Necessity of Dual Batteries

[LandCruiserPhil]

FWIW, we have started to test these little micro battery jumper systems like these.

http://shop.antigravitybatteries.com/micro-start-xp-3/ I honestly thought they are BS, but we tried one on our Limo that seems to always have a dead battery. Well it was so dead that you did not even hear a door chime or nothing. Hooked up that little sucker and sure as SH(*$t it started. Did not think it would do it, but it did. Well worth carrying is a battery backup for not a lot of money.

I have started my LC 3 times back to back with NO battery installed

Some like anything else have not had the same results. Mine was part of large Toyota dealership purchase for the service department last Aug and no failures so far.

 

[LandCruiserPhil]

One of the biggest advantages of a dual battery system is protecting the individual batteries so if one system has a drain that depletes the battery you have the second system to recover. EX: you leave the lights on, you can jump from the aux battery, or the fridge door is left open and runs down the aux you still have the main battery to use for starting. No experience with the jump bags but it seems like one more piece of gear to carry and maintain to me.

For my needs one battery is not enough to make it through the night without depleting it more than 50%. With duals I deplete both batteries much less making the batteries last longer and not stress the charging system by one battery being 50% and the other 100%.
Also wiring both batteries in parallel you have no controls to fail. The money spent on a dual battery charging system you can buy a jump bag that can be used for many other things than jumping your LC and have money left over in most cases.

 

[george_tlc]

Even prior to dieing your combined voltage will read low giving you a heads up

Hmm, I've had batteries fail and they just don't hold a charge anymore. The 2nd 'good' battery in that case would make it appear that the pair of batteries were still good, since open circuit voltage would be provided by the 'good' battery.

I prefer to keep my batteries isolated and run fridge etc from one of them. Even in hot climate I've never seen more than 20 amp.hours pulled overnight from an ARB fridge and then solar takes over as the sun kicks in. With 100AH batteries life is good.

Anyhow, as long as you're happy with your setup that's great. Like I wrote, lots of ways to set up a dual battery system and what works for one person may not suit another.

The high current li-ion/poly packs can push some serious current out. Lots of RC type packs can easily push 100 to 200A out safely. They are deceptively high performance/capability for the size

cheers,
george.

 

[LandCruiserPhil]

.......
Anyhow, as long as you're happy with your setup that's great. Like I wrote, lots of ways to set up a dual battery system and what works for one person may not suit another.

........

cheers,
george.

The best take away ▲this▲

Know and understand your needs when you consider dual batteries

 

[rusty_tlc]

Check out my signature and dual battery write up

Basically it's just the signal that activates the warning bulb on the dash if the alternator/regulator is not 'happy'. I splice into it at the fuse panel behind the main battery and feed that to a automotive relay (low current coil) to activate it.

I have a similar scheme on my patrol, but needed to 'invert' the polarity of the signal.

cheers,
george.

Nice trick I'll remember that next time I do an install.

 

[atomicshawn]

The nice thing about the marine switch is self jump start is easy (especially for my wife who has needed to do it while I've been away/out of the country) and the other is if you have a winch since it provides you a way to select which battery (or both) is used to power the winch or not when not in use (no paper clip shenanigans)...

...Benefit of military clamps, you can leave the cables alone and just slip the clamps of the battery.

I've gone a little beyond just Ignition to turn on the solenoid, I use a signal (I call it alternator_good) that fires up ONCE the alternator is running and putting out charge to drive a relay that operates the solenoid. Since the aux does all the aux duties (e.g. fridge, camp lights, ham radio etc) I don't want its discharge state to parallel (via the solenoid) the main battery UNTIL the alternator is putting out charge (i.e. the engine has actually started and running)...

x2 on the military clamps and the switch + wife advantage. Also there is also some measure of comfort for me at the thought of being able to keep the monster power circuits for both winches isolated with ability to connect quickly... effortlessly.

...dual battery system is protecting the individual batteries so if one system has a drain that depletes the battery you have the second system to recover...

A little extra power running the winch and compressor is a nice little advantage too, but from my perspective what rusty is saying here is the whole point.

 

[rusty_tlc]

...

A little extra power running the winch and compressor is a nice little advantage too, but from my perspective what rusty is saying here is the whole point.

