Walmart Batteries Limits

somepriests
somepriests Registered Users Posts: 7 ✭
in Off Grid Solar & Battery Systems #1
Does anyone out there have any experience with the Walmart Everstart Maxx Marine 29DC batteries?

I am trying to optimize the batteries I own until they are at the end of their useful life and then move over to some batteries more apt for solar applications. Here is my setup:

2 Hyundai 260Watt/24 Volt Panels in Series
MC4 connectors
FlexMax 80 Charge Controller
4 Walmart Everstart Maxx Marine 29DC batteries (Deep Cycle) - Sealed Lead Acid wired Parallel for 12 Volt system/476 AH

Here are the questions:

1. What is the highest voltage limit any of you guys have seen that the batteries can take without damage? 12.7, higher?
2. What is the maximum limit of voltage I should set my charge controller to for Bulk Charge and the least I should set for Absorption. The Charge controller defaulted to 14.4 and 13.8
3. Can these batteries be Equalized? Remember they are SEALED Lead Acid. I can't pop the tops on them and check for specific gravity.

I know the easy answer is to junk them and go with a Flooded Lead Acid, but at this point I am trying to get what I can out of these.

Thanks,

Steve
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Comments

  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
    Re: Walmart Batteries Limits

    Steve;

    Your FM80 does not have a 'Bulk' Voltage. it has Absorb, Float, and Equalize Voltages.

    Since these are sealed batteries you're sort of stuck; you can't actually check to see whether or not any Voltage is doing the job right. As such, stick with the defaults. Do not equalize; the higher Voltage is likely to open the valve and let out gas (water of the electrolyte separated as Hydrogen and Oxygen). This can't be replaced.

    Check the charging current through the Absorb stage. If you are getting down to around 2% current (no loads) by the end of a 2 hour Absorb the Voltage set point is good enough. If it takes longer Absorb to get there you need to increase the Voltage. Go in 2/10 increments. Do not exceed 14.8, as that is likely to be in "open valve" area. It is also a good idea to have a remote temperature sensor on the batteries.
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #3
    Re: Walmart Batteries Limits

    My opinion is that these batteries are NOT sealed in the sense of SLA, but rather probably Lead Calcium batteries and Low or NO maintenance, as have become common in the Automotive battery segment.

    Have seen these batteries, but forget just how well "sealed" the cell covers happen to be.

    But, in any case, probably no need to EQ them, and traditional Auto regulator settings should be fine. Opinions. Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • techntrek
    techntrek Solar Expert Posts: 1,372 ✭✭✭
    #4
    Re: Walmart Batteries Limits

    I used these in my 22 kw bank, 16 in series @ 192 volts. Not sealed at the time. Definitely had no problem with a much higher voltage.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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  • somepriests
    somepriests Registered Users Posts: 7 ✭
    #5
    Re: Walmart Batteries Limits

    Thanks again. I am learning as I go, so this is a huge step up from the HF panels I had a couple of months ago. I do enjoy it when it all comes together.

    I will incrementally increase the voltage. We will see how long it takes to get through the absorption stage.

    I heard it is unwise to pop the caps on these. Is that true? Can they be "modified" and refilled?
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  • H2SO4_guy
    H2SO4_guy Solar Expert Posts: 213 ✭✭✭
    #6
    Re: Walmart Batteries Limits

    I have opened VRLA 'Sealed' batteries and added distilled water with a syringe many times. Sometimes I think the life has been extended, but when I get them they are headed for the smelter anyway. If they are not up to snuff what do you have to lose? The warranty? If it is out of that, then they are all worth the same amount......lead weight, unless you are selling them by the unit, which is only a good deal for you if they are smallish batteries. I usually wait until I get a pile of them and trade them in. It doesn't pay to travel unless I have about a ton or so.
    12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
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  • PNjunction
    PNjunction Solar Expert Posts: 762 ✭✭✭
    #7
    Re: Walmart Batteries Limits

    I would NOT equalize a maintenance-free FLA battery like those Everstarts that don't have removable caps. When I use flooded, I make sure they are not MF. But for now, just treat them right.

    Injecting water into a sealed VRLA like an agm, turns it into a badly performing flooded battery, not designed to be fully flooded in the first place, aka the "absorbed" in the AGM. If you must, you now treat it like an FLA, which means cutting way back on the maximum charge current for one. You are also facing much higher self-discharge rates like an FLA, and nothing is engineered right. Kind of like putting automobile gasoline in an aircraft engine. You might get down the runway, but I wouldn't fly with it!
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  • hidrologo
    hidrologo Registered Users Posts: 8 ✭✭
    #8
    I have 12 29DC Walmart Everstart batteries powering my 48V offgrid system. Why? Because they have an exchange policy with no pro-rating and if the battery tests bad, Walmart people just exchange it and you don't have to argue with someone about whether you mistreated their battery or whether you had purchased enough batteries to provide power for your house. My warranty on my Surrette Rolls batteries was not honored (due to overcharge undercharge issues) and for my MK East Penn AGM batteries the place that I bought them from kept insisting that they were good even though they lost charge overnight with almost no load.

    My system works pretty well with the occasional replacement of a battery. I have tenants and tenants tend to be rough on batteries - they generally aren't solar people. I hope to get 2-3 years out of most of them. 

    The 29DC batteries are not sealed. You can pop the tops off with a screwdriver. Unlike many wet marine batteries they lose very little water but you can add distilled water if they are low, but don't overfill. The parameters that are used in my system are:
    Absorb: 58.0 Absorb time: 2 hrs
    Float: 54 V Float time: 1 hr.
    Equalize 58.8 V 1 hr
    Refloat: 49.2 V

    These are parameters that were set by my solar expert while I was overseas. I believe that the system was equalized once, but I think that the equalization voltage should be higher to be effective as I have read online that a 12V marine battery needs about 16V to get it to boil. I do think that the batteries will last longer with an occasional equalization as they are acid batteries and I believe that the plates sulfate on all pb acid batteries. I am a bit reluctant to try a higher equalization voltage until I hear from someone that has taken that route.
    When I do I will probably test on my 4 weakest batteries. Would like to hear from others using these batteries.

     




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