Charge settings check

Re: Charge settings check

This is the Interstate Battery Charging FAQ:

-Bill

http://www.batteries-faq.com/activekb/questions.php?questionid=1

Charging recommendations for 6-volt deep cycle batteries. GC2-XHD, GC2-HD, GC2-RD










































































Notes: 1. All charging voltages shown above are for 80 degrees F. For every 10 degrees above 80 F reduce voltage by 0.028 VPC. For every 10 degrees below 80 F increase the voltage by 0.028 VPC.
2. VPC = Voltage Per Cell
3. Charging current; C = The amp hour (Ah) capacity rated at the 20 hour rate.
4. Float condition is for long term storage / (several weeks) inactivity. 5. Equalize every 4 to 8 weeks or when the difference in specific gravity readings vary by 0.020 points or more and always after a normal charge.

Other Charging Notes/Tips/ Definitions: Temperature Compensation: Increase voltage by .028 volts per cell for every 10 degrees below 80 F. Decrease voltage by .028 volts per cell for every 10 degrees above 80F. Typical phases on multi-stage chargers: Bulk: Initial phase where the voltage builds and the most current is provided to the battery. This is typically where the maximum current that the charger is capable of providing is supplied to the battery. i.e. A 10 amp charger will provide at or near 10 amps during this phase. Absorption: The phase where the voltage set point is held constant. Current will decrease gradually during this point as the battery internal resistance comes up. Float:

The maintenance or finishing phase of the charging cycle. Voltage is set at a minimum during this phase (usually 13.0c-13.5v) and current drops significantly. The battery should be nearly complete by the time this phase is reached. An anti sulfation stage may be added where voltage spikes to high levels for very brief time periods for a set amount of time determined by the charger manufacturer, to convert the battery active material back to it's original state. Badly sulfated batteries will not usually respond to this charging regime and will need to be replaced.

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Re: Charge settings check

I would start with these numbers... Monitor water usage (refill every ~2 months when cycling seems to be reasonable, filling every less than 1 month is probably over charging, and not filling every 6 months is probably under charging).

You want to batteries to fizz somewhat near the end of charging--And you can adjust the absorb time (as well as voltage set point) to get the battery bank ~90% State of Charge (several times a week on average).

More or less, solar RE systems have a limited amount of time to charge during the day (maybe ~6 hours on average over the year of "reasonable" sun for a fied array). So, that means, for batteries being cycled (say below 75% SOC), you need to get them recharged "somehow"... That means higher voltages and longer absorb times (especially during winter).

You may even end up with different settings during winter/summer months.

2320 Watts * 1/59 volts charging * 0.77 panel+controller derating = ~30 amps peak "average" charge current
30 amps / 464 AH capacity = 0.065 = 6.5% Rate of charge

You have close to a minimum array for charging a daily use battery bank--So it will probably spend "less time" at the absorb set point (less than 80% SOC, battery bank is usually below absorb set point, above ~90% the batteries will be at set point--At higher charging currents, the set point will be reached sooner --- like 85% or lower SOC).

So, how has your Specific Gravity been looking? Are you getting the battery bank >90% SOC at least once or twice a week?

If the batteries are using lots of water and/or getting "hot", then lowering your set point voltage and/or absorb time (2-4 hours vs 4-6 hours) would be good.

-Bill

PS: With my "non-expert" eyes, I don't see these values as being "high" for a flooded cell battery. They seem quite mild and may need to be raised (especially during winter/short charging periods).

Re: Charge settings check

verdigo wrote: »

Specific gravity is 2.70-2.75.

1.270 sg to 1.275 sg?

-Bill

Re: Charge settings check

That is typically pretty much a full charge.... You are not cycling them very much at this point--So you do not need to run on the high side for voltage/absorb time.

-Bill