So I just bought a 2012 6.2 250. I have to say that I am NOT terribly impressed with the factory battery cables. I plan to add a separate house battery in the back, as well as a front winch in the near future. I'd like to put a couple of military terminals on the battery to simplify the hook up, and take advantage of the opportunity to upgrade to fatter cables, too. Ideally, I'd like to have the cables made up and ready to go before I start disassembling the system. I was wondering if any of you could give me some idea of what kind of lengths I will need for the starter and ground cables?

 

I would leave the factory ones on there. If it ain't broke, don't fix it. You should only need a decent charge wire to the aux battery. Are you going to use a isolator for that? And it will run the winch?

 

The winch is going to need 2/0 cables to the battery, and I really don't see any way of doing that with the stock factory cables on it.


Regards
John

 

It would be better to run the 2/0 battery cables to the aux battery. That way you would not be running your main starting batteries down with the winch.

The aux battery would be charged by the truck's alternator through a battery isolator. The isloator lets the truck's alternator charge the aux battery, but the rest of the truck does not "see" the aux battery and the aux battery does not "see" the rest of the truck and it's batteries. The wire going from the isloator to the aux battery probably only needs to be 8 or 6 gauge. It's only job is to charge the winch aux battery as you are driving down the road.

 

I guess a little more clarification is needed.


The plan is to put a cap on the back for a sleeping area. There will be an AGM house battery back there to provide power for a powered roof vent and a 12 volt Engle compressor fridge, as well as powering a laptop, etc.


The house battery and engine battery will be tied together with a continuous duty solenoid when the engine is running, which I think is a far better set up than diode isolators which drop the voltage. I was thinking 2 gauge wire between them to minimize voltage drop and maximize amperage over that distance.


The winch will actually be able to pull power from both batteries as well as the alternator when the engine is running. Plus, I believe I can wire it so I can throw a manual switch to energize the solenoid, and thus use the house battery to jump start the engine if the engine battery is low.


And it will be cheaper to run 2/0 wires to the engine battery than all the way back to the house battery.


Regards
John

 

I would run a smaller wire to the house battery and put a circuit breaker in the line. If you run that large cable, and you happen to run the house battery really low(it should be a deep cycle type) when you throw that continuous duty relay on, there is nothing to control the current, the two truck batteries are going to try and charge the house battery with as much current as possible, which will be alot since there are two and you have hooked that large wire inbetween. I suspect the solenoid would burn out, or the house battery may overheat and explode.

You really should not charge the house battery at a vary high rate. I would run a 10 gauge wire and have a 30 amp circuit breaker in the line. If the battery is really low the 10 gauge wire will help hold it down some, and if it gets out of hand the 30 amp circuit breaker will trip, cool off, apply power again and if it needs to, trip again till it gradually brings the house battery up closer to a full charge.

If you want something fancier, look at some marine sites, they have "smart relays" now that can control the charging without the voltage drop.

I don't think a deep cycle battery is going to do much to help start a large diesel engine. I would not pursue that.

 

Franklin, I really appreciate your taking the time to respond to my question.


A couple of things you don't seem to be aware of.


Lifeline AGM batteries are true deep cycle batteries. Nevertheless, they also have decent cold cranking amp ratings. The Group 30 model has 150 amp hours and is rated for 700 CCA. And Lifeline says they can take as many amps as you can throw at them when you are recharging - several hundred will not hurt them. In point of fact, Lifeline says that too little a charge rate is actually detrimental to their longevity.


The problem with some of those fancy marine ACRs, like the ones that Blue Sea Marine sells, is that they can be fooled by solar panels. They will keep the two batteries connected together if EITHER battery is higher than 12.7 volts.


Your point about the circuit breaker was excellent advice. I had been planning to use 100 amp fuses on each end, but I may now rethink that and consider a circuit breaker instead.


Oh, and I don't have a diesel, I have the 6.2 gas engine.


Thanks again for your comments.


Regards
John

 

I would still be afraid to charge a battery at a very high rate, but if they say it's ok then they ought to know what their batteries are designed for. If you use a circuit breaker, then you can design the highest rate of charge it will see with that. And of course match the wire size to handle the worst case.