[RE-wrenches] Aging Batteries

Fri Oct 27 14:06:53 PDT 2023

I have had a much different experience with older batteries.

1. check the SG and volts under load like at night.  And see if there are any weak ones.  Since you have 2v cells you can afford to lose a few.  

2. If they all check out more or less equal, and i’m guessing that they are using lots of water, then I lower the charge volts, and/or absorb time.  
Because the internal chemistry is dying and in my experience going higher volts ( unless its a sulphation issue) just creates more heat, and hydrogen gas with greater risk of issues, and more water use and mess.  Its not going to fix the chemistry. 

3. lower the LBCO all the way down and if using AGS then lower the volts on that to and also reduce the run time/abosrb time.  

Good luck,

Jay

> On Oct 27, 2023, at 9:49 AM, Howie Michaelson via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
> 
> Hey Will, 
> 
> At the risk of being overly simplistic and obvious, have you kept good specific gravity records over the years? Are they showing lowered or uneven readings?  I've often been able to get some more life out of flooded batteries by raising the charge and equalize voltages, particularly if these are Rolls 2- volts. I've been known to run the bulk charge as high as 31 sometimes and equalize up to 32 with longer run times (2.5 - 3 hours) for off grid, assuming that there aren't any particularly weak cells.  
> 
> You can also do a simple load test on each individual battery and if you find a very weak or dead one, taking it out of the string often improves capacity (if you've already tried recovering it through extra charging). Of course, you would would need to adjust the inverter and CC settings appropriately. 
> 
> Which model of 2-volts are these? 
> 
> Again, sorry if this is all too obvious for you.  Just getting back to basics.
> 
> Good luck, 
> Howie
> 
> On Fri, Oct 27, 2023, 11:27 AM Mac Lewis via RE-wrenches <re-wrenches at lists.re-wrenches.org <mailto:re-wrenches at lists.re-wrenches.org>> wrote:
> Hi Will,
> 
> I'd keep inching the start voltage down and see if it helps.  Sometimes old batteries just operate at a lower voltage and will sag more under load but they will still carry the load OK
> 
> Of course you can:
> 1.  Do all of your high power stuff when the sun is out.
> 2.  Disable the generator start at night and see where the voltage goes by morning, perhaps a load kicks on and the voltage is sagging enough to kick on the generator from voltage.  It helps if you can plot the voltage over night to see what is happening.  (Victron battery monitors are really cool for this).
> 3.  Load starting can help limit overall run time.
> 
> Sometimes you can do inventive things with Quiet time that will limit generator starting.  Not sure what inverter system you have.
> 
> On Fri, Oct 27, 2023 at 9:03 AM White, Will via RE-wrenches <re-wrenches at lists.re-wrenches.org <mailto:re-wrenches at lists.re-wrenches.org>> wrote:
> Hello Wrenches,
> 
>  
> 
> I installed my off-grid system in 2008. It’s 24 V using 2 V industrial FLA batteries. As you can imagine after 15 years the capacity of my battery bank is significantly less than it used to be.
> 
>  
> 
> For logistic reasons, I won’t be able to replace them till around June of next year, but it’s not even into winter yet and my generator is already running every day.
> 
>  
> 
> Does anyone have any tips on how to get through the winter on these batteries while minimizing generator run time? I’ve got two FM80’s with 3.8 kW of PV, two VFX3524 inverters, and a Kohler RES12 generator. I haven’t changed any settings since I installed the system.
> 
> 
> Thanks,
> 
> Will
> 
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