Electrical problem

[kavm]

Camper: 2021 5.0, 2 solar panels, 2 lithium batteries, EMS, Inverter, a DC only compressor fridge.

Problem: Last year, we winterized and stored the camper in covered in-door but not heated commercial parking. We had engaged the battery disconnect and confirmed that it had turned off the power to the lights and refrigerator, etc.

On Monday, we pick up the camper and find the batteries dead. We do not know if they were completely discharged or BMS simply stopped them from providing external charge. The lighting in the camper and, very importantly, the power jacks to lift the camper for hook up, etc. had no power.

Our storage facility is, thankfully, full service. They provided boost to the battery and also used a forklift to raise the coupler. That allowed us to add blocks underneath the jack legs and let us hitch up. About an hour of connected driving and a morning later, the batteries show a full charge yesterday.

This is the second time our batteries were fully discharged (not sure that's what happens or whether the BMS stops it from providing external charge). The previous time, I had created a thread on the forum and received much appreciated and generous help - https://www.escapeforum.org/forums/f...elp-21554.html

In fact, we were following up on the advice in that thread in the excursion where we ran into this issue. Yesterday, we had a tech install the following:

1. Victron battery monitor - https://www.amazon.com/gp/product/B075RTSTKS
2. Solar disconnect - https://www.amazon.com/gp/product/B0746DLP7S

The battery discharge situation happened the day earlier. Since this seems to (too) happen often - we just bought NOCO Boost HD GB70 2000 Amp 12-Volt UltraSafe Lithium Jump Starter https://www.amazon.com/gp/product/B016UG6PWE to our kit.

Advice Sought: The camper is now back in the storage but we are left wondering as to the cause and the course of action. Whether it is even a good idea to use the battery disconnect. Without it, the storage place can connect our camper to power a couple of days prior to pickup.

Please note that the camper is back in storage. We are planning a camping trip in mid April. So, can follow directions at the time.

We will return to our tech a bit later on a different matter (Trailer TPMS and camera installation) in May or later. We can also ask his help.

[kavm]

Any advice?

[HABBERDABBER]

I don’t know what.
I guess you could manually disconnect them by unhooking a battery cable.

[Shiny]

The battery monitor should provide an accurate indication of current flow. What did it show with the battery disconnect switch off?

Any chance your emergency brake switch/pin had been activated?

[kavm]

Originally Posted by Shiny

The battery monitor should provide an accurate indication of current flow. What did it show with the battery disconnect switch off?

Any chance your emergency brake switch/pin had been activated?

We did not have the battery monitor installed when this happened. This discharge happened when it was parked over the winter. We just had the installed after the event.

Next time we go camping, we can try to activate the battery disconnect switch and see if the battery monitor shows anything.

Emergency break was not activated.

[SWCO]

Originally Posted by kavm

Any advice?

You could install an inexpensive manual disconnect on the ground side of your battery (or batteries), just a knob you turn by hand to connect/disconnect the battery from the system. I used this successfully to keep the battery up on an old farm tractor that had an electric drain I never did diagnose. Much more convenient that disconnecting a cable.

[kavm]

Originally Posted by SWCO

You could install an inexpensive manual disconnect on the ground side of your battery (or batteries), just a knob you turn by hand to connect/disconnect the battery from the system. I used this successfully to keep the battery up on an old farm tractor that had an electric drain I never did diagnose. Much more convenient that disconnecting a cable.

Thank you! That's an idea. If we don't find something, we may indeed go that route.

[MVA]

Originally Posted by HABBERDABBER

I don’t know what.
I guess you could manually disconnect them by unhooking a battery cable.

I concur. I would disconnect the positive cable from the lithium battery to ensure there is no minute current draw.
It appears that the batteries are either self discharging or there is a current draw in the trailer that the battery disconnect may not stopping. If it is the former problem, the batteries will still discharge. If the latter, they will not.

[Iowa Dave]

Do the carbon monoxide detector and the propane leak detector draw their power from the batteries and are they left running even with the battery switch off?. It seems to me that this “phantom draw” has been discussed in the past but it’s been some time ago. My mower has a
Wet cell garden tractor sized battery. When I was done with it and had run it for a couple hours mulching leaves, I shut it off, made sure the driving lights were off and let it set. That was mid November. Last Monday I turned the switch, choked it and it fired up after a solid starter speed for about 15 seconds. It’s a lot simpler than the Escape but the point is that the storage building gets down to -10 or -15F several times a winter. Same is true for my tractor/loader but it gets started a few times over winter to move snow. Check for phantom draws.
Iowa Dave

[kavm]

Thank you! There are some good thoughts here for us to pursue. I will also search for phantom draws.

The other question is - how harmful is it for the lithium batteries to be discharged through these parasitic draws - and then be charged up?

