Dual Battery Install - Ford F150 Forum

hiredman77 · 02-18-2011, 05:03 PM

Hey guys:

I did a pretty primitive dual battery install today and it turned out well and really cut down on the voltage drop at low RPM's. It took some research to find a battery that will work and fit where I wanted it to.

I welded up a bracket for the battery to sit in and bolted it into the spot where the factory jack used to sit on the inner fender. Then I unbolted the vacuum canister and smog filter. They were bolted to the inner fender by 2 bolts each. I drilled new holes and relocated the smog set up closer to the battery.

Then the vac can I made a new L shaped bracket bolted it to the fender and reattached it.

I ran them in parallel because all I was after was a little more oomph for the -20 winters here and for low rpm amperage. I am fully aware that all i did was make one giant battery and if I leave my lights on they both will go dead. Some day down the road I will put in an isolator but for now this will do juuuuuust fine.

PS I did clean everything up and make it nice n tidy before calling it done.

Skink · 02-18-2011, 05:33 PM

Not too bad - the only thing I would have done is kept the red for red and black for black, only for consistency ... but it's your truck and you know what's what so really it's a non issue.

hiredman77 · 02-18-2011, 05:49 PM

Totally wanted to! I live in the sticks and our Napa only had black 1 gauge. So it was bout all I could get...i supposed they do sell red duct tape

mr7confused · 02-19-2011, 12:08 AM

ok im totally curious...how is this different from connecting two nine volt batteries together? i mean are there issues with the power switching back and forth or double voltage? i dont know this much about DC current haha

hiredman77 · 02-21-2011, 12:03 PM

Its the same but it differs in how you hook them up: series or parallel.

http://www.zbattery.com/Connecting-B...es-or-Parallel

What I did was just made on giant battery. You could take 2 6V and wire them in parallel to make em 12V.

No issues with power switching back and forth as it is a constant 12V with no fluctuations in power. If I were to go parallel I would have ended up with 24V and smoked my wiring.

flandersander · 02-21-2011, 12:48 PM

That's pos to pos and neg to neg right? Seems easy enough.

**ymeski56** · 02-21-2011, 12:57 PM

What size Alternator?

Mechanicalmike08 · 02-21-2011, 02:29 PM

hey man you better be carefull cuz i dont think you installed a battery isolator and if one the batteries has a lower voltage when you shut ur truck off they will discharge each other, unless the batterys came from the same plant at the same day they usually will have a problem unless a isolator is installed, check my thread i started about my dual battery install

djhives · 02-21-2011, 02:53 PM

Wont this stress both of your batteries?

In a parallel circuit each component shares equal intensity.

If you alternator is meant to put out 13.8-14.2 volts when running --lets just average it to 14 volts-- then that means your battery receives a 14 volt charge.

If you place two batteries in parallel this means each battery is only getting a 7 volt charge! True they are only each putting out 7 volts apiece but doesnt the battery have a 'optimal' recharge happiness rating? In other words is a lower charge on each battery damaging the cells in some way?

Or does it act kind of like a trickle charger.

Not knocking yourset-up - I love it in fact! I love anyone who does anything DIFFERENT with their cars - just curious!

hiredman77 · 02-21-2011, 03:34 PM

y: 135 out of a stang.

Mike: no isolator...yet. Not too concerned with it at this point as both batteries are new. The only thing I needed them for at this pt is for the -20 temps we have been having and getting enough juice to crank it over. Also this absorbed a lot of the load that my dual fans pull. Paired together they sit and hold a solid standing 12.6V. What isolator did you go with?

I will eventually go for a switched set up but for now this will do mighty fine.

DJ: as I see it this set up acts (and I always stand to be corrected) not as 2 separate batteries but 1 giant bat. The same could be said of a single batt that if one cell gets weak it pulls down all the others. Its still a 12V set up and gets the same amount of charge just a much longer load capacity and cranking duration due to increased size of batt. Like swapping out a 10 gallon gas tank for a 20 gallon tank...fuel still flows out at the same rate just more of it there.