Renogy 200ah BT LifePO4 7.6 Volts

[RyanD1981]

Hi All,

I was given a new Renogy 200ah LiFePo 4 Bluetooth battery with a known issue. I’m here to find out if it’s something I can fix before possibly getting rid of the battery.

The battery voltage sits at around 7.6 volts, it won’t take a charge.

Wondering if you all could give me some insight. The battery came like this brand new to the gentleman who bought it a few months ago. It’s never been used in the winter, never been over discharged by him or abused.

Any help would be appreciated.

 

[sunshine_eggo]

BMS is likely engaging discharge protection. A standard charger likely won't recognize it unless it can be configured to operate as a power supply.

Options:

Put it in parallel with a 12V lead acid.
Apply 12V to it with a power supply of some kind.

 

[RyanD1981]

I’ve done that with an adjustable DC power supply… it charges it slightly to apx 8 volts, but then will settle back to around 7.6 after a few hours.

 

[Tomthumb62]

As a last resort, you can always tear open the battery and harvest the cells, but it’s also possible there’s a single bad cell (or two) and you’d need to find a suitable replacement. But if you’re not the tinkering type, then best to pass it on to someone who is.

 

[RyanD1981]

For sure I’d love to try it… Is it fairly easy to swap out a bad cell?

 

[sunshine_eggo]

As a last resort, you can always tear open the battery and harvest the cells, but it’s also possible there’s a single bad cell (or two) and you’d need to find a suitable replacement. But if you’re not the tinkering type, then best to pass it on to someone who is.

+1

Cut it open!

 

[sunshine_eggo]

For sure I’d love to try it… Is it fairly easy to swap out a bad cell?

Probably not at all. It will simply be a a learning exercise. You might find it's a bad BMS, and you can replace it and have a functional battery.

 

[Tomthumb62]

For sure I’d love to try it… Is it fairly easy to swap out a bad cell?

Watch some of Will Prowse’s YouTube videos of cutting open a sealed lifepo4. He has a lot of them. If you have the right tools (and wear a proper respirator), it doesn’t look too difficult. Pretty sure there is at least one video of Will opening a Renogy lifepo4 battery. Be aware that once you cut it open, the opportunity for dead shorts is real and if your short a cell outside the BMS circuit, you can end up with thermal runaway. Lifepo4 is one of the safest lithium chemistries, so it’s not going to explode or burn your house down, but it will get rather warm and smoke a lot. So keep your metal tools out if there and if you do need to use a wrench or screwdriver, just be careful and you’ll be fine.

You can watch videos of lifepo4 “fires” if you want to get an idea of what can happen. Will has a famous video of a Chins prototype lithium battery in full flames when he intentionally punctured it, but that isn’t a lifepo4 but rather NMC chemistry.

 

[RyanD1981]

Does anyone know what kind of cells are in those Renogy batteries, as in — would I be able to buy a suitable replacement cell?

 

[Tomthumb62]

Does anyone know what kind of cells are in those Renogy batteries, as in — would I be able to buy a suitable replacement cell?

Even if someone replies, most likely you’ll have no idea until you cut open the plastic case. If you order a new cell (assuming that’s what you need and not a new BMS, which I’d encourage to get anyways unless you’re trying to pinch pennies), it will be wasted money if that’s not what you need or your order the wrong cell. Or you’ll need to then buy more cells to match the one you bought and you’ll have a good learning experience how to DIY a lifepo4 battery pack.

OPEN IT UP, YIP YIP!

 

[RyanD1981]

Even if someone replies, most likely you’ll have no idea until you cut open the plastic case. If you order a new cell (assuming that’s what you need and not a new BMS, which I’d encourage to get anyways unless you’re trying to pinch pennies), it will be wasted money if that’s not what you need or your order the wrong cell. Or you’ll need to then buy more cells to match the one you bought and you’ll have a good learning experience how to DIY a lifepo4 battery pack.

OPEN IT UP, YIP YIP!

I appreciate this. This is all new to me, so wish me luck.

 

[Tomthumb62]

I appreciate this. This is all new to me, so wish me luck.

Ask specific questions and people will answer. Questions like “where do I start!?!” tend to get fewer high value replies.

Have you seen any of Will Prowse’s battery tear down videos? He’s got a lot including some older renogy models. Helps you get the idea of how easy to difficult it might be to open it up. I haven’t done one yet but feel like I’ve learned enough I could tackle it. Do it in a garage or something in case of a dead short that bypasses the BMS. No big fire or explosion with lifepo4 but there would b be lots of smoke that you don’t want to inhale. Go slow and careful until you open a few batteries and you’ll be fine. There are few reports on this forum of things like dead shorts and smoking lifepo4.

And good luck!

 

[Brucey]

Hi All,

I was given a new Renogy 200ah LiFePo 4 Bluetooth battery with a known issue. I’m here to find out if it’s something I can fix before possibly getting rid of the battery.

The battery voltage sits at around 7.6 volts, it won’t take a charge.

Wondering if you all could give me some insight. The battery came like this brand new to the gentleman who bought it a few months ago. It’s never been used in the winter, never been over discharged by him or abused.

Any help would be appreciated.

Did he get it replaced under the Renogy warranty? If not you may be able to get it swapped for a working one, without cutting it open?

 

[RyanD1981]

Did he get it replaced under the Renogy warranty? If not you may be able to get it swapped for a working one, without cutting it open?

He got a replacement

 

[mikefitz]

would I be able to buy a suitable replacement cell?

May be welded buss bars, may be pouch cells.
Try battery wake up procedures.

How to Wake Up a Sleeping LiFePO4 Battery - Footprint Hero

Learn how to wake up a sleeping LiFePO4 battery by jumping it with another battery. This easy method gets your lithium battery out of sleep mode.

footprinthero.com

Open the battery and apply a 12 volt charger to the cell pack bypassing the BMS, if possible use a charger/ power supply, where the voltage can be reduced, monitor battery state. If the pack takes a charge the battery BMS may wake up.

Examine everything.