Any volts at the house battery?

 

You mean the actual van battery, right? The van starts fine. Now the auxiliary battery, I'm not sure. Thinking probably not

 

It could be totally flat, charger might not wake up if it doesn't see volts on the auxiliary ("house") battery. I have an MPPT in my shed that works that way, thought it was toast until I put a good battery under it.

 

So I checked the leisure battery and it's at 2.3V, CCP battery at 14.3V
I don't understand how the leisure battery would stop the B2B from trying to charge it, especially since there's plenty of power coming from the van. Do I need to drive a lot to get it back up to speed? Even so, nothing is happening with the charger.

 

Just saw your reply. That's gotta be it. I guess I have to jump that battery some way? I also (don't laugh) just realized there's no battery under the hood. Looks like I'm going to be a real soldier once I hit the open road, huh

 

Assuming it’s not a lithium battery you can run jumper cables off the starting battery while you drive. If it’s a flooded battery keep it well ventilated, it will be releasing enough hydrogen to possibly be a hazard.

 

Kisae got back to me, and yes it sounds like the house battery needs to be at 8V+ to keep the charger alive. Instead of jumping it off the driver seat battery I think I'll jump it from my car. Gotta be the issue.

 

If you're measuring 2.3V at your house/leisure battery, it's way past dead. Most "smart" B2B chargers have protection circuitry/programming that won't try to charge unless your battery is above some set voltage. Even 10V would be considered pretty dead for a flooded lead acid (FLA) battery. Lower voltages can indicate a fault, like a shorted cell, so it wouldn't be safe to try to charge it under those circumstances.

This is assuming the voltage you're measuring is actually the combined/series cell voltage of FLA, AGM, or lithium, rather than some internal protection circuit that's been tripped on a lithium battery's BMS.

You'd get more meaningful responses if you say what type of leisure/house battery you have.

 

It's the Weiss 100Ah AGM, and apparently it slow drained while sitting.

 

There are few, if any, batteries that enjoy sitting without a maintenance charge either periodically (lithium) or constantly (FLA, AGM, etc).

 

I would suggest a cutoff switch for the house battery itself. What likely happened is the charger drained the battery.

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I just had this problem myself. I hooked up an external battery charger to my house battery for a bit to get the voltage up. Then all resumed as normal once I fired up the van (with battery charger disconnected) and the b2b took over charging again.
The house battery was just too dead.

 

I've had some luck with smart battery chargers (e.g., Noco) reviving batteries that seemed dead. The one I have has a special mode to repair/recover. That said, I've had some batteries that were well and truly dead after discharge and neglect. When you get your house battery sorted, you need to have a shore charger that plugs in (or solar) to keep the battery topped off. A simple battery saver charger will do it, or use a hard-wired inverter/charger such as a Magnum.

 

The same thing happened to me recently when my van went to the shop for well over a week. I have a Kisae Abso DMT1230 hooked up to my house AMG battery. The Kisae would not turn on except for a momentary blue screen. My back up is a C-Tek smart charger within the system. I ran an extension cord to it, plugged it in and the house battery charged up over night. The Kisae is now functioning normal again, must that 8 VDC limit it has. I have since added a second cut off switch between the house battery and charger/components (the other cut off is between the van battery and the house battery). Now I can totally isolate the house battery if needed.

 

Just FYI, isolating a battery isn't enough to keep it from losing energy (voltage). It will self-discharge, thus needs a constant trickle charge. This is for lead acid.

Lithium also self-discharges but has different long term storage requirements, usually involving a lowered charge but check with maker for details.

 

I used to store a pickup truck 8 months a year with the negative cable disconnected, Every Fall that battery started the truck without additional charging.

 

I finally heard from Kisae and determined that the dead house battery is likely the issue. Cutoff switch going in, STAT. Thanks for the great input, everyone!

 

one more question, though - Isn't the 80A breaker from the CCP the same thing as a switch

 

Yes. But that is used to cut the power from the chassis to the house battery/charging system. You also need a switch on the positive lead from the house battery to the charger and the rest of the loads to keep anything from being powered and drawing power from the battery.