I've winched out of Rubicon with a broken differential, off and on winching for half a day. Winching is all about the battery and the 8274 is not an amp miser winch, I had plenty with a Optima Red top in my FJ40. I doubt many people would do that much winching in a single day. I don't have a huge amp hour battery and the FJ40 only puts out 45amps, winching doesn't use as much battery as most seem to think.

 

[DickM]

My "untried" solution to the dual battery dilemma was to install a second alternator in place of the smog pump on the 60 which charges the house battery. This setup, with a pair of jumper cables, seems simple, redundant and reliable. I have no real world experience with it yet as the motor swap is dragging on, but it seemed like a good place to start. (no pun intended )

 

[rusty_tlc]

My "untried" solution to the dual battery dilemma was to install a second alternator in place of the smog pump on the 60 which charges the house battery. This setup, with a pair of jumper cables, seems simple, redundant and reliable. I have no real world experience with it yet as the motor swap is dragging on, but it seemed like a good place to start. (no pun intended )

Google "on board welder" you can rig that second alterantor to be a welder and charge batteries.

 

[DickM]

Google "on board welder" you can rig that second alterantor to be a welder and charge batteries

Just when I thought the list was getting shorter.........

 

[atomicshawn]

Two batteries, two alternators, a manual transmission (I'm assuming is how your 60 is equipped) so you can push start if the starter fails, maybe throw in an spare coil & fuel pump in your tool bag, and a welder to fix everything else. Dang, that 60 will be unstoppable.

 

[JCruse]

To the OP; I'm curious, what were the makes, sizes and ages of your two batteries when the one (Odyssey) failed?

 

[atomicshawn]

The main that failed was an Odyssey 34R-PC1500T. It was purchased new and installed 28 months before failure.

The secondary was also an Odyssey 34R-PC1500T. It was purchased new and installed 17 months before the older main failed. It appears to be healthy, and has since been moved to the main position.

I replaced the failed battery with a new Interstate MT7 34R AGM. Historically I've had good luck with Interstate, but they haven't offered an AGM until recently. I've heard good things about the quality and design of their new line. Time/abuse will tell I suppose...

 

[cruiserpilot]

If your batteries are failing at that fast a rate. I would look for some kind of parasitic electrical draw going on.
Something is drawing down your batteries.

I have a 60 wagon, wiring is 30 yrs old. I run 2 batteries, 2 alternators,
2 winches, trying to keep accessories on one side, factory truck stuff on the other. I had local electrical shop spend
a few hours cleaning up my starting/ignition wiring, installed separate relay to starter, and in the end I hope to have
eliminated most of the lose ends to my system. Install battery disconnects to the neg side when the truck is sitting,
and I have isolator switches to accessories so when I just running around they have no power. Like I need power to my
winch when grocery shopping, or power to dual 130 W driving lights around town.
Just offering my idea, I think you should easily get 4-6 yrs or more out of todays batteries. J

 

[Mr Cimarron]

I'm pretty much running the same setup as LandCruiserPhil. Two batteries run in parallel just like on the factory Cummins. I've thought about isolating one but I pretty easily talk myself out of it. I do leave my truck plugged in with a NOCO 2 bank charger when in the garage. Solar charged when its outside. Fridge running 24/7. For the price of separating two batteries you can get a nice 100W solar setup. Last week while changing the oil I unknowingly knocked the alternator connector loose. Tach wasn't working and alternator wasn't charging the battery. I noticed it when we drove off into town and at first I thought it was only the tach not working but noticed the volt gauge a bit low. Solar kept the battery charged good enough that we had no problem starting the truck several times while running errands around town. I do like the idea of having a backup battery for jump starting but it's just way down on the list of things to do.

 

[atomicshawn]

If your batteries are failing at that fast a rate. I would look for some kind of parasitic electrical draw going on.
Something is drawing down your batteries.

