Charging voltage for T-105s
Continuing my quest to learn everything I can about batteries and charging... Moved on from the group 24 Interstate, may mess with it more later. Also put the hydrometer with the floating balls whe...
Forum Discussion
Since this thread touches on a Psychotic Schumacher going to too high a voltage, and I got some new quick connects, I reassembled my Schumacher sc2500a.
I put new 10AWG wire right to the terminals on the circuit board, replacing the stock horrible 12awg which loved to get super hot passing just 25 amps. Some 45 amp anderson POwerpoles crimped and soldered to the 10awg, are about 12 inches away from the circuit board.
I attached it to the screwy31 over about 24 inches of 8awg, whose resting voltage was 12.33v, and set it to 25 amps and left it on starting battery, as opposed to the deep cycle or the AGM/Gel settings.
This thicker shorter 10awg allowed a maximum of 29.3amps to flow on the 25 amp setting, best previous measurement was 26.5 or so and the wires and powerpoles stayed cool..
The voltage reading on the Schumacher was a full volt LOWER than actual battery voltage measured at the terminals.
After 20 minutes I smelled charging battery, battery voltage was 15.4v, Schumacher voltage reading, 14.2v. It was accepting 19 amps at 15.4v, and gurgling and fizzing.
I set up an exhaust fan so as to not breathe charging fumes.
I let it go on the screwy31 for another 20 minutes. Battery terminal voltage 16.25v Schumacher display 15.3v, accepting 13.25 amps.
While I am not much concerned about the screwy31, this was just way too much current at way too high a voltage.
I pressed the selection button to choose AGM. After a few seconds the green light came on indicating full charge. Once battery voltage fell below 13.6v the Schumacher started increasing amps to hold 13.6v. 5 minutes later it was accepting 5.6 amps at 13.6v, so quite far from being anywhere near full charge. I'll let it go overnight at 13.6v.
It appears my 10awg wire made the voltage display even further off than before, and the Schumacher is even more crazy than before.
There is no internal potentiometers to perhaps calibrate the schumacher voltmeter. It does apparently believe its own voltmeter
but still, even if it actual battery voltage was 15.3v and not 16.25v , 13 amps on a single flooded group31 battery at 15.3v is simply abusive, and at 16.25v is asinine.
Other times it remains in the 14's for an hour or 2 but switches to float well before the battery is fully charged, and I would have to remove surface charge and restart it, lather rinse and repeat before the SG would max out, but sometimes it would go back upto 16.4 battery gurgling volts or even higher and shut itself down..
They only sold this charger for a short while before pulling it off the shelves, and then the maximum amperage was 15 amps from this same general layout of charger and they still went to too high a voltage:
https://www.youtube.com/watch?v=5BF8FB__iR8&list=UUoPqTkOluQsuu3RpGnxVwFw&index=41.
I'm not quite sure how Schumacher has gotten these chargers past the lawyers. It seems that they do exactly the opposite of most other smart chargers in that they blow right past absorption voltage with high amps and make a flooded battery gurgle and fizz. probably make an AGM open its vents.
I'll likely just use this on the 2 amp setting from now on, or just use it on the AGM setting and force float mode at 13.6v, but I'll never put it on a battery I care about again and leave it unattended unless I force it into float mode.
I put new 10AWG wire right to the terminals on the circuit board, replacing the stock horrible 12awg which loved to get super hot passing just 25 amps. Some 45 amp anderson POwerpoles crimped and soldered to the 10awg, are about 12 inches away from the circuit board.
I attached it to the screwy31 over about 24 inches of 8awg, whose resting voltage was 12.33v, and set it to 25 amps and left it on starting battery, as opposed to the deep cycle or the AGM/Gel settings.
This thicker shorter 10awg allowed a maximum of 29.3amps to flow on the 25 amp setting, best previous measurement was 26.5 or so and the wires and powerpoles stayed cool..
The voltage reading on the Schumacher was a full volt LOWER than actual battery voltage measured at the terminals.
After 20 minutes I smelled charging battery, battery voltage was 15.4v, Schumacher voltage reading, 14.2v. It was accepting 19 amps at 15.4v, and gurgling and fizzing.
I set up an exhaust fan so as to not breathe charging fumes.
I let it go on the screwy31 for another 20 minutes. Battery terminal voltage 16.25v Schumacher display 15.3v, accepting 13.25 amps.
While I am not much concerned about the screwy31, this was just way too much current at way too high a voltage.
I pressed the selection button to choose AGM. After a few seconds the green light came on indicating full charge. Once battery voltage fell below 13.6v the Schumacher started increasing amps to hold 13.6v. 5 minutes later it was accepting 5.6 amps at 13.6v, so quite far from being anywhere near full charge. I'll let it go overnight at 13.6v.
It appears my 10awg wire made the voltage display even further off than before, and the Schumacher is even more crazy than before.
There is no internal potentiometers to perhaps calibrate the schumacher voltmeter. It does apparently believe its own voltmeter
but still, even if it actual battery voltage was 15.3v and not 16.25v , 13 amps on a single flooded group31 battery at 15.3v is simply abusive, and at 16.25v is asinine.
Other times it remains in the 14's for an hour or 2 but switches to float well before the battery is fully charged, and I would have to remove surface charge and restart it, lather rinse and repeat before the SG would max out, but sometimes it would go back upto 16.4 battery gurgling volts or even higher and shut itself down..
They only sold this charger for a short while before pulling it off the shelves, and then the maximum amperage was 15 amps from this same general layout of charger and they still went to too high a voltage:
https://www.youtube.com/watch?v=5BF8FB__iR8&list=UUoPqTkOluQsuu3RpGnxVwFw&index=41.
I'm not quite sure how Schumacher has gotten these chargers past the lawyers. It seems that they do exactly the opposite of most other smart chargers in that they blow right past absorption voltage with high amps and make a flooded battery gurgle and fizz. probably make an AGM open its vents.
I'll likely just use this on the 2 amp setting from now on, or just use it on the AGM setting and force float mode at 13.6v, but I'll never put it on a battery I care about again and leave it unattended unless I force it into float mode.
