Should I go AGM or Gel?

[a64pilot]

You forgot one that is very important for most boaters.
Gel is more tolerant of partial charge cycling, an AGM should be fully charged as often as possible, wet cells and especially Gel seems more tolerant of not always being fully charged.

I have a quality AGM bank and do my best to maintain it according the the manufacturers directions, which means most days at least a half hour generator run, but if I had Gel, I wouldn’t likely have to run the generator at all.

[Adelie]

Maine Sail has indicated in the past on his website that you get a lot more cycle life out of Gels if you take care of them.

Also AGMs can burnout your alternator if it’s not well regulated. And AGMs need to be charged high C for best longevity which requires alternator use most days and a high capacity alternator if you have a larger bank otherwise you won’t achieve the high C charging the AGMs need.

[duncan_ellison]

OP here.

Thanks to everyone who contributed to this topic.

The final conclusion is that since the Gels I already have, have lasted so well and the replacements will be identical types from the same manufacturer (East Penn), then I'll be going down that route and taking advantage of the NAPA deal to save me about $500 on the pair.

Thanks for all the inputs regarding batteries made of exotic materials, it's all very interesting, but paying 3 - 4 times the price regardless of the benefits just isn't an option for me.

[Sea Flyer]

Lithium is the best way to go. Smaller lighter and more usable AHs and will last much longer

[duncan_ellison]

Thanks, Sea Flyer, but that wasn't the question I asked.

[tomtriad]

I've had both gel and agm, and I find the agm give me more longevity and more amphours for the same size battery. They both employ a gel paste for the electrolyte. The main difference is the agm plates are rolled into a cylinder whereas the gels have vertical plates and are more subject to degradation if they get sulfated (which will happen when you over discharge them). Any 12 volt battery is technically considered "dead" if the voltage drops down to 10.5.If you run them down below that they will not be able to recover completely and develop full charge. You may get away with it because you have excess capacity for your needs, but you're not doing the batteries any favor by leaving them deeply discharged for months at a time. A smart mppt regulator on a solar panel would keep them topped up when the boat is in storage, and that would be a good thing no matter what kind of battery you wind up with.

I've had best results with Lifeline AGM's; they are completely sealed and long lived. Utility companys (cell towers) bury them underground for emergency use and they last for years. Here's a link if you care to explore: https://lifelinebatteries.com/produc...eries/gpl-4dl/

[carlwk3c]

Originally Posted by makobuilders

So do these lithium batteries risk any of the spontaneous combustion issues that we've seen with phone batteries and scooters and such?

LiFePo4 is a different chemistry than cellphone/computer batteries.
It’s at leasr as safe as any of the lead acid types, probably moreso.
The other advsntages, such as high charge acceptance, about 2x more usable capacity at about 1/3 the weight in the same volume, and significantly longer life are, IMO, compelling and justified the initial cost. I expect that, over their life, they will be more than cost competitive with the 2-3 replacements of lead acid they will outlive.
We’ve had ours to over a year and couldn’t be happier.

[mako]

So from what I've been reading here, it seems that the gel batteries have very similar characteristics to standard FLA, just that they have gas recapture so are sealed. Is this correct?

[Boatsie]

Originally Posted by makobuilders

So from what I've been reading here, it seems that the gel batteries have very similar characteristics to standard FLA, just that they have gas recapture so are sealed. Is this correct?

Yes. Some similar characteristics.

Gel cells are highly efficient low current batteries.
I think AGM (absorbed glass mat) batteries are preferred over flooded lead acid because the plates are holding the fluid hence much safer as no spillage if the casing breaks.

AGM will handle more current but they tend to only be higher current acceptable when charged. Eg above 70% or whatever particular to brand model.
Unfortunately, they tend to charge ok up to about 80% and then they reduce their take of current. The last 20% doesn't charge very fast.

Balance that..

They could be ideal batteries if you want lower cost to buy, larger ballast, preferred luxury is admiring the environment and hence with a low draw system and can continually charge them with a soft gentle swell such as wind-electric, solar-electric, prop shaft-electric and a bicycle built with 2. �� feet pedals torquing an alternator.

New AGM (noting same scientists are advancing all battery systems, eg gel too) can be found to draw down to 20% but we'll find the high current use of they will still be up top. I do not understand the newer gel solutions reported as high current. Gels were low current efficient storage of energy.
Gel, FLA, AGM share many similarities.
A friend designed split house systems whereas bank 1 would draw down to a set level then switch to bank 2 while bank 1 took days to recover and obtain saturation but I'd suggest the draw currents didn't go high because such tends to spill electrons over a high flow electron rivers bank.
All three like to be left on a slow charge after about 80% capacity.. Give or take with brands and makes.

Nathan

[mako]

Thanks Nathan. For my particular usage profile the FLA/Gels would best match. In what situations would FLA be a better choice? Is lower cost the only reason?

I have checked the performance specs on some industrial 2V batteries and they appear to be quite similar to each other.

[Boatsie]

Originally Posted by makobuilders

Thanks Nathan. For my particular usage profile the FLA/Gels would best match. In what situations would FLA be a better choice? Is lower cost the only reason?

I have checked the performance specs on some industrial 2V batteries and they appear to be quite similar to each other.

Makobuilders
I don't know.. I use FLA in the car because they handle the high current starts. But the car doesn't pitch and roll, slap and take toll on the battery. Wouldn't want them to break.
Gel cells tend to be low current but very high efficiency to maintain hold the energy if used as low current batteries. I have a high current gel cell in my motorbike. It doesn't do what they write it does as well as a FLA would. It came with the bike and was fairly new when I bought the bike. It is treated well. I'm constantly charging it and resting during rides on hill tops such to get a wheel start because it fails often.

FLA. High current bursts. Keep charged. Potential hazard if damaged.
AGM. Better with a boat. Much similar to FLA. No spillage if broken.
Gel. Awesome if low current. Very low losses of energy. Much like AGM but they don't like high currents. None of them do.

I don't understand boat equipment. We cruised with an icebox. Fished at night. We used a weather station radio twice an hour. 200+Ah lasted us a month; easily. We'd knot worry and adjust sheets. Skipper would run the iron sail to charge them. I remember 10 litres (1/2 of 1 tank)
being used per 2-4 weeks as a normal. Iron sail was only charger we had. Block of solid ice lasted us 3 weeks.

I'm researching too bro. Mind storming earlier.. Scored a project. Years later I'll find something ocean capable and vary habit to suit the batteries she carries. I like the look of gel cells, LEDs, a radio, a fridge and as many chargers that fit without hindrance to sail or swell.

Best of luck..
Nathan

[Boatsie]

If interested.. Only ever used tillers. We'd sail at nights and sleep on the tiller. Skipper would take watch. A less on.
Sudden changes in variables would wake the helm or she'd stay balanced and slept kept.
Your welcome

[marty9876]

Slightly off topic - Napa (gel) batteries are the same as East Penn/Deka correct? Eg https://www.napaonline.com/en/p/NBP8272

I’ve had the AGM or Gel debate all winter and decided on gel’s - 20% off is certainly attractive.

[marty9876]

Originally Posted by marty9876

Slightly off topic - Napa (gel) batteries are the same as East Penn/Deka correct? Eg https://www.napaonline.com/en/p/NBP8272

I’ve had the AGM or Gel debate all winter and decided on gel’s - 20% off is certainly attractive.

Found a old Mainesail post along with numerous other hits, Napa is supplied by East Penn Deka. Got 3x group 31’s for my boat, $243/each before tax and core exchange, great price. Thanks OP for the 20% discount!

[duncan_ellison]

Just got it confirmed from East Penn directly. NAPA AGMs and Gels are made by them (at least the 4 / 8D sized ones are, probably the others too).