ouR escaPOD mods

I use the GIMP to crop and resize the photos. I could add annotations to the photos and highlight details, but I haven't so far. I may start doing that. I'm going to skip the diode for now and see how it behaves. We may have to make a short trip so I can test it, but that won't be until after I can safely dewinterize the water system. Another reason for this was that we travel with a full fresh water tank, so eliminating 90 lbs of battery weight is a good thing.

A diode would go in the +12v line from the tv battery, allowing current flow only toward the trailer. I had an old class a RV I set up like that.

But I wouldn’t at this point. There will be a voltage drop across the diode which might make it hard to get the Li battery fully charged and StephenH has already determined that his 12v line to the tv is disconnected when the ignition is off. So, backfeeding isn’t likely to happen anyway except for a few seconds while starting the tv engine. If it turns out that isn’t the case, or the Li battery is drawing too much current from the alternator, or is overcharging then that would be a good time to add a diode into the circuit.

Originally posted by offgrid If so you might be fine with only an isolator relay disconnect between the trailer and the tv. You need something to keep from dumping the Li battery charge back into the tv battery when the alt isn’t charging, because the Li battery stays at a higher voltage than the lead acid battery doesrpm before you decide what to buy. As long as you keep a close eye on everything while testing you should be . You could connect up and see what kind of charge currents and voltages and alternator temps you get at idle and at 3000ok.

The 40a fuses will limit the current flow to the trailer battery to 40a if the circuit from the tv goes through them, I’ve never checked to see if that’s the case. But you should still have a fuse or cb in line on the +12V conductor near the tv battery in case there is ever a fault on the conductors to the 7 pin connector. Those are usually 10awg so a 30a cb is appropriate. The aftermarket kits like I have from etrailer have you install that cb on the vehicle body just near the battery.

The bms will self protect the battery but shouldn’t be depended on to provide day to day charge regulation. Think of it as a backup system. Unlike a lead acid battery, Li batteries will last longer if not charged to 100% SOC, so 14.8V is too high anyway.

Yes, what Battle Born is saying is consistent, you pobably have enough series resistance in the 12V trailer feed so excessive charge current is not a problem. You should also have a 30A breaker in that line already, right? Do you have an ir thermometer to check alt temp while you’re testing?