Gel battery monitoring??

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Re: Gel battery monitoring??

Postby SandyP » Wed Mar 28, 2018 1:34 pm

gpigeon wrote:...../....
So, if we have any other Energystore owners there....
1.what do you do with regards to boosting and equalising?
2.how old are your batteries?
3. how often do you monitor voltages across each cell?
4. have you noticed any drop off in performance?
5. If so, what was it you noticed?
Thanks.


Whilst I do not have your brand of batteries, our GEL batteries are 7 years old now and re your questions :

1) Normally, equalising charges are not required however the maker of our batteries indicates that if you see large discrepancies between the individual cell voltages when at float charge then an equalisation charge should be done.This may happen after exhaustive discharges, inadequate charging or when the battery temperature has been non-uniform. Our equalisation is 0.4V above our absorb voltage and takes ~4 hours.
2) 7 years
3) Once a month of if I know there have been issues with periods of incomplete recharging of the batteries.
4) Not at this stage.
5) N/A

According to our battery manufacturer the batteries take up to 4 years before the variation in cell voltages can settle down. Initially they indicate that we may see our cell float voltages vary from -0.1V to +0.2V (from your float setting) with this reducing to +/-0.05V over time.
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Re: Gel battery monitoring??

Postby gpigeon » Thu Mar 29, 2018 6:50 am

SandyP wrote: exhaustive discharges, inadequate charging or when the battery temperature has been non-uniform. Our equalisation is 0.4V above our absorb voltage and takes ~4 hours.
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[/quote]

"SandyP"....exhaustive discharges???? To what SOC do your batteries normally drop to? Max. to date? Inadequate charging??? Do your batteries get back to 100% SOC every day?

Exide are saying 58.8V for "boost" & "equalise" (2 hrs. @ 30 days). 57.6V for "absorb" & 55.2V for "float".

Schneider are saying NO boost or equalise!! 56.3V for "absorb" & 54.5V for "float".

Not much difference really and I am wondering does it really matter???

I have just had a look at the Hoppecke battery manual. Impressive 64 pages compared with a lousy 3 pages of the Exide manual!!!!
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Re: Gel battery monitoring??

Postby Gordon-Loomberah » Thu Mar 29, 2018 7:49 am

Do Schneider say no EQ for your battery in particular, or batteries in general?

gpigeon wrote:Exide are saying 58.8V for "boost" & "equalise" (2 hrs. @ 30 days). 57.6V for "absorb" & 55.2V for "float".


Any EQ time at high voltage is reducing your battery life a bit, so it should only be done when required, rather than on a regular basis, if you want to maximise your battery life. I wouldn't do any EQ if the cells are within +/-0.05V of the average.
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Re: Gel battery monitoring??

Postby jules » Thu Mar 29, 2018 8:06 am

There's a significant difference between Exide's 55.2V float and Schneider's 54.5V. Different brands and types of batteries can have differing float etc. voltages so the manufacturers figures are probably the best ones to go with there, unless there's strong evidence to the contrary.

There's also quite a difference between Exide's equalize/boost voltage of 57.6 and Schneider's absorb of 56.3V. As a brief boost [less than 10 minutes] the 57.6V might be ok but used to equalize for 2 hrs. it does seem quite high @ 2.4V above the float value. That's more like the sort of figure you'd see for a conventional lead-acid battery.

edit: see Gordon's post above :D
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Re: Gel battery monitoring??

Postby gpigeon » Thu Mar 29, 2018 8:38 am

Gordon-Loomberah wrote:Do Schneider say no EQ for your battery in particular, or batteries in general?

Any EQ time at high voltage is reducing your battery life a bit, so it should only be done when required, rather than on a regular basis, if you want to maximise your battery life. I wouldn't do any EQ if the cells are within +/-0.05V of the average.

Hi Gordon,
Schneider say No eqalisation for any Gel batteries.

re your suggested +/- 0.05V dev.
I have measured the cell V's 3 times since July 17. Deviation from avg. on those occasions was .042, .029 & .069. The min/max V,s of that latest reading (16 Feb) were 2.204 & 2.487.
The "mid point" V deviation from the Victron 702 monitor was 1.9%. I think the max allowable specified is 2%, so we are getting close. Generally however, that deviation is around 0.2%.

I will do another reading over the next day or so (raining today!!!) and see how things are.
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Re: Gel battery monitoring??

Postby SandyP » Thu Mar 29, 2018 8:37 pm

gpigeon wrote:
"SandyP"....exhaustive discharges???? To what SOC do your batteries normally drop to? Max. to date? Inadequate charging??? Do your batteries get back to 100% SOC every day?


Minimum SOC to date has been ~45% however under normal use it is around 80% when the place is occupied otherwise it is ~95% (running inverter, FW internet, router, cctv cameras etc. = ~3adc load on the battery bank 24x7).
The batteries do not always get back to 100% SOC every day and I see and "inadequate charging event" as being a period of 3 or more days without getting back to 100%SOC.

Currently, after 7 years of use, there is one battery (1st one on the +ve side of the bank) that is showing signs of persistently higher voltage when the battery bank is being floated.
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Re: Gel battery monitoring??

Postby gpigeon » Sat Mar 31, 2018 7:28 am

Ok, so I now have some communication going on between "Exide" & "Schneider" so I may get some clarification on this Equalizing charge issue.

I took another set of readings of all 24 cells yesterday....
Min V 2.273
Max V2.318
Avg V 2.291
Total V 54.99
This gives V dev to avg of 0.018V
according to the Victron 702 the mid point % dev was 0.1%.

That all looks pretty good tp me so I think I will go along with your suggestion Gordon....ie only perform Equalisation when the V dev to avg exceeds 0.05V.
However, I'll wait and see what the techo experts from Exide & Schneider come up with this next week.

SandyP...do you carry out Equalisation on your Hoppechke's?
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Re: Gel battery monitoring??

Postby SandyP » Sat Mar 31, 2018 12:25 pm

gpigeon wrote:SandyP...do you carry out Equalisation on your Hoppechke's?


Yes, only began doing equalisation charges over the last 12 months due to the one battery voltage being "off spec".
Here is a plot of the Eq. charging from my Victron BMV-700
BlkAbsFltEq.jpg
Eq Charge trace
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Re: Gel battery monitoring??

Postby Gordon-Loomberah » Sat Mar 31, 2018 12:39 pm

That's quite a long time at Veq SandyP, did the batteries get very warm?

Do you just run it for a set time, or monitor voltage and stop EQing when they are equal?

Normally with flooded cells, if you want max battery life, you'd stop EQing when the SGs were within spec range, but of course that isn't possible with gels, so voltage is all you have to go on.
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Re: Gel battery monitoring??

Postby SandyP » Sat Mar 31, 2018 2:06 pm

Hi Gordon,
I always want follow the Hoppecke manual which indicates that the equalisation charge process can be at a max voltage of 2.4V/cell for a period of up to 48 hours with the charge current not more than 20A per 100Ah nominal capacity. The charge process must end if the bat temps exceed 45 deg C and equalisation ends when the cell voltages do not rise for a period of 2 hours.
In my case the battery bank temps did not change at all, maybe as the charge current during equalisation was <1amp (ave. 0.5a)? Also the eq. voltage is only 0.4V above the abs. voltage - interestingly I have never "felt" any heat in the batteries during abs. or eq. charging.
The eq. stopped due to lack of solar input and at this stage the battery voltages had almost stabilized.
8 x Suntech 190W panels, FM60, VFX3024, Mate2, 12 x 2V 620Ah Hoppecke GEL OPzV batteries
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