Anybody ever thought of adding a third battery to the system? Being that the OEM stater is so demanding, I figure I could mount a battery on the frame rail and run the cables up to the other battery on the passanger side. Anybody tried this?

I just happen to have an extra Interstate MegaTron 1000ca laying around with nothing to put it in. Hate for it to go bad from sitting around.

I think 2 good batteries and good connections/wires is more than enough. Many have just used 1 with ok results.

My truck usually starts within seconds on the starter. If you have long cranks on a DS IP truck you have other problems.

Not sure on mech IP's but expect 2 batteries are also more than adequate in a good operating truck.

I would only do a 3rd battery in really hot or cold climates ( I am talking extremes).

2 batteries are better than 1, dunno 3 might even the odds that a cell might go bad and drain other batteries instead of making truck more reliable.

Unless you're running a winch or another accessory that sucks up a lot of electricity, you will not see improved cranking simply by adding a third battery.

If you've got slow cranking with 2 new matched batteries, you've probably got dirty connections at the grounds and at the starter.

Upgrading the cables will do much more than adding a third battery. Replace all cables with welding leads and you will see an improvement.

Good way to put extra strain on alternator and hurt fuel economy.

Ditto alternator issues... batteries put a demand on the charging system. Adding accessory loads to the mix, now you'll need more power from the alternator, or a second alternator - now you've really opened a can of worms.

Actually using the alternator to charge the batteries adds a load, but if they are already charged there is no issue. Besides the alternator is NOT there to charge the batteries only maintain them and run the vehicle's electronics. And because an alternator only provides the amount of power as is needed, if your batteries are charged, you wont notice a MPG change. ;) I can speak with certainty on this issue as I installed a 190amp HO alternator into my 4runner with its 181ci v6 on 2 ultra deepcycle batteries. MPG change? Zilch.

But in any event getting an Ohio Generator 350 amp alt would provide MORE than enough current. ;)

I do run a good sized amp for my CB which requires 50 amps. I have 1/0 wire running to it from one of the batteries. I also have a winch I use on my tag along trailer that I use from time to time, but neither of which are used at the same time nor seem to load the engine to any extreme. The winch I use is fairly small (3000 lb) but when I do upgrade it one day, I know I'll need the extra amps. I've already looked into the brackets neccessary for a dual alternator setup from the local GM dealership, probably in the $100 range, minus the alternator.

Other than the glow plugs being wore out on my engine, it turns over fine with the current batteries. Just takes a few revolutions for it to fire up.

I don't want a third battery, but I would love to run group 31 comercial batteries aka real truck / tractor batteries. I need to spend some time with a tape measure because I need two new batteries.

Carey

Has anyone ever dedicated one battery to house and the other to starter, with both being charged via a battery combiner (Wests Marine)? This would solve the problem of dissimilar batteries, and one dead cell killing both batteries. The voltage of the entire system wouldn't drop on startup. This might solve the Sol-D problem.

Has anyone ever dedicated one battery to house and the other to starter, with both being charged via a battery combiner (Wests Marine)? This would solve the problem of dissimilar batteries, and one dead cell killing both batteries. The voltage of the entire system wouldn't drop on startup. This might solve the Sol-D problem.

No one's done it to my knowledge on this forum however you could probably do it much cheaper than a "battery combiner" using a starter solenoid to parallel the batteries when the vehicle was running. At shut down the solenoid would open thus keeping the batteries separate with the engine off.

One side of the solenoid's coil goes to ground, the other to your vehicles ACC circuit (fused of course at 10amps.) Now on the wire that connects the two battery's + terminal you put the solenoids in so that interrupts it. (using the main terminals of the solenoid).

If amperage is an issue just run 4 starter solenoids in parallel! ;)

http://www.westmarine.com/webapp/wcs/stores/servlet/producte/10001/-1/10001/223149/0/0/battery%20combiner/All_2/mode+matchallpartial/0/0 This is the kind of thing I'm talking about. $92.

Yup just a big fancy solenoid!

I don't want a third battery, but I would love to run group 31 comercial batteries aka real truck / tractor batteries. I need to spend some time with a tape measure because I need two new batteries.

Carey

The batteries in our semi's at work are only 850ca, of course there's 4 of them though. Our previous KW's we had only had 3 - 850's in 'em. Our newest '07 (pre-emission) trucks use the new Denzo gear-reduced starters, so we really don't need 4 batteries any more.


Way I see it, if 2550ca will crank over a C15 in sub-freezing temps, dual 1000ca (2000ca) in my truck should crank over a 6.5. I'd still like to have that extra 1000ca for reserve. :D