Perhaps Capacity is Not King
I don't want to derail the current "charging AGM batteries" thread more than I already have.
During the course of that thread I was shopping for AGM batteries, trying to determine which ones could be properly charged by the sources I am likely to use. I wanted AGM because I've compromised two sets of paired group 27 Crown flooded's by not refilling them in time.
I had to be honest with myself, that my ~200 watts of solar returns a great majority of the overall amp hours I remove from my battery bank, and this is not likely to change.
My research into the recharge requirements by AGM's basically revealed that they all recommend a minimum bulk current. Odyssey claiming no less than 0.4C, some others more in line with flooded batteries at ~0.2C. Lifeline saying Pound them with as much as you possible can, but don't exceed 14.4v
Now we've all heard the solar recommendation of 100 watts per 100 amp hours of battery, but this figure is on the low end of the 5-13% of battery capacity recommended on AZ wind and sun forums.
My Crowns say to feed them 12 to 18 amps per Hundred amp hours of capacity. I had two '27s rated at 115 each, and on the best days in the summertime, they were splitting 13amps or so between them and still having a cycling compressor fridge reducing that to about 10 amps 20 minutes of each 60. There is a third '27 in the engine compartment which usually is not part of the solar current. Manual control.
My amp hour counter said they were returning to 0 amp hours from full. All indications were that they were returning to full, even SG readings, but they were getting only half the recommended bulk current listed by the manufacturer.
Now, I've been blaming my lack of watering them for their early demise at about 600 cycles to ~75% average SOC, but what if they were ALSO compromised by receiving only half the recommended bulk current cycle after cycle?
I use anywhere from 30 to 60A/h overnight, every night, and 8 days out of 10, 11 months a year, My solar seems to be able to return the amp hour counter back to or very close to zero.
Perhaps if I had just one house battery cycled to 50% nightly, I could come closer to meeting this 12 to 18 amp bulk current listed by Crown. Sure it would be cycled deeper and Peukert would have more to say about it all, but If I can get 2 years out of one battery, instead of 2 years out of 2 batteries, well, I come out ahead, cause I have not gotten more than 2 years out of the last two sets of Crowns.
My highest load is about 10 amps when recharging this laptop while on watching Tv and the fridge compressor kicks on, in regards to Peukert
Now my current set, which are dying fast, only had 3 of 12 cells in which the plates were slightly exposed, and that was over a year ago, so I am not sure how big an effect that had had on their lifespan. The SG in those cells returned to normal and if I did not write it down, I would have forgotten which had gotten low just by looking at SG readings
Having just one battery to water would be significantly easier in my set up, as 3 of the far cells are very difficult to reach unless I also remove my fridge. Sure I would have less of a buffer Zone for when the skies go gray for days on end, but I still have an isolated engine starting battery. I can always plug in when I need to, but I really prefer to not have to.
All three of my group '27's need replacement, Soon. Very soon, possibly yesterday.
I am seriously considering reducing my house bank to single group 31 or perhaps just a single group 27.
I am also thinking about replacing the engine battery with one of those High CCA AGM's that claim deep cycle ability. If I run down my house battery to the dangerous level I could always feed it with the engine battery and likely still not risk engine starting the next day. My alternator basically has no issues meeting and exceeding this 0.4c bulk requirement, even if it was required to share the current with the house battery. My current Schumacher can also meet the 0.4c requirement if it were connected only to the AGM. I do plan on getting a real converter in the 45 to 60 amp range.
Anyway 3 days ago I was ready to drop 650 dollars on 3 sears DHP group 65
Earlier today I was considering spending 760 dollars on 3 Full river group 27's AGM's
Or ~900$ on 3 Northstar group 27's, but determined my ability to recharge them with my methods would be woefully inadequate, if the manufacturers recommendations are required for good lifespan
But now I am thinking about spending ~ 350$ on one Single Flooded group 31 deep cycle and one group 65 DHP/Odyssey engine starting AGM battery, and I can cut that by a hundred dollars by just getting a flooded Engine battery.
So I'm thinking capacity is not king. Perhaps having too much capacity is the reason, or some degree of the reason, why my batteries have been not lasting as long as expected.
I am wondering how important this recommended minimum bulk current is to a flooded battery. I spoke to Odyssey's tech today and he said do not bother with their batteries if I can only feed them 0.05C, and other AGMs are similar or in the 0.2C range with Lifeline saying give them as much as you can possibly feed them upto 500 amps on a hundred amp hour battery
No doubt having only one battery to check and refill will have me less reluctant to do so. If I do not get it in time, I'm only compromising one battery, not two.
There is also the advantage of driving around town up and down hills with one less 62 LB paperweight in a 6400GVwR van. As far as charging an AGM and Flooded in parallel when driving, well I have a clamp on Ammeter so I can see how much the AGM is robbing of what is available.
Discuss.
During the course of that thread I was shopping for AGM batteries, trying to determine which ones could be properly charged by the sources I am likely to use. I wanted AGM because I've compromised two sets of paired group 27 Crown flooded's by not refilling them in time.
I had to be honest with myself, that my ~200 watts of solar returns a great majority of the overall amp hours I remove from my battery bank, and this is not likely to change.
My research into the recharge requirements by AGM's basically revealed that they all recommend a minimum bulk current. Odyssey claiming no less than 0.4C, some others more in line with flooded batteries at ~0.2C. Lifeline saying Pound them with as much as you possible can, but don't exceed 14.4v
Now we've all heard the solar recommendation of 100 watts per 100 amp hours of battery, but this figure is on the low end of the 5-13% of battery capacity recommended on AZ wind and sun forums.
My Crowns say to feed them 12 to 18 amps per Hundred amp hours of capacity. I had two '27s rated at 115 each, and on the best days in the summertime, they were splitting 13amps or so between them and still having a cycling compressor fridge reducing that to about 10 amps 20 minutes of each 60. There is a third '27 in the engine compartment which usually is not part of the solar current. Manual control.
My amp hour counter said they were returning to 0 amp hours from full. All indications were that they were returning to full, even SG readings, but they were getting only half the recommended bulk current listed by the manufacturer.
Now, I've been blaming my lack of watering them for their early demise at about 600 cycles to ~75% average SOC, but what if they were ALSO compromised by receiving only half the recommended bulk current cycle after cycle?
I use anywhere from 30 to 60A/h overnight, every night, and 8 days out of 10, 11 months a year, My solar seems to be able to return the amp hour counter back to or very close to zero.
Perhaps if I had just one house battery cycled to 50% nightly, I could come closer to meeting this 12 to 18 amp bulk current listed by Crown. Sure it would be cycled deeper and Peukert would have more to say about it all, but If I can get 2 years out of one battery, instead of 2 years out of 2 batteries, well, I come out ahead, cause I have not gotten more than 2 years out of the last two sets of Crowns.
My highest load is about 10 amps when recharging this laptop while on watching Tv and the fridge compressor kicks on, in regards to Peukert
Now my current set, which are dying fast, only had 3 of 12 cells in which the plates were slightly exposed, and that was over a year ago, so I am not sure how big an effect that had had on their lifespan. The SG in those cells returned to normal and if I did not write it down, I would have forgotten which had gotten low just by looking at SG readings
Having just one battery to water would be significantly easier in my set up, as 3 of the far cells are very difficult to reach unless I also remove my fridge. Sure I would have less of a buffer Zone for when the skies go gray for days on end, but I still have an isolated engine starting battery. I can always plug in when I need to, but I really prefer to not have to.
All three of my group '27's need replacement, Soon. Very soon, possibly yesterday.
I am seriously considering reducing my house bank to single group 31 or perhaps just a single group 27.
I am also thinking about replacing the engine battery with one of those High CCA AGM's that claim deep cycle ability. If I run down my house battery to the dangerous level I could always feed it with the engine battery and likely still not risk engine starting the next day. My alternator basically has no issues meeting and exceeding this 0.4c bulk requirement, even if it was required to share the current with the house battery. My current Schumacher can also meet the 0.4c requirement if it were connected only to the AGM. I do plan on getting a real converter in the 45 to 60 amp range.
Anyway 3 days ago I was ready to drop 650 dollars on 3 sears DHP group 65
Earlier today I was considering spending 760 dollars on 3 Full river group 27's AGM's
Or ~900$ on 3 Northstar group 27's, but determined my ability to recharge them with my methods would be woefully inadequate, if the manufacturers recommendations are required for good lifespan
But now I am thinking about spending ~ 350$ on one Single Flooded group 31 deep cycle and one group 65 DHP/Odyssey engine starting AGM battery, and I can cut that by a hundred dollars by just getting a flooded Engine battery.
So I'm thinking capacity is not king. Perhaps having too much capacity is the reason, or some degree of the reason, why my batteries have been not lasting as long as expected.
I am wondering how important this recommended minimum bulk current is to a flooded battery. I spoke to Odyssey's tech today and he said do not bother with their batteries if I can only feed them 0.05C, and other AGMs are similar or in the 0.2C range with Lifeline saying give them as much as you can possibly feed them upto 500 amps on a hundred amp hour battery
No doubt having only one battery to check and refill will have me less reluctant to do so. If I do not get it in time, I'm only compromising one battery, not two.
There is also the advantage of driving around town up and down hills with one less 62 LB paperweight in a 6400GVwR van. As far as charging an AGM and Flooded in parallel when driving, well I have a clamp on Ammeter so I can see how much the AGM is robbing of what is available.
Discuss.
