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yourrealdad avatar image
yourrealdad asked

Renogy battery is in BMS state. How to use BMV-712 to unlock

Hello,

I have a Renogy 100Ah LiFeP04 battery hooked up to a Victron Smartsolar MPPT 100/30 and a BMV-712 (in a van). I believe that my battery has been discharged too low from the BMV itself and is now in a BMS state of protection. My voltage reads 0 with a multimeter at the poles. Renogy has said that I need to use the BMV to "restart" the battery, but can't tell me how.

At this point hooking the solar to the battery results in no charging and the MPPT goes to float, BMV reads 13.7v, and once unplugged from the solar everything shuts down pretty much immediately.

What do I need to do or have I ruined a battery?


Thanks

BMS
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7 Answers
JohnC avatar image
JohnC answered ·

Hi. I'm not sure what the BMV is supposed to be able to do to revive their dead batt/bms. Nor it seems do they, aside from vague references and 'buy our mppt charger'.

Even on their own forum - http://renogy.boards.net/thread/291/renogy-100ah-li-batteries

There's a link there though that might help explain what you're up against: https://batteryuniversity.com/learn/article/low_voltage_cut_off

I'd expect a 'real' BMS to protect from this situation in the first place.

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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

I'm guessing here, but might be worth to try:

-cell voltages are probably too low to charge with 'normal charging current' (this would damage them)

-battery protects itself from that

-try applying 10-11 volt at 0,1 A from an adjustable power supply and see if it does something, could try even lower voltage, we don't know how the Renogy BMS determines to connect again.

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Bill avatar image
Bill answered ·

You need a charger like a NOCO to unlock it. I picked up a NOCO Genius last week just in case I did something similar. -Bill

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yourrealdad avatar image
yourrealdad answered ·

I know I am not supposed to ask questions within the question (seems an odd way to do it), but before I continue down this road of trying to wake up the battery, is this even safe at this point? It has been in BMS for probably at least 5-6 weeks is my guess. Would prefer to not have a battery explode in my face.


Thank you for the replies

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

You maybe should ask Renogy how to reactivate a nearly dead battery(of if it's possible at all...).
If someone can give you a clear answer than it's the manufacture of the battery.

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yourrealdad avatar image
yourrealdad answered ·

I did call Renogy. They said I need to use the BMV-712 to reactivate it and to contact Victron, hence why I am here, because unless I missed something this is really the only way to get support from Victron. I see no US support number.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

There is nothing a BMV-712 can do to restart the battery, it's just a battery monitor.
So if Renogy can't or dont' want to say you how you can revive the battery I think the battery gone.

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solardude avatar image
solardude answered ·

Have you tried connecting another battery to it in parallel, ie, jumpstart it? I’ve had a few LFP batteries go into low voltage protection and this revived them.

You might also try to adjust the MPPT to a lower voltage/amperage such as 11V/1A and see if that will restart it.

There isn’t anything magical a certain device does to reset it, it just has to take a small charge and get above its low voltage cutoff point. It’s entirely possible that the cells or bms was damaged, in which case the battery would be toast.

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ejrossouw avatar image
ejrossouw answered ·

From the Renogy maual. Maybe worth pointing this out to Renogy and ask what they mean by it.

"The BMS will protect and shut the battery down (0V) when it is over-discharged or short circuited. In these rare cases the user will need to activate the battery using an external device that has lithium battery activation feature. If the Lithium batteries voltage shows 0V the battery is not defective but in its protection setting. Please contact our Tech Support team at 909-287-7100 for any questions about the BMS."

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yourrealdad avatar image yourrealdad commented ·

Yep, that is what I did, and got little in the way of support. They just told me to contact Victron to figure out how to have the BMV restore the battery. I just bought this to hopefully awaken the battery:

https://www.amazon.com/gp/product/B00AHG7O74/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

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ejrossouw avatar image ejrossouw yourrealdad commented ·

Hopefully all turns out well. At least 0V is not all bad news.

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todd-lemke avatar image todd-lemke yourrealdad commented ·

To reactivate the bms when it has gone into safe mode (under voltage or short circuit) under the cap nearest the positive terminal there is a wire with an empty connector. If you find a board it is under the other cap. You will need to short the wires together and it will reset the bms. Once the bms is reset put it on a charger and it will charge. Note: this will reset the meter on the Bluetooth app and you will need to charge it all the way up to set it. I found this out after I popped my battery apart because it was not working I was thinking the bms gave up the ghost and needed replacing. In doing so I found alot about these batteries.

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