Dual Battery hookup?

seafarinman · 04-12-2003, 10:14 AM

I was wondering what would be the best way to hook up a dual battery setup. I have a pair of Optima red tops with one in the bed of my truck in a marine battery box. I have seen the isolators, so would I just disconnect the alternator lead from the battery and connect it to the isolator input, and run separate leads to each battery? If I did this, what gauge would be required? Also where can I get those heavy duty grommets for running the cable through the floor of my bed? Has anyone done this?

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Salue · 04-12-2003, 10:24 AM

When I had the dual battery setup on my '87, I followed Joe Chacon's write-up. It seems that his site is no longer available, at least I can't get to it. But, the way he did it and the way I followed did not have an isolator. So it was just two batteries wired in parallel with a main switch between the Positive wires so that when I didn't want to drain from the main battery, I just turned the switch so that it wouldn't drain from it and only drain from the accessory battery. Then when I wanted to recharge the acc. battery, I'd turn the switch so that it would get current when driving and would recharge both batteries. I don't think this is the best way to do it but it was the easiest. I know that if you do it this way, the less charged battery would take some charge from the higher charged battery until they were about even. I think you going the isolator route is better. I would like to do this to my '94, so keep us posted. Have you considered putting the extra battery in the engine? I'm considering doing this by doing the intake mod in the tech section but altering it a little so that I would have a spot to put the second battery where the air filter currentl lies.

Whatever you do, please take pics.

Salue

Cebby · 04-12-2003, 10:32 AM

For an isolator, do what you said, run the alternator wire to the isolator. Then run wire to each battery. 4 Ga. should be more than adequate. If you still have your stock alt that is. If you have a hi-amp model, the alt to iso wire might want to be 2Ga or 1/0. Be sure to fuse the wires with the appropriate value fuses.

Here's a link for
snap in bushings.

These are what I use when passing through metal. They make a ton of different sizes. The snap right in, then I hit the wire with a little silly cone to make it watertight.

MNBOY · 04-12-2003, 12:36 PM

I'm not sure it is the best way, but I'll explain how I have mine set up. I have a cap on my truck with interior lights and a 12v plug for running a small TV or laptop. (I live in my truck for days at a time while in Moab or similar places) The lights and such are run off a second battery mounted in the bed, which is connected to my main truck battery with 2 ga. battery cable and a high voltage on/off switch. This way I can turn the switch to on if I want some extra power while running the winch, but it stays separate from the starting battery. The secret to keeping the second battery charged is a little device called a battery combiner. I work in the marine industry, and these are pretty common on larger boats that run multiple batteries. The combiner installs between the two batteries, and only charges the second battery after the first is back up to a certain voltage, meaning your starting battery always has enough charge to start the truck. It's kind of like an isolator, but the isolators have a large voltage drop that prevents the alternator from ever fully charging either battery. I think the only place to get the battery combiners is at a marine store called West Marine, but they have a reasonably priced model that works great with stock alternators.

partszar · 04-12-2003, 03:46 PM

I'm not sure if this is what your thinking about but I saved the picture for reference material incase I wanted to put a aux. battery in my bed. I have a cap on my truck.

jruz · 04-12-2003, 07:56 PM

One other suggestion...for the extra battery, use a deep cycle battery such as the Optima Yellow top. That way, when you run it 'til its empty (watching TV or whatever you do), it will come back alive without a problem. Frequently draining a Red top over time will kill it a lot faster.

Jim

Cebby · 04-12-2003, 08:10 PM

Quote:

Originally posted by partszar
I'm not sure if this is what your thinking about but I saved the picture for reference material incase I wanted to put a aux. battery in my bed. I have a cap on my truck.

Isn't that diagram the one that was blowing fuses? I remember that thread, let me see if I can find it...

Cebby · 04-12-2003, 08:13 PM

Here's the thread.

914runner · 04-12-2003, 10:21 PM

I am thinking of adding a second battery for some acc. I will be adding later on. Would someone please tell me what parts I would need other than a second battery and wire(not sure what guage though)?
Thanks

seafarinman · 04-12-2003, 10:34 PM

Thanks for all of the info. I am planning on cleaning up the wire "forest" on the + terminal of my battery, with only the winch, stereo, and the original circuits running from the main battery. I want to run all of the accessories from the "rear" battery- Off-road lights, 800W/1100W inverter, bed mounted outdoor 115V receptacle, 200W tripod worklight, canopy lighting, and other accessories, etc. I think that I will look into installing the inverter. Does it need to be close to the alternator/main battery? I was looking under the hood and space is awful scarce there! Thanks again everyone.

codlord · 04-13-2003, 02:01 AM

Regarding the "diagram that was blowing fuses" that was mine and it certainly was blowing fuses, however I have since sorted the problem (sorry forgot to update the thread). I have updated details on my site:
http://www.showmesome.info/hilux/workshop/battery.htm

Basically I used 35 amp wire and a 35amp fused relay and all is fine now (although I would have my doubts wether the system would cope with the draw from a winch or something like that but thats not an issue for me).

