Will - here's a sad tale of three Weize battery failures

[2WheelJon]

The Story of Three Weize Battery Failures​

I bought two Weize 100 Ah LiFePO4 batteries from Amazon in August, 2022. I put them in my RV, wired in parallel. When on shore power the batteries are charged with a Progressive Dynamics model #PD9100L, LiFePO4 compatible charger rated at 60 amps. When not connected they are charged by two Renorgy 100 watt solar panels connected through an Epever solar controller.

The batteries worked flawlessly up until January, 2024. At 6:24 am on January 5 the batteries discharged from 13.4 volts to 13.01 volts. They were in my RV but disconnected from everything by way of a master disconnect switch. At the time of the discharge there was 0 amperage draw – there was no electrical load on the batteries. They are monitored by a Victron shunt monitor. At right is a picture of the monitor readout showing this unexplained voltage drop, as well as a 0 amp draw.

At this point I contacted Weize technical support and, at their suggestion, removed the batteries from the RV and individually charged them using another, LiFePO4 compatible charger. I charged them back up to a resting voltage of 13.43 volts, and put them back in the RV.

All seemed well and the batteries held their state of charge. Nothing was used electrically. Then, on the morning of January 8, the batteries again mysteriously discharged, again with no amperage draw. At right is another picture of the readout from the Victron shunt monitor for this second unexplained discharge, showing a drop in voltage to 12.86 volts.

I removed the batteries, went through the same recharge procedure, reinstalled them and they again sat fine for two days. Then, for the third time they again discharged with no load on them, going down to 12.89 volts.

At this point Weize technical support told me to return the batteries which I did. They then sent me to new batteries which I received in late Jaunary, 2024.

These batteries worked fine until June, 2004 when the batteries were drained to 12.89 volts when using a small space heater run through a 1500 watt inverter. The batteries were placed on charge using the onboard Progressive Dynamics charger. One charged back up, the other stayed at 12.89 volts. Attempts to recharge this battery using different chargers failed, including trying to jump it with another battery to wake up the BMS. Again, a series of emails back and forth with Weize technical support resulted in them agreeing to take this battery back and send me another. The new (third) battery has just arrived and will be installed in the RV with all of my fingers crossed.

 

[42OhmsPA]

13.43V is not enough to fully charge your batteries, you're only hitting 3.3575V / cell, if they are balanced. I'd take them to 3.425-3.475V / cell.
I bet you'll have the same issues with the 3rd battery if you don't increase charging voltage.

Do they have bluetooth so you can see individual cell voltages? I'm also betting the cells are out of balance with your low charging voltages.

The Story of Three Weize Battery Failures​

I bought two Weize 100 Ah LiFePO4 batteries from Amazon in August, 2022. I put them in my RV, wired in parallel. When on shore power the batteries are charged with a Progressive Dynamics model #PD9100L, LiFePO4 compatible charger rated at 60 amps. When not connected they are charged by two Renorgy 100 watt solar panels connected through an Epever solar controller.
View attachment 226540
The batteries worked flawlessly up until January, 2024. At 6:24 am on January 5 the batteries discharged from 13.4 volts to 13.01 volts. They were in my RV but disconnected from everything by way of a master disconnect switch. At the time of the discharge there was 0 amperage draw – there was no electrical load on the batteries. They are monitored by a Victron shunt monitor. At right is a picture of the monitor readout showing this unexplained voltage drop, as well as a 0 amp draw.

At this point I contacted Weize technical support and, at their suggestion, removed the batteries from the RV and individually charged them using another, LiFePO4 compatible charger. I charged them back up to a resting voltage of 13.43 volts, and put them back in the RV.

All seemed well and the batteries held their state of charge. Nothing was used electrically. Then, on the morning of January 8, the batteries again mysteriously discharged, again with no amperage draw. At right is another picture of the readout from the Victron shunt monitor for this second unexplained discharge, showing a drop in voltage to 12.86 volts.
View attachment 226541
I removed the batteries, went through the same recharge procedure, reinstalled them and they again sat fine for two days. Then, for the third time they again discharged with no load on them, going down to 12.89 volts.

At this point Weize technical support told me to return the batteries which I did. They then sent me to new batteries which I received in late Jaunary, 2024.

These batteries worked fine until June, 2004 when the batteries were drained to 12.89 volts when using a small space heater run through a 1500 watt inverter. The batteries were placed on charge using the onboard Progressive Dynamics charger. One charged back up, the other stayed at 12.89 volts. Attempts to recharge this battery using different chargers failed, including trying to jump it with another battery to wake up the BMS. Again, a series of emails back and forth with Weize technical support resulted in them agreeing to take this battery back and send me another. The new (third) battery has just arrived and will be installed in the RV with all of my fingers crossed.

 

[mikefitz]

unexplained discharge, showing a drop in voltage to 12.86 volts.

That's not a discharge of power, its a reduction in voltage. This is possibly due to the BMS entering protection mode, or the BMS failing.
With Weize being low cost batteries, the BMS will be a 'budget' version.
I assume the chargers are set to charge voltages over 14 volts and the quoted 13.43 is the resting volts after charging is completed

It's always an advantage paying a little more for a battery with Bluetooth communication with the BMS. At least you can see what's happening inside the battery.

It appears Weize may be using pouch cells in their batteries that may not be as reliable as prismatic cells.

If you end up with 'dead' batteries that are not replaced by Weize it's possible the cell pack could still be used with a replacement BMS

 

[Crowz]

Ive had mine since November 22, 2022 and they are doing great. I charge them daily to 13.5 to 13.8 depending on the weather and they drained to at least 50% soc a daily and sometime down in 20's soc. Still working great so far.

The old weize I have are the prismatic celled ones since I got them around Will's first tear down. The later ones he tore down were junk which is why I switched to Chins for my 12v's and my 48v's.