# Battery Isolator vs Battery Separator



## nate456789 (Aug 11, 2009)

I posted this on DieselPlace without much feed back other than I need to run the same batteries. But I am running an optima for the plow side. Can anyone give me some thoughts on this? Here is my Post -

I have a 2009 Chevy truck - 6.0 - with 160 Amp Alternator - DR44 - I bought a Sure Power Isolator to run dual batteries for snowplowing. I have ran them on other trucks with no issues.
Went to install the isolator and come to find out my 2 wire alternator is not compatible with isolators and it recommended a battery separator.
My Questions:
Will a separator work as good as the isolator? Especially with a plow.
Has anyone used this setup? I use an Optima Battery with a std one.

Is there an isolator compatible with this alternator?
My truck has a place set up for dual batteries - How does GM recommend running dual batteries?

Thanks!


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## 2COR517 (Oct 23, 2008)

Most dual battery setups are wired in parallel. Doesn't matter if you have two or twenty, the alternator sees one load.

I like isolated batteries too. I have my strobes, work lights on the AUX battery. I can run them with the truck off until the battery is dead. Truck will start right up. My AUX battery is isolated with a simple relay. I am going to upgrade some of my wiring, and use a Trombetta continuous duty relay/isolator. So when the truck is on, they function as two batteries wired in parallel. This is actually best for plowing. Shut the truck off, and you still have an isolated battery if you need that.


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## nate456789 (Aug 11, 2009)

I am starting to get the feeling that nobody runs battery isolators from the responses.
I understand that dual batteries are in parallel. But if you have batteries that are not matched the weaker battery will eventually shorten the life of the stronger battery.
I am running a standard 730 cca battery along with an optima. That is not a matched combination. The optima has a deeper cycle and works very well with a plow.

On my other trucks I have an isolator that keeps the optima isolated from the truck's system other than the alternator feed. The lights and interior barely even flicker when plowing using this configuration.
To me this is ideal because it is on it's own circuit and not on the rest of the truck's system.


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## nate456789 (Aug 11, 2009)

So one more question - the Trombetta that you are using is a relay system? So does that really mean that the batteries are not isolated but in parallel then?
So does that plow effect the rest of the truck's system? I am not really sure how th relay systems work. 
Anyone have a good explaination on this?
Thanks


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## 2COR517 (Oct 23, 2008)

When the relay is energized, both batteries are tied together. The unequal battery drain only applies when there is no charge source connected. When the truck is running, it doesn't matter.


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## nate456789 (Aug 11, 2009)

Well that makes since.
I didn't see on the trombetta site any relays labeled as Battery separators.
Do you have a model or part number of the one that you are using?

I also found this one http://www.ase-supply.com/ProductDetails.asp?ProductCode=SP-1315-200
I have used the Sure Power equipment before with no issues.

Thanks for the info.


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## 2COR517 (Oct 23, 2008)

I need to dig through some e-mails.


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## B&B (Nov 4, 2006)

You likely haven't gotten many replies due to the fact that this subject get's brought up time and time again every year.

First, don't confuse an isolator with a switchable on off continuous duty relay as a means of separating the batteries. For max effectiveness of having two batteries you don't want an actual isolator on a dual battery plow equipped truck as it defeats the purpose of trying to supply max current to the plow with the extra battery...or at least as much as the system is physically capable of.

You do however want to wire it through an ignition on only relay (like 2COR is describing) and run the same batteries. Use the search word "isolator" in the advanced search box and you'll find _days_ of reading about this subject.


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## nate456789 (Aug 11, 2009)

Thanks B&B -
This thread is excellent http://www.plowsite.com/showthread.php?t=55865


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## 2COR517 (Oct 23, 2008)

B&B;833948 said:


> ....(like 2COR is describing) ...


If YOU won't call me the Dog Napper, who will? 

I'm telling yah, it's not going to stick


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## B&B (Nov 4, 2006)

2COR517;834260 said:


> If YOU won't call me the Dog Napper, who will?
> 
> I'm telling yah, it's not going to stick


You gotta post your Tahoe story in the off topic first. Then it'll stick


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## nate456789 (Aug 11, 2009)

2COR is this the Relay that you used?
http://shopping.murcal.com/Catalog/Bear-DC-Contactor-Family/114-1211-020
Thanks


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## 2COR517 (Oct 23, 2008)

That should work. 100% duty cycle, 225 amp capacity. 

B&B, do you concur?


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## B&B (Nov 4, 2006)

2COR517;837659 said:


> That should work. 100% duty cycle, 225 amp capacity.
> 
> B&B, do you concur?


I do. Trombetta's are some very nice and reliable solenoids.


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## massbowtie (Feb 19, 2003)

*golf cart colenoids*

work great for this. its designed for continuous run and is rated more amps than youll need. the one i use i got off the internet for $25. dollars,dont remember where but just google electric golf cart solenoid. i run the factory ac delco and a sears marine battery that has all my extras connected directly to the marine battery. have done this to 3 trucks now and havent had any problems.something i found out about my 09 gmc is there is tsb about adding relays/solenoids to the truck..it requires the use of a diode across pos.and neg. posts of solenoid to prevent electrical spikes from burning up any of the factory systems.


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## nate456789 (Aug 11, 2009)

Do you have anymore information about this diode?
I did a quick search on TSB and didn't find anything.
Does it go with the relay or at the batteries?

What diode are you using? Part number and or size?
Thanks


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## hawk2wp (Nov 17, 2009)

Any more info on the diode?


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## nate456789 (Aug 11, 2009)

I never did use a diode.
I installed the dual batteries with the above mentioned relay and everything works fine.
No issues yet.

Pictures of the install are at the bottom of this thread
http://www.plowsite.com/showthread.php?t=93349


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