I read that you should NOT use very heavy guage wire between the two batteries (in this sort of relay-based system) becuase this can allow a large flow of electricity between a discharged battery and a charged battery - better to use smaller wire so that you get a trickle charge.

Cebby · 04-13-2003, 05:12 AM

Quote:

Originally posted by codlord
Basically I used 35 amp wire and a 35amp fused relay and all is fine now (although I would have my doubts wether the system would cope with the draw from a winch or something like that but thats not an issue for me).

I read that you should NOT use very heavy guage wire between the two batteries (in this sort of relay-based system) becuase this can allow a large flow of electricity between a discharged battery and a charged battery - better to use smaller wire so that you get a trickle charge.

If Rome goes the isolator route, it will be a non issue. Thanks for the update.

04-12-2003, 10:24 AM	#2 (permalink)
Salue Registered User Join Date: May 2002 Location: Washington Posts: 309	When I had the dual battery setup on my '87, I followed Joe Chacon's write-up. It seems that his site is no longer available, at least I can't get to it. But, the way he did it and the way I followed did not have an isolator. So it was just two batteries wired in parallel with a main switch between the Positive wires so that when I didn't want to drain from the main battery, I just turned the switch so that it wouldn't drain from it and only drain from the accessory battery. Then when I wanted to recharge the acc. battery, I'd turn the switch so that it would get current when driving and would recharge both batteries. I don't think this is the best way to do it but it was the easiest. I know that if you do it this way, the less charged battery would take some charge from the higher charged battery until they were about even. I think you going the isolator route is better. I would like to do this to my '94, so keep us posted. Have you considered putting the extra battery in the engine? I'm considering doing this by doing the intake mod in the tech section but altering it a little so that I would have a spot to put the second battery where the air filter currentl lies. Whatever you do, please take pics. Salue __________________ '99 4runner SC '97 Land Cruiser '87 turbo 4runner...Sold '91 4runner...Sold '94 4runner...Sold

04-12-2003, 10:32 AM	#3 (permalink)
Cebby Contributing Member Join Date: Sep 2002 Location: Pittsburgh, PA Posts: 11,246	For an isolator, do what you said, run the alternator wire to the isolator. Then run wire to each battery. 4 Ga. should be more than adequate. If you still have your stock alt that is. If you have a hi-amp model, the alt to iso wire might want to be 2Ga or 1/0. Be sure to fuse the wires with the appropriate value fuses. Here's a link for snap in bushings. These are what I use when passing through metal. They make a ton of different sizes. The snap right in, then I hit the wire with a little silly cone to make it watertight. __________________ UZswap.com A site dedicated to sharing info for swapping the Toyota/ Lexus UZ (V8) engines into Toyota Trucks and 4Runners. My 4Runner 1993 4Runner, 1UZ (V8) auto dual ultimate crawler, double locked, 35's on beadlocked SR5 alloys, low lift, hacked fenders, tubbed firewall, custom armor TOOLandFAB.com A discussion forum dedicated to tools, fabrication & workshops. See my JD2 Bender Hydro Conversion BUY THIS 2008 CALENDAR

04-12-2003, 03:46 PM	#5 (permalink)
partszar Contributing Member Join Date: Feb 2003 Location: Deltona FL Posts: 72	I'm not sure if this is what your thinking about but I saved the picture for reference material incase I wanted to put a aux. battery in my bed. I have a cap on my truck. Attached Thumbnails __________________ Paul "We sleep soundly in our beds because rough men stand ready in the night to vist violence on those who would do us harm" 85 SR5 EFI M/T 4wd custom 2.25in exhaust rear true-trac diff 31x10.5x15 winston M/T on 15x7 alloys Front Range Off-Road Severe use front frame brace Front Range Off-Road front bumper OME suspension INSTALLED!! NWOR greasable spring shackles custom rear bumper w/spare tire carrier Warn 8000 winch TRD Level 1 cam

