Which is better: Lead acid (SLA) or GEL?

[okrobie]

I'm replacing batteries on a 48V electric scooter. Currently 4 - 12V 18AH SLA's. I notice that pricing on SLA vs. GEL, is sometimes on a par with one another. Which is better? Thanks, Jim

PS I built a set of 12V Lithium Ion batteries out of recycled laptop cells 18650's with not so good results, so for this thread, lets leave that option out of the conversation. I'll start another thread for those issues.

 

[AussieRider]

G'day mate.
SLA or sealed lead acid contain liquid electrolyte while in gel the electrolyte is a paste.
Then there's AGM or absorbed glass mat which uses fibreglass mat kinda like a sponge to hold the acid electrolyte .
All 3 have slightly different characteristics as to ideal charging voltages, CC / CV thresholds & charge rates
But are close enough to be able to use the same chargers.
It's best to keep SLA upright so the liquid acid covers the plates properly while GEL & AGM can be mounted in any position.
One thing though is if an impact cracks the case, SLA can leak acid over your bike and / or you.
GEL & AGM will dry out, lose a cell & not charge up.
Hope this helps

AussieRider

 

[okrobie]

G'day mate back atcha,

Thank you for your detailed reply. That's excellent valuable information.

I am also searching for the "YMMV" info. "Your mileage may vary" That's a familiar tag line for vehicle advertising up here.

I would like to know things like charging time, expected number of charges, driving range etc.

Is there much difference on stuff like that? Thanks

 

[john61ct]

GEL is a lead (acid) chemistry.

SLA means nothing special, just not FLA.

Both AGM and GEL are VRLA, which is a subset of SLA.

Proper deep cycling battery is what you need

from a well respected maker, most important, more so than chemistry.

Value and choices depends on what market you're in, for Oz/NZ maybe Full River AGM is best afaik.

GEL can last a very long time but requires special custom setpoint adjustable charge sources, very easy to murder by overcharging.

AGM also has finicky requirements for maximum lifespan, at least compared to FLA

which at least in NA market, is far better value.

Best deep cycling AGM in NA are Odyssey, Northstar and Lifeline.

 

[okrobie]

Hi John, thanks for your well studied advice. I made my purchase but you won't be happy with me. I took the easy route and bought the lowest cost, fastest delivery GEL batteries (MightyMax?). I bought a 48V charger that say's that it is compatible with GEL and AGM. Your advice seems well researched so I'll probably regret my impulsive choice. Thanks, Jim

 

[john61ct]

Likely better than generic SLA. Where are you located?

See if you can get a data sheet on both or either.

Compare what the charger actually does

using an accurate DMM right on the post

before voltage drops to Float.

Ideally also log amps with an ammeter.

Post back here and maybe we can help you get good longevity.

I've seen Sonnenschein GEL cycled daily for 9+ years losing less than 20% capacity, but they are the best.

If Mighty Max are actually made by EPM/Deka those are good too.

 

[999zip999]

Make sure all batteries are of same voltage before putting it in series Spirit lead batteries like to sit fully charged always so do your best to keep them fully charged always so they have a long life do not let him sit dead.
18650 from my laptop are batteries that are meant to sit on the top of your table they're not design to propel you you have to buy quality cells. From IMR battery or some reputable dealer. Used cells from a laptop is like buying your batteries at the 99 cent store.

 

[okrobie]

Hi John, thanks for your well studied advice. I made my purchase but you won't be happy with me. I took the easy route and bought the lowest cost, fastest delivery GEL batteries (MightyMax?). I bought a 48V charger that say's that it is compatible with GEL and AGM. Your advice seems well researched so I'll probably regret my impulsive choice. Thanks, Jim

Well, you may not be surprised to hear that the MightyMax batteries were awful!!! They had high internal resistance right out of the box averaging 22 mohms.

The good news is that even though I was negligent by reporting the problem a week past the Amazon one month replacement deadline, The Amazon customer service rep who took my call, went beyond the call of duty. He tried to put me on a conference call with the manufacturer but they failed to recognize my order and would not honor the factory 1 year warranty and had no solution to offer. He then conferenced with management and was pleased to tell me that Amazon would replace my batteries at their expense and from a different manufacturer and they will arrive today.

Needless to say my customer loyalty to Amazon just went up by a gazillion points. I suspect that MightyMax may not be an Amazon vendor for much longer.

I'll let you know how it goes from here. Thanks, Jim

 

[john61ct]

Yes I'd heard elsewhere MM were ordinary, IOW crap.

Was hoping the GEL might be an exception.

Thanks for reporting back.

Amazon is not where to look for good value for deep cycling batteries.

Call the three manufacturers I reco above, ask for distributors nearby.

 

[okrobie]

Well the replacement batteries arrived but... They were MightyMax and all had the identical internal resistance problem. I talked to Customer Service and they promised a full refund, and again they said to keep the batteries. They stated that the previous CSR would never be allowed to promise to send a different brand. Their order/replacement software would not allow that to ever happen.

Now that I have six brand new albeit defective ones, makes me wonder if these pulse style de=sulpherization battery chargers can do what they claim to do. I bought a cheap one once at Northern Tool, but it had no effect on internal resistance. I didn't really expect much, but it was a good charger so I never sent it back or anything. The better ones cost about the price of a new set of batteries. I'll do a search to see if this board contains any info.

 

[john61ct]

No, near universal consensus among experts they are snake oil.

Plenty of gullible consumers and of course the sellers say otherwise.

No credible objective evidence of them doing anything.

But manually "equalizing" with a regular charger set at higher voltage will indeed slow down the wear acceleration of PSOC abuse.

But just ensuring you get to 100% Full charge (as per endAmps) at least every 2-3 cycles

and not going lower than 50% SoC

will help you get at least a couple hundred cycles out of them.