Refilling SLA's (Sealed Lead Acid Battery), Like Refilling a Car Battery

by thermoelectric

293K96264

Intro: Refilling SLA's (Sealed Lead Acid Battery), Like Refilling a Car Battery

Have any of your SLA's dried up?
Are they low on water?

Well if you answered yes to either of those questions, This Instructable is for you

DISCLAIMER
I TAKE NO RESPONSIBILITY FOR ANY SPILLAGE OF BATTERY ACID, INJURY, STUFFING UP A GOOD SLA ETC.

STEP 1: Materials/Tools

Tools
  • Safety Glasses (So you don't get mild battery acid in your eyes (like I did))
  • Funnel or something to put water into the cells
  • Very small flat-head screwdriver
  • Needle-nosed pliers
  • Battery Charger (optional)

Materials
  • De-ionized water (you can use tap water but it's not reccommended)
rimar2000 says:
You can also use rain water without problem. But it must be very clean. You can collect it whit a clean plastic sheet as funnel, and a clean plastic barrel as container. IT IS FREE!!!
  • Dry or nearly empty SLA

STEP 2: Pry Off the Cover

Use the small flat head screwdriver to pry off the cover, There are usually some slots that it will fit in.

This will not work on the SLA's with a single cover for each of the valves unless they have pry holes.

STEP 3: Take the Cell Vents Off

For this step use your safety glasses

Using your needle nosed pliers, Pull off the rubber vent covers.

Be careful because this could spit battery acid at you (NOT GOOD!)

STEP 4: Add Water to the Cells

For this step use your safety glasses

Add De-ionized water/water to the cells by using your funnel or similar.

Warning, You have to estimate how much water to add, Adding too much will cause it to leak/spit when being charged.

STEP 5: Put the Rubber Caps Back on and Charge

For this step use your safety glasses

You should probably charge it before putting the caps on so the water can boil off......

Put all the caps back on the cells.

Connect to a battery charger and put a towel or rag over the SLA in case it was filled to much and needs to vent, If it vents it will probably pop off the rubber caps, Just put them back on.

STEP 6: Put the Cover Back On

Once you have checked the battery is good, Put the cover back on.

Use any type of mild to strong adhesive to stick the cover to the battery, remember not to fully seal the top so that the gases can escape.

Now you're done!

Report how good/bad your refilled battery has performed.

Remember to comment I like comments

255 Comments

Eld 1 year ago

Some helpful ideas but potentially very misleading for someone who might have an AGM SLA battery that looks just like these. AGM batteries are visibly dry inside by design and should not have any liquid apparent in them except for what is absorbed by the Absorbant Glass Mat. If you battery is an AGM then do not add water unless you are aware of this, as you will likely ruin your battery and splash acid about!

kc4qzd 4 years ago

The article was great, and I'd like to add a few key things I have learned doing this:
1. If the battery has completely dried out (from electrolysis) the end result will be a battery that may work, but have very limited capacity after filling it up.
2. It is best to add distilled water BEFORE the battery starts to lose capacity. Once the glass mat material dries up completely, the lead plates react with air and create a coating that renders them just about useless.
3. Add water as a preventative maintenance task, not as a fix. I have never successfully resurrected a battery with a shorted cell or one that was completely dry.
4. I service all the batteries in all the UPS's at home and work every 2 years, and generally replace them every 5 or 6 years. On mission critical servers, I remove the batteries after 2 years and top them off with distilled water and then use them in less critical areas.
Amount of water typically used to fill these batteries after 2 years of being on float (typically at 13.5 volts):
12V 12AH batteries: 10mL per cell.
12V 7AH batteries: 6mL per cell.
5. The goal is to make the white glass mat separator material damp, and NOT to have any extra electrolyte on top of the plates. If you open the caps and can physically see that the white separator material is wet, DO NOT ADD ANY WATER. If you add too much water and flood the cell, you are guaranteed to have a big nasty mess of acid and whatever it dissolved and possibly ruined equipment.
6. Batteries do eventually wear out whether or not you keep them maintained. Adding water as directed in this article will certainly add extra years to your batteries. Keep in mind that each time the battery is run down and recharged some capacity is lost. This is due to the rough texture of the lead plates (to give more surface area) smoothing out.
7. NEVER cycle batteries on purpose. It is a myth that cycling or exercising
lead acid batteries is needed to keep them in shape or prevent "memory." That only applies to Nickel Cadmium batteries.
8. It is best to keep any lead acid type battery fully charged whenever possible. After depleting the energy from a battery of this type, it should be recharged immediately unless it is hot. (greater than 40C) When storing batteries, fully charge them and then put them on a charger every 3 months to keep them topped off.

I hope this helps some people out there. If you have any questions feel free to leave a comment!
Craig

lowuihon 3 years ago

I have a SLA DEEP CYCLE battery 100Ah for my solar power system It's been used for about 3.5 years now. I pried open one of the two lids and inspected the inside but i couldn't see any liquid except the black color when i use a small bamboo chopstick to dip inside. I would like to know if this is the sign of drying up of its electrolyte and should I refill water? Thank you!

beaucom85 3 years ago

Trojan Said the gravity by default is 1.277 with th hydrometer

kevstanz56 5 years ago

Folks, I have a korean 150A SLA battery which doesn't charge for long and consequently doesn't last long. It used to charge for almost 2 hours on a 30A charger I had and now it shows its fully charged in less than half an hour. Having read you tutorial I decided to pop open the seal and take a look. I found the acid levels quite high already. I did add a little distilled water to them and resealed it back. I have not noticed any difference at all. Still charges and depletes fast. What could be the problem?

karinventer 5 years ago

Hi
can i use normal car battery acid to fill the lead acid battery

dev.emeftah 5 years ago

For Tmyrbatry UPS should have enough knowledge in electronics

Or read articles and books in the field

UPS battery repair is not easy

You can also visit the articles on this site https://vcenter.ir read -ups and Ernie get help

with regards

SurvO 6 years ago

Hi, thanks for the information u provided. I want to find out if it will work on deep cycle inverter batteries? I have a Sealed Maintenance Free Deep Cycle Inverter Battery, I finally pryed it open, removed the cap when I looked inside slightly bent the battery, I didn't see any liquid inside. Could it be that the battery was made like that, or the liquid is completely dried off? The good thing is that it can charge to 12v and above but does not last long. Will this your approach work on my battery?pls reply

SurvO 6 years ago

Hi, thanks for the information u provided. I want to find out if it will work on deep cycle inverter batteries? I have a Sealed Maintenance Free Deep Cycle Inverter Battery, I finally pryed it open, removed the cap when I looked inside slightly bent the battery, I didn't see any liquid inside. Could it be that the battery was made like that, or the liquid is completely dried off? The good thing is that it can charge to 12v and above but does not last long. Will this your approach work on my battery?

maclee4real 6 years ago

Hi, thanks for the information u provided. I want to find out if it will work on deep cycle inverter batteries? I have a Sealed Maintenance Free Deep Cycle Inverter Battery, I finally pryed it open, removed the cap when I looked inside slightly bent the battery, I didn't see any liquid inside. Could it be that the battery was made like that, or the liquid is completely dried off? The good thing is that it can charge to 12v and above but does not last long. Will this your approach work on my battery?

amiir 7 years ago

hey guys. i have 12V SLA battery and it wasn't use 1 years. after charging its not save power as it should. the voltage was 3.6V and it dies after 10Sec. i collect some rain water and clean it with cotton filter. refill the 6 cells and charge the battery for 5H. in first hour it takes 0.3 ~ 0.9A and in next hours 2.6Amps. is it normal? what was my mistake? the voltage is 7.78 now and its not die fast. it can provide 7.78V for a LED lamp almost 3hours. what should i do to make it 12V or near 12?

ciprkfupm 7 years ago

I've recovered four SLAs three 6Volts and a 12V sla. First of all if the battery voltage is 0V or say less than 2Volts just filling it with distilled water and connected it to the original charger will not work especially due to massive sulfation in the battery. Also the elctrolyte present in the battery after refilling is mostly water and almost no acid. To get your battery to atleast 80% of it previous state I did the following:

1. Pry open the battery cover and remove the rubber caps and fill with distilled water, but make sure that its slightly flooded inside the cell compartments but not overflowing.

2. Now you will need to desulfate the SLA, which means you have to apply a larger volatge at least 18 Volts with 2Amps or above. I usually connect the SLA to a 19V 6.5A laptop adapter till the battery starts bubbling and after some time the battery becomes slightly hot remove the 19V supply.By now some of the water is converted to sulphuric acid, now you have to proceed with extreme caution.(NOTE: This step should be done only with the rubber caps open)

3.Once the voltage is 5.7V+ for 6V SLA and 10 to 11V for 12V you can connect the battery to your original sla charger. It will charge like normal. Remove after an hour or so. Close the rubber caps and seal the plastic lid with epoxy glue and once set pu the sla back on original 6V or 12V charger and it will work fine.

4. After a few cycles of use yor battery capacity will improve greatly like mine. I recovered a Panasonic, 2 Fiamm GS and a BB Battery.

maclee4real 6 years ago

Hi, thanks for the information u provided. I want to find out if it will work on deep cycle inverter batteries? I have a Sealed Maintenance Free Deep Cycle Inverter Battery, I finally pryed it open, removed the cap when I looked inside slightly bent the battery, I didn't see any liquid inside. Could it be that the battery was made like that, or the liquid is completely dried off? The good thing is that it can charge to 12v and above but does not last long. Will this your approach work on my battery?

alexsa3 6 years ago

am rely confused confused on what i should add to my T-power NP100 - 12 12v100AH sealed rechargeable battery, i went to some battery shop they gave me an acid to add, i added but its not working. what best can i do to put my battery back to normal, thanks

D6equj5 6 years ago

Hi,

I've done everything in your instructable but my batteries still don't hold a charge and struggle to even get to 7volts. Any ideas?

Thanks

D6

RandyD66 6 years ago

Many people mistakenly believe that if a 12v battery charges and reaches the voltage of a charged battery (12.8v - 13.2v) that that indicates the battery is good. That is not the case. You can have an 80Ah battery indicating 13.2v, but nearly ZERO CAPACITY. Capacity is the ability of the battery to store a charge...not just reach a voltage point. Adding water to a badly sulfated battery is not going to help.

If you have a mildly sulfated battery, you can try connecting it to a 12v 1 amp solar panel for about a week. If the battery is salvageable, this will help. If after a week the capacity has not risen measurably, the battery should be properly disposed of.

aduy 10 years ago

ok so im helping a friend repair his electric skateboard, its got four of these 12v 8ah batteries SLA. now the voltage is supposed to be 24 but wheni measured it, it was around 8 or 10. the charger wont kick in to charge it up so i put a dummy load on the line and have gotten it up to about 20v, but with a small load on the batteries it still drops down to 10 volts. i have now tried adding water to all of the cells, and im currently charging it up to see how it does. are the batteries just dead or can they be salvaged? btw the batteries are 2 in series and then two of those in parallel to make 24v 16ah.

ryanrocks714 7 years ago

http://batteryuniversity.com/learn/article/how_to_store_batteries

JonathanR185 7 years ago

Does an SLA battery have an expiration date if I never fill it with acid?

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