My Screwy 31
First off let me say I am not stressing over this. It's just a battery, it is only money, it is meeting my overnight needs, but it is displaying strange behavior, and I am curious as to why.
So the battery in question in a USbattery Group31 flooded deep cycle rated at 130 amp hours. I bought it late November last year.
I am cycling it nightly, anywhere from 25 to 70 amp hours, averaging in the low 30's. Recharging is primarily done by 198 watts of solar, sometimes assisted by short duration blasts by the alternator, and occasionally recharged with a 2/12/25 amp Schumacher charger on various settings.
Anyway I have before taken SG readings when various tools indicated they were fully charged and found levels alarmingly low.
I did some rewiring to allow this battery to be recharged independently and isolated and let the Schumacher do whatever it wanted with it a few different times, and this was kind of scary going up into the 16 volt range. However it did get the SG back up into the green at 1.270 or above.
After this treatment, the battery seemed to perform better in terms of overnight voltage held for the same amount removed, and I've been playing with my solar voltage setpoints and monitoring SG every few days (dropping daily) and averaging low 30's overnight amp hour removal.
Anyway the solar yesterday was not quite able to make my amp hour counter return to 0 amp hours from full, so I switched all loads to my other battery and put the Schumacher on the '31 on the 2 amp setting, and it went all happy green light on me quickly. My inline meter said it was taking 2.4 amps at 13.43 volts. I put a 50 amp load on it to drop voltage below 12.6 and restarted the Schumacher. Within a few minutes it had gone all happy green light again, and I left it alone. 6 hours later it was taking 0.4 amps to hold that 13.43. 8 hours after that and the Schumacher was cycling on and off, giving it about .25 amps for about 5 seconds then nothing for 15 seconds to hold 13.43v.
I removed the Schumacher. I waited 4 hours. No loads on battery at all. Voltage reads 13.23.
I bust out the hydrometer and take readings on the 3 easily accessible cells. 1.225, 1.220 and 1.225. Ambient temps in mid 60's battery case reads 64.5f.
This was after a dozen or so bulb squeezings to stir electrolyte, and to get all bubbles off the float. The electrolyte is clear.
Perhaps my Hydrometer is inaccurate I think, so I bust out my plastic one I trust less, but it concurs with the Turkey baster Hydrometer pretty much exactly on all 3 cells.
I bet if I cycle the battery to 50% tonight, then set the Schumacher loose on it tomorrow, it will get the SG back upto the greens.
I just find it bizarre that this battery can refuse any more charging current at acceptable voltages, holds high resting voltages as if fully charged, yet when a SG reading is taken, it is very low.
This seems to me as if this battery likes to be exercised harder and recharged at a higher rate with higher than normal voltages. That shallower cycles and lesser recharging currents make this battery appear to be fully charged, but the SG of the electrolyte says otherwise.
Yet it still meets my overnight needs even when the SG does not get back up into the greens.
I've never monitored SG on any other battery so closely so have no real basis for comparison. My experiences with this particular battery have me curious as to what is going on in there, and perhaps we can all discuss this and fill in some blanks.
So the battery in question in a USbattery Group31 flooded deep cycle rated at 130 amp hours. I bought it late November last year.
I am cycling it nightly, anywhere from 25 to 70 amp hours, averaging in the low 30's. Recharging is primarily done by 198 watts of solar, sometimes assisted by short duration blasts by the alternator, and occasionally recharged with a 2/12/25 amp Schumacher charger on various settings.
Anyway I have before taken SG readings when various tools indicated they were fully charged and found levels alarmingly low.
I did some rewiring to allow this battery to be recharged independently and isolated and let the Schumacher do whatever it wanted with it a few different times, and this was kind of scary going up into the 16 volt range. However it did get the SG back up into the green at 1.270 or above.
After this treatment, the battery seemed to perform better in terms of overnight voltage held for the same amount removed, and I've been playing with my solar voltage setpoints and monitoring SG every few days (dropping daily) and averaging low 30's overnight amp hour removal.
Anyway the solar yesterday was not quite able to make my amp hour counter return to 0 amp hours from full, so I switched all loads to my other battery and put the Schumacher on the '31 on the 2 amp setting, and it went all happy green light on me quickly. My inline meter said it was taking 2.4 amps at 13.43 volts. I put a 50 amp load on it to drop voltage below 12.6 and restarted the Schumacher. Within a few minutes it had gone all happy green light again, and I left it alone. 6 hours later it was taking 0.4 amps to hold that 13.43. 8 hours after that and the Schumacher was cycling on and off, giving it about .25 amps for about 5 seconds then nothing for 15 seconds to hold 13.43v.
I removed the Schumacher. I waited 4 hours. No loads on battery at all. Voltage reads 13.23.
I bust out the hydrometer and take readings on the 3 easily accessible cells. 1.225, 1.220 and 1.225. Ambient temps in mid 60's battery case reads 64.5f.
This was after a dozen or so bulb squeezings to stir electrolyte, and to get all bubbles off the float. The electrolyte is clear.
Perhaps my Hydrometer is inaccurate I think, so I bust out my plastic one I trust less, but it concurs with the Turkey baster Hydrometer pretty much exactly on all 3 cells.
I bet if I cycle the battery to 50% tonight, then set the Schumacher loose on it tomorrow, it will get the SG back upto the greens.
I just find it bizarre that this battery can refuse any more charging current at acceptable voltages, holds high resting voltages as if fully charged, yet when a SG reading is taken, it is very low.
This seems to me as if this battery likes to be exercised harder and recharged at a higher rate with higher than normal voltages. That shallower cycles and lesser recharging currents make this battery appear to be fully charged, but the SG of the electrolyte says otherwise.
Yet it still meets my overnight needs even when the SG does not get back up into the greens.
I've never monitored SG on any other battery so closely so have no real basis for comparison. My experiences with this particular battery have me curious as to what is going on in there, and perhaps we can all discuss this and fill in some blanks.
