T&T: Battery Charging Questions

[John Wix]

I am charging 4 Trojan T-105 6- volt batteries connected in the usual 
serial/parallel configuration to result in 12 volts.  While under way, they 
are being charged by a Balmar 621-100 alternator with ASR-5 regulator. By 
generator or shore power, they are charged by a Xantrex MS-2000 inverter 
charger.  Both methods of charging use a battery temperature sensor 
connected to the negative post in the middle of the 2 pair (per installation 
instructions).

If the batteries are depleted enough to result in bulk phase charging more 
than about 15 minutes, both battery temp sensors report temperatures rising 
to the mid-120 degrees F.  The regulator cuts off charging around 122 
degrees and lets things cool off.  After eight hours of running, I end up 
with a net zero charge. I will be experimenting with a different belt load 
setting on the regulator to see if I can reign in the charge rate.

The Xantrex charger will let temperatures rise to 150 degrees if I dont 
intervene (this happens if batteries are depleted to less than about 65%).  
I have verified these temps with an infrared thermometer.  However, the 
outside negative post (connected to the common round bus) shows temperatures 
substantially less  in the order of 20 to 30 degrees less.

Questions:
Are these temps in the expected range?
Why is the internal negative so much hotter than the outside?

Thanks in advance for any insight,

John Wix
Monk 36
Safe Return

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