Home Forums Truck Camper Adventure Forum Electric rig? Reply To: Electric rig?

James Young

Not interested in a generator if I can avoid it. I notice that some class Bs are sold with “underhood generators” AKA a second alternator. Some pickups are sold with “heavy duty alternators”. Equivalent? Bad idea? Find it odd that I don’t see it mentioned in truck camper discussions.

I am not an auto electrician by any means but from what I understand, with my solar at least, the AGM batteries do not simply take on board whatever is thrown at them.

There is an initial BULK charge, a ton of solar or charge from your truck alternator for example satisfies this quite well. This accounts for 80% of the battery capacity. After this initial bulk charge the batteries want less, the controller reduces the charge accordingly and it enters an ABSORBTION stage. At this point even if you have a truck running and a ton of solar the batteries do not use it, they just want a smaller amount. This accounts for just under the final 20% of battery capacity. After that you end up with batteries requiring even less. A FLOAT charge that takes ages and take the batteries up to around 100%. Then there is a final stage that you will rarely get to unless plugged in, so we plug in to shore power every 6 or 8 weeks to get that final bit overnight that keeps the batteries in good condition.

So … having a heavy alternator will help if your truck doesn’t provide much bulk charge at the start. But after that, the benefit tails off significantly. That bulk charge accepts a lot of juice quickly. This means that you don’t actually need much solar to continue those later stages of charge. If you had full solar amps you wouldn’t be using it.

If we have a drive in the morning and ok solar during the day then we are back up to 100% (but not ‘full charge’) by the evening.

A basic explanation from a relative novice. Happy to be corrected by someone.

2007 Dodge 3500
[5.9 Cummins, Stick Shift] + [XPCamper V1E]