Chasis Batteries

[Jon Wehrenberg]

What started this thread was a question regarding chassis batteries. That in turn prompted a discussion relative to heat because there is no heat compensation on the alternator or any way to control ambient temps.

I would be very interested in having someone whose AGM or Gel Cell batteries are located in an enclosed compartment rig up some way to measure and record temperatures, especially in the summer in the southwest. When I was involved with Interstate and their new Gel Cell batteries the temps in the engine area where my battery racks were exceeded 130 degrees F on a 60 degree day. This despite the fact the door was slotted, the floor was open and the bus movement caused a lot of air flow.

Despite temperature compensation I would expect battery compartments not vented to the atmosphere such as those enclosed for aesthetic purposes or hidden from view on warm days are also getting warm. What I don't know is the definition of warm. I do know 130 was unacceptable.

[truk4u]

Ben,

I obtained the Lifeline account for POG and can assure you there was never any mention of a promotional price. The bottom line, they just dumped POG to save the advertising money thinking we would all just continue to buy at whatever the going price just happened to be.

[phorner]

Maybe one of those wireless temperature transmitters could be stashed somewhere in an enclosed area to monitor the temperatures. I have one in my inverter bay and the batteries seem to last about a year or so.

Mine is an Oregon Scientific indoor/outdoor thermometer that will accept up to 3 remote temperature transmitters, but I'm sure there must be others as well.

[Jon Wehrenberg]

Interesting Paul......When I got our coach it had a lead/acid battery in the electrical bay for generator start. I did not want acid fumes vented where the PLCs and all the circuit breakers were so I switched it out to an Optima which I believe is an AGM.

At 5 years of age I replaced it with another one, and I still use the old one as the battery for my trackhoe.

I don't know what temps are present in that compartment, but whatever they are the battery life was not compromised. The battery however is not contained in a case, but sits open. I removed the case when I removed the lead/acid battery.

[Mark3101]

Ben,

I obtained the Lifeline account for POG and can assure you there was never any mention of a promotional price. The bottom line, they just dumped POG to save the advertising money thinking we would all just continue to buy at whatever the going price just happened to be.

FWIW, I got all 6 of my 8-D's replaced at Millennium last month for $629.00 each.

[jack14r]

I bought 6-8D's last June on the POG deal from Lifeline and they were $434.16 each.Does anyone know what dealer cost is today?

[jack14r]

I put a remote thermometer in the chassis battery area yesterday and drove home about 2.5 hours yesterday,the outside temperature was 75-80 and the highest recorded on the remote was 115 degrees.I would think that if the ambient was 20 degrees higher the battery area would also be 20 degrees higher,so 130 degrees would not be unusual.

[Jon Wehrenberg]

Jack,

When we were doing the testing on mine they were early designs. AGM was not even on the market. From what I have read the least affected by higher ambient temps was lead acid, followed by gel and then AGM. No battery is completely tolerant of heat, just that some are less affected.

Before inverters and chargers with temperature compensation batteries could be ruined by thermal runaway, in which as the battery got hotter, it absorbed more charging current, which in turn made it hotter, which caused it to absorb more charging current.

I have no knowledge of this, but if I were to guess the batteries are more tolerant of heat because of the temperature compensation in the inverters, BUT....there is no compensation for higher temps when runninng down the highway and charging via the alternator. I think the reason for the higher than ambient temps you saw may be in part due to heat radiating off the road. A highway sitting in the sun on a warm day can radiate some high temperatures.

[Woody]

What is the proper voltage indication while underway?

I noted today 26.4V

[Jon Wehrenberg]

I presume that is the chassis voltage and I believe 27.7 or thereabouts is the set point for the voltage regulator.

That voltage will vary depending on loads (such as OTR)

The small analog gauge I have is reasonably accurate, but if in question I always check the voltages at the battery terminals with a digital multi-tester just to get a value not influenced by potentially bad connections or long wire runs.