Electrical troubleshooting help

[oldwave]

Thank you, OldWave! We aren’t handy, so it’s probably not easy for us. But, we are going to find someone to install the Victron BMV-712. We will ask that person to also look into installing a solar disconnect. So, I have now added this item to our list.

Question: We are planning on a winter trip from SLC to Big Bend NP in December. While we are traveling South precisely to get to above freezing temperatures, we will definitely come across sub-zero temperatures for some of that trip. What precautions do we need to take with the lithium batteries and solar panels? Even if we have a solar disconnect switch, wouldn’t the tow vehicle try to charge the batteries if we are driving in below zero temperatures.

The bms should protect you in this scenario if the batteries get too cold, they will shutdown. No I am assuming that the escape supplied batteries have this function, most modern batteries from reputable brands have the cold shutoff. It would be worth your while to inquire from the manufacturer. That said, I think that the alternator dc to dc charger might be before the disconnect switch. A little out of my knowledge as my trailer is 4 years old with a basic solar install, not a lithium version. There are some more talented electrical gurus on this forum or maybe escape could illuminate the wiring on this system. What I would avoid is the long term storage charging scenarios at sub zero temps .

 

[kavm]

Thank you very much, oldwave! After this experience, we will have the battery disconnect on and refrigerator off for all storage.

 

[alanmalk]

The bms should protect you in this scenario if the batteries get too cold, they will shutdown.
...

I've been researching cheap lithium batteries and note that most (all??) in that price range do not have cold temperature cutoff. You must ask!

One example (sub $400 US):
Ampere Time LiFePO4 battery has built-in BMS to protect it from overcharge, over-discharge, overcurrent, and short circuit with excellent self-discharge rate.

 

[oldwave]

I've been researching cheap lithium batteries and note that most (all??) in that price range do not have cold temperature cutoff. You must ask!

One example (sub $400 US):
Ampere Time LiFePO4 battery has built-in BMS to protect it from overcharge, over-discharge, overcurrent, and short circuit with excellent self-discharge rate.

I have also, I don’t know what escape is using, certainly not battleborns that I can tell. Looks like it may be gopower sun cycles.
I looked them up and they list over and under temperature protection. That’s encouraging

 

[kavm]

Escape is using Go Power lithium batteries - likely https://gpelectric.com/products/100ah-lithium-iron-phosphate-solar-battery/

I do not know if there has been any update between the batteries installed in our camper earlier this year and the link I posted.

 

[oldwave]

Escape is using Go Power lithium batteries - likely https://gpelectric.com/products/100ah-lithium-iron-phosphate-solar-battery/

I do not know if there has been any update between the batteries installed in our camper earlier this year and the link I posted.

Looks good they have all the features you need

 

[alanmalk]

Looks good they have all the features you need

Except for the price. I'm seeing $999 at eTrailer. Yes, they should have a low temperature cutoff function in the BMS.

 

[rubicon327]

To summarize, the Lithium battery has a protective circuit that completely disconnects the battery - to protect it from serious damage - when the voltage drops too low. It is called a BMS and it will not reconnect the battery until 14 volts (varies a bit with manufacture) is applied. Your conventional charger may, or may not, provide this voltage when connected - because it thinks there is no battery! A simple 14V battery charger with no "smarts", and only an amp or 2 of power, will do the trick.

This is something that varies a lot from the old days of lead-acid. A dead lead-acid battery is a big load, while a dead LFP battery may not "exist".

Alan: This is interesting. FWIW I believe the WFCO-8955LiS that would be provided from Escape when lithium batteries are selected does provide a charging voltage even with no battery present. In the manual is a functional test that includes disconnecting the battery and checking for voltage.

 

[Centex]

Alan [alanmalk]: This is interesting. FWIW I believe the WFCO-8955LiS that would be provided from Escape when lithium batteries are selected does provide a charging voltage even with no battery present. In the manual is a functional test that includes disconnecting the battery and checking for voltage.

So you got my curiosity up and I just ran a quick test on the WFCO 8955LiS in my new 5.0 where I already had the panel-cover removed providing easy access to the LA/LI switch and it's sitting on shore power:

• Battery Disconnect "Off" (battery disconnected)
• Voltages measured (Fluke VOM) at the pigtail installed by ETI in dinette overhead cabinet
• WFCO set to "LA" (for lead-acid battery, my default) = 13.22 volts
• WFCO set to "LI" (for lithium battery) = 14.64 volts

Note that my August 2021-build trailer, even though ordered with the standard single 12V lead-acid battery, was delivered with the WFCO 8955LiS power center.

Just FYI from Alan E.

EDIT - I left the battery disconnected and the WFCO toggled to "LI" - gotta run some errands now but I'll report back this evening IF the voltage drops to a lower value.

 

[oldwave]

Except for the price. I'm seeing $999 at eTrailer. Yes, they should have a low temperature cutoff function in the BMS.

He already has these batteries

 

[rubicon327]

So you got my curiosity up and I just ran a quick test on the WFCO 8955LiS in my new 5.0 where I already had the panel-cover removed providing easy access to the LA/LI switch and it's sitting on shore power:

• Battery Disconnect "Off" (battery disconnected)
• Voltages measured (Fluke VOM) at the pigtail installed by ETI in dinette overhead cabinet
• WFCO set to "LA" (for lead-acid battery, my default) = 13.22 volts
• WFCO set to "LI" (for lithium battery) = 14.64 volts

Note that my August 2021-build trailer, even though ordered with the standard single 12V lead-acid battery, was delivered with the WFCO 8955LiS power center.

