I have a H6 pro charger that currently has locked firmware and a 14.8V lithium ion battery. I am not able to get the charger to charge the battery, I believe it is over-drained as the battery is reading 2.3V on the charger and also when testing with a multimeter.
Is there anyway to get the battery to charge? I have tried to unlock the firmware following the guide (H6 Pro Charger Firmware Unlock Guide), however it is not working. After downloading the loader and connecting the micro-USB, when the H6 turns on instead of updating the firmware. How can I unlock the firmware so that I can recharge the battery?
I will leave others to respond to your question about unlocking the H6 because I have not yet done this to mine.
In case you are not aware, sorry if you are, I would not trust a battery that has been discharged to 2.3vdc. If you choose to proceed, make sure you take great care to manage the risk of fire when charging. The life expectancy for this battery will also be degraded if it is truly at such a low SOC.
I’d agree with Jason - if a 4S battery pack has been discharged to 2V, TOTAL voltage, it has unfortunately been rendered useless. If a battery is slightly over-discharged, with voltage only slightly less than 3V per cell (12V, as 4S = 4in series, and for BR battery, 6 sets of these in parallel), the H6 charger will recognize this and slow-charge at first, to limit the amount of damage to the battery.
When an individual lithium-ion 18650 cell is discharged below 3V, its internal resistance has been permanently and significantly raised. Some copper might have dissolved into the electrolyte solution, and dendrites, metallic lithium crystalline structures could have formed that can pierce membranes they shouldn’t (this is happening on a microscopic level.) That higher internal resistance means the capacity, and cycle life, have been radically reduced, and while exposing it to higher voltages may recharge it to normal seeming levels, the risk of fire when doing so or operating the battery afterwards is considerably higher. Yikes!
Sorry for the news
It’s can be quite an interesting topic if you drill down into what’s happening on a chemical level!
Thanks for the replies. @tony-white do you know what the internal resistance values should be reading if the battery was reading as normal? Putting in an order for a new battery to power our ROV, but am curious to know about the resistance anyway.
Hi @Sam31 -
It takes a specialized measurement tool to know the internal resistance - I’m afraid I don’t know any values to be on the lookout for. Generally, when the voltage drops faster under load the internal resistance is higher.
