At 0.07 volts there is not much chance that old AGM would ever be useable.
I have owned one of these 4 amp chargers for 5 years and believe it works somewhat
https://www.pulsetech.net/store/12v...tery-maintenance-charger-desulfator.htmlI wish it had another led light for 90% Charge level between the 75% and 100% leds that are provided.
Pulsetech claims they do not use simple voltage to judge percent charge,
but “charge current acceptance”
which I take to be similar to impedance.
It takes a long time to go from 75% charge to 100%
sometimes 36 hours.
I put a $21 Kill-A-Watt power meter on it to get a better sense of how things are going.
https://en.wikipedia.org/wiki/Kill_A_Watthttps://www.pondliner.com/kill-a-wa...q2I6i6gIVc-W1Ch05YA3oEAQYAyABEgL29vD_BwENo load it consumes 2 watts.
When starting to charge a lead acid battery that was below 12.3 static voltage the Pulsetech will use 48 watts and the led for 25% charged will light. When it gets to 100% charge it will show 4 watts being consumed by the Powetech.
When the Powertech is charging a battery
an AM radio will have a lot of radio frequency interference (RFI) buzzing noise at 530 kilohertz.
