Normally in the process of discharging and charging you will get some water loss, but the acid stays in solution. But, if the battery has been abused and the electrolyte loss is due to gassing off - some of the acid can be carried off by the hot steam vapors - hence acid loss can occur.
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In this case you would need to replace the lost acid.
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Hmm... mixing anhydrous (100% pure) Acid is dangerous.
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You only need like 5% in solution for a battery. So the problem is adding the right amount (and yet not killing yourself in a flash explosion)...
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The easiest is to buy battery electrolyte at a battery shop. It is pre-mixed at 5%.
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But, you already have electrolyte in the cell, so adding like 20% of a cells capacity with 5% electrolyte is not that good a deal. You see if your solution has boiled off (for various reasons) and carried say 40% of your suspended acid with the vapor - then adding the 20% of lost electrolyte solution (currently at like 3%solution) with 20% of 5% solution will only give you about 4% over all!!! So what to do???
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Drain the cell and add fresh electrolyte? Hmmm... sounds good, but the battery has to be unloaded (disconnected totally). and how do you do this without stirring up the settlings in the bottom of the cell???
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So many issues.
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The best thing would be to top off the battery with water (just like everyone suggests). Then charge the battery completely, let itrest for a few hours. Put a Carbon Plie tester on it and run it down to about 60% DOD (40% with deep cycle). Verify and top-off the cells with water and recharge agian.
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Repeat the wait state and take specific gravity readings. Then calculate how off yourreadings are. This will determine the solution that you will need to add to bring the battery back up.
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Go to a battery shop that rebuilds batteries (there aren't that many) and see if they will mix the electrolyte for you. take your readings and "your" hygrometer with you. (not all hygrometers are created equal - better to be safe and find out the failings of your hygrometer now that after they mix the wrong electrolyte concentration.).
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In the worst case - buy 25ml of Anhydrous Sulfuric Acid and mix your own electrolyte. Most flooded cell batteries use sulfuric acid (but some use hydrochloric acid - so make sure you know which one).
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To mix acid you need:::
1) A faceshield and a pair of safety glasses (preferable goggles).
2) a Pair of elbow length rubby gloves (not vynyl).
3) a rubber apron. (also wear long sleeved shirt - preferably denim).
4) a 5-lb box of baking soda.
5) a 100ml and a 250ml heavy duty beaker (lab glass).
6) two 5-gallon jugs of distilled water.
7) a 100 ml gradutaed beaker is recommended (but a common glass bakers measuring cup will suffice).
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To mix electrolyte...
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First measure about 10 ml of acid into a 250-ml beaker (you can put more in - but I recommend you get the process down pat first - the reaction can get unsettling to a novice and take you by surprise - not good!).
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Always mix water into the acid (NEVER MIX THE ACID INTO THE WATER - You cannot Control The Reaction and the reaction of acid into water will be immediate).
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You slowly add water (using the hydrometer as an eye dropper to hold and add water) until you reach the solution you want).
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The percentages are really a matter of simple math...
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Looking for 5% you add 200ml of water to 10ml acid = 210ml (not really accurate but will be withing .75%).
So for 6% add 200ml of water to 12ml acid (11.5ml would be more accurate).
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Using this method you can easily mix your electrolyte solutions to bring any abused battery electrolyte solution ratios back to norm (BUT YOU CAN ALSO OVER DO IT AND BURN THE CELLS UP TOO!!!).
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Always check and re-check with a hydrometer as you go. Remember your target is to get the readings and concentrations back to norm. not supercharge the battery..
information was curtsey of
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