Surrettes, still trying

Re: Surrettes, still trying

1300 AH at 12V?

Re: Surrettes, still trying

Blackcherry04 wrote: »

I removed 560 amp hrs over two days and ran a recharge @ 178 amps @ 14.9v ( took about 10 hrs )

You removed 560 amp hours and then had to put more than 1780 amp hours back into them? Sounds closer to an electric heater than a battery.

Re: Surrettes, still trying

Hi BC04,

OK, so you know that you did not exit Absorb due to time, but rather, it ended based on End Amps (?).

And, regarding the discharge, the rate of discharge has a Peukert factor, as you well know, and have compensated for this?

Have mentioned in the past that I believe that there is a Peukert effect in charging, as well. Very high charge rates result in lower "efficiency" of the charge, I have guessed.

You know batteries, and have more varied experience with them than I. And technically, the Capacity of these batteries is rated as if the electrolyte was 1.280, rather than the shipped SG of 1.265 (for almost all Surrettes). So your bank is probably about 1235 AH -- not that this would explain what you are seeing.

And, in the past you mentioned that you had Floated this bank over the Winter. Do you have a number of cycles on this bank at this point?

With similar-sized banks here, limit charge current to about 125 Amps max, and have not had this issue. As noted in the past, on a deep discharge to about 50% of 20 hr Capacity, These banks will need to really finish recharging on the second day when using an EA of 11.9 A at 14.5 V (Temp comped) equivalent. (a 48 V bank here). Believe that to be able to recharge these batteries on a single day, without changing the EA value, the Absorb voltage would have to be raised a few tenths of a volt. And, all of these batteries were made in 2005. One would expect the charge efficiency to decrease with age, but, these batteries may have a bit different plate metallurgy than do the current vintage Surrettes -- more Antinomy might cause more vigorous gassing, and so on. Sure do NOT know for sure.

It can be difficult to accurately measure the battery charge current on a 50 mV 500 A shunt. And, small errors in EA readings can have a fairly large effect on Absorb duration, as the slope of the finishing current is quite flat at the end of a full Absorption.

Guessing done for now. Good Luck, Vic

Re: Surrettes, still trying

Blackcherry04 wrote: »

Just going by the fact I can hear them bubbling and gurgling during absorb. But it is a point taken that is still could be only part of the plate and they are stratified

That is my point... that bubbling may not be from the lower parts of the plate. You may find that no amount of time at 14.9 volts will destratify a battery, but just a few tenths higher works.

I also wonder about temperature stratification in tall batteries... if the bottom of the battery is cooler than the top, the bottom would need a higher voltage than the top.

--vtMaps

Re: Surrettes, still trying

DMJ72 wrote: »

This may help, From Rolls' RE Tech bulletin :

[img]https://dl.dropbox ... ][/img]

DM172,

Am certain that this snippet that you posted, is from Surrette Bulletin 614, which disappeared from the Surrette site a number of years ago. Have been told that this was "controversial" within Surrette. Certainly the deep, deep discharge to completely DEAD @ 1.83 Vpc is something that I would never do intentionally, although, suppose this DOD would depend upon what if any current of any discharge happened to be. Also (waiting) to fully recharge at 30 days maximum seems to be pushing it, as well.

Surrette had mentioned, in at least one version of this Bulletin, that it was prepared for off-grid users who had Charge Acceptance concerns, and also were concerned about needing to run a genset every day to fully recharge batteries in inclement weather (etc). The poor charge acceptance appeared to have resulted in seldom/never cycling the battery very deeply. So deep and very deep discharges were suggested as a way of freshening the plates.

Agree with BC04, that ending Absorb at 2% of 20-hour Capacity, would reasonably severely undercharge any of the Surrettes here, at any reasonable Absorb V. Banks here need just under 1% of C, at reasonable Vabs for a full recharge.

And, BC, the rapid fall in charge current, to/below 2% of C seems curious. We are at 2% about 40 - 45% of the way through Absorb, and, that last part of Absorb is a gradual taper to the EA of about 11.9 A at 58.1-ish Volts. This Vabs bould be a bit lower, but have been skipping a Bulk for three days (the CC "Bulks" only to Vfloat each of these skip days, and then just maintains that for the day). Each skip day, the battery does get 60%, or so recharge, just not a full charge.

BC04, I do wonder about the accuracy of the charge current measurement. The charge currents you have noted, must be read from the Charger/s, at least for the EA value being met ... forgot to look around in this Thread and others to see if you have a Trimetric, or something that uses an accurate Deltec (or similar) Shunt. As noted before, making an accurate measurement form a 50 mV shunt can be difficult with many DMMs, although a Trimetric (so similar) device should be accurate enough.

Am using Classics and the WBjr with Deltec shunt, and appears to be very accurate (with a very small amount of jitter).

Surrette gives very good Tech Support, via 800-number telephone, and e-mail. As you probably, Steve Higgins, who spent some years at Outback Power is now Tech Support Manager at Surrette - so there IS someone there with RE background ... realize that you have Grid power available, but Steve has a lot of experience.

Still pondering the behavior of your Surrette bank ... these batts sure behave differently than any of the three Surrette banks here. FWIW.
Good Luck, Vic

Re: Surrettes, still trying

Blackcherry04 wrote: »

Based on this voltage ( 15.2v ) I can only raise the SG level .025-.030 per charging hour.

Blackcherry04 wrote: »

If I am at 1.220 after 5 hrs of absorb @ 15 v, I am in trouble. There is definitely something wrong in the way they accept a charge. Keep in mind that it took 20 hrs to raise them back to 1.265 last time out.

Have you considered raising your absorb voltage a few tenths of a volt? You only have two parameters to play with... absorb time and absorb voltage.... if you can't get there with longer time, then try getting there with higher voltage.

My L-16 bank cannot get up to 1.27 SG in a day's time at 29.2 volts absorb, but at 29.6 volts I can usually get there in 2 - 2.5 hours. It's too soon to say (4 years) whether the higher voltage is shortening their life, but I'm sure that the lower voltage will lead to sulfation.

--vtMaps

Re: Surrettes, still trying

Vic wrote: »

Wayne, great that your Surrettes are doing well. Your break-in process is probably similar to the one used here. Hope yours work out well, too.

Good Luck to you both. Sure am hoping for the best! Vic

Thanks for your comments Vic, and it's good to know my break-in process has been similar to yours, that yours are working out well for you.
Not kidding, the ones I have now, compared to the attention demanding Power Battery units, are acting more like (or almost) install and forget batteries. Perhaps because of the light duty they are tasked with, but the old ones had the same life. And after 11 years of dealing with 3 parallel strings, I LOVE the single string! Hope we'll still be saying that in 5 or 10 years.