Solar Battery Charge Issue

[KenS999]

Hello I have a 100W Renogy solar suitcase charging two AutoZone Duralast lead acid Marine deep cycle group 24 batteries. Batteries are 3 years old. Lately I have noticed the charging cycle time drastically increasing especially during the absorption phase of the charge cycle. Charging is now nearly twice as long as before. I have cleaned and inspected the terminals and connections. I have checked individual cell fluid levels as well. These batteries have been babied and never taken below 12.3V. My power usage requirements are minimal and have not increased.

I am wondering if these batteries are just getting long in the tooth as far as charging cycles? Would investing in a good specific gravity battery tester be the next step?

Thanks, Ken

[Almot]

It appears there are 2 different Voyagers - Traveler Voyager and another "Voyager". Slightly different manuals. One says "120 minutes constant voltage Boost charge" (must be Absorb). Another one must be what you have, 2-4 hours Absorb and unclear current setpoint 0.2-1.0A. Both have some Chinglish issues - I think Renogy don't make or design their controllers, it's a relabeled mass product from China. No adjustments in either one, except for changing the Abs voltage by changing the battery type.

Good news (in your case) is that it was keeping battery at elevated voltage for hours. But you don't know this elevated voltage - it could be that it didn't reach 14.7 or only reached it for a few minutes before it timed out.

If you have nothing else to do you may get a two-mode Ecoworthy that BFL has :), and adjust Abs duration by setting and re-setting Float higher or lower depending on the weather. But it doesn't do 16.2 equalization.

[BFL13]

pianotuna wrote:
BFL13,

It sounds as if you would love a blue tooth capable charge controller. They are much easier to set up.

You have to get up out of your comfy chair once in a while!

[pianotuna]

BFL13,

It sounds as if you would love a blue tooth capable charge controller. They are much easier to set up.

[BFL13]

I have a controller that gets to the set Vabs (goes to 15)and drops to Float. So I set the float voltage to 14.5 (highest it will go) so that acts like Absorb at 14.5v till sundown. It depends on how cloudy it gets how long Absorb needs to be. Every day is different around here, can't just leave the controller alone set to whatever.

[KenS999]

I agree that a check of specific gravity may shed some light on why this sudden issue has appeared.

Really didn't see anything in the manual as far as adjusting absorption time. Tomorrow I can play with the menu but I do know there are not many options outside of selecting battery type and toggling between input voltage,amps and I believe total input amp hours. The way that I originally interpreted it was that absorption can run anywhere from two to four hours?

[KenS999]

Really didn't see anything in the manual as far as adjusting absorption time. Tomorrow I can play with the menu but I do know there are not many options outside of selecting battery type and toggling between input voltage,amps and I believe total input amp hours. The way that I originally interpreted it was that absorption can run anywhere from two to four hours?

[Almot]

...forgot to mention: equalize them manually, don't wait for that 28th day. Switching controller to Calcium mode might do the trick. Disconnect one battery, bring it up to 15.5 and let it boil for 2-3 hours, keeping an eye on it from safe distance 😉

[time2roll]

Almot wrote:
Looks like Absorb voltage is fixed (and so is Float), but Absorb timer is adjustable from 2 to 4 hours, and Absorb stage will end regardless of the timer if current drops to 0.75/1A. And then it says "if current <0.2A the stage will end". Confusing but this doesn't give a reason to blame the controller.

I think before replacing the controller with another one, you should check SG and try to equalize batteries after fully charging it. Preferably at home when you're not using them, or - better yet - if you have 12V supply. I would agree with BLF that they are in a bad shape.

Unless the setting was somehow reset to 4 hours from 2 hours. What is the default?

[BFL13]

https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf

You can't go wrong by pretending your batts are Trojans (if they aren't) and following this guide as best you can.

Note the 16.2v for equalizing and how and when to do that procedure. Your controller says it can do 15.5v with "calcium" so do that at least. Better than 14.x .

You can hit 16v by disconnecting the array from its controller (after the batts are full) and going solar direct on the battery. Keep a good watch so you can stop when the voltage gets there and the SG is up where it belongs.

Trouble is it takes all day just to get the batts full, so you can't equalize that day, but you want the batts full in the morning to kick off the equalizing. answer is split bank. run the rig on one battery overnight and let the other sit full till morning, do it, and then swap around and do the other batt. so you have to find a window in the forecast for four days of sunshine. Once you do that, you are good to go back to normal for a month or so.

Solar is hard on batts by not ever getting them truly full every day, so they gradually sulphate. You need an hydrometer to see what is really happening, but not often while camping. something to do at home--wear old clothes that don't mind having lots of holes eaten in them from acid 😞

also at home you have shore power, so you can run the converter. Most converters can't do more than 14.4-14.6 so here is one that can do 13-16.5v manual adjusting. So there is how to do the Trojan 16.2, eg. or any other charging spec. dial it down to any float voltage too.

https://www.boatandrvaccessories.com/products/powermax-pm3-60lk-12-volts-60-amp-power-converter-batt...

[Almot]

Looks like Absorb voltage is fixed (and so is Float), but Absorb timer is adjustable from 2 to 4 hours, and Absorb stage will end regardless of the timer if current drops to 0.75/1A. And then it says "if current <0.2A the stage will end". Confusing but this doesn't give a reason to blame the controller.

I think before replacing the controller with another one, you should check SG and try to equalize batteries after fully charging it. Preferably at home when you're not using them, or - better yet - if you have 12V supply. I would agree with BLF that they are in a bad shape.

[KenS999]

So then what would you recommend as far as better charge controller capabilities above and beyond what is listed in my charge controller spec sheet shown above for charging lead acid batteries? Thanks.

[KenS999]

[Almot]

KenS999 wrote:
What is puzzling to me is that I would always reach Full/Float at 13.6 volts by midday in southwest Arizona according to the charge controller display... until just recently. I guess my charge controller must have been lying to me for the last 3 years and I did not know it. I just don't know.

When my battery was new, it would reach 14.6, stayed there for 1 hour as per controller settings, and go into Float before noon. When it was dying, it would still go into Float on most days but the process was taking much longer. Solar was keeping it alive, just barely, but it was really dying, lights dimmed when I run run water pump after dark.

Another possibility is that your Absorb time is too short so controller is forcing battery into Float before giving it enough juice at the boost stage. As a result, battery would remain undercharged.

[BFL13]

It depends on what you do with the portable set. IMO posters are under-estimating what a 100w panel could do in a blue sky all day scenario.

It depends so much on your latitude and time of year, but eg, at 49N in May, with a 130w panel measuring with Trimetric monitor and best I could, I got 90AH tilted up and "tracking", 70 AH tilted up facing South all day, and 56 AH lying flat.

so scaling down from 130 to 100, that would be:
Tracking- 69AH
Tilted up to South- 54AH
Flat- 43AH

Note--"Equalizing" means taking the full batts to 16 volts till their SG stops rising. NOT to be confused with the miss-named "equalizing" some chargers do every so often to their "boost voltage" of 14.x volts which is not designed to equalize, but just to stir the electrolyte as a de-stratification measure.

IMO your batteries are near death from undercharging and sulphation. Call those your "learner set" 🙂

Next time around follow the charging specs for whatever batteries you buy, which could mean getting a proper charger or controller that can do those specs.