Max Charging Current of typical GC2 battery
Say the GC2 battery bank has been drawn down to 25-50%, what will be the max current they will initially accept? For sure it's greater than the ~24A max my solar charger has reported as that was l...
Forum Discussion
The usual 10% charging rate recommendations are for longer battery life as measured in number of cycles.
Meanwhile an RVer has to meet camping situations and get it done.
My requirement is to do 50-90s in two hours or a few minutes more (generator hours as set by the campground) if I cheat, and that 40% recharge has to be enough AHs to get me by till the next recharge.
I know I use about 70AH a day in summer plus at least another 70 in winter, so to get by in winter using 140AH where that is 40%, that means I need a bank with 350AH or more. So that is four batteries at 440AH (but that is at 25C and this is winter at 5C, so knock 10-15% off that 440 and you get say 380AH and your 50-90 is now about 152AH, which is enough to get by.
OK so how to replace 152AH in two hours? See ugly graph where the 70amps did it on a 220AH bank. This is a 380AH bank so 380/220 x 70 = 121 amps.
I need a generator that can run a charger doing at least 121 amps and a 121 amp charger. Turns out my 3000w Honda can handle 130amps worth of non-PF corrected chargers before popping a breaker. My collection of Vector chargers could do 130a.
Since then I have gone over to PowerMax adjustable converters, and their 100 amper is PF corrected. The Honda can run it and a PM3-55 amper without popping its breaker for a total of 155 amps initial charge. I crank the voltage to 15.2v at 5C which is the same as 14.8v at 25C. (Good luck with your 14.4v converter :( )
Target has been met and then some. Which is good because the furnace can use over 100AH a night and it is dark longer and so forth, so it can be 200AH a day --BTDT several times.
So how to get by really? Going to need more battery bank and cheat some on the two hours even at that 155 amps. But no problem--nobody else is nearby in the park and the rangers are all hiding inside where it is warm, and don't care about your generator, so you can do it! :)
Just to complete the math on that-- 200AH is 40% so 100% is 500AH needed where that is maybe 85% in the cold from a rated bank of 588AH so you need say four T-1275s at 150 each, or six T-105s at 225 x 3 = 675.
So that all works until you get AGMs rated at 100AH each and it says do not recharge at more than 27 amps per battery!!!! Oops, now what?
600AH minimum needed so that is six of those 100AH AGMs and six x 27 is 162 amps. Saved! 155 is my max with the Honda and the two chargers. But it will take a bit longer than the two hours to complete the 50-90, more like an extra half hour. So cheat! Do it when the rangers are out there with their chain saws going and they won't notice your Honda at all. :)
Also keep the AGMs inside your rig where it is nice and warm and gain 10-15% in AH capacity (but do not overcharge them so badly that they vent!--ie, do not go over that 27a per 100AH limit in the spec--unless your AGMs specify they can do more like some can)
So just get it done and if the batteries only last six years doing that instead of twelve by following the 10% charging rate recommended, too bad. You want to go camping or not?
Meanwhile an RVer has to meet camping situations and get it done.
My requirement is to do 50-90s in two hours or a few minutes more (generator hours as set by the campground) if I cheat, and that 40% recharge has to be enough AHs to get me by till the next recharge.
I know I use about 70AH a day in summer plus at least another 70 in winter, so to get by in winter using 140AH where that is 40%, that means I need a bank with 350AH or more. So that is four batteries at 440AH (but that is at 25C and this is winter at 5C, so knock 10-15% off that 440 and you get say 380AH and your 50-90 is now about 152AH, which is enough to get by.
OK so how to replace 152AH in two hours? See ugly graph where the 70amps did it on a 220AH bank. This is a 380AH bank so 380/220 x 70 = 121 amps.
I need a generator that can run a charger doing at least 121 amps and a 121 amp charger. Turns out my 3000w Honda can handle 130amps worth of non-PF corrected chargers before popping a breaker. My collection of Vector chargers could do 130a.
Since then I have gone over to PowerMax adjustable converters, and their 100 amper is PF corrected. The Honda can run it and a PM3-55 amper without popping its breaker for a total of 155 amps initial charge. I crank the voltage to 15.2v at 5C which is the same as 14.8v at 25C. (Good luck with your 14.4v converter :( )
Target has been met and then some. Which is good because the furnace can use over 100AH a night and it is dark longer and so forth, so it can be 200AH a day --BTDT several times.
So how to get by really? Going to need more battery bank and cheat some on the two hours even at that 155 amps. But no problem--nobody else is nearby in the park and the rangers are all hiding inside where it is warm, and don't care about your generator, so you can do it! :)
Just to complete the math on that-- 200AH is 40% so 100% is 500AH needed where that is maybe 85% in the cold from a rated bank of 588AH so you need say four T-1275s at 150 each, or six T-105s at 225 x 3 = 675.
So that all works until you get AGMs rated at 100AH each and it says do not recharge at more than 27 amps per battery!!!! Oops, now what?
600AH minimum needed so that is six of those 100AH AGMs and six x 27 is 162 amps. Saved! 155 is my max with the Honda and the two chargers. But it will take a bit longer than the two hours to complete the 50-90, more like an extra half hour. So cheat! Do it when the rangers are out there with their chain saws going and they won't notice your Honda at all. :)
Also keep the AGMs inside your rig where it is nice and warm and gain 10-15% in AH capacity (but do not overcharge them so badly that they vent!--ie, do not go over that 27a per 100AH limit in the spec--unless your AGMs specify they can do more like some can)
So just get it done and if the batteries only last six years doing that instead of twelve by following the 10% charging rate recommended, too bad. You want to go camping or not?
