MJLorton Solar Power and Electronic Measurement Equipment Forum

Solar Power => Solar Power => Topic started by: freedom123 on December 16, 2016, 04:16:05 AM

Title: Help with Lead crystal batteries
Post by: freedom123 on December 16, 2016, 04:16:05 AM
I have a solar installation with 29 solar panels through two Victron charge controllers feeding power into a Deltec
battery bank of 16 type 6-CNFJ-170 arranged in 4 banks of 4 to give 48V. The batteries are 16 months old.
The inverter is a Victron 8 kW 48V model.
The house base load is 650 W to 800 W. No geyser etc. Only minimal lights and 4 computers and 1 TV running.
The battery bank should deliver 4X170 AmpH = 680 AH at 48V.
ie +- 30 KwH
So the bank should hold the supply for more than 30 hours.
The battery bank lasts only max 4 hours.
I do not think that the batteries have been abused.
They have never been drawn down below 42V.
Can the experts please help with restoring the battery bank capacity.
Maybe the batteries have built up a memory.
I thought maybe to draw the batteries down to 0 or 1 V and recharging.

Title: Re: Help with Lead crystal batteries
Post by: SeanB on December 16, 2016, 11:18:29 AM
Some measurements will help. Disconnect each bank ( just one link in the middle is easiest) in turn on a sunny day after they have reached float voltage, and measure the open circuit voltage of each battery in each position in each bank. Measure after the bank has been isolated for 10 minutes, so the batteries can reach some equilibrium. This will tell you if there is a single dead cell in the pack, as the voltage will be lower than the rest of them.

As well check the voltage across the inverter battery terminals, to see if there are poor connections losing power, and to see that the low voltage cut out agrees with the voltage reported by the inverter.