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
Boy oh boy, this is the exact reason I recommend serious battery users to establish new battery parameters for themselves, with their brand and type of battery. Data that OEM furnishes can only be interpreted as being ballpark especially with C/factors.
I charge my flooded batteries at 5% of rated amp hour capacity until electrolyte maxxes out. If I use a constant current discharge format, I note voltage way-points according to time at discharge. 30 minutes, X voltage, 60 minutes and so on. This will give me -rough- idea of VA capacity. When I reach a guesstimate of where 50% remaining "should be". I stop the load and wait for the chemistry to settle. The hydrometer tells me how far off my guesstimate was.
This can be done with an amp hour meter, but the whole point of the issue is WHERE THE VOLTAGE decides to settle at when according to the hydrometer and according to the amp hour meter, the accumulator has reached 50% discharge. If it was a perfect world, remaining voltage, amp hours, and specific gravity would all agree. Down here I have to work with tropic blend gravities and this skews ampere hours, voltage and amperage values. "Gee I am proposing using a 13.8 kWh bank but acid density will reduced from 1.280 to 1.265". Do the numbers add up. What happens when the operator expects 900 ampere hours from his batteries but they deliver 770? I have news for some folks - discharge EXACT AMPERE HOURS from a bank using different Peukert values and at the end you end up with a remaining ampere hours value that is different - even after letting a battery sit overnight. This is not really relevant with a small RV bank but the issue is this, managing a battery bank for energy -AND- time degradation (due to age) is infinitely easier with a kWh meter. Tesla and Volt adopted the same principle I was using in the 1980's. If I had conducted life-cycle testing using straight ampere hours, I would have gone nuts.
Yes, ampere hours reveal much more than determining remaining battery capacity by voltage. Hydrometer testing demands waiting until electrolyte becomes uniform. This is the primary effect of Peukert. Gee, how about we agitate the acid and see what effect it has on Peukert. Gee what if we present the plates with a gross excess of acid volume and see what that does. What effect does 1.300 SG have on the Peukert effect?
But again, may I stress kWh is most valuable when used for comparing IS/WAS electrical values in an RV environment. In the 80's I had to have an A to D board built, and hire a Cal Tech student by the name of Patel, to monitor and de-bug a multi-channel DC kWh testing computer program. It amounted to a gigantic budget buster.
I charge my flooded batteries at 5% of rated amp hour capacity until electrolyte maxxes out. If I use a constant current discharge format, I note voltage way-points according to time at discharge. 30 minutes, X voltage, 60 minutes and so on. This will give me -rough- idea of VA capacity. When I reach a guesstimate of where 50% remaining "should be". I stop the load and wait for the chemistry to settle. The hydrometer tells me how far off my guesstimate was.
This can be done with an amp hour meter, but the whole point of the issue is WHERE THE VOLTAGE decides to settle at when according to the hydrometer and according to the amp hour meter, the accumulator has reached 50% discharge. If it was a perfect world, remaining voltage, amp hours, and specific gravity would all agree. Down here I have to work with tropic blend gravities and this skews ampere hours, voltage and amperage values. "Gee I am proposing using a 13.8 kWh bank but acid density will reduced from 1.280 to 1.265". Do the numbers add up. What happens when the operator expects 900 ampere hours from his batteries but they deliver 770? I have news for some folks - discharge EXACT AMPERE HOURS from a bank using different Peukert values and at the end you end up with a remaining ampere hours value that is different - even after letting a battery sit overnight. This is not really relevant with a small RV bank but the issue is this, managing a battery bank for energy -AND- time degradation (due to age) is infinitely easier with a kWh meter. Tesla and Volt adopted the same principle I was using in the 1980's. If I had conducted life-cycle testing using straight ampere hours, I would have gone nuts.
Yes, ampere hours reveal much more than determining remaining battery capacity by voltage. Hydrometer testing demands waiting until electrolyte becomes uniform. This is the primary effect of Peukert. Gee, how about we agitate the acid and see what effect it has on Peukert. Gee what if we present the plates with a gross excess of acid volume and see what that does. What effect does 1.300 SG have on the Peukert effect?
But again, may I stress kWh is most valuable when used for comparing IS/WAS electrical values in an RV environment. In the 80's I had to have an A to D board built, and hire a Cal Tech student by the name of Patel, to monitor and de-bug a multi-channel DC kWh testing computer program. It amounted to a gigantic budget buster.
