resolve problems with their computers when needed. In the meantime, my wife began working at a landscape supply yard that did not sell plant material, brick and hardgoods only. I left EDS to become a husband/wife team that transformed a small landscape supply yard into a large full service supply yard and plant nursery for retail and wholesale customers. I have since formed a partnership with the owner of the landscape yard in a separate business. (It is probably obvious to many which company this is, but mentioning it here may violate the rules of this forum). I have also very recently started a landscape company with my 18 year old son. Yes, I was twenty when he was born. This certainly is more information than Dave0 gave and isn't my complete history, but may explain to others my unique history and experience in the auto industry, the landscape industry, and the computer industry.

Dave

"I would be a member of MENSA but I'm to lazy go take the test"


----------



## DaveK (Jul 9, 2001)

As much as I do not want to revive or keep this thread alive, after re-reading the entire conversation, I feel that there are a few things that need to be clarified as there was misinterpretation of my statements.

I will keep it brief, to the point, and as simply stated as possible.

A few times, it appears that my point was mis-interpreted by at least two people, even though I carefully worded my posts to avoid confussion. I will be even more careful this time.

Both misinterpretations imply that I said that having 2 batteries is bad. I never said that, and in fact, my very first sentence in this thread was "I have been thinking about installing a second battery."

-------

First misinterpretation. 
CT18fireman 
"My original post told Geoff to use two batteries without an isolator in order to give his pump and other accessories more current. My whole point is that even if it does decrease battery life in theory (I have not found this to be true) that it would still be worth it in being able to run all equipment when plowing and not risk cooking an alternator or the truck dying out." 

Even WITH an isolator, Geoff's pump and other accessories will have more current by using 2 batteries.

I never said that having two batteries without an isolator will decrease battery life per se. 
Having 2 batteries will not decrease battery life. 
a) If they are the same capacity and age. 
OR
b) If they are different capacity and/or age and have an isolator. 
------

Second misinterpretation. 
Dave0 
"Having two batteries does NOT cause sulfation." 
I did not say that having two batteries causes sulfation.

Sulfation is from 
1) Overdischarging. 
2) Infrequent or inadequate complete recharging. 
Both of which plow trucks are more suceptable to than the average car.

Dave0 
"The most common cause of sulfation is a heavily discharged battery(low S.G.) exposed to freezing temperatures... 
...This is VERY common in vehicles unused for extended periods in the winter months." 
------

And now an update on my truck. 
I have just installed a second battery WITH an isolator for $41.91 plus tax, including the cost of the battery.

I purchased a slightly used battery from an auto salvage yard for $15 plus $2 for a core charge (since I didn't have an old one to exchange). I first measured the location under the hood to determine the maximum physical size that I could use. At the yard, I had a choice of about 25 batteries. The one I purchased is at most 4 months old, since the "date of purchase" on the battery is Aug. 01. It has 850 CCA . The salvage yard has a 30 day warranty. I then took the battery to the auto parts store to have it load tested. (many parts stores will do this for free. This one did). It passed the test. While there, I purchased 2 regular battery terminals at 99¢ each for the secondary battery, 2 heavy duty terminals at $1.99 each for the primary battery since there are two 4 gauge cables connected to each of these. And 1 continuous duty solenoid for $12.95. The only battery cables they had were premade up to 50" for $12.99 each so I did not buy them there. I went to an electrical supply store and purchased 10 feet of 4 gauge at 60¢ per foot for a cost of $6.

1 battery $15.00
1 core charge $2.00
2 termminals $1.98
2 HD terminals $3.98
1 CD solenoid	$12.95
10 feet 4 gauge $6.00
Total	$41.91 +tax

I installed it as a basic isolation system.
Batteries are joined when ignition is on,
isolated when ignition is off.

Benefits:
Dual batteries, which provides:
Plenty of reserve capacity
Less stress on alternator
Automatic isolation, no in cab switch to deal with.
Ability to self jump
Isolation when off (even if one battery has internal shorts or low specific gravity, it will not effect the other battery which will remain at full charge) AND (if I were to leave my lights on till the main battery is dead, I still have a fully charged battery to self jump with)

Next addition: In cab push button switch to power solenoid from secondary battery, allowing self jump or extra CCA when needed. Estimated cost: a few bucks.


----------

