Hi folks, does anyone have experience with the AEG AL1218 cordless drill charger?

The charger and the drill work fine, but the old Ni-Cd battery packs are completely dead, so I swapped out the Ni-Cds for 18650s and added a little BMS board.

The charger is smart enough to handle Ni-Cd, NiMh and Li-ion from 12 to 18V, but how does it know which is which? There are four terminals on the battery. +VE, T1, T2 & -VE and on my NiCd pack there is a 6.8k NTC thermistor wired between +VE and T2, with T1 unused.

My guess is that the wiring of the thermistor tells the charger which battery technology to expect. Assuming there is always a thermistor and that either T1 or T2 is always used, there are five ways it can be connected. Before I try my newly-constructed Li-Ion packs, I'd like to be sure the charger will treat them nicely.

Does anyone have any experience of these chargers, or even a circuit diagram?

Thanks!

 

I don't have knowledge on that specific device but usually the thermistor is there to prevent overheating the battery during charging, and only that. It doesn't convey information on the battery chemistry.

The charger can likely infer the chemistry type by the voltage and how it responds to charging.

 

I don't have knowledge on that specific device but usually the thermistor is there to prevent overheating the battery during charging, and only that. It doesn't convey information on the battery chemistry.

The charger can likely infer the chemistry type by the voltage and how it responds to charging.

Thanks for taking the time to respond. I agree that sounds reasonable and it's possible that the T1 connection, which is populated on the charger PCB but unused on my batteries, may simply be there for backward compatibility with earlier models, but I'm uncomfortable with words like probably and likely.

I'll have to do the sensible thing and measure the current that the charger delivers.

 

You might try looking up how battery charger chips are typically wired. The data sheet should also explain how it decides which chemistry you have.