New capacity rates for old batteries?

WaterWheelWaterWheel Registered Users Posts: 220 ✭✭✭

I was talking to someone in the tech dept at NAWS last week on a different subject and out of curiosity asked about pricing on another set of Crown 6v 395 amp/hr L-16 batteries.       I purchased 8 last August (local solar guy ordered from the factory, great price) and was considering doubling my battery bank so I needed matching batteries. 

He kept suggesting the Crown 440 amp/hr size and when I reminded him I need to match what I already had (395 amp/hr)  he said they were the same battery.        Due to changes in industry standards on how to measure amp capacity most battery manufacturers were increasing their rated amp capacities.

Anybody else noticed that battery ratings may have climbed???    Either way I'm leaving my battery size rating at 395 amp on the Conext battery monitor although I've noticed that the battery voltage after a cloudy day indicated more energy remaining in the battery than the Conext SOC meter does.

I have not used specific gravity to check the meter vs voltage readings yet to see which one is more accurate about remaining power in the batteries.

Conext XW6848 with PDP, SCP, 80/600 controller, and conext battery monitor

18 SW280 panels on Schletter ground mount

48v 790 amp/hr Crown battery bank

Comments

  • BB.BB. Super Moderators Posts: 26,768 admin
    Lead Acid Batteries are probably within 10-20% of of rate/nominal capacity (worst case) of actual cell to cell rating. They just are not that exact.

    It is possible that these are the same battery and mfg. tolerances, plate material/processing, etc. have allowed the factory to "bump up" capacity rating because the "average" process is more efficient (this is very common for electronics and solar panel mfg.... the 245 watt panel now is rated at 250 or 255 watts). Sometimes that can also be "binning" results too.

    The last major issue is the specific gravity that they fill the battery bank with. Obviously, you really do not want to mix batteries with different SG fills (higher specific gravity means higher capacity and slightly higher battery voltage--And can cause shorter battery life).

    If the batteries are within ~10% of each other--I would consider them to be "identical" for our purposes.

    At least, my guesses.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • WaterWheelWaterWheel Registered Users Posts: 220 ✭✭✭
    I had considered that they may have increased the SG of fill to raise capacity.      Since I live in a warm state that could further shorten battery life in my warmer climate.

    Conext XW6848 with PDP, SCP, 80/600 controller, and conext battery monitor

    18 SW280 panels on Schletter ground mount

    48v 790 amp/hr Crown battery bank

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