Corona-times.. home-office..
Need my car for a trip next monday. Didn't move it for ~6 months. Battery measured ~1,7V.
[I really need to disconnect the battery when leaving the car unused for longer periods of time..]
What could I do?
Two-point strategy:
1. trying to reanimate the dead battery (takes the whole weekend).
2. buying a spare battery to be sure the car can be moved.. (buying a car battery on a Saturday in covid times is pricey, don't ask...)
2. was done quickly at a local shop.
1. is still in progress but seems to bring back the battery (52Ah):
First try: Special car battery charger with 14.6V but practically no current draw.
Second try: HP 6643A at 35V, 5A, CC mode: Battery started at ~26V, went down and settled at ~11.9V after 4h.
After the voltage had dropped to under 12V I noticed that the HP6643A put out loads of heat.
So I switched to my HP 6632B at 14.4V, 4A, CC mode to charge the battery from that ~11.9V to 14.3V at 0.7A now after roughly 11h.
Seems to have lost some capacity (charging isn't lossless..), put in ~55Ah.
Will test tomorrow by putting it back into the car and check voltage while starting the motor etc. Curious..
For measuring the battery's voltage I used one of my 34401 DMMs at 6 1/2 digit resolution.