I have a 60 wagon, wiring is 30 yrs old. I run 2 batteries, 2 alternators,
2 winches, trying to keep accessories on one side, factory truck stuff on the other. I had local electrical shop spend
a few hours cleaning up my starting/ignition wiring, installed separate relay to starter, and in the end I hope to have
eliminated most of the lose ends to my system. Install battery disconnects to the neg side when the truck is sitting,
and I have isolator switches to accessories so when I just running around they have no power. Like I need power to my
winch when grocery shopping, or power to dual 130 W driving lights around town.
Just offering my idea, I think you should easily get 4-6 yrs or more out of todays batteries. J

For sure, a battery should last 4-6 years plus. I had a conventional wet cell (Interstate) in my first 4x that lived to be over 8 years. And yeah, the premature failure of the Odyssey is suspect, and I appreciate throwing out ideas. The only argument I have about a possible parasitic draw or any other charging system failure is lack of any other symptoms. The 60s been the DD for about a year now, and the 80 will sit up to a week or more. Never random dead batteries. Not even a slow start. Starts strong every time. Well... except for that one time in the middle of freakin nowhere. And it did crank slow on the first day of that trip, and got progressively worse each day until it totally flat lined and wouldn't hold a charge day 3. But things were fine on the trip after switching to the secondary, and it continues to be asymptomatic since swapping a new battery into the system. I've had no problems since the failure in the desert, and it's been about six weeks. So yeah, pretty sure it was just a junk battery.

Your 60 sounds sweet! Where might one find more info? Got a write up on it anywhere?

 

[NLXTACY]

My setup seems to be completely different then everyone else's. I have dual batteries running a HellRoaring Isolator but I designed my setup so that my main battery does ONE thing, start the truck. Everything else goes off the AUX. No combiner, its always isolated. Its a crazy rare day if the main battery dies. But if it does then I just jump myself using my own cable setup. If the AUX dies I could care less because as long as I can start the truck I am golden. The alt can take care of the rest. You can see what I did in my sig below.

Edit: there is also an 80amp Blue Sea circuit breaker that I have for the main power. I use that as a theft deterrent and also if the truck will be sitting for a long time to keep battery from parasitic leaks which I know I have at least one of. But I also have a 15A fuse that I jumper between both sides of the circuit breaker to make sure the ECM and radio always have power.

 

[canman]

My setup seems to be completely different then everyone else's. I have dual batteries running a HellRoaring Isolator but I designed my setup so that my main battery does ONE thing, start the truck. Everything else goes off the AUX. No combiner, its always isolated. Its a crazy rare day if the main battery dies. But if it does then I just jump myself using my own cable setup. If the AUX dies I could care less because as long as I can start the truck I am golden. The alt can take care of the rest. You can see what I did in my sig below.

Edit: there is also an 80amp Blue Sea circuit breaker that I have for the main power. I use that as a theft deterrent and also if the truck will be sitting for a long time to keep battery from parasitic leaks which I know I have at least one of. But I also have a 15A fuse that I jumper between both sides of the circuit breaker to make sure the ECM and radio always have power.

I did this when I installed mine, but I used a Surepower isolator.

 

[cruiserpilot]

My setup seems to be completely different then everyone else's. I have dual batteries running a HellRoaring Isolator but I designed my setup so that my main battery does ONE thing, start the truck. Everything else goes off the AUX. No combiner, its always isolated. Its a crazy rare day if the main battery dies. But if it does then I just jump myself using my own cable setup. If the AUX dies I could care less because as long as I can start the truck I am golden. The alt can take care of the rest. You can see what I did in my sig below.

Edit: there is also an 80amp Blue Sea circuit breaker that I have for the main power. I use that as a theft deterrent and also if the truck will be sitting for a long time to keep battery from parasitic leaks which I know I have at least one of. But I also have a 15A fuse that I jumper between both sides of the circuit breaker to make sure the ECM and radio always have power.

My two batteries are separated always, except I use a start relay solenoid for starting only as it's a 12HT and doesn't seem to like starting
on one battery. Mind, I haven't tried to use single battery start since we got in there and cleaned it all up. I looked at your set up when I put mine all together.
Shawn, I should put up some pics but keep getting caught up in other stuff. Someday soon. J

 

[LandCruiserPhil]

Phil,
so if you have your 2 batteries permanently wired in parallel, how do you know when one has died?

cheers,
george.

Just had one of my batteries go bad in my parallel set up. The problem was very easy to ID. When I would stop my batteries would read full but when I would return after a short time my voltage was read 12.0-12.1. A load test showed a bad battery replace with another 4 year old $60 Optima blem. All good to go with voltage readings back to normal.