Since we will usually be using our new batteries with moderate discharges of hopefully under 50% most of the time, I decided to run a test of the batteries and charger to see what to expect in the real world once they are installed. Hopefully, it will also give some insight to how they will behave off of the engine and solar charging also. The cable length issue and getting the charger to start bulk automatically were already fixed when this was run.
The batteries are Lifeline GPL4CT 6 volt GC2 case batteries wired series first than parallel for a total of 440ah at 12 volts. Charger is a 100 amp Magnum setup for return (ending) amp float transition and with 14.5 volt absorption that is temp controlled.
The batteries had been charged totally as series pairs, not together, as the state of charge was quite different between them. It was done as return amp transition, so they were as full as they would get.
I used a hotplate running through the Magnum 2000 watt PSW inverter for most of the draw down, running at 65 amps with some off time when the hotplate thermostat cycled. Some was also done testing things like DW's home hair dryer to see how much it would pull and if the batteries could do it. (173 amps of DC). On average it was at about the 8 hour discharge rate, which is much faster than we usually use power as we would be in the 100-200 hour rate.
The 65 amp load dropped the voltage by about .5 volts compared to rested batteries. I only had two spots to test, at the start and finish, but it was the same at both.
I monitored the current coming out of each of the batteries over the entire discharge time, and it was never more than 1 amp difference between them. I was very surprised, and happy, about that.
At the end of the test, stopped when 220ah had been removed, the batteries were reading 12.13 volts. They recovered to 12.3 volts after a couple hours rest. This is very surprising as the 12.3 volts on the 8hr discharge curve would only be 32% discharge, not the 50% indicated by the 220ah removal. It is even less than expected if we were at the 20 hour rate where it would indicate a 40% discharge. Either the batteries are performing way better than predicted, or the chart is wrong, or I am doing something wrong, as that is a pretty significant difference.
Here is how it looks on the state of discharge chart
The batteries are Lifeline GPL4CT 6 volt GC2 case batteries wired series first than parallel for a total of 440ah at 12 volts. Charger is a 100 amp Magnum setup for return (ending) amp float transition and with 14.5 volt absorption that is temp controlled.
The batteries had been charged totally as series pairs, not together, as the state of charge was quite different between them. It was done as return amp transition, so they were as full as they would get.
I used a hotplate running through the Magnum 2000 watt PSW inverter for most of the draw down, running at 65 amps with some off time when the hotplate thermostat cycled. Some was also done testing things like DW's home hair dryer to see how much it would pull and if the batteries could do it. (173 amps of DC). On average it was at about the 8 hour discharge rate, which is much faster than we usually use power as we would be in the 100-200 hour rate.
The 65 amp load dropped the voltage by about .5 volts compared to rested batteries. I only had two spots to test, at the start and finish, but it was the same at both.
I monitored the current coming out of each of the batteries over the entire discharge time, and it was never more than 1 amp difference between them. I was very surprised, and happy, about that.
At the end of the test, stopped when 220ah had been removed, the batteries were reading 12.13 volts. They recovered to 12.3 volts after a couple hours rest. This is very surprising as the 12.3 volts on the 8hr discharge curve would only be 32% discharge, not the 50% indicated by the 220ah removal. It is even less than expected if we were at the 20 hour rate where it would indicate a 40% discharge. Either the batteries are performing way better than predicted, or the chart is wrong, or I am doing something wrong, as that is a pretty significant difference.
Here is how it looks on the state of discharge chart