04-12-2003, 08:13 PM	#8 (permalink)
Cebby Contributing Member Join Date: Sep 2002 Location: Pittsburgh, PA Posts: 11,246	Here's the thread. __________________ UZswap.com A site dedicated to sharing info for swapping the Toyota/ Lexus UZ (V8) engines into Toyota Trucks and 4Runners. My 4Runner 1993 4Runner, 1UZ (V8) auto dual ultimate crawler, double locked, 35's on beadlocked SR5 alloys, low lift, hacked fenders, tubbed firewall, custom armor TOOLandFAB.com A discussion forum dedicated to tools, fabrication & workshops. See my JD2 Bender Hydro Conversion BUY THIS 2008 CALENDAR

04-12-2003, 10:21 PM	#9 (permalink)
914runner Contributing Member Join Date: Oct 2002 Location: Tigard, Oregon Posts: 2,083	I am thinking of adding a second battery for some acc. I will be adding later on. Would someone please tell me what parts I would need other than a second battery and wire(not sure what guage though)? Thanks __________________ 1997 Toyota 4Runner, 3.4L (5VZ-FE), 5-Speed (R150F), 4WD, 4.10's, 33's 1998 Toyota 4Runner, 3.4L (5VZ-FE), 5-Speed (R150F), 4WD, 4.10's, 33's 1991 Toyota 4Runner 4 Door, 3.4l (5VZ-FE), 5-Speed (R150F), 4WD, 32's, 4.10's

04-12-2003, 12:36 PM	#4 (permalink)
MNBOY Contributing Member Join Date: Apr 2003 Location: Seattle, WA Posts: 786	I'm not sure it is the best way, but I'll explain how I have mine set up. I have a cap on my truck with interior lights and a 12v plug for running a small TV or laptop. (I live in my truck for days at a time while in Moab or similar places) The lights and such are run off a second battery mounted in the bed, which is connected to my main truck battery with 2 ga. battery cable and a high voltage on/off switch. This way I can turn the switch to on if I want some extra power while running the winch, but it stays separate from the starting battery. The secret to keeping the second battery charged is a little device called a battery combiner. I work in the marine industry, and these are pretty common on larger boats that run multiple batteries. The combiner installs between the two batteries, and only charges the second battery after the first is back up to a certain voltage, meaning your starting battery always has enough charge to start the truck. It's kind of like an isolator, but the isolators have a large voltage drop that prevents the alternator from ever fully charging either battery. I think the only place to get the battery combiners is at a marine store called West Marine, but they have a reasonably priced model that works great with stock alternators.

04-12-2003, 07:56 PM	#6 (permalink)
jruz Guest Join Date: Oct 2002 Location: North Bend, WA Posts: 1,093	One other suggestion...for the extra battery, use a deep cycle battery such as the Optima Yellow top. That way, when you run it 'til its empty (watching TV or whatever you do), it will come back alive without a problem. Frequently draining a Red top over time will kill it a lot faster. Jim

04-12-2003, 10:34 PM	#10 (permalink)
seafarinman Registered User Join Date: Jul 2002 Location: Kitsap County WA Posts: 978	Thanks for all of the info. I am planning on cleaning up the wire "forest" on the + terminal of my battery, with only the winch, stereo, and the original circuits running from the main battery. I want to run all of the accessories from the "rear" battery- Off-road lights, 800W/1100W inverter, bed mounted outdoor 115V receptacle, 200W tripod worklight, canopy lighting, and other accessories, etc. I think that I will look into installing the inverter. Does it need to be close to the alternator/main battery? I was looking under the hood and space is awful scarce there! Thanks again everyone. __________________ DEPLOYED Again! 1994 SAS 2RZ/R151F=244:1! 1988 Toyota 4Runner SR5

04-13-2003, 02:01 AM	#11 (permalink)
codlord Registered User Join Date: Mar 2003 Location: UK Posts: 26	Regarding the "diagram that was blowing fuses" that was mine and it certainly was blowing fuses, however I have since sorted the problem (sorry forgot to update the thread). I have updated details on my site: http://www.showmesome.info/hilux/workshop/battery.htm Basically I used 35 amp wire and a 35amp fused relay and all is fine now (although I would have my doubts wether the system would cope with the draw from a winch or something like that but thats not an issue for me). I read that you should NOT use very heavy guage wire between the two batteries (in this sort of relay-based system) becuase this can allow a large flow of electricity between a discharged battery and a charged battery - better to use smaller wire so that you get a trickle charge. __________________ Hilux Surfing - The site dedicated to the Toyota Hilux Surf/4Runner

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