Is an 8ah 24v charger needed or is 5ah 24v charger OK?

[Windmaker]

I was fortunate enough to have someone donate an electric wheelchair to me this past year, but I've also recently had an unfortunate experience in purchasing two supposedly excellent quality, U.S.made, gel batteries, but they went south on me almost immediately. The "gooder" news is that my vendor contacted the manufacturer and they are going to send two replacement batteries under the warranty. The vendor also relayed to me that the manufacturer recommended that I upgrade my 5ah, 24v charger that came with the chair to an 8ah, 24v charger for these two 50ah gel batteries.

That produces my question.....would an 8ah charger be all that much of an improvement for the health of these two 12v gel batteries over the current 5ah charger? Since the cost would probably be a one hundred dollars or more added expense to purchase such a new charger, it should be a significant improvement, I would think. Or to the contrary, do you think the 5ah charger is just fine? Apparently the wheelchair manufacturer thought so when the chair was produced about ten years ago, because to my knowledge the gel batteries were basically the same then as they are today...or weren't they?

 

[Ykick]

I'm confused why a charger would be rated with Ah? Unless they're playing sales engineering/marketing games chargers are sold by how many A (amps) they deliver. Ah (amp hour) is the unit for battery capacity.

I

 

[Jon NCal]

The larger charger is not going to make the battery last longer, just charges it more quickly.

 

[999zip999]

If your battery BMS battery management system can handle the higher output amps of the more powerful charger then it's okay what is the watt
rating of each charger ? Is it the proper charger for the battery SLA lipo lifepo4 nmc or what's it for. Maybe a sticker ?

Do you have a multimeter what is the voltage of a charger ?

 

[Gregory]

Gel batteries require a slow charge. C/20 is commonly mentioned i.e 2.5A for a 50Ah battery. Going faster is detrimental to their health.
AGM is more forgiving.

Unless your dealer is advising a new charger because the old one is poorly regulated or doesn't have a proper float profile, I'd say he's full of shite and is just trying to sell you an unnecessary part.

 

[Windmaker]

I'm confused why a charger would be rated with Ah? Unless they're playing sales engineering/marketing games chargers are sold by how many A (amps) they deliver. Ah (amp hour) is the unit for battery capacity.

I

My bad....I apologize for the misstatement.....it should have been amps, not ah that I used....stupid is as stupid does, or something like that. I think I watched the Forest Gump movie too many times.

 

[Windmaker]

The larger charger is not going to make the battery last longer, just charges it more quickly.

That was my first thought when I heard the recommendation. Unless I learn differently, that's what I'm accepting and keeping my $100

Thanks for your input.

 

[Windmaker]

If your battery BMS battery management system can handle the higher output amps of the more powerful charger then it's okay what is the watt
rating of each charger ? Is it the proper charger for the battery SLA lipo lifepo4 nmc or what's it for. Maybe a sticker ?

Do you have a multimeter what is the voltage of a charger ?

I don't have a multimeter. I don't know the watt rating of my existing charger(not cited anywhere on surface of the charger), and I haven't yet purchased an 8 amp charger, so I can't give you the watt rating on it either. The batteries are 12v 50ah gel SLA batteries and a tech from my wheelchair manufacturer said the charger should work just fine with gel batteries. Hope I've answered all of your questions. Thanks for your help.

 

[Windmaker]

Gel batteries require a slow charge. C/20 is commonly mentioned i.e 2.5A for a 50Ah battery. Going faster is detrimental to their health.
AGM is more forgiving.

Unless your dealer is advising a new charger because the old one is poorly regulated or doesn't have a proper float profile, I'd say he's full of shite and is just trying to sell you an unnecessary part.

Hey mate....thanks for your comments. The dealer didn't recommend the new charger, their cust. svc. agent just relayed the recommendation from the battery manufacturer rep they spoke with and who knew only my charger amp rating and nothing else. I kinda had the same impression as you expressed above, because the MK battery company does sell an 8 amp charger, but since I'm relatively naive about these matters I thought I'd better float the question on this forum to be more certain. What's more, they also recommended charging the batteries every night, whether you used the chair or not. That's the first time I've heard that recommendation. The tech from the chair manufacturer advised charging gel batteries for no less than 8 hours after each use (even for just a few minutes), but no more than 15 hours at a time. There was no comment concerning a BMS. It certainly gives me pause as to why there are so many different views on proper battery maintenance floating around.

I've attached a picture of the charger that came with the chair and I think the replacement cost for this unit was between 2-3 hundred dollars, so I'm assuming it was (10 years old) and still is a good quality charger.