Gel batteries VS Lead acid batteries

Do any of you know much about these Gel batteries.
The only involvment I have with them is when I replaced two on a friends “mobility scooter”.
When I talked to the manufacture of the scooter, they said that if you let them drain to nothing they can never be recharged.
That is what happened…the person was hospitalized and no one was there to plug in the charger.

I ask because I know my friends plow truck has Gel batteries, new from last year, but I also know that the batteries are dead now.
I know he must have wired something up wrong and something is draining the batteries, but he doesn’t care to fix the problem.
I really don’t care to work on the thing anyway…he’s a “throw the trash on the floor until it blocks your view” kind of guy & I wouldn’t
drive this heap on the road without the paramedic’s following close.

So my question is can these batteries be recharged from a total discharge.


You can recharge a gel-cell battery but it requires a special battery charger.


We have gel batteries in ou flashlights and ups (computer battery backups) at work. In a power outage they go dead, the guys use the flashlights till they are dead. One time does not kill them but the more times they go dead the quicker they die in my experience.

The only place I’ve seen gel batteries used is in cleaning equipment. I think the advantage is that you can charge them indoors without creating a hazard. I don’t know if it’s true, but I once heard that OSHA requires lead acid batteries to be charged either outdoors or in a room with separate ventilation, similar to a hood.

Maybe someone with more technical knowledge can explain why or whether this is really the case.

I tried to recharge the scooter batteries when I got them out and on the bench, but they kept tripping the fault on the charger.
I tried to talk him out of Gels last year, because I knew he didn’t even glance at this plow truck off season, let alone start it now and then.
He said that if they went dead he’d just return them…he’s got a warranty!!!

Thanks @Tester & @Barkydog.

I’m not kidding about the trash in this truck. I’ll bet you could fill 2 five gallon buckets…just from the passenger floor. Old sticky soda cups, food wrappers, bottles, cans, etc… I thought that I’d be nice once, and cleaned his other truck when it was in for work once. In all the trash I found 4…four… old cel phones. How can you not clean your vehicle once, in the time it takes to break 4 cel phones.


Thanks @Whitey, for the input.


You’re welcome.

Okay, it’s coming back to me now. I’m remembering more.

I was working at a cleaning supply distributor in 1997 or 1998, and a representative from Windsor cleaning equipment was explaining the benefit of gel batteries. It was that you didn’t have to worry about them falling over on their sides or being tilted.

With that said, I’m willing to bet the gel batteries in question are deep cycle batteries, so you should be able to run them down without damaging them. We had deep cycle batteries installed on a bus that would sit unused a lot at my old job, and they wear out like any other rechargeable batteries.

On a mobility scooter, using deep cycle batteries makes sense, but on a plow truck, I’d rather use regular lead acid batteries and hook them up to a smart trickle charger when the truck sits. In fact, that is what I would recommend for your friend, especially if he isn’t interested in fixing the electrical problem that is draining his battery.

Gel-cell batteries can take more abuse than regular lead/acid batteries.

Because of the gel between the plates, this prevents the plates from coming loose from sudden shock. As in a plow truck.

Where with a lead/acid battery, the plates within the battery can short out from sudden shock.


Gel batteries ARE lead-acid batteries…It’s just that the electrolyte has been gelled so they can’t spill…The cells are usually round, but not always…Getting one to recover from a total discharge successfully depends on how long it was left in a totally discharged state…When charging, (a 12 volt) battery, the voltage must never be allowed to exceed 15 volts…When being charged, as they approach full charge and the voltage starts to climb the charger must cut off before that 15 volt figure is reached or the battery can be overcharged and damaged…If deeply discharged, they can be charged at a high rate for a while but as the state of charge climbs, the charging rate must be reduced to avoid damaging them…These batteries are sealed as they don’t gas when charged properly. But if charged at to high a rate or overcharged, they will gas and blow the seals, destroying the battery…

Your charger should to have a gel/agm setting

If it doesn’t, you may be out of luck

Personally, I think gel batteries are overrated

I say this, because they cost nearly twice as much as a conventional battery, but they don’t seem to last twice as long

They last a little longer, but not enough for me to think it’s worth it

Unless the vehicle manufacturer specifically calls for gel batteries, I think you’d be best off installing something more conventional

I’m just talking about cars and light trucks, not RVs or off-road equipment

Those vehicles might have criteria that I’m not aware of

These batteries are useful in applications where a maintenance free battery is needed. Most are of the deep-cycle type but they will work as starting batteries too…They are popular in Marine and aircraft, emergency lighting systems and in remote, unmanned facilities…Since they are leak-proof and spill proof they can be transported without restriction…With no out-gassing, they can be installed in small, unventilated compartments…

THanks for all the input everyone.

I’ll check out and suggest that he get a charger that will charge Gel batteries, but I’m sure he’ll just try to return them to the parts house.

I’m sure he bought them just because they are the newest thing out…not that they would take the punishment of plowing better.
This is an old Tahoe that is falling apart and I think he keeps all the seats folded down so he has room to throw all the parts that fall off.

I too would never buy one for this type of application…maybe if it was my daily driver!!!But then I wouldn’t have an electrical drain, and wouldn’t be letting the truck sit idle with two flats for six months either.


Most battery chargers will not charge a fully discharged battery of any type because as soon as you turn on the charger, it sees the dead battery as shorted cables and its protection circuits kick in. The trick to get around this is to hook you a good battery in parallel (i.e. jump start) and let it transfer a small charge, then hook up the charger.

There are some battery chargers that can condition a battery that has been completely discharged and left in that state for a while. This applies to gel batteries as well a liquid lead acid batteries. For all practical purposes, there is no difference between charging a gel or liquid battery. The chemistry is the same for both.

There are also deep charge and high energy versions of both batteries. The big advantage to gel batteries is that they don’t outgas so they are safer to use in indoor applications such as UPS or battery backups. They are also a little more vibration tolerant.

gel batteries are also used in high vibration scenarios. you will often see gel batteries in motorcycles due to the vibrations…and also the issues resulting in a crash or the vehicle being on its side. improved safety.

I researched a little bit this AM on NAPA for chargers and I only found one that was compatable with charging Gel batteries. It was a 900MA charger. I’ll research a little more over the weekend.

I also talked to the owner and he did buy two new lead acid batteries for it, but they have been on ther floor of the truck ever since last March.

@Kieth; that’s a great idea about tricking the charger. I had a battery that kept tripping my fault on the charger, though I knew the battery was not that old. I never knew that a charger would look at a totaly dead battery as a short. I replaced that battery, but had I known this trick, it may have worked and saved some money.


Any charger that can charge a liquid lead acid battery can charge a gel lead acid battery. The chemistry is identical. Just because a charger does not list itself as a gel battery charger does not mean it wont work.


Thanks @Keith; I was under the impression that they had to be charged at a very low rate (amps) because they were sealed so well that they could explode or crack the case with a regular charger.


Thanks for the link Tester.


Gel/AGM batteries do have the same chemistry as flooded lead-acid batteries, but they are less tolerant of high charge voltages.
Some chargers for flooded batteries are too agressive for gel/agm.
Most of what are called “gel cell” batteries are actually AGM, which use liquid electrolyte trapped in a fiberglass mesh.
True gel batteries are pretty rare these days.
Spiral wound batteies like the Optima are more robust than flat-plate AGM.