Solar Charge-Need Help With Setting Battery Type

[Random Painted Highway]

I have two Centennial DC24MF batteries that i want to charge with my solar panel, but i can't tell what setting to use on the charge controller and i hope someone can help.  My choices are, according to Renogy: The Voyager provides 7 battery types for selection: Lithium-ion, LiFePO4, LTO, Gel, AGM, Flooded, and Calcium Battery.  

Link to battery site:
http://www.centennialbatteries.com/products_rvmarine.html



I think it would be flooded.

Thanks for any help you can offer.

 

[John61CT]

I'd say flooded, if you're on the margins of getting back to 100% Full as normal with mostly solar inputs.

If in storage, very light cycled, getting to Full early in the day, then backing off to AGM may help them last longer.

Next replacement time, come back and ask here for advice about longer lasting better value / quality ones.

 

[Random Painted Highway]

I'd say flooded, if you're on the margins of getting back to 100% Full as normal with mostly solar inputs.

If in storage, very light cycled, getting to Full early in the day, then backing off to AGM may help them last longer.

Next replacement time, come back and ask here for advice about longer lasting better value / quality ones.

Thanks John61CT, i appreciate your guidance!  These batteries came with the motorhome, but when replacement time comes around i will look to you for some advice.

 

[highdesertranger]

I am guessing those are sealed lead acid(SLA). it really doesn't say on the website. I would get a hold of them and ask them. charging with the flooded profile might be to much. highdesertranger

 

[John61CT]

Yes, flooded but "no maintenance" = SLA (VRLA) but not AGM.

 

[John61CT]

charging with the flooded profile might be to much.

Hence the if/then qualification in my advice above, FLA setpoint is better but not if it leads to regular / extreme overcharging.

If have to choose only one for both scenarios then AGM is safer, but never getting to Full is just as abusive.

With cheap starter batts not really worth getting into the weeds too much.

Only the top quality makers have good tech support readily available to customers, very rarely a mass market maker sold in big box.

If they don't even publish detailed spec sheets or charge profile details on their web site. . .

 

[highdesertranger]

after rereading your choices you might want you might want to use the calcium setting. call Renogy. highdesertranger

 

[Trebor English]

Starter batteries commonly have calcium added to the lead plate alloy to reduce water consumption.  That's why starter batteries go years without having water added.  That's what they mean by "maintenance free" which is different from AGM or Gel.  There is no valve regulating internal pressure to cause hydrogen and oxygen to recombine.  The calcium makes it happen.  

Consider using the "calcium battery" setting.  Since this battery is a maintenance free starter battery expect derision from people who know that their batteries are better than yours.  If you limit discharging to 25% rather than the 50% recommended for golf cart batteries they will probably last quite a while.  

If the battery has a RC or reserve capacity rating instead of a 20 hour amp hour rating, that's the number of minutes it can produce 23 amps (used to be 25).  Divide by 60 to make hours, multiply by 23 amps to make amp hours.  A quarter of that, 25%, should be your limit.  

If you have to remove the battery to read the label and don't want to do that, you can presume that 50 to 80 amp hours is in the neighborhood.  That means10 to 20 amp hours useable for each battery.  

Since they are flooded you can use a hydrometer to check the specific gravity unless they glued the caps on the cells.

Since you actually will be draining and recharging more than starting, check the electrolyte.  It might need some distilled water.  It would be a shame to have the battery die at 2 years due to lack of water when they could have gone 3 or 4 years.

 

[Random Painted Highway]

I have a call into Renogy to see what they say. Thanks for all the advice. I know the batteries are not too expensive, but i want to preserve what i can until i get new ones.

 

[Weight]

Centennial Battery recommends a slow charge for their Deep Cycle batteries, but don't explain more than that. Your group 24 battery is 75 amp hour, when new.

 

[frater secessus]

I'd also see if I could gently pry off that faceplate at the bottom of the pic. Some "maintenance free" batts are just plain SLA as John points out. And some of those can be opened up, watered, and closed up again. If so, I'd run them as flooded and water as needed.

 

[Random Painted Highway]

Well we went on our two week mobile living trek and used the solar panel with setting the charge controller on flooded and had no issues. Solar panel and batteries worked great! It was so fascinating to watch the panel,controller and battery working together. We did use the generator twice during that time to run the microwave. Thanks for everyone's advice and insight. I'll try post a couple pics of the trek in another post. Thanks!

 

[frater secessus]

Thanks for following up in the thread.

I find watching the system work fascinating, also. "Solar TV" or something.