Capacity Testing and 20 HR Rating
I'm thinking about doing a capacity test on my four GC2's. They have a 20hr rating of 215Ah. One thing I'm curious about is how the 20hr rating would have been determined. Being 6v, would they h...
Forum Discussion
Regarding the Load:
Killawatt's Amp Reading varied between 19.8 and 20.5, and averaged out to 20.45a (13 readings at 45 minute intervals). But this does not include fridge and meter draws of about 1a... so very close to a 21.45a load.
Trimetric's Amp reading varied between 21.4 and 22.4, and averaged out to just less than a 21.7a load. (41 readings at 15 minute intervals)
Using Trimetric's Amp Hour counter, I divided Amp Hours depleted by the Elapsed Time to determine load. So, for example:
-64.3 Ah / 3 hrs = 21.43a load
-119 Ah / 5.5 hrs = 21.64a load
-173 Ah / 8.0 hrs = 21.63a load
-216 Ah / 10 hrs = 21.6a load
At 1/2 hour intervals, 20 readings averaged out to 21.4575a
So I'm fairly confident the Load was very close to the 21.5a I was shooting for. My only concern is that the Trimetric was programmed to a 430Ah Capacity, beforehand, so I cannot help but wonder if it's calculations might be somewhat predetermined? So to put that worry to rest, I considered the resulting OCV, which was 12.15v, one hour after test. This seems in line with what most report as Vbatt at 50% soc. It also jives with my estimates, after a few 50% discharges, last fall.
Killawatt's Amp Reading varied between 19.8 and 20.5, and averaged out to 20.45a (13 readings at 45 minute intervals). But this does not include fridge and meter draws of about 1a... so very close to a 21.45a load.
Trimetric's Amp reading varied between 21.4 and 22.4, and averaged out to just less than a 21.7a load. (41 readings at 15 minute intervals)
Using Trimetric's Amp Hour counter, I divided Amp Hours depleted by the Elapsed Time to determine load. So, for example:
-64.3 Ah / 3 hrs = 21.43a load
-119 Ah / 5.5 hrs = 21.64a load
-173 Ah / 8.0 hrs = 21.63a load
-216 Ah / 10 hrs = 21.6a load
At 1/2 hour intervals, 20 readings averaged out to 21.4575a
So I'm fairly confident the Load was very close to the 21.5a I was shooting for. My only concern is that the Trimetric was programmed to a 430Ah Capacity, beforehand, so I cannot help but wonder if it's calculations might be somewhat predetermined? So to put that worry to rest, I considered the resulting OCV, which was 12.15v, one hour after test. This seems in line with what most report as Vbatt at 50% soc. It also jives with my estimates, after a few 50% discharges, last fall.
