Bernie and Carols Isuzu fit out.

[T1 Terry]

Are they really gel electrolyte batteries, or are they actually AGM batteries? Gel batteries are an absolute pain in the rectum to get fully charged and keep them fully charged, they do no suit long term solar only charging use as the sun doesn't shine long enough to get all the sulphur out of the plates and back into the electrolyte because the charging voltage must be held low to stop gassing which forms bubbles between the plate and gel electrolyte, this reduces the contact area which in turn reduces the storage capacity.
If they are actually AGM batteries the bulk voltage goes up to 14.8v and absorption voltage to 14.4v and should be held there for at least 4 hrs if the system is being used in cycling mode, float is only for systems that have longer charging capability like a mains charger, the sun doesn't shine long enough to actually require a reduced float voltage except out in the open in the middle of summer. The 13.6v float is for batteries remaining on a mains charger for more than 12 hrs, the other voltages are for batteries that are kept as pets

T1 Terry

13.8??

The 13.8v is float voltage. The battery will trickle charge at that voltage but it will take 24hrs or more to get the battery anywhere near fully charged. The 14.8v end of boost stage gets the battery up to 70% to 80% SOC depending on the charge rate, the higher the current (amps) the lower the percentage of fully charged. The reason is the internal resistance within the lead acid battery chemistry, they can only use a certain amount of current in the chemical conversion process required to get the sulphur back out of the lead plate and back into the sulphuric acid so any more current causes the voltage to rise and this results in an early shift from the boost phase to the absorption phase within the solar controller.
So, when you see the battery voltage reach 14.8v it does not indicate the battery is fully charged, it is only some where between 70% and 80% charged, the remaining charge absorption rate is much slower on a sliding scale down to a few amps anywhere above 90% full.
This is the reason for most knowledgeable people to say the battery needs to reach the end of boost by lunch time, so it has the rest of the day's sun/solar to get the batteries closer to 100% charged.
For some reason the lead acid battery brigade never corrects the mistake when some claim their battery is full again by lunch time simply because they see the controller switch from boost stage to absorption stage, the battery is really only at the 70% to 80% charged at this stage. If the battery doesn't ever reach this stage and it is in cyclic use then it isn't even reaching 3/4 full. If you consider the battery is at its max discharge point at 50% full or 50% discharged the real useable battery capacity is now only 25% before the battery is dragged down below the 50% full stage. This continual excessively deep discharging and never returning to 100% charged leads to rapid sulphation of the plates and a permanent loss of capacity.
I think I'd better stop about here as this subject goes on for ever just about and probably needs its own thread so I don't send innocent readers into a coma

T1 Terry

[BernieQ2]

Battery charger sat all night at 13.3 same on multimeter give or take a poofteenth .
At 9am I disconnected the battery charger and have been doing readings each 1/2 hour .
Reading the controller and the multi , I will at some time maybe not today put the solar panels back on.....I now have a clamp meter at my disposal .
Bernie .

[T1 Terry]

Terry they are agm batteries. When they get to 14.4 The solar controller goes to float, cannot hold at 14.4.. at the moment they are connected to my battery charger it's only 10amp and showing 13.3 did go to 13.8 so it's on float voltage confirmed on my multimeter . The solar panels are not connected. But the controller is connected to the batteries, it shows a soc of 56% ?? I will leave the charger on all night, tomorrow I will have access to a clamp meter. Personally I think my controller is not working .Correctly.
As a experiment I did connect the panels today and the indercated voltage was 14v and soc at 100% , when disconnected dropped back to 12.9 and soc at 53%???? We have Sun here from 7am till now it's still up.
Bernie

The controller is using voltage to determine state of charge, that is why the figures are every where and the disconnected SOC is probably the one closest to reality. The rapid voltage rise when the charge is connected means the battery is heavily sulphated, if the charger has a flooded cell setting try that and activate the equalise function for 30 mins at a time with a 30 min break with the charger disconnected. Repeat the process until the battery will hold a higher voltage while under load. The load should be around 5 amps per 100Ah capacity (60w @ 12v) a headlight globe will do the job but disconnect the load when the battery voltage drops below 12v. The idea is to start cycling the battery again to shift some of the sulphation out of the lead plates. The first stage is to clean the surface to allow the inner area of the plate to release the trapped sulphate and at this point you will start to see the battery voltage hold above the 12v at end of discharge point for a bit longer. You will know you are getting some where when the battery remains above 12v after the 30 min load cycle and the 30 min charge cycle begins again and you can switch the equalise mode off at this point.

T1 Terry

[BernieQ2]

Thanks Terry, I will do that after this little experiment I'm doing at the moment .
I can set the charger to flooded but that's about it . Its just a charger not victron or such .
Can also set the solar the same .
Bernie .

[jon_d]

Bernie's batteries are VRLA Gels.

SUNGEL is a CSIRO design.
The documents indicates that VRLA Gel batteries voltage at 100% is 12.81V
Section 6.3 shows the SOC vs Voltage for Gels.

http://www.rfiwireless.com.au/media/PDF ... -13-07.pdf


and the Victron document shows the charge and float voltages for VRLA gels.
https://www.victronenergy.com/upload/do ... ies-EN.pdf

Mine rest at 12.8 too.

[T1 Terry]

Thanks Jon, so they are genuine GEL electrolyte batteries, for get all the stuff I said regarding trying to disulphate them, it won't work well with GEL electrolyte batteries as the gassing required to clean the plates will produce bubbles between the gel and plate resulting in lost contact area.
I noticed in section 3.0 titled OVERVIEW that the rated capacity is at a 120hr rate, 5.4 amp discharge rate from a 650Ah battery ya gotta be kidding. The 12v units look to be rated at 103Ah at a C10 rate, roughly 10 amp max discharge for 5 hrs to the 50% SOC point from fully charged but weighs 40kg, 160Ah at a C10 rate weighs 59kg and supply 16 amps for 5 hrs.... still not really suited to RV use in my book.

T1 Terry

EDIT: I see in section 5.2 they can handle a 15v equalisation charge so maybe they could be saved

[BernieQ2]

Back again , so after all these years I have been wrong and they are "gel" batteries my original was bought as a AGM but obviously I was "duded"
So where do we go from here , after much swearing to move battery so I could confirm that it was gel . And its 250amp my original one .
Do I stop doing the flood battery setting it has taken the volts to 15v but then I turn the charger and solar off .
At rest they now sit on 12.8 . But with a soc of 54% , to me that's still half full?
What next?
Bernie .

[Dot]

Back again , so after all these years I have been wrong and they are "gel" batteries my original was bought as a AGM but obviously I was "duded"
So where do we go from here , after much swearing to move battery so I could confirm that it was gel . And its 250amp my original one .
Do I stop doing the flood battery setting it has taken the volts to 15v but then I turn the charger and solar off .
At rest they now sit on 12.8 . But with a soc of 54% , to me that's still half full?
What next?
Bernie .

you iriot Bernie, even I know what batters I use

[BernieQ2]

Like you telling me suppin I don't know Dot?
Pic of last weeks camp at Mingo Crossing , with the new canopy thingy over the front door .
Bernie .

DSCF2626 (Custom).JPG

[Dot]

that looks good Bernie