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
Definitely not trying to walk the tight wire or go over voltage. I am trying to validate and feel safe with the OEM float voltage (along with the accuracy of my instruments and power supplies).
When my New AGMs are still just a few percent below fully charged, they can sit for days and days at float at the proper temp, barely, sloooowly, gaining charge.
When they are truly full, just a tenth of a volt high with temps outside in the low-mid 70s seems to develop a stray bubble here of there in less than an hour. It seems at times even just the OEM float voltage will do this. How would anyone not testing for this gas from the valves ever know it is happening? Crazy swags at this level of out gassing and the water it would remove suggest it would be years before that level of gassing would remove many ounces of water. So it may not matter.
I wonder if in the end I may need to run .05 or .1 v less than the recommended float if I really want to float full time.
Next thing I am going to do is run some temp studies at different voltages for float on a full battery. Mex suggested this and I got an IR gun (the one the chemist uses to make his tea on Breaking Bad in fact). Mex told me even one degree of temp increase to too much so I am going to look for that as a sign the energy in is exceeding the self discharge. The exothermic nature of the valves means they heat up even before a bubble of gas escapes, I believe, due to their catalytic purpose of recombining the oxygen and hydrogen back into water. I will check both terminal temp but also the temp of each valve. Hmm thinking about that the temp of each valve under heavy charge may actually show me which cells are stronger, and I could see if the temps settle closer together over time as the string settles in to run as a more balanced set of cells.
One thing this all convinces me of is running AGMs in an untemp-controlled environment without temperature compensation can leave them chronically undercharged, overcharged, or oscillating between states with the weather. It's amazing to me they do as well as they do in starting ignition lighting service. Maybe it is because most starting batteries are chronically undercharged and AGMs handle this better than Flooded batteries. It still kills them, but supposedly they sulphate from it more slowly.
Jim
When my New AGMs are still just a few percent below fully charged, they can sit for days and days at float at the proper temp, barely, sloooowly, gaining charge.
When they are truly full, just a tenth of a volt high with temps outside in the low-mid 70s seems to develop a stray bubble here of there in less than an hour. It seems at times even just the OEM float voltage will do this. How would anyone not testing for this gas from the valves ever know it is happening? Crazy swags at this level of out gassing and the water it would remove suggest it would be years before that level of gassing would remove many ounces of water. So it may not matter.
I wonder if in the end I may need to run .05 or .1 v less than the recommended float if I really want to float full time.
Next thing I am going to do is run some temp studies at different voltages for float on a full battery. Mex suggested this and I got an IR gun (the one the chemist uses to make his tea on Breaking Bad in fact). Mex told me even one degree of temp increase to too much so I am going to look for that as a sign the energy in is exceeding the self discharge. The exothermic nature of the valves means they heat up even before a bubble of gas escapes, I believe, due to their catalytic purpose of recombining the oxygen and hydrogen back into water. I will check both terminal temp but also the temp of each valve. Hmm thinking about that the temp of each valve under heavy charge may actually show me which cells are stronger, and I could see if the temps settle closer together over time as the string settles in to run as a more balanced set of cells.
One thing this all convinces me of is running AGMs in an untemp-controlled environment without temperature compensation can leave them chronically undercharged, overcharged, or oscillating between states with the weather. It's amazing to me they do as well as they do in starting ignition lighting service. Maybe it is because most starting batteries are chronically undercharged and AGMs handle this better than Flooded batteries. It still kills them, but supposedly they sulphate from it more slowly.
Jim
