May Ng

what do you mean wiring the batteries cables """""""""" fduran la miarda I have a 2007 dodoge with a 5.9 and jan 10 I replaced the batteries so far so good this week end I went to san diego and I boil over the right side and the left was hot so I replaced the alternator and 2 new batteries I drove home and what again blow the batteries again vo on the left was 14.61 right side was 18.54 volts please help me toooo

Lary Ellis (Top)

To understand the problem you need to understand how the charging system works.

The alternator senses the charged state of the batteries via a temperature sensor under the driver side battery, this tells the system how much voltage to apply in order to bring the battery's up to full charge.

The Alternator feeds the passenger side battery and from there the charge heads over to the drivers side via the battery crossover cable, thus tying the two batteries together.

The downside to this set up is if there is a dirty cable end, a bad cross over cable, a faulty temperature sensor under the drivers side battery or bad ground it will effectively cook the passenger side battery by overcharging in an attempt to charge the drivers side battery.

Common cures are simply finding the bad cable or connection and fixing it. The cables often look fine but can be corroded under the insulation out of view...the same can be found on the connections at the alternator, or the ground wires.

I would first check all cables and wires to be sure they are not corroded, then do the same for every connection or wire leaving the alternator. I would also check the temp sender under the drivers side battery if it is faulty it will also cause the system to over charge.

No short cuts here, you need to check and replace or clean as necessary to ensure you have good connections.

PWong

ALL the electrical loads (except the grid heater) on the truck were hooked up to the driver side battery.
At this time of the season the ECM's target system voltage would be 14.8-15V on the driver side battery.
Because of the restriction of charging current flow to the driver side battery, the driver side battery never got charged up to the target voltage.
ECM would keep pushing up the charging voltage until it sees the target voltage.

PWong

Should have the SAME readings, NO VOLTAGE DROP across the two positive posts of the two batteries.

May Ng

Pwong you are corect battery cable from right to left not making contact or interminnt resulting in overcharging the right side thanks