Harming Batteries by Overcharging

[my t30]

Howdy Folks,

So I have a question that's I've been looking for the answer to for a while.
My question is this, While equalizing(or just in charging), is it possible to damage a FLA battery by charging it for too long, if the temperature and fluid of the battery remain in safe limits?

For example, I've had equalizing charges go on for 6 hrs with the SG still slowly rising, But I stopped because I was worried about damaging the batteries by overcharging.

Just on a side note, how bad is it to have 1 odd length cable in a battery bank. I have a 48v 350AH bank, 8 batteries in series, that because of location has 6@1ft cables, and 1@4 ft cable. I am thinking now that was a mistake but I didn't know much when I put it in. 

Thankyou for your time.

[mike90045]

in series batteries, cable length is not an issue, amps are the same anywhere in a series circuit.
If it's way long, you may loose enough voltage to need to bump the controller up another 0.1V

In a parallel battery bank, the 1 long cable will increase resistance enough, that that one string, will suffer.

[Vic]

my t30,

As a general rule,   for FLAs,  try to limit the battery current to 5% of 20-hour Capacity or below,   once Veq is reached.

Temperature-compensate the EQ Voltage,  and,   or course use the BTS on all charge sources.

Watch the average battery temperatures.   Personally,  have not let battery temps rise above about 87 degrees F,  during an EQ.   Some manufacturers say to STOP an EQ,  if battery temps rise to 115 F.

It is quite possible,   that  higher battery temperatures would make it easier to drive the sulfates on the plates back into the electrolyte solution,  at elevated temperatures ...

Do not know the nature of your FLA batteries,  but if they need EQs that are in the six-hour range,   that doing more timely EQs are in order.   Assuming that you are counting EQ time,   as the time spent at Veq,  not EQ MPPT (if you are suing MidNite CCs).

For long EQs,  like you are noting,  it is quite possible that some of the time spent at Veq is via Grid or genset power.   So it would be good if you are using a charger,  not a CC,  that the Veq also be temperature compensated.   This can be done manually,  if it is not automatic,  if the charge source has a variable EQ voltage setting.

It is good to keep battery interconnects relatively short,   but as mike noted,   in a series circuit all currents are equal,   so you are just looking at the total voltage drop for all interconnects,  plus those from the battery to the inverter.

Also,   if it can work for your layout,  you can cable batteries  in a U configuration,  to avoid the longer lead from the end of a single (linear) string of batteries,   if that is your situation ...

FWIW,   Vic

[niel]

wow, was that a dyslexic blooper.

(if you are suing MidNite CCs)

[my t30]

You betcha I'm suing!   Going to be hard though, because I cant think of anything that midnight has done to me short of awesome service.

Yes, I am guilty of some neglect on the batteries. But I'm working on it.

From what I have seen, by the time Veq is reached, my battery current is under 5%. So I should be good there.

For temperature, I've never seen my batteries hit 87 degrees, that I can remember. But I'll keep an eye on it.

So the general consensus is that if the temperature and fluid are kept in check, then I should be good?  BTW has anyone else ever had to do a really long equalize before?

Thank-you Vic and Mike, I appreciate it

[dbcollen]

Rolls-Surrette has instructions for "Corrective Equalization" for their batteries, it involves long periods of high voltage and low current, while monitoring temperature and electrolyte level. I have used their procedure on some batteries for around 50hrs with good results. Their procedure is appropriate for all FLA batteries.

[Westbranch]

Can you tell us the battery make  and the charging parameters you are using?
There may be some fine tuning needed to your settings but without knowing what you use we are blind.. and can only make more generic comments.

hth