Just FYI from Alan E.

EDIT - I left the battery disconnected and the WFCO toggled to "LI" - gotta run some errands now but I'll report back this evening IF the voltage drops to a lower value.

Thanks for confirming. No issue either for those of use incorporating the Xantrex Freedom XC inverter/charger as its feature list includes: Dead Battery Charging Down to 0 Vdc

 

[rmitch]

Kavindra sorry to hear you are having problems. The learning curve can be steep in the beginning. But you have a great resource here, sounds like there is some real electrical knowledge on this board. Keep at it and you will get it figured out. Here's to a great trip south in December.

 

[Centex]

....

• Battery Disconnect "Off" (battery disconnected)
• Voltages measured (Fluke VOM) at the pigtail installed by ETI in dinette overhead cabinet
• WFCO set to "LA" (for lead-acid battery, my default) = 13.22 volts
• WFCO set to "LI" (for lithium battery) = 14.64 volts

....
EDIT - I left the battery disconnected and the WFCO toggled to "LI" - gotta run some errands now but I'll report back this evening IF the voltage drops to a lower value.

Follow-up as promised:

• Left unattended for ~6 hours with battery disconnected and WFCO set to "LI"
• sometime in that interval output dropped from 14.64 volts to 13.73 volts
• toggle to "LA" and immediately back to "LI" - output is 14.64 volts again

That's the end of my 'testing' - now back to my default "LA" setting (my battery is the standard 12V lead-acid) with battery connected.

Y'all have fun!

 

[kavm]

Kavindra sorry to hear you are having problems. The learning curve can be steep in the beginning. But you have a great resource here, sounds like there is some real electrical knowledge on this board. Keep at it and you will get it figured out. Here's to a great trip south in December.

Thank you, Ross! Indeed - it is a great resource and source of support. And, bit by bit, we are adding to our knowledge and experience. Plan to tackle winterizing next months

 

[Jack!]

• Battery Disconnect "Off" (battery disconnected)
• Voltages measured (Fluke VOM) at the pigtail installed by ETI in dinette overhead cabinet
• WFCO set to "LA" (for lead-acid battery, my default) = 13.22 volts
• WFCO set to "LI" (for lithium battery) = 14.64 volts

Hey, Thanks much for this test. The other day I was hunting for the Li battery specs for the WFCO LI ready charger and couldn't find everything I wanted on the web or in UTube. This real world test is a lot better in any case.
Is the LI/LA selector an actual switch or a jumper?

Thanks again!

 

[kavm]

Disconnect switch should be fine. The danger is trying to charge when the batteries are very cold, a good bms will prevent that though. I don’t know if you have a solar charger disconnect switch, but would recommend that also, they are cheap and don’t take much to install:


https://www.explorist.life/how-to-wire-a-solar-disconnect-for-a-diy-camper-electrical-system/

Sorry to revive this old thread - but I have an update and need a second opinion! Following up from last year's battery troubles, we purchased a Victron BMV 712 battery monitor as Dave kindly advised us and a 2P 250V Low-Voltage DC Miniature Circuit Breaker for Solar Panels Grid System din Rail Mount(63A) Breaker DC Circuit Amp Solar Double Pole and per - https://www.amazon.com/gp/product/B0746DLP7S

But, we had trouble finding a suitable installer for these items before we winterized and put the camper in storage. Picking it back up I have found a mobile RV tech who is willing and seems able to install these two things for us. I also shared the video for installing the circuit breaker with him - https://www.explorist.life/how-to-wire-a-solar-disconnect-for-a-diy-camper-electrical-system/

My question relates to the circuit breaker. The mobile tech thinks that the video pushes a dual solar disconnect (with both positive and negative terminals of the battery being disconnected). He believes that to be an overkill and finds a disconnect for the positive terminal sufficient. He thinks there is no true ground in the camper anyway, if I understood his point correctly. He is willing to do it the way it is shown in the video but is advising me against it to spare the extra effort and expense.

I don't really know enough to decide if he is right or not. My first priority is to do it right - whatever that is.

I would very much appreciate advice on this matter.

 

[tdf-texas]

The mobile tech thinks that the video pushes a dual solar disconnect (with both positive and negative terminals of the battery being disconnected). He believes that to be an overkill and finds a disconnect for the positive terminal sufficient.

You mobile tech is correct. There is NO reason for having a breaker on both the positive and negative. Also, a breaker is not needed on a solar panel. To test a solar panel's current, you short the tow leads together and measure the amps. You cannot over current a solar panel.

Sometimes a breaker is installed, not for current protection, but to be used as a switch to disconnect the solar panel(s) when maintenance is needed on the solar controller.

What is missing is a fuse or breaker on the positive output of the solar controller to the battery.

ps. I watched the video for a laugh - that guy has no idea what he is doing.

 

[kavm]

Tom - Thank you so much! Much appreciated. I can now proceed with the approach the Mobile Tech is proposing.