# Dual Batteries?



## R3Dside (Oct 9, 2011)

So I have come to a point where I need dual batteries. My F150 severely dims the the lights when I raise the plow. The radio will even cut out. I have had mechanics me to put in an Optima Yellow top and or run dual batteries. (Add new battery in parallel to effectively double my amps and stay at 12 v). I want to do this first and maybe later upgrade the main battery leads to a huge gauge like 1 ga or even 00. (If this all works I may even add a dual battery setup to my atv as it will be plowing too (winch, lights) 
My question is, is there a theoretical limit to the Amps the system will be able to handle? Current battery is a 750 cca tested at 610. So if I add a 800 or 1000 and had a third in line, can you reach a point where it is too much amps? Also could I run a deep cycle boat battery in with my current battery? Or are the to too dissimilar in makeup?
Any insight appreciated! Thanks.


----------



## Spool it up (Oct 30, 2012)

imo , wired incorrectly


----------



## clark lawn (Oct 7, 2005)

Your batteries need to match both size (cca) and age. The weaker one will draw the other down to its level. You can put as big a battery as you want. The amp problem will ne on how large the amp draw is, if all your running is the truck accessories and the plow then you should have no problem with the stock wire gauge. If you start to add things and increase your amp drawthen you will need to increase wire size.


----------



## R3Dside (Oct 9, 2011)

Ok thanks. That helped. I may try to have two used batteries in The system until I can upgrade both, or just buy one new one and run it with the old one for a short period of time. Would running a deep cycle (used, already here so free) mess anything up being tied to a "regular" non deep cycle type battery.?


----------



## jasonv (Nov 2, 2012)

Deep cycle batteries are probably a good idea. Something to think about, though, is that your problem may not be battery capacity, but the ability of your alternator to keep up. If your average draw is greater than your alternator's output capacity, then no matter how many batteries you hook up in parallel, it will run them all down.

If your battery tests to 610 CCA, that should be plenty. I think you first need to upgrade your alternator.


----------



## R3Dside (Oct 9, 2011)

I had thought that too but the alternator has been replaced about two years ago. Personally I think the battery is getting tired. Even w/o plow, aux lights, light bar, salter, etc... At night when I kick my fan on the headlights just slightly dim from that. That is w/o any accessories on the truck. I think I will either put a huge battery in or add my deep cycle into the tool box. I think the mechanic had tested the alternator, I would think that would be the last to go, considering its pretty new.


----------



## Rick547 (Oct 9, 2009)

R3Dside;1514663 said:


> I had thought that too but the alternator has been replaced about two years ago. Personally I think the battery is getting tired. Even w/o plow, aux lights, light bar, salter, etc... At night when I kick my fan on the headlights just slightly dim from that. That is w/o any accessories on the truck. I think I will either put a huge battery in or add my deep cycle into the tool box. I think the mechanic had tested the alternator, I would think that would be the last to go, considering its pretty new.


Check your wiring. If it is old their is a very good chance it is failing. Corrosion in the wiring will cause poor amperage flow to plow, lights, radio, etc. Also clean the battery post and check all the ground wires and clean them where they attach to the frame.


----------



## jasonv (Nov 2, 2012)

Alternator is not necessarily the last thing to go, especially if its a refurb (most replacement alternators are).

Now having the lights dim with just the blower, that is indicating that the problem is NOT the battery. The alternator should have no problem at all running the blower without the lights dimming.

The alternator has a regulated output voltage, should be to about 14 or 14.5 volts. The battery is 12 volts. So what is happening is when the blower goes on, it is enough extra load to pull the voltage down to something closer to the battery level. This sounds very much to me like bad wiring or weak alternator. When the load increases, the alternator output should increase to keep the voltage at 14-ish, so either the alternator isn't keeping up, or the wire is too high of resistance for the power to get across.

What you can do is test the voltage at the alternator itself with no load and with full load. If full load voltage is significantly lower, the alternator is shot. If full load voltage is the same, then you've got a bad wire.


** MAKE SURE that all of your wire terminals are CLEAN AND TIGHT. Especially the wires connecting the alternator to the battery!!!


----------



## forbidden (Dec 22, 2010)

The alternator runs the whole show. You probably do have a bad battery. Replace the alternator with a much larger purpose built one and not a rewind. The worst thing you can do is stick a rewound alternator in there. More windings in the same size case coupled with high current draw = excessive heat buildup and alternator failure.

Ohio Generator makes top quality purpose built alternators. Do some research on the BIG 3 wire upgrade as you should do this as well. The more efficient you can make the charge and grounding circuits, the easier the system will run. Try sucking air through a garden hose, you will get an idea of what a high amp draw device does to an electrical circuit.


----------



## MickiRig1 (Dec 5, 2003)

Use the search function on the light blue line above.
Search: No power, Charging, Duel Batteries, Lights dim etc.
You will find hours of reading on the subject. It comes up every year.
Our Ford ambulances at work, have frame mounted setups to carry more batteries.
We have 4 batteries on each E-350.


----------



## R3Dside (Oct 9, 2011)

Thanks everybody for the help. I'm starting to get my head around this. I now plan on doing a "big 3" upgrade or at the very least a upgraded ground strap. I cannot easily find where it connects to the frame. Could not find a diagram online but might be able to get it on a lift today or pull a diagram off off Mitchell's. after that I will either buy an optima yellow top at 750 cca or a non agm, lead acid type battery nearing 1000 cca. If my ground strap is not corroded then this issue is probably a poor performing alternator. And yes it was a reman. But at least is has a lifetime warranty on it.


----------



## jasonv (Nov 2, 2012)

R3Dside;1515980 said:


> Thanks everybody for the help. I'm starting to get my head around this. I now plan on doing a "big 3" upgrade or at the very least a upgraded ground strap. I cannot easily find where it connects to the frame. Could not find a diagram online but might be able to get it on a lift today or pull a diagram off off Mitchell's. after that I will either buy an optima yellow top at 750 cca or a non agm, lead acid type battery nearing 1000 cca. If my ground strap is not corroded then this issue is probably a poor performing alternator. And yes it was a reman. But at least is has a lifetime warranty on it.


Easy way to upgrade your ground is to simply run a huge gauge wire from one of your alternator mounting bolts straight to the battery negative terminal.


----------

