Introduction: How to Revive Old Lead Acid Batteries
If you are like me you probably have old lead acid batteries sitting somewhere probably discharged
If you dont use lead acid battery always charge it before and recharge it every 3 monts
battery replacement ipad air wifi 🔴how to battery replacement ipad air wifi for I ve tried this method on maintenance free lead acid, sealed lead acid and lead acid batteries , only difference is that maintenance free and SLA have hidden caps
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Step 1: You Will Need
-Adjustable PSU or Taper Charger (Smart chargers wont work)
-Distilled water (you can also use rain water)
Step 2: Measure Battery Voltage
Connect multimeter to your battery and check voltage
Your battery shoudnt be lower than 11.8v (30%) in open circuit
If you read lower than that you will need to revive it if its higher than that try to just charge it
100% = 12.73 the 1 last update 2020/07/14 v
90% = 12.62 v 100% = 12.73 v
90% = 12.62 v
80% = 12.50 v
70% = 12.37 v
60% = 12.24 v
50% = 12.10 v
40% = 11.96 v
30% = 11.81v
20% = 11.66 v
the 1 last update 2020/07/14 10% = 11.51v10% = 11.51v
Step 3: Inspect the Cells
Place paper towels on your working areas
Now if you have SLA or maintenance free battery you will need to remove lid with screwdriver
Put on gloves and remove caps
battery replacement ipad air wifi 🔴how to battery replacement ipad air wifi for Do this in well ventilated area
Wipe any wet spots with a paper towel
Then look inside cells and you should see white fabric that is dry
If you see brown fabric with white lumps your battery is probably sulfated and your chance of reviving battery is really bad
Step 4: Add Water
Take a syringe and fill each cell with water and look if fabric is absorbing water
Slowly shake battery and let it rest for 10 minutes
Step 5: Turn on Your PSU
Now you will need to connect your multimeter to show you how much battery the 1 last update 2020/07/14 is drawingNow you will need to connect your multimeter to show you how much battery is drawing
Set your multimeter to 10A and connect it in series with charger and battery
battery replacement ipad air wifi 🔴how to battery replacement ipad air wifi for When you connect it to the battery an it should draw 100-200mA
battery replacement ipad air wifi 🔴how to battery replacement ipad air wifi for Thats sign of dead battery
Set your psu to 14v or connect your charger and let it sit for day or two
After that your battery should for 1 last update 2020/07/14 draw 500-1000mA After that your battery should draw 500-1000mA
Then just leave battery and calculate how long battery should charge
Ah capacity = Amps that your battery is drawing x hours
For my battery 8Ah = 0.39A x 20,5 h
Step 6: Testing Battery
Now leave your battery for 1h and hook it up on car hadlight or any 12v bulb
Voltage the 1 last update 2020/07/14 of battery shoudnt drop lower than 12vVoltage of battery shoudnt drop lower than 12v
Step 7: Edit: 28.04.2019
At the time i wrote this instructable i was 15, i didn''s about 4y old) which is way too low for 7Ah battery and second one got 4424mAh which is kinda fine. I opened them up, instead of distilled water i used sulfuric acid that i got from old lead acid battery. I used pulse charger that i made and first battery didn''t say that pulse chargers (or desulfators) work but in my experience they did help with two battery while i had no luck with third one. I also tried simple 12V transformer and bridge rectifier and i had no luck bringing that first battery to life, it simply got hot and voltage dropped even further down to 6V which is a sign that cells are most likely damaged.
Desulfator/Pulse charger is simple 555 timer with 1khz signal turning mosfet on and off (1ms turn on time) with about 18V pulses up to 10A.
Method shown in this instructable works but your result will vary a lot. You might have luck and restore your battery or it may be damaged way beyond repair. Pulse chargers may work but if your battery is beyond repair just get a new one (you will also get discount by returning old one when buying new). Capacity will also vary, some batteries might be close to original capacity but if plates or electrolyte are bad it will have low capacity.
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battery replacement ipad air wifi 👍how to battery replacement ipad air wifi for 3 years ago
I know you put a lot of passion and effort into this project. I commend you on this. However when lead acid batteries fail, regardless of the variant, they simply cannot be revived and expected to produce even 40% of their original capacity. They are truly disposable after failure. Also, do not interfere with lead acid battery insides; you don''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
Reply 2 years ago
buy a replacement battery or spend the extra money to purchase the acid necessary to properly have a specific x to y ratio of water to acid.
If you keep adding water, you''t be low. If you have to add water you haven''t forget to wear goggles. I have a SLA I can't wait to try this on. Thanks.