Flooded Cells vs. Gel Cell Batteries

Johnb · Jun 10, 2015

Until something MUCH better comes along I am going to stick with flooded batteries. Top up the water every second month and enjoy a life cycle cost of about $10 per battery per year.

I have just never had any problems with this. The only thing is you have to pay a bit of attention to their needs.

UnME · Jun 10, 2015

How about AGM? I understand that they don't have the reduced charging voltage requirements and are still quite the upgrade. They also reduce sulfates from caking up on the plates and can withstand more cycling frequency. Im sure you've done your homework on this kind of stuff but I really enjoyed this article on batteries... It brought a lot of 'light'?

http://www.batterystuff.com/kb/articles/charging-articles/how-do-i-pick-a-battery-charger.html

Maine Sail · Jun 11, 2015

dlochner said:
The batteries need to be replaced on my boat, currently have 4 GC flooded cells.

Thinking of changing to gel cells. The onboard charger is a Pro Mariner Pro Nautic that can appropriately charge the batteries at the dock. However, the alternator is an 80 amp internally regulated alternator and the budget is not sufficient to change to an externally (and adjustable) regulator this year.

The question is simple, will the alternator damage the batteries while charging? Next year's budget could support an external regulator, so we are talking one season of abuse. Or would it be better to stay with flooded cells?

Long term plans include adding solar as a charging source.

Thanks for the insights.

Dave

Flooded batteries would be fine but you could also consider the new Firefly AGM which will handle 14.4V and is extremely sulfation resistant. They can also be regularly cycled to 80% depth of discharge so a smaller bank can be used. Only available in a Group 31 case but very impressive AGM batteries. You'd probably not "ruin" the GEL's but you would certainly eat into their life some..

GEL batteries are great deep cycling batteries, some of the best in lead acid, but they need to be installed as a system if you want the optimal cycle life.

Deka has recently begun suggesting that 14.4V to 14.6V is safe for these batteries but has failed to produce those of us in the industry any relevant testing data to back this up. For Deka they win if they can sell more batteries charged at flooded or AGM voltages but they soon forget the reason GEL batteries still have a bad rap, because they tried this once before....

I have documents from Deka showing that a charge voltage of just 0.7V above the recommended 14.1V (temp compensated) results in a 60% reduction in cycle life.. Even just 0.3V results in an approximate 20% reduction in the lab. In the real world this seemed to be worse because people would charge at 14.4V without temp compensation which could really equal 14.8V if the batteries were hot enough..

From Deka: (this is what they opined for well over 20 years until the marketing department demanded 14.4V to 14.6V on the label...):cussing:

Gelled Electrolyte Disadvantages: (the bolding is from Deka, not me)

Charge voltage must be limited to extend life (13.8 to 14.1 volts maximum at 68°F)

Automatic temperature-sensing, voltage-regulated chargers must be used

If you are not going flooded you could consider the Firefly AGM.

woodster · Jun 11, 2015

Maine Sail said:
Flooded batteries would be fine but you could also consider the new Firefly AGM which will handle 14.4V and is extremely sulfation resistant. They can also be regularly cycled to 80% depth of discharge so a smaller bank can be used. Only available in a Group 31 case but very impressive AGM batteries. You'd probably not "ruin" the GEL's but you would certainly eat into their life some..

GEL batteries are great deep cycling batteries, some of the best in lead acid, but they need to be installed as a system if you want the optimal cycle life.

Deka has recently begun suggesting that 14.4V to 14.6V is safe for these batteries but has failed to produce those of us in the industry any relevant testing data to back this up. For Deka they win if they can sell more batteries charged at flooded or AGM voltages but they soon forget the reason GEL batteries still have a bad rap, because they tried this once before....

I have documents from Deka showing that a charge voltage of just 0.7V above the recommended 14.1V (temp compensated) results in a 60% reduction in cycle life.. Even just 0.3V results in an approximate 20% reduction in the lab. In the real world this seemed to be worse because people would charge at 14.4V without temp compensation which could really equal 14.8V if the batteries were hot enough..

From Deka: (this is what they opined for well over 20 years until the marketing department demanded 14.4V to 14.6V on the label...):cussing:

Gelled Electrolyte Disadvantages: (the bolding is from Deka, not me)

Charge voltage must be limited to extend life (13.8 to 14.1 volts maximum at 68°F)

Automatic temperature-sensing, voltage-regulated chargers must be used

If you are not going flooded you could consider the Firefly AGM.

is there a list of sellers ...where some one can purchase these firefly bats

Maine Sail · Jun 11, 2015

UnME said:
How about AGM? . They also reduce sulfates from caking up on the plates and can withstand more cycling frequency.

Unfortunately none of that is really true