I recently got a Yuasa PowerSport (6N5.5-1D- 6V 5.5Ah) bike battery. Since, amazon does not sell it with the acid, it has to be purchased separately from a auto store or self prepared. I went with the later and prepared a 37% sulfuric acid solution using a 98% ACS H2SO4 reagent. If I'm correct flooded Lead acid batteries use 36-38% sulfuric acid electrolyte. I had prepared the acid solution yesterday. A little while ago I added the prepared acid to the battery and immediately upon adding the lead plates died/bubbled a bit and the battery is getting warm (not hot!). Is this normal or something is wrong with my battery?

The battery shows a voltage of 6.62V. While charging the battery for the first time can I use a constant voltage charger. Can the charging voltage be 7.2-7.5V like SLA or should it be lower for a flooded cell?

 

For 6V charge it at 6.9V .

 

Sounds like a bit high on the acid concentration. Assuming you are using 18.4 molar H2SO4 with a density of 1.84 g/ml, then a 30% solution with water (density 1.0g/ml) should give you a final SG of just over 1.25. After initial charge, that may increase a bit. Don't see anything about SG on the battery specs, but generally anything over 1.25 is undesirable in regards to battery life.

 

For 6V charge it at 6.9V .

This for a flooded cell right? I mean on SLAs I've noticed them mention to go from 7.1 to 7.2V for cycle use.

 

Sounds like a bit high on the acid concentration. Assuming you are using 18.4 molar H2SO4 with a density of 1.84 g/ml, then a 30% solution with water (density 1.0g/ml) should give you a final SG of just over 1.25. After initial charge, that may increase a bit. Don't see anything about SG on the battery specs, but generally anything over 1.25 is undesirable in regards to battery life.

Thank you for the update. I contacted Yuasa and the engineer told me that I can use anywhere from 36 to 38% acid concentration. That is around 37.57mL of acid for preparing 100mL 37% acid solution I guess?

 

Yes, that is correct. Be sure to add the acid to water, not the other way around. Then after you have approximately (but less than 100 mL) of cooled solution you can carefully adjust to final volume with water.

 

Yes, that is correct. Be sure to add the acid to water, not the other way around. Then after you have approximately (but less than 100 mL) of cooled solution you can carefully adjust to final volume with water.

Yes, I have to constantly run chilled water around the glass vessel I'm preparing the solution in. It's a long process mainly due to the enormous heat this thing generates. Especially if you have to prepare for a large battery that required a liter or more.

Oh yeah, other way round water into such a large quantity means RIP to face and eyes!

 

... use distilled water. Tap water often has a high mineral content, which may enter into the chemical reaction somehow.

 

... use distilled water. Tap water often has a high mineral content, which may enter into the chemical reaction somehow.

Of course. I used de-ionized water since I had access to plenty of it.