I haven't driven my '97 PSD for 3 days, this AM once again barely enough juice to activate the starter solenoid. Once again disconnected the batterys and checked for draw w/analog volt meter and it registared about 1/4-1/2 volt.

Pulled the batterys and had them checked and passenger side was bad, drivers side was good but 31/2 yrs old. Replaced them both.

Question:

Will one bad battery drag the other down? Does a diesel engine need both batterys to start the engine?

This dead battery thing is driving me nuts. In dash gauge indicates that the system is charging.

Roger

 

Good questions Roger. I have wondered about that as well. I replaced both batteries this past year just because.

I think, and others will correct me if I'm wrong, two batteries are needed because of the compression ratio of the diesel engine. Two batteries are needed to turn over the starter and overcome the compression.

That's my .02 worth.

 

Yes one battery will drag the other down, and yes ID moose it takes a lot of juice to to crank these heavy, higher compression engines, but most epecially to crank the engine after cycling the GP's. The GP's suck a lot of Bat power for 10-20 seconds depending on temp then you have to crank this big old engine that is a lot of draw.

kawa if one batt was bad and down a 10 volts the other batt is going to try and keep it up at 12 so the one battery can drain the other battery dead. Also a bad battery can cause the voltage regulator to burn out of your alternator if left to long. (on our trucks it would more likely take two bad batteries for that)

 

Kawa, Yes always replace both Batteries. Bkcowboss hit it right on the head. It will save you a head ach down the road. Good luck.

 

Kawa, wouldn't hurt to get charging system checked, you can have voltage on guage but not much amprage. You can get inductive amp meters that you just lay on the heavy batt. feed wire and it will read amp. I haven't seen them at any stores but a tool dealer should have them. It's been awhile but I think $50or less,very handy though

 

I think that all of you guys are absolutly correct. CowBoss, the bad battery was registering 10 volts, just like you said. I have a shunt Amp meter and at idol it reads, (I foreget, but I think) around 20 amps.

I charged both new batterys and connected them this AM and everything not only worked but worked faster, louder but with more gusto.

Thanks for all of your replys, advise and comments they were and are greatly appreciated.

Roger

 

i was told by a diesel mecanic that its 12volts with 12volt assist is the reason for 2 batteries

 

I don't know what he is talking about ,it is twelve volts period. The batteries are connected on the pass.side terminal.Power is drawn from both equally not one backing the other.

 

The batteries are hooked up in parallel. When one gets drained they both drain at the same time. Kind of like having one big battery.

 

Thank you! If they were hooked up in series then you would have 24 volts and fry everything electric in the truck that was turned on.

 

the reason for 2 batteries is the glow plugs, the truck will start fine on one battery, the second merely gives more reserve time,

 

One question comes to my mind: if you recharge only the pass. side bat, you are charging also the drivers side? or you have to recharge one by one.?

 

if they are hooked up then both will be charged but its best to remove the terminals and charge the batts seperate

 

As usual, cOOn, mercy.