Battery cutoff circuit breaker trips while charging

mbeckerpasha

I have a 2020 T@B Boondock camper with AGM batteries.  I have charged the batteries many times prior to a trip using a garage outlet. I have tried to do this recently and the battery cutoff circuit breaker keeps tripping. I have a surge protector inline. I live in Arizona and it is hot here. Might this be the problem? I appreciate any feedback.

pthomas745

What circuit breaker?  The main 30 amp breaker?  Or the battery charging "fuse" in the converter? 

mbeckerpasha

The main 30 amp breaker, located in the same compartment as the battery cutoff

pthomas745

That might indicate a short in a cable, or a short somewhere where the power enters into the trailer. You might want to take a close look at your connections where the power enters the trailer behind the shore power receptacle (unplugged, of course).   If you have a separate power cable, you might want to try it.

mbeckerpasha

Good thought. I will check out the two house receptacles I have tried. Both are 20 amp, GFCI.

Sharon_is_SAM

@mbeckerpasha - it sounds like you have a 400.  If so, the circuit breaker located in the hatch by the battery switch should be a 40 amp.  

mbeckerpasha

Hello, yes, sorry about that. It is actually a 2021 T@B 400 Boondock. Yes, it is a 40 amp. This is the one that is tripping.

Sharon_is_SAM

There were reports of the circuit breaker tripping when the single AGM battery was very depleted.  I would check the voltage first, then try charging with a smart charger if it is very depleted.

mbeckerpasha

Thanks for that, will do.

tphaggerty

I had the same problem. The charger is rated at 55 amps in the 400, but that only happens when the charger goes into boost mode, which normally only happens when the battery is very low. Not sure why NuCamp uses the 40 amp circuit breaker since it trips every time the charger goes into boost mode. My guess is that the charger wires aren’t really rated to support 55A, but then why put in a 55a charger…

One way around this without changing the charging setup (which is what I did eventually) is to charge the batteries enough in another way (tow vehicle, trickle charger, solar) so that boost mode doesn’t kick in on the built in WFCO converter/charger. With AGM batteries, boost mode on the standard charger only seems to kick in when the battery is very low, say less than 30% SOC or so. (There are multiple threads on boost mode charging issues with the WFCO charger).

Before I made my changes (which involved changing the WFCO for a Progressive Dynamics charger, shortening the charging wires and replacing the 40a breaker switch with a 60a switch) I was able to get the batteries to charge without tripping the breaker by turning on every 12V appliance in the Tab (fans, lights, refrigerator after unplugging the 110 cord) while charging. This seemed to reduce the charge going into the battery enough to keep the breaker switch from tripping (since the charger is now driving all those other loads). After an hour or so, the battery was charged enough so that the charger dropped out of boost mode, back to normal charging at something like 30a. 

I really don’t understand why the T@b 400 charging system is setup this way, I’m not an electrician so my understanding of this could be way off base, but it seems like it doesn’t make sense to have a 55a charger in a system that seems to be designed to limit charging to 40a (based on the supplied breaker in the battery box area). I know that there will be folks jumping in saying that you should never go that low on AGMs, and I understand and agree in general, but sometimes it happens and the fact that the charging system as built can’t handle it is a real problem (IMO).

Dutch061

In a 2020, especially if it is a 400 I find it hard to believe that with the factory WFCO charger and location that it ever goes into Boost (14.4 volts) charge mode. Which is why it takes 24 to 36 hours to charge the batteries and why I done what I done to get around this. I have posted this in other threads, so I am not going to repost here.

On the PD9260VCV I installed, it is already fused so I didn't add additional protection to the circuit. Instead, mine is connected directly to the battery junction block.

Doesn't sense that turning on all 12 VDC would keep the breaker from tripping, as the power still has to go through the breaker.

This winter, I will add to the thread of "modifications" all of the things I have done.

Brad