AGM Charge Rates and Times
I am interested in knowing how fast AGM deep cycle batteries charge, especially in the upper SOC range. Things to consider: - Ah Capacity of battery/bank - starting SOC or DOD, or Ah's consum...
Forum Discussion
I can try and test the 13.8v acceptance on my Group 27 Northstar AGM versus my Screwy flooded 31.
From previous cycles of both, I can notice that when I set the MW voltage to 14.9v and let my Meanwell dump 41 amps into either. The Voltage rises faster on the flooded battery, and once battery voltage approaches 14.5v amps start tapering.
But it is not an even test as the AGM is 90 AH and the Screwy 31 claims 130AH, and now has over 330 deep cycles on it and the AGM, perhaps 30.
I do notice my AGM can accept more alternator amps than the flooded battery can. The larger flooded 31 tops out at about 75 to 80 amps when depleted, the Smaller Northstar AGM-27 will take 105a when my alternator belt starts squealing, so I don't really know how much it can take when depleted. Somewhere north of 105amps.
All I can say definitively is, is that my NS AGM cranks my engine faster, and holds higher voltages the next discharge cycle the higher the recharge rate is.
Odyssey AGM says a minimum of 40 amps for their 100AH group 31 when deeply cycled. So no low and slow solar recharge with these, if you believe their engineers. Northstar makes many similar claims as to performance and lifespan as Odyssey, so I've been using this 40% charge rate as the minimum for my NS AGM, and only cycle it deeply when I have grid power to run my MeanWell, or enough driving to do so that my alternator can quench the depleted battery at a high rate at least until the point where amps start tapering below 30.
I also have been making sure I only stop 14.7v after amps to hold 14.7 drop below 0.4a, and I have seen it take as little as 0.2A to hold 14.7v.
This Northstar battery has a rested OCV of 13.06v, and it held that for 3 weeks when I flew cross country for the holidaze.
I know this minimum high recharge rate does not float many people's boats. I'll believe the manufacturer and my own observations.
From previous cycles of both, I can notice that when I set the MW voltage to 14.9v and let my Meanwell dump 41 amps into either. The Voltage rises faster on the flooded battery, and once battery voltage approaches 14.5v amps start tapering.
But it is not an even test as the AGM is 90 AH and the Screwy 31 claims 130AH, and now has over 330 deep cycles on it and the AGM, perhaps 30.
I do notice my AGM can accept more alternator amps than the flooded battery can. The larger flooded 31 tops out at about 75 to 80 amps when depleted, the Smaller Northstar AGM-27 will take 105a when my alternator belt starts squealing, so I don't really know how much it can take when depleted. Somewhere north of 105amps.
All I can say definitively is, is that my NS AGM cranks my engine faster, and holds higher voltages the next discharge cycle the higher the recharge rate is.
Odyssey AGM says a minimum of 40 amps for their 100AH group 31 when deeply cycled. So no low and slow solar recharge with these, if you believe their engineers. Northstar makes many similar claims as to performance and lifespan as Odyssey, so I've been using this 40% charge rate as the minimum for my NS AGM, and only cycle it deeply when I have grid power to run my MeanWell, or enough driving to do so that my alternator can quench the depleted battery at a high rate at least until the point where amps start tapering below 30.
I also have been making sure I only stop 14.7v after amps to hold 14.7 drop below 0.4a, and I have seen it take as little as 0.2A to hold 14.7v.
This Northstar battery has a rested OCV of 13.06v, and it held that for 3 weeks when I flew cross country for the holidaze.
I know this minimum high recharge rate does not float many people's boats. I'll believe the manufacturer and my own observations.
