Charging antimony-free VRLA batteries without float
Here is a proposed much lower float current method to charge non-antimony batteries. Supposedly better than traditional float. Low current float for AGM
Forum Discussion
Trying to find the routine for max battery life.
When bringing the AGMs into service my research showed that all strings vent a little from the stronger cells for the first few weeks. When I reconditioned my car AGM which ran flat, the procedure was actually designed to create bubbling and a small amount of venting.
I devised a simple way to find with each battery if there was any gassing going on by routing the vent hose into water or floating a ring of distilled (in case it were ingested) water on top. Based on watching these, and based on following manufacturer recommended charging protocol with various different chargers, it is my belief that AGMs vent a *little* (at a level you cannot hear or smell) far more than their owners may realize.
For example after our power outage, the first real use of the AGMs in production (I've still yet to load test them - need better short cables for the big inverter), I thought they were charged back to full. But this is tricky. I have found if they are really full they will have a voltage of 12.93v after 24 hours. They were only at 12.87.
I noticed the smart charger (I know, I know!) floats other batteries within a few hundredths of the manufacturer recommended float and temp was within a few degrees of 77, so I gave it a try. After not too long I saw a bubble, then a few minutes later one from another cell.
Because I do not leave them full time on float but top them off at least once a week, it is possible the string has not fully gone though it's initial equalization (supposed to take weeks under full time float) after which that initial minimal outgassing is supposed to stop.
SO I decidedly want to stay away from any venting (the bubble is not a bubble in free electrolyte, but it is still gas that escaped the regulation valve and was not recombined internally to electrolyte in the battery). The reconditioned AGM did make some bubbling noises as part of the reconditioning procedure. ABsolutely that dried out the AGM some but it restored capacity compared to a badly sulphated AGM that it was.
My desire here is to be able to really float indefinately, without any undected venting taking place. I think to really do that I am going to need a temperature compensated float charger.
Looking at the paper it was interesting to see what happens to a battery between no charging and an upper bound of float charging. I don't trust any charger I have yet to leave on the battery 24x7. Cranking something slightly to the low side is interesting to me - not sure if that or the daily cycles of solar would do the battery more good (since the battery sits not charging all night every night and does a tiny shallow cycle every day due to tiny self discharge).
Really it is more for my learning than anything else. But getting my little string on a near telecom grade of standby charge since it's usage is very much more like standby service than cycling service is just a bit of a hobby at the moment.
Jim
When bringing the AGMs into service my research showed that all strings vent a little from the stronger cells for the first few weeks. When I reconditioned my car AGM which ran flat, the procedure was actually designed to create bubbling and a small amount of venting.
I devised a simple way to find with each battery if there was any gassing going on by routing the vent hose into water or floating a ring of distilled (in case it were ingested) water on top. Based on watching these, and based on following manufacturer recommended charging protocol with various different chargers, it is my belief that AGMs vent a *little* (at a level you cannot hear or smell) far more than their owners may realize.
For example after our power outage, the first real use of the AGMs in production (I've still yet to load test them - need better short cables for the big inverter), I thought they were charged back to full. But this is tricky. I have found if they are really full they will have a voltage of 12.93v after 24 hours. They were only at 12.87.
I noticed the smart charger (I know, I know!) floats other batteries within a few hundredths of the manufacturer recommended float and temp was within a few degrees of 77, so I gave it a try. After not too long I saw a bubble, then a few minutes later one from another cell.
Because I do not leave them full time on float but top them off at least once a week, it is possible the string has not fully gone though it's initial equalization (supposed to take weeks under full time float) after which that initial minimal outgassing is supposed to stop.
SO I decidedly want to stay away from any venting (the bubble is not a bubble in free electrolyte, but it is still gas that escaped the regulation valve and was not recombined internally to electrolyte in the battery). The reconditioned AGM did make some bubbling noises as part of the reconditioning procedure. ABsolutely that dried out the AGM some but it restored capacity compared to a badly sulphated AGM that it was.
My desire here is to be able to really float indefinately, without any undected venting taking place. I think to really do that I am going to need a temperature compensated float charger.
Looking at the paper it was interesting to see what happens to a battery between no charging and an upper bound of float charging. I don't trust any charger I have yet to leave on the battery 24x7. Cranking something slightly to the low side is interesting to me - not sure if that or the daily cycles of solar would do the battery more good (since the battery sits not charging all night every night and does a tiny shallow cycle every day due to tiny self discharge).
Really it is more for my learning than anything else. But getting my little string on a near telecom grade of standby charge since it's usage is very much more like standby service than cycling service is just a bit of a hobby at the moment.
Jim