[rubicon327]

Originally Posted by kavm

The other question is - how harmful is it for the lithium batteries to be discharged through these parasitic draws - and then be charged up?

It’s not good for them. The BMS should shut the battery off at a low voltage cutoff but it can still self-discharge over time to complete destruction. Honestly if your trailer isn’t tempered and plugged in to shore power over the winter to provide charging the best thing to do is probably pull them out at about 80% SOC, take them inside and just let them be. With nothing connected they will have a very, very minimal self-discharge. Or as suggested make sure the batteries are completely disconnected with no phantom loads. By the way the Victron batt monitor also has a small draw itself and has been blamed online for killing boat batteries sitting in the off season.

[HABBERDABBER]

Originally Posted by kavm

The other question is - how harmful is it for the lithium batteries to be discharged through these parasitic draws - and then be charged up?

It depends on how deep they were discharged (lowest voltage) maybe for how long they were "dead", temperatures may have had some impact, manufacturer, battery chemistry (type of lithium)......you get the picture.....no quick & easy answer.

But compared to typical lead acid batteries, they are much more tolerant of deep discharge....some tolerant of very deep discharge.
You'll likely be just fine & OK, but you have some electrical demon to find and purge.

[elongest]

Your battery switch disconnects your battery from your trailer circuits, but your solar is still connected directly to your battery. I would look into your solar system for some type of load when it is not producing a charge while inside the storage building. My understanding is the controller must always be connected to your battery when the panels are connected to the controller. If the solar went through the battery switch you could damage your controller when the battery is switch is turned off. I could be wrong but just my guess.
Eddie

[kavm]

Originally Posted by rubicon327

It’s not good for them. The BMS should shut the battery off at a low voltage cutoff but it can still self-discharge over time to complete destruction. Honestly if your trailer isn’t tempered and plugged in to shore power over the winter to provide charging the best thing to do is probably pull them out at about 80% SOC, take them inside and just let them be. With nothing connected they will have a very, very minimal self-discharge. Or as suggested make sure the batteries are completely disconnected with no phantom loads. By the way the Victron batt monitor also has a small draw itself and has been blamed online for killing boat batteries sitting in the off season.

Thanks Dave! Taking the batteries out of the camper is a hassle we would like to avoid. But, we can disconnect them.

It’s good to know about the Victron battery monitor draw as well.

Thanks!

[kavm]

Originally Posted by HABBERDABBER

It depends on how deep they were discharged (lowest voltage) maybe for how long they were "dead", temperatures may have had some impact, manufacturer, battery chemistry (type of lithium)......you get the picture.....no quick & easy answer.

But compared to typical lead acid batteries, they are much more tolerant of deep discharge....some tolerant of very deep discharge.
You'll likely be just fine & OK, but you have some electrical demon to find and purge.

Thanks! I will google for an electric shaman

[kavm]

Originally Posted by elongest

Your battery switch disconnects your battery from your trailer circuits, but your solar is still connected directly to your battery. I would look into your solar system for some type of load when it is not producing a charge while inside the storage building. My understanding is the controller must always be connected to your battery when the panels are connected to the controller. If the solar went through the battery switch you could damage your controller when the battery is switch is turned off. I could be wrong but just my guess.
Eddie

Interesting. We also installed a solar disconnect. So, we could engage that to avoid this…

[John in Santa Cruz]

some of those BMS will turn the battery off if it gets below 32F or so, and not turn it back on until the internal temperature is 40F

ideally you long-term store a LFP battery at around 50% charge, really anywhere from 20-80% ... they should hold a charge for months if there is no loads.

you can always install one of these right at the main battery negative terminal
https://www.amazon.com/dp/B001N72FES

[BobG]

A few things:

1. The BMS probably has a low temperature feature that turns off charging when the temperature is near freezing. It doesn't turn the battery off. It can continue to be used and discharged.

2. The battery manufacturer may have a published procedure for storing their battery. Like John says, many say store at around 50% SOC and disconnected.
3. After what the batteries have been through, I would be thinking about checking each battery individually to see if they both have full capacity. If each one has full capacity then I would charge them individually to full charge (BMS shuts off charging and both have the same voltage) and then connect them to the trailer system. If the batteries are out of balance, then one battery will feed into the other causing loss of capacity of the system and maybe other problems.

[rubicon327]

Good article on winter lithium battery storage from Battleborn…
https://battlebornbatteries.com/faq-...our-batteries/

[HABBERDABBER]

I had a 5W solar panel trickle charging a small sailboat lead acid battery. I recall that a charge controller was not needed at that system size. I recall reading that at night, the panel could discharge the battery, but not enough to make a big difference and the next day would be back to snuff.

Besides the parasitic load of your control electronics, it is possible you have a "gone bad" blocking diode.

This is just mere speculation, and I am no solar guru.

https://solarenergyhackers.com/can-s...harge-battery/