Battery is not charging

I just assembled my DIY MNT reform kit. I am afraid my batteries aren’t working correctly. Right from the beginning the battery symbol in the top right column of the OLED blinked. It stopped after I completely charged the device. Now after all cells are empty the top right battery blinks again and the OLED shows wired values, e.g. 5.3 V for some cells. After more than 4 hours of charging the total voltage increased from 3.3 V to 3.5 V but the total current is still zero A and the percentage is ???%. I swap the batteries from the left to the right battery holder but the OLED still shows the same blinking cell in the top right column.

After disconnecting the power supply the MNT reform doesn’t boot nor the OLED is awake (as expected with this low voltage/current).
Does anyone has an idea what I did wrong. Or is one of the/are multiple batteries damaged?

Sounds like some batteries are damaged or just discharged too low. The blinking batterie is something many (myself included) have seen and should vanish after some time.
These batteries discharge kinda quick and you cannot bring the charge back just by plugging in the charger. You might need to buy a few new batteries(luckily they are not very expensive).
This discharge should not happen, when the batteries are just “lying around”.
The Operators handbook gives some information about the handling and types of batteries you can use. It can be found on-line if you didn’t buy a copy.
I hope this answer is of help to you

@morl0ck thanks for your answer. After reading the operators handbook I must admit that I left the MNT Reform on battery until it died (and let it without power supply for many days). So I guess my batteries are deeply discharged.
I just ordered a set of new batteries.

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Sorry for your trouble. In some cases, LiFePO4 batteries can be brought back to life by charging them outside of Reform in a 18650 charger that supports LiFePO4 (for example NightCore), or a current limited power supply (like a cheap lab power supply) set to a low voltage like 2V.

PS: Make sure to buy LiFePO4 batteries only, not LiIons.

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I also left the reform unattended for 5 days and have the same behavior. The batteries are not charging anymore. I would try to revive them by charging them outside the Reform, but is there a way to disconnect the battery pack without having to open up the bottom plate every time ? Has someone come up with a better DIY solution ?

Thank you for this hint! I wouldn’t have otherwise tried to recover with my lab power supply and bought new batteries.

I had left the batteries in the device for a few days (<2 weeks) and some cells were down to below 1V.

I disconnected the battery holders, removed the battery cells and put one battery cell back. I connected the clips of my lab power supply (GOPHERT CPS-3205) to the holder in the right polarity, set it to 2V and 0.25A and waited until current was low (~25mA). That recovered 6 out of 8 cells.

I couldn’t find spec sheets for the delivered batteries, but current values around a tenth of the cell’s capacity should be OK (i.e. 180mA for 1800mAh batteries) based on my later reading.

The other two cells showed voltages below 2V, so I charged them again at 2V and 0.1A and waited until the current showed <15mA, that recovered all cells.

I also made a mistake after the first try of recovery: Since two cells still showed as bad on the battery monitor on the OLED screen, I removed one cell while power was still connected to identify the bad cell on the battery monitor. A few seconds later, magic smoke happened.

After immediate disconnect of everything and initial panic, I found one resistor which is charred (R28). Surprisingly enough it still measures the same resistance values as the other resistors of the same type. I suspected that’s a sense resistor, but after looking at the schematics I’m not sure what it’s for.

I let it charge for a short while and cell voltages looked good, but I won’t use the reform with batteries until I sourced a new resistor and replaced it.

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This is a bit alarming, I must say. What is the recommended way to keep the batteries from ceasing to take charge? Will I need to take the batteries out when I’m not using the device? How long until the batteries fully discharge?

I think one or two weeks, but I don’t have conclusive data yet as I use my Reform pretty much every day.

Thanks for the idea of bringing the batteries back outside the Reform.
My batteries were down to 0.3 ~ 0.6V and I used my lab power supply.

Interestingly when limiting the voltage to 3.2V and the current to 500mA the resulting voltage when connecting the batteries ramped up to 2V within a few (5-7) seconds.

I loaded them to get 2.8V which lasted about 40-60 seconds.
After ‘kicking’ all eight batteries this way they were at least at 2.6V when putting them back into the Reform which made the charging circuit accepting the batteries and properly charge them to the end.

Don’t know whether this approach fits the ‘specifications’ of the batteries - follow this idea at your own risk :sunglasses:

One day after this action the batteries are still at 100% - so I wanted to share my experience at least.