I just received Miller ML-102 from FT. I decided to check charging voltage, so I put an aluminum foil stripe between the battery and positive terminal. I have a cheap multimeter that I connect to a charger “-” (there is enough space without the foil) and to a “+” trough the foil stripe. The voltage jumps up and down for about 0.02-0.03v. I’ve stopped the charging when it was jumping 4.26-4.29v (the indicator led still was red), the battery out of the charger measured 4.24v.
Can I measure a charging voltage this way?
Is this charger OK or should I contact FT?
Thanks
All charger IC chips vary from one chip to another in termination voltage. Usually ±1% or ±1.5% (4.137 – 4.263v).
Has a battery ever measured higher then 4.24v off your charger? Measured as soon as the indicator shows its done. What version ML-102 do you have?
I have ML-102 v5. The only one FT has in stock. About 5s after charging was done battery voltage was 4.25v.
My question is should I rely on battery voltage after charging is done or on the voltage inside the charger while charging?
Update: Looks like it was power supply causing the problems. When I connected the charger to my computer’s USB port the voltage wasn’t jumping anymore, the charging stopped at 4.22v, the battery was 4.20v.
Hi maybe I can help as I had a similar problem today with my charger board from fasttech that uses the same TP4056 IC.
While the board I have charges fine on a 5volt USB port, it overcharges on my power supply set to about 6volts.
The higher the input voltage to the board, the more it overcharges the battery.
What I found was that while the voltage regulation of the IC was good, it has poor thermal stability and goes into a kind of thermal runaway when the
input voltage is high, and the IC, being a linear device has to dissipate a lot of heat.
The higher the input voltage, the more heat is generated, the IC gets hotter, and the output voltage rises.
Solution is to heatsink the IC better, or keep voltage down to around 5v to minimise heating.
The Ml-102 specs state 5volt input. the usb socket is as rated usb standard 5v. No real surprise if someone goes outside the specs then results aren’t what is required.
Mind you might be interesting to see if it would be possible to charge 4.3v-4.35v cells consistently without to much detriment to its lifespan, by over ‘volting’ its input
I didn’t notice it getting hot. Also my power power supply is 5v, no extra voltage here. I guess I’ll just connect the charger to computer port to finish charging.
Another problem with it - it won’t take my laptop pulls for emergency charger. It charges for about 5 min ~3% of my iphone’s battery and then stops. Samsung 26F I bought from BG work fine. I did expect them not to perform as well as new cells, but at least to get something. They can power my convoy L4 for about 40 min, convoy S2 (2100ma) for about an hour. Hard to believe the charger needs higher current than these flashlights. (For refernce it takes about 2h to deplete the samsung battery with the charger, about 80 min with convoy S2.)