[RE-wrenches] Trojan L-16s

[Drake]

Hi Larry,

I will bump up the absorb voltage to 29.6 V. How 
long do you think the bank should stay in absorb 
at that rate?  The bank now seems healthy, with 
the bad battery replaced.  It does accept charge, 
without going high prematurely.  The max charge 
rate from the array is around C/10. The system 
can also be fast charged from a Honda 6500 
inverter generator through the Outback 3524 VFX.

We have a Trimetric meter on the system. The 
discrepancy between the percent charge and the 
voltage is what demonstrated that we had a problem.

Thanks,

Drake



At 09:30 PM 7/19/2013, you wrote:
>Hi Drake,
>
>It always concerns me when I hear that a battery 
>bank reaches absorb setting very quickly. It 
>typically means one of two things: very few AH 
>were removed from the bank; the battery bank has 
>sulfated cells due to chronic undercharging. Far 
>too often I find the latter to be true.
>
>Healthy batteries will accept current and hold 
>the charge voltage down with a fairly linear, 
>slow climb to absorption voltage. Sulfated 
>batteries do not accept current well which 
>allows voltage to climb rapidly as the battery 
>presents little load on the charging system. I'm 
>not sure how this plays into your original post 
>about a bad cell but it seemed worth mentioning.
>
>My opinion is to aggressively charge, by using 
>higher voltage, large flooded batteries. This is 
>especially true when the PV system is moderate 
>or undersized. 29.6 volts is what Trojan 
>recommends. You can go as high as 32 volts on 
>the L-16's but make sure the temperature 
>compensation is installed properly and working. You will use more water.
>
>One last comment, I highly recommend that ALL 
>off grid systems have a battery capacity monitor 
>installed. It's kind of like flying an airplane 
>without a fuel gauge
it might not end in disaster.
>
>Larry Crutcher
>Starlight Solar Power Systems
>
>
>
>On Jul 18, 2013, at 1:11 PM, Drake 
><drake.chamberlin at redwoodalliance.org> wrote:
>
>Tom,
>
>The batteries usually reach absorb voltage 
>shortly after the sun hits the array. The reason 
>the bank wasn't working correctly is that one 
>cell was dead in one of the batteries.
>
>I could increase the absorb time to 4.6 hours 
>and the voltage to 29.6, especially since the 
>bank has a new battery. That is longer and 
>higher than I'd previously heard recommended. 
>What would be the effect on water 
>consumption?  How did you calculate the absorb time?
>
>Thanks,
>
>
>Drake
>
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