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

Comments

[aduy]

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.

[hansonsux]

I have my doubts this will work, because unlike other Lead batteries, "Sla" batteries like the ones in Ups's or scooters etc. are AGM type. The GM is "glass mat". The mat is in between the plates and holds the electrolyte like a sponge. There is the possibility the battery is dry, but more likely the batteries are sulfated anyways. Even if you did icrease the capacity of the battery, sulfation damage will likely limit your sucess. In AGM sla's, larger sulfate crystals grow and press against the glass mat, and when they get really big, warp/destroy the pates. Minor sulfation can be reversed in AGM's, but any larger crystals that haven't destroyed the plates yet will not be able to fall away and remain stuck in the glass mat. Which will mean a permanent rise in internal resistance.

"Refilling" is a bit of a misnomer, since AGM batteries are a "starved electrolyte" system whereas there is no loose electrolyte beyond what is soaked up into the glass mat. If you take the case off of one of these batteries, there will be no electrolyte leakage as it is entirely contained within the glass mat.

[andersonhdj]

Don'y know if anyone has posted this, old lead acid batteries can be desulphated by charging with a Glauber's salt solution.
Thereafter a thorough rinsing with distilled water to wash all the loose sediment out , allowed to drain and refill with electrolyte.
Used to recover motorcycle batteries this way.

[PCelec]

may give a try got 7 old batteries form 3 old UPS units. 3 are relitivly small aprox 7/5AH 2 of them sound like they fell apart inside and make rataling noises. the other one i may try this, the other 4 are heavy duty say 17AH/20hr think those are defintly worth a try fixing. oly one ups would still run off batery power. rest were bad so probly use the bateries for solar projects.

[Objectivityiskey]

If the battery is "dry" try filling it with a solution of distilled water and Alum, but first rinse the battery acid out with a solution of distilled water and backing soda until the acid is nutralized. Much safer than acid, and now you have a rechargeable alkaline battery. Try it, and you will be pleased! Don't forget to understand the word "solution" when mixing the water and Alum. Alum is sold in the spice section of most food stores.

[chnaveed.alam]

thanks for nice upload
can i charge 6 v lead acid battery with 12 volt charger

[thermoelectric]

It's not advisable unless you watch the voltage closely, it wouldn't take much to boil the electrolyte right back out.

[ron12]

How can I tell if my sealed lead acid scooter battery needs fluid. How can I tell how much to add. I don't see any fluid in the cells. I do not want to over fill. Thanks Ron

[The 4th Doctor]

i heard somewhere that epsom salts can be good for desulfating batterys

[Electronics Man]

So if I have a couple of old SLA's that are completely dead, Will doing this revive them?

[thermoelectric]

I can't say it will revive them, but if they're dead, there's no harm in trying. Chances are they're probably sulphated though. Try a desulphator after refilling them?

[Electronics Man]

Thanks for the help!
I successfully revived 5 batterys today and three of them have been sitting dead for at least a year. The other two just needed topped off. I'm so glad I found this instructable, anyone can do this!!!

[ajazmd13]

good

[cenzo188]

I just did this with an old alarm system battery that I use whenever I happen to need 12 volts out in the field. It was totally and completely dry. I filled it just as stated here and charged it with my power supply set to 14 volts current-limited to 1.5 amps, the voltage and current that was specified on the battery label.
So far, it's held its charge for 24 hours and can supply adequate current.

CONCLUSION: It works.

[dsandds2003]

You can use distilled water. You can buy it, get it out of your dehumidifier or from your air conditioner. You can also boil water and let it cool. Some auto stores also still carry battery acid.
Do NOT fill above the plates. You can use a needle and syringe from an ink filling kit.
When charging you should use a charger that shuts off when it reaches 13.8 to 14.4.
If you fill above the plates the battery will get HOT and start to deform the battery.then it is junk.
Just some tips i have learned over the last year.
Keep up the great work.

[uberdum05]

Have just refilled one of my 'reused' electric scooter batteries so hopefully it will charge. Fingers crossed...

[anuragmahajan152]

Thank You Very Much

[Daniel Deacon]

ive overfilled mine its just leaking now :( what do i do should i keep chargeing it?

[snowluck2345]

how do you know if a battery is low on water?

[czarmatra]

Is it not acid like in the 12v car battery? with a 1275 SG. Or just plain old clean water?

[thermoelectric]

Well, You can add acid, That's probably better, But you can use distilled water, i'm pretty sure...

[BruceLyn]

Hi, can I add the swimming pool acid instead of water? thx

[thermoelectric]

Hydrochloric acid? Yes, But not too much.

[chamunks]

I have both Hydrochloric acid and Sulfuric acid and some high accuracy ph test strips would you recommend trying to be a chemist here and actually adding acid? Like would it really be a big benefit with all of the risk involved?

[cpreble]

i have tried a combo, you all know the RISK of combining acids. I had learn t along time ago that some work and some are rather explosive. I also can maintain a 14.8 volts in a 12 v lead acid battery, downsize the alt, or eliminate it all together. I play with Tesla theories for the recharge of the battery, and gain HP. When doing this you must have everything across the board. your # are very spot on. But can be ramped up.
Have gone to 24. with very min loss and better performance for cars all around, they also act as my solar gen and inverter backups.
This is a very good Instruct, but outside the box, there is alot more you can do.
I wish to thank you for this.

[BruceLyn]

Thank you.

[czarmatra]

i am starting to recycle. so far mostly car batteries, now i have a bunch of these, all dry, wasnt sure if they were a gell sealed, or just ad acid. There was nothing to take out of the thing, so i assumed acid, but i hate to assume. And thanks for the instructable

[thermoelectric]

Okay.

[nverma]

great ......I really thank you for grant me the info at free cost.............thanks see you soon after d work is done

[Fragmaster]

Update
I just reconditioned a pair of 12V 2.3Ah batteries with great results! These 2.3Ah batteries are holding their charge much better than the 12V 7Ah battery that I reported below. The 2.3Ah are hovering around 12.58V while the 7Ah has fallen to 9.05V on its own. I think I'll try a desulfator circuit to improve the 7Ah battery's performance and post my findings, that'll take a while though.

Still an excellent tutorial! Last year, my aunt got a used electric mini motocross bike, the batteries wouldn't charge, and I made the $60 mistake of suggesting that she buy new ones. Thanks to this tutorial I'll make sure to never shell out money for new Pb s until I give refilling a try.

[Fragmaster]

I used distilled water, a 12V regulated power supply, and a Thunder AC6 charger to monitor charging time, voltage, current, and power.

Breakthrough! My battery works great now! I was using a car battery charger with dual rates, but I think that charger couldn't handle the resistance of the newly added water (I think I over-filled it). Recently, I bought a Thunder AC6 multi-charger [It's absolutely great! I highly recommend anyone dealing with batteries, especially RC enthusiasts to buy one.] and it's safety features wouldn't charge the newly filled SLA battery, it was giving me a "low voltage" warning. So I hooked my battery to a 12V regulated power supply for about 30 minutes so the battery's voltage could reach about 11v. Then I immediately set my AC6 charger to 1.5A of charge current and connected it to the battery. It worked! The AC6 took 368 minutes to pump 9000mAh into that battery [overnight, so I couldn't check it all the time], evaporated the excess water, and magically saved me $35! The battery is now holding 11.851V and seems to be as good as new! I'll put it through a discharge/charge cycle to get it over 12V, but so far so good!

Thank you thermoelectric! Great money-saving Instructable!

[vdanvung]

hi there, good hack. just wandering i got one which when i charge my charger say its full charge, but when connected there only 5v. the battery is 6v 12ah. do i need to refill.

[12V]

i had exactly the same problem with my 12v 7.2ah and my 6v 4ah.
i connected the 12v one in series with 1 12v Christmas bulb and connected it to a 30v power supply for 3 minutes and immediately** connected it to the charger, it worked though it did not hold as much power as new.
exactly the same with 6v bu you MUST USE 2 bulbs otherwise they will blow.

**less than 2 minutes.

[Fragmaster]

12V (the person) is right, though I think I used a more conservative approach to solving this problem that most 12v chargers seem to have.
Simply hook your battery to 12v power supply for about 20 to 30 minutes (no serious risk of overcharging anything). This will get the internal voltage of the SLA to a threshold level (which I believe is something like 10v) so your 12v batter charger can do actual work on the battery.
After you'vw waited the 20 to 30 minutes, disconnect the 12v power supply and immediately connect the 12v battery charger.
The charger should then do its job.

I hope this comment helps answer some people's questions.

[thermoelectric]

I don't really know, but if you want to "bite the bullet" you can

[thermoelectric]

Well, I don't think so but if you want to risk the battery you can try it....

[vdanvung]

thx

[thermoelectric]

You're welcome

[sandesh_sk1]

Just wanted to know, during this whole process is there any chances of battery exploding?

[Fragmaster]

Any chances? Yes. You could always "cross the streams" and find a way to blow stuff up if you decide to mess with batteries in a moving car or "on a boat". But you'd probably only end up spilling battery acid on yourself, not blowing anything up.
Legitimate chances? Not really. Even if you overfill your battery and the pools of water between cells touch one another, the battery won't explode or arc.
Keep in mind that we are talking about refilling dead batteries that will not charge to 12V, but if they're truly dry, they shouldn't hold much charge at all. Mine was stuck at 0.178V before I reconditioned it with distilled water. That means that you don't mess with charged SLA batteries!!! 12V seems like chump change, but remember that Amps kill and Amps is what you'll get if you do something stupid.
The time that the battery is most vulnerable to failure and/or explosion is the same with all batteries, when it is charging. I'm not a battery expert, but Ive dealt with quite a few and overcharging is the greatest hazard to a batter, in my opinion (besides shorting them out of course). However, most chargers have several safeguards against overcharging, so don't obsess about it if you're using a "charger". If you're using a power supply, you should be more careful and monitor your battery's temperature while it charges, so make sure that you have about 6 hours of free time.