SG readings - batteries toast or is my hydrometer out?

[Danjwilko]

Hi all,

So long story short I took readings around 3 months ago of my 8 115ah batteries after fully charging prior to putting into the bank (2 were toast and wouldn’t charge well at all). Readings all in the green around 1275-1280.

Anyway I’ve noticed voltage drop on day to day usage and my shunt seems to be losing ah around 5ah every couple of days according to its sync levels when hitting float. So first stop check batteries before redoing settings.

I decided to take SG readings once fully charged all the cells are within 1200-1205 range. I thought it a little odd so got a new bottle of distilled water and promptly took a reading, which was well off the top of the earring tube by about an inch. Didn’t even lift off the base even with a wiggle.
I was under the impression it should have read 1100 or as close to it as possible.

Am I incorrect and batteries actually toast or am I in need of a new hydrometer?

Cheers all.

Appreciate any input. Il be picking up a new hydrometer tomorrow either way just in case - two results always better than one.

 

[sunshine_eggo]

How many times have you equalized since then? Most recommend a 30-90 day equalization interval.
Are you using temperature compensated charging?
Have you confirmed the battery is charging to the set voltages with a separate voltmeter?

Water is 1.000

Cheapest option is another hydrometer.

SG readings should be taken AFTER a full charge and float for 2+ hours. Intake and expel the electrolyte 3 times before taking a reading.

1.250-1.255 is the lower end of nearly fully charged with most at 1.265+ (1.278 for Trojan) depending on type and alloying elements.

If every single one of your cells was 1.275-1.280 three months ago, and all of your cells are in the 1.200-1.205 range, it just sounds like you need some equalization.

 

[OzSolar]

Here's the one you need.

https://www.amazon.com/dp/B007CW8Y9S?ref=nb_sb_ss_w_as-reorder-t1_k6_1_9&amp=&crid=264P0DMIZ5OY0&amp=&sprefix=hydromter

 

[Prince Of Darkness]

AND, use ONLY Steam-Distilled Water, for topping-up electrolyte levels.
Rinse your high quality Hydrometer three times, with that distilled water, after each SG measurement session.

Have your charge settings changed, since you have noticed these lower SG readings?
What ARE your Absorb and Float voltage settings?
What is your Absorb time setting?
What brand and model number are your batteries? And are the batteries all the same age?

Enough questions for now, thanks for answers, Luke

 

[sunshine_eggo]

@Danjwilko

It was very polite of you to like all our posts.

Anything to add?

 

[Danjwilko]

How many times have you equalized since then? Most recommend a 30-90 day equalization interval.
Are you using temperature compensated charging?
Have you confirmed the battery is charging to the set voltages with a separate voltmeter?

Water is 1.000

Cheapest option is another hydrometer.

SG readings should be taken AFTER a full charge and float for 2+ hours. Intake and expel the electrolyte 3 times before taking a reading.

1.250-1.255 is the lower end of nearly fully charged with most at 1.265+ (1.278 for Trojan) depending on type and alloying elements.

If every single one of your cells was 1.275-1.280 three months ago, and all of your cells are in the 1.200-1.205 range, it just sounds like you need some equalization.

Apologises for the delay in replying been absolutely flat out very little time to do any testing or anything.

Honestly I’d never heard of the equalisation setting until I looked through the mppt.

I have just periodically switched them off the charging circuit when nearly full and topped them off with an external smart charger. Let them sit for 12hrs and test the voltage (to ensure all were the same and then connect them back up).

I’ve not tested the sg readings yet with the new hydrometer as I haven’t had time unfortunately.

Il ensure they all get a full charge and go through the equalisation and take some readings and go from there.

Il double check all the settings and get them posted up (more than likely tomorrow afternoon after the old work shift).

 

[sunshine_eggo]

Apologises for the delay in replying been absolutely flat out very little time to do any testing or anything.

Honestly I’d never heard of the equalisation setting until I looked through the mppt.

I have just periodically switched them off the charging circuit when nearly full and topped them off with an external smart charger. Let them sit for 12hrs and test the voltage (to ensure all were the same and then connect them back up).

I’ve not tested the sg readings yet with the new hydrometer as I haven’t had time unfortunately.

Il ensure they all get a full charge and go through the equalisation and take some readings and go from there.

Recommend you fully charge, float for 2 hours and THEN check SG. You need a baseline before you decide to equalize.

 

[Danjwilko]

Recommend you fully charge, float for 2 hours and THEN check SG. You need a baseline before you decide to equalize.

Update finally:
New hydrometer still reads off the chart for water, so not sure what’s happening there.

All readings are all 0.020+ on the new hydrometer. So fully charged and float for 3+ hrs
All are between 1.215-1.220 took a while with 36 cells to check and double check.

Currently going through a manual equalisation at around 31v.

 

[sunshine_eggo]

Update finally:
New hydrometer still reads off the chart for water, so not sure what’s happening there.

All readings are all 0.020+ on the new hydrometer. So fully charged and float for 3+ hrs
All are between 1.215-1.220 took a while with 36 cells to check and double check.

Currently going through a manual equalisation at around 31v.

Good that they're all above 1.200 and good that they're within .005.

Equalization is definitely needed. Standard is 32.4V unless the manufacturer specifies otherwise. Temperature compensation applies.

 

[Danjwilko]

Good that they're all above 1.200 and good that they're within .005.

Equalization is definitely needed. Standard is 32.4V unless the manufacturer specifies otherwise. Temperature compensation applies.

It’s using the standard 8% setting at the moment, looks to have dropped a little on voltage so may have been adjusting. Currently at 30.20v
Il adjust it up but being a little over cast not sure if it will hit the 32.4v target. Need more solar.

 

[sunshine_eggo]

It’s using the standard 8% setting at the moment, looks to have dropped a little on voltage so may have been adjusting. Currently at 30.20v
Il adjust it up but being a little over cast not sure if it will hit the 32.4v target. Need more solar.

As the battery temperature increases, it's not uncommon for voltage to drop a little. Make sure you monitor temperatures. Some allow as high as 120°F. I prefer ~100°F if the ambient is 75°F or below. if they get hot, you want to stop equalization and allow them to completely cool to ambient.