And Another Battery Question

[Katdaddy]

We just got back from our yearly trip to the Cades Cove. No hookups in the campground, so we are dry camping. I equalized the batteries right before we left and after resting overnight the batteries voltage showed 90%. We get to the campground and set up and voltage shows 70%. I have a solar panel and it would show the batteries fully charged by the end of the day, but as soon as the sun went down they went back down to 70ish%. Sams Club golf cart batteries. The temps at home before we left when I checked everything was in the 80s. Temps in the mountains were low 60s during the day and low 40s at night. I let the batteries rest overnight when we got home yesterday and voltage back to around 100%.
So, does altitude affect readings? I have a chart that I printed of web some years back that shows voltage readings according to temperature. That chart shows the 12.30 reading at the temps we were experiencing as between 90 to 100%. Is this in any way accurate?
With the solar panel we have plenty of juice, just trying to understand what is going on.
As always, thanks for all your help.

[MEXICOWANDERER]

Goosing the hydrometer bulb lightly ensures the bobber is vertical and free. It'll jiggle up and down.

If you cannot get the reading up to 1.280 or individual cells are uneven then your cells are sulfated and need equalization. Read the Rolls Battery download and follow the instructions. Then say HELLO to perhaps 20% more amp hour capacity.

[Katdaddy]

pianotuna wrote:
You can order one here:

https://www.bradyinstruments.com/products/battery/pro-battery-hydrometer-set-wcorrection-thermometer

Thanks!

[wa8yxm]

Ok charging voltage is around 14.6 likely less with solar but anything over 13.5 will do. 13.6 is "Float, full charge"
Less than that indicates the batteries never filled full. though 90% is often good enough.

RESTING voltage is a fair indication of battery state of charge. but you are not reading resting voltage.

What type of charge controller do you have PWM or MMPT?
And You might wish to add a panel rather than a pair of GC2
Though adding a pair of GC-2 won't hurt.. If you don't heave enough solar panels it won't help either.

[MEXICOWANDERER]

Buy a 18" of 2" black plastic pipe from Home Despot. Have the salesman help you get a cap for one end and a bushing and threaded plug for the other end. The hydrometer rubber bulb and tip act as shock absorbers.

Suck up a few charges of clear water after use. Tip up and clean out the bulb. This will keep the rubber like new for years.

[pianotuna]

You can order one here:

https://www.bradyinstruments.com/products/battery/pro-battery-hydrometer-set-wcorrection-thermometer

[Katdaddy]

MEXICOWANDERER wrote:
The ambiguity would be found with a hydrometer. There must be a hundred discussions on this forum about hydomerers usage, links, types and brands.

My Samsung cellular goes from 100 to 50% in three hours. Then from 45% to 12% shutdown the next hour. Next to useless.

Go to
Http://www.rollsbatteries.com
Download their battery manual
You have batteries exhibiting classic signs of partial sulfation.

Yes, I have decided that the hydrometer is going with me next year.
On a related note, I gave a cheaper hydrometer. I know that you have recommended a Francis Freas. I’m having trouble finding where to purchase one. Can anyone help with a website or store?

[MEXICOWANDERER]

The ambiguity would be found with a hydrometer. There must be a hundred discussions on this forum about hydomerers usage, links, types and brands.

My Samsung cellular goes from 100 to 50% in three hours. Then from 45% to 12% shutdown the next hour. Next to useless.

Go to
Http://www.rollsbatteries.com
Download their battery manual
You have batteries exhibiting classic signs of partial sulfation.

[Gjac]

How did you fully charge your batteries when you were home by solar or a battery charger? A fully charged battery should read more that 90% overnight. Did your son turn on the heat during the night? I assume you had a fairly long ride to get to Cades Cove and your alternator and solar should provide some charging along the way so to be at 70% SOC is a mystery. How many amps does your solar and alternator provide? How long was your drive was it at night? Now that it is home and fully charged I would disconnect the power and see how long it takes to drop to 90%. Then check each cell with a voltmeter or hydrometer and see if one or more cells are bad. I never had good luck with any hydrometer, mine always read 1.375 even in distilled water unless you have a real good one I find the volt meter easier to use. Last question when you measure battery SOC are you looking at a controller reading or using a multi meter at your actual battery posts?

[BFL13]

Must be an unknown 12v load when camping that is not on when at home. Not sure what it could be that draws it down 0.3v. Some inverter draw?

Sorry I implied you don't look after your 6s.

[Katdaddy]

BFL13 wrote:
What DC load is on the batts while camping for that 12.3 that is not on at home for that 12.6?

You can't tell "90% charge" with a load on the batts. You can get a voltage but can only guess at the % of capacity, and you have to guess at the capacity too, since it changes with temperature.

Your batts are no doubt sulfated somewhat from lack of time at 14.8v and equalizations to 16v from time to time, so they might have more of a voltage drop under load that batteries in better shape.

The loads are exactly the same. That is what is confusing me.
I exercise the batteries regularly. I draw them down to around 50% and then apply a 14.8 charge while checking the SG. Equalized right before this trip.

[Gdetrailer]

Katdaddy wrote:

2oldman wrote:

Katdaddy wrote:
The solar would show the voltage up to 13.00 during the day and then it would again drop to 12.30 after dark.

What does 'the solar would show' mean? The panel on the controller? During full sun?

The readout on the controller and my volt meter would read 13.00. Never had what I would call full sun. The most input I saw was 48 watts. The batteries read 12.30 when we got there and, with solar each day read 12.30 when we left.

Your batteries never got close to 100% "full".

13.00V from your panels was nothing more than trickle charging at the max.

Generally your battery needs to see 13.2V just to keep up with the internal self discharge of the batteries.

To effectively cause some meaningful charging to happen you need voltages of 13.8-14.4V.

Flooded Lead Acid batteries typically will have a fully charged resting voltage of 12.8V give or take .1V..

12.3V? Yeah, you have discharged or wornout batteries and your solar is not enough to fully charge them..

[BFL13]

What DC load is on the batts while camping for that 12.3 that is not on at home for that 12.6?

You can't tell "90% charge" with a load on the batts. You can get a voltage but can only guess at the % of capacity, and you have to guess at the capacity too, since it changes with temperature.

Your batts are no doubt sulfated somewhat from lack of time at 14.8v and equalizations to 16v from time to time, so they might have more of a voltage drop under load that batteries in better shape.

[Katdaddy]

2oldman wrote:

Katdaddy wrote:
The solar would show the voltage up to 13.00 during the day and then it would again drop to 12.30 after dark.

What does 'the solar would show' mean? The panel on the controller? During full sun?

The readout on the controller and my volt meter would read 13.00. Never had what I would call full sun. The most input I saw was 48 watts. The batteries read 12.30 when we got there and, with solar each day read 12.30 when we left.

[Katdaddy]

pianotuna wrote:
Katdaddy,

90% after sitting idle for 24 hours?

Yes.