When to equalize

mountainman · June 2018

I have 2 6 volt gc batterys in series. 1 reads 1.275 other 1 reads 1.260. What's the recomended spread for eq.

Estragon · June 2018

From what I've read, some recommendations are time based (eg. monthly), and the SG based ones seem to be ~ 1-2pt variance. At 1.5pt variance, I'd probably go ahead and do an EQ assuming you haven't done one recently. Check water level, but don't fill right up (to avoid spillage)

I check mine each long weekend, so about every 3 months, and normally have to do at least one round (2hrs) of EQ.

mcgivor · June 2018

There are many schools of thought regarding equalization, some say once per month, others recommend every 6 months others say when the SG differs > 0.03 between cells, the latter is probably the best, in my opinion. Equalization is a stressful event for the batteries, but it is sometimes nesesary to perform, the SG is probably the most accurate means of determining what is actually happening. Keeping records is important to determine a trend, we all do that right? No we respond to a crises, it's good to hear you are taking readings, but it would appear the spread is minor, there is always difference between batteries, even if produced on the same day. Keep an eye on things with regular testing. Most battery failure is the result of undecharging, what are your current settings and battery manufacturers recommendations?

mountainman · June 2018

Specs on my batteries, don't include voltage or sg numbers or frequency on eq. Other than 1-3 hrs or until sg quits rising.

mcgivor · June 2018

Mine don't have any recommendations either, so I used Trojan specifications as a guide, tweaking voltage to see what works best, it seems their recommendations are pretty accurate for GC batteries, my preference is to run hot, by extending bulk at 29.6V for an hour before reducing to 29.2V for absorption for 24V nominal , or 14.8V and 14.6V for 12V nominal. It really depends on nightly loads, lightly loaded may require a less aggressive charging regime, but that's what works for me.

mountainman · June 2018

Just found this charge at c/10 at 2.583 per cell for 3 to 4 hrs maximum charge time 10 hrs. 15.5 volts charging?? I've been charging at 2.42

Estragon · June 2018

Mine are 2.55vpc - 15.3 for 12v bank. IIRC, setting is as recommended by US Battery.

mcgivor · June 2018

mountainman said:

Just found this charge at c/10 at 2.583 per cell for 3 to 4 hrs maximum charge time 10 hrs

Specifications for your actual batteries? Generally a C20 is used as a guide 15.49V is getting pretty close to EQ, proceed with caution.

mountainman · June 2018

Friend just sent me the specs 2.40 bulk 2.40 absorb 2.55 finish charge terminate after 3hrs and 2.55 eq. I'm new please explain. I no of bulk, absorb, float and equalize. What is finish?

Estragon · June 2018

Finish is a sort of mini-EQ.

mountainman · June 2018

I wonder is this Every day?

Estragon · June 2018

I think so (or however often the battery is recharged).

I prefer to set my Vabs a bit higher (2.45 vpc) and just do EQ as needed, and it seems to be working out okay for me. Like @mcgivor said, EQ is hard on the battery.

mountainman · June 2018

My first thoughts were you set up solar and use the power. I see now it's a bit more complicated. Thanks

mcgivor · June 2018

There is always a learning curve, some controllers have advanced settings which allow custom setpoints, such as boost or finish, which are very similar in concept. Lower priced units generally do not have such features, but there is always a way around, by setting voltages a little higher. The learning curve involves paying attention to all the parameters, depth of discharge, loads, charging, equalization etcetera, there is no set rules but rather guidelines, what works for one may not nesesarally work for another. To be frank, assume the first batteries as sacrificial, many loose the first bank prematurely, mostly to cronic undercharging, if you manage to get it right the first time, consider that a bonus. Creating a signature or posting exactly what equipment you have, will alow others to make more accurate suggestions.

MrM1 · June 2018

I have to set my Vabs to 2.61 vpc -

- or my Trojan L16 bank does not reach 1.277 on all cells. Its not that it cant do it at 2.54pvc, its just that if I set the Vabs lower than 2.61 the CC will drone on at 2-3 amps at the end of the charge until it either times out or runs out of daylight and then I sometimes dont reach 100% SG. And yes, 2.-3 amps is closer to .5% of the battery AH, but if I terminate at 2% I am no where near close to 100% SG. So yes there is a lot to it and yes there is a lot of trial and error getting it dialed in.

But I got to wonder, is 2.61 like a mini EQ ... or is it really hard on the batteries to do that hi a Vab daily?

Estragon · June 2018

2.55v is the recommended EQ voltage for my L16s (US Battery), and seems to work. 2.45 for daily absorb to ~1% of C seems to mostly work, but I do have to EQ every few months.

Maybe there's something in plate alloys or construction that means some batteries need higher voltages than others?

Do your batteries gas lots and heat with Vabs at 2.61? Using lots of water?

MrM1 · June 2018

I use about a quart or less of water per month for 12 cells in the L16s at 2.61vpc. The temp of the batteries never goes above 33C (and that rarely and only for the last few hours of charging) even in ambient temps of 35+C

When I tried charging at 30.5 Vabs or 2.54 I never used any water, although the cells were gassing slightly.

Estragon · June 2018

Temp not too high IMHO. My 12 L16s (36 cells) use 1-2 gallons per 6 month season, so a bit less but in the same ballpark. Sounds like the higher absorb voltage is what your bank needs to me.

When to equalize

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