> the difference between being 1cm over the plates to being 3cm over the plates I calculated SG would be about 1.30 if you are missing 2cm from a S-605. Maybe it was overfilled with acid mix.https://www.thesolarbiz.com/media/catalog/product/r/o/Rolls_Surrette_S-605_Data_Sheet.pdf
Ako said, " ... Looking at the fact sheet it stated theres 57mm reserve fluid above the plates , that is a lot however it shows 12kg difference between dry and wet weight , thats 4 kg of fluid a cell so 4 ltrs per cell ...".
A bit of nit to pick, but, the above is true if the fill fluid is pure water. For the speced electrolyte -- 1.280 --, the electrolyte weight would be about 3.125 kg.
The speced Electrolyte Reserve, is most often the total distance from the top of the plates to the top of the shoulder of the fill tube -- the point of overflow of the jar. This is customarily a electrolyte height is not something that anyone could use, in practice.
Trying to calculate the effect of adding make-up water on a cell's SG is fairly difficult, due to having too little real data, and the difficulty of testing the effect of adding water upon measured SG, IMO.
It would be nice to know the number of Ah removed from these batteries on a typical night. This would help in determining the actual DOD of the batteries. Deep-Cycle batteries DO need to be cycled. Frequent charging of lightly-cycled batteries can cause some SG anomalies, although, perhaps not from nominal 1.265, to 1.300 SGs.
There are probably several things going on with this bank. FWIW, Vic
Ako, Thanks for the info on your readings on Ah consumed and returned ... did not know/forgot that you had the ability to report this.
One other thing; for whatever reason, it appears that your CC is doing a "Re-Bulk", after the end of Absorb -- this is when the CC begins another charge cycle, after the first on a given day.
Generally, most of us try to avoid this, unless the system has a relatively small battery, and/or large, infrequent loads during the day (like pumping water).
This could easily add battery charging, that you really might not want/need.
Usually, there is a setting, like Re-Bulk voltage that could fine-tune this to the needs of your system.
Just guessing, and perhaps you have carefully set this function, for the needs of your batteries, but it seems that this is adding some uncertainty/unpredictability to the operation of the system, IMO.
Later, thanks, Vic
mcgivor, Thanks for that info, the function is similar, although the effect of "overcharging" is PROBABLY reduced, but it seems to create uncertainty.
If this undesirable function is not triggered by battery voltage, then perhaps it is based upon PV in voltage, but, to me, it would be of NO use, and undesirable, particularly in a system that appears to suffer from "overcharging" the batteries. If a system has adequate battery Capacity, then Floating out the end of available sun would be preferable than increasing the Float voltage (or however one chooses to look at it.
IMO, for this system, as it appears to be operating, REDUCING the Float voltage seems in order.
The Surrette batteries in use here, use a Vflt of 52.4 (26.2 per 24 V), as has been recommended for a number of years. This recommendation has been increased in the past few years. But, we do NOT need that boosted Vflt, let alone, a second attempt at a Bulk near the end of the day.
As always just IMO. FWIW, Vic
> A bit of nit to pick, but, the above is true if the fill fluid is pure water. For the speced electrolyte -- 1.280 --, the electrolyte weight would be about 3.125 kg.12kg is 12kg. So you must mean volume = 3.125 liters. It would be interesting to see confirmation that SG on a fully charged balanced battery doesn't rise further if you overcharge. I expect that the reason no further SG rise isn't used for determining full charge is that it's impractical.
YES, jonr, had wondered if I had made that mistake, later, but got wound up in projects and forgot to check.
Surrette specs many, many things, but the reserve volume to some stated height might be useful, but there are variables in the way these batteries are made that might make that less than useful.
Thanks Ako, for the info.
Guess, that if when in Float later in a day, and a larger load comes on, that the CC returns to Bulk -> Absorb, until the end Absorb parameters are again met ... dunno, we like mysteries.
Back to work now, will re-read your post above. Thanks, Vic
Ako, that 12 = 12 comment from jonr, am sure, was meant for me and my error in a previous post.
YES BB Bill, that 1.280 was my assumption for the nominal electrolyte density, as the relevant specs are based on 1.280 SG fill electrolyte . That was what was used to estimate the nominal volume of 4 kg of electrolyte ... There still be errors in my previous post ... just buried in plumbing projects ... no time ...
FWIW, Later, Thanks, Vic
Ako, Thanks for providing the Float and early Bulk SGs.
There is more variation in the SGs than I would have guessed. AND, for those measurements, it seems that your high SG situation, is not as extreme, as you noted before -- perhaps some of your changes to the charge parameters are helping (?),
If this were my battery bank, would try to discharge it deeper than normal -- to about 65-ish percent SOC. Watch the voltage on the second battery in the table (the one with the lowest SG cell), or the SG of that battery/cell during the discharge. Deep-cycle batteries DO like to be cycled relatively deeply, on occasion.
After this discharge, fully charge the bank, and EQ it in the lower range of the recommended EQ voltage, if possible with the TS-60. Would recommend trying to recharge the battery immediately after this discharge, as letting a fairly deeply-discharged battery sit, off-charge is not the best thing to do.
If you could try charging only that battery with a 6 V charger, that might be even better. If doing this, the output of that charger must not have its output connected to the safety ground, or either AC input connection ... am not certain where you are located, and the standards used for safety grounding, and weather the battery has a connection to any safety ground in your system. If you have a 6 V charger, you could quite possibly charge this lagging battery while the system is running in Float. This might be an adventure that you might not want to try.
FWIW, just some opinions, Vic