Conflicting info on Gel

[Jemplayer]

I am looking for some opinions here. I was to understand that gel batteries were not suitable for cycle usage and therefore no good for a an off grid solar system.

However, after some reaserch, I have found that Both Trojan and Victon Energy (among others) manufacture these and specify them specifically for renewable energy and solar applications??

I am very confused. I would like to put in a sealed battery due to the constant maintainance of FLA's, esp as they age, but I am now lost as I am getting totally conflicting info from these industry leading companies, as to the suitability of Gels for cycle applications. ???

[Willy T]

What do you want to hear ?? That it's false statement that you can charge them above C/20 & 14.1v without damage. That temperatures above 70° F or so really does not cause electrolyte to dehydrate. That voids in the gel will heal it's self and the loss in capacity will return.

No one I know has received good service from them, if you believe you will, buy them and post back.

[Living Large]

I am looking for some opinions here. I was to understand that gel batteries were not suitable for cycle usage and therefore no good for a an off grid solar system.

However, after some reaserch, I have found that Both Trojan and Victon Energy (among others) manufacture these and specify them specifically for renewable energy and solar applications??

I am very confused. I would like to put in a sealed battery due to the constant maintainance of FLA's, esp as they age, but I am now lost as I am getting totally conflicting info from these industry leading companies, as to the suitability of Gels for cycle applications. ???

I am a novice, but I believe among negatives would be susceptible to more easily being damaged by overcharge than FLA, and cost. The cost is the tradeoff in convenience for not taking FLA on as a second child. I was looking at LFP batteries, also for convenience, also for low internal resistance, and they also need to be carefully treated in terms of charge - not under or over charging them.

[sdold]

Is it possible that you are confusing "gel" with "AGM" (Absorbed Glass Mat)? Both are sealed, but the AGM is suitable for RE uses, while the gel type is usually not.

[Sunking]

I am very confused. I would like to put in a sealed battery due to the constant maintainance of FLA's, esp as they age, but I am now lost as I am getting totally conflicting info from these industry leading companies, as to the suitability of Gels for cycle applications. ???

Different aproach.

You must have more money than you know what to do with right? You must also be very lazy right?

You have to answer YES to both questions to use Gel batteries. Otherwise you are a fool.

A T-105 is a 6 volt 225 AH battery. It cost roughly $130.00 at your local golf cart or floor machine shop. With proper care 2 to 3 years service Using 30% capacity daily, for 2 years service life the power from the battery will cost.you 400 watt hours per day x 730 days is 292 Kwh. That is a cost of 44.5 cents per Kwh or 3 to 4 times more than what you can buy it from the power company. Horrible economics using inexpensive FLA battery.

But hold the bus, if you think using FLA is horrible, look at Gel and AGM. The Trojan TE35-Gel will cost you roughly $330 and is the 6 volt 220 AH equivilent of the T-105. If you never screw up you might get 2 years out of it. 1 year or less is realistic. All it takes is one over charge or one over discharge and you destroy the battery. Gel batteries do not tolerate any abuse. FLA is tough as nails. But ignore that and only look at economics. Assuming again 30% DOD and 1 year service 400 wh per day x 365 days = 146 Kwh. Battery cost is $330/146 Kwh = $2.26 per Kwh. That is 5 times more than FLA or 15 to 20 times more than the power company.

So if you insist on using gel: Are you a Lazy Rich SOB, or a Fool? We would really like to know your answer.

[Jemplayer]

Sunking, thank for the costs breakdown. However, not applicable to me. Batteries are more expensive were I am, and the cost diff between the T105 and gel is neg. just to prefice, I am not looking Trojan gels rather another brand hat is imported, but had many hundreds of batteries in the field with good results thus far after 18 months in.

I take all the points made. I am still not sure why when clearly this tech is not suitable for daily cycling, they are being earmarked as a very good and viable option for this purpose? Baffleling.

Ok so then back to FLA we go.

Two banks of T105's at 48 volts (I.e.2 banks of 8) giving 450ah, or one bank of the Trojan L16 420ah premium line. About a 28% price difference?

[Sunking]

Gel batteries do not tolerate any over charge. They must be CHARGED SLOWLY, Solar requires FAST as you only have a few hours, not 24 hours required for Gel. Gel charge rate is 20 hours, and Solar requires 8 to 10 hours or faster. If you charge a Gel to fast or over charge, will dry the Gel out and cause cracks and voids. The damage is permanent and accumulative. Think about the Jello Salad your Mom made last Christmas and you just found in the back of the fridge. You cannot fix it. You could have sworn it was Cherry, not Lime.

Gel batteries are for Emergency Egress Lighting, and Alarm Systems. That is an Emergency Standby Operation. They have very small chargers and operate at a slightly lower voltage.

[PNjunction]

I take all the points made. I am still not sure why when clearly this tech is not suitable for daily cycling, they are being earmarked as a very good and viable option for this purpose? Baffleling.

Daily solar cycling with sealed batteries, be they Gel OR AGM is hard to do *properly* in practice, mainly due to a time-constraint to actually finish the charge, (even with the proper different chemical absorb voltage ratings) otherwise they walk themselves down in capacity and performance.

Basically, to get an agm fully charged, one needs to provide at least 6-8 hours or more of float after a proper absorb to get that last 1% in. This is impossible, even in the best of solar insolation areas for daily cycling. And it does not matter how high-quality your agm is even if you can hammer it at 1C! It *still* needs a "finishing" float to complete the job. Note that the "finish float" is different from a "maintenance float". Many get this wrong - just dropping to float, even if done after a proper absorb, is NOT enough for daily cycling. You need 6-8 hours, and hopefully at 13.8v, and not at 13.2v!

Gel needs the same long "finishing float". But to make matters worse, most gel's have limitations on the initial charge current as Sunking points out. Even if one is aware that gels are designed for no more than 14.1v to get the rated cycle life out of them, the double whammy of a low initial charge rate, combined with the need for a finishing float make them the least desirable for *daily cyclic* solar. Note you don't see any charts showing the difference between charging gel's at 14.1v vs charging them at 14.4v in order to not make the average consumer with a 14.4v charger mad.

So... the usual design goal is to get up to and out of proper absorb as fast as you can to get the longest float in. In an area with only 2 hours of solar insolation, that is BAD NEWS, even if you only discharge 10% DOD!

Hard core daily cycling with sealed batteries needs some good engineering up front (like the IUI protocol) - either that, or just accept the eventual walk down in capacity and performance.

If one isn't doing 24/7 daily cycling, then a sealed battery's needs can be met much easier.