Chassis Battery Charging

[cmillsap]

I was getting the bus ready today to take it to the upholstery shop early in the morning so they could start work on upgrading the fabric on our sofa, valances and dinette stools. It had been about ten days since I had started it to charge up the chassis batteries. I went to start it and all it would do was weakly try to turn over the big DD60.

The damn chassis batteries were dead! Obviously, I wasn’t going anywhere in the morning unless I figured out how to solve the issue. Now I don’t have a 24V battery charger and since the batteries were a little over two years old, I decided it was a good time to replace them. I didn’t bother to check each battery as several people had told me that chassis batteries in a Prevost average about a two - year lifespan. So I went to NAPA and bought four 31 series sealed lead acid batteries to replace them. I paid $122 each for four NAPA Commercial Series batteries and installed them in about an hour.

Now if this had happened with either of my three prior Wanderlodges, I would have not been stranded due to a good electrical system design. One thing I really liked about the Wanderlodge was that both the chassis and house battery system was 12V. This provided the ability to tie the chassis and house battery banks together.

If the chassis battery bank had discharged, it was possible to use the house battery bank to start the engine. This was possible because Bluebird installed a control circuit that allowed you to connect the two systems together momentarily simply buy holding down a momentary switch while you started the engine.

Then there was also the ability to have the inverter/chargers charge both battery banks simply by flipping a switch. That made it very convenient to keep the chassis/start batteries charged through shore power or the generator. Another positive was that the generator was capable of charging both banks. So if you had dead chassis batteries, you could charge them simply by running the generator.

Conversely, the Prevost chassis is a 24V system and the converters use a 12V system to supply power to the 24VDC to 120VAC inverter/chargers to power the installed household items such as the fridge and TVs.

Because the voltages are different, you lose the ability to connect the two systems together. Therefore, the chassis battery bank is totally dependent on the 24V alternator to keep the chassis batteries charged. So the bus engine needs to run periodically to keep the chassis batteries charged. The frequency is dependent on the age of the batteries. Some converters have installed solar panels or a 24V battery charger which can be manually turned on to charge the chassis battery bank. My Marathon doesn’t have one or if it does, I haven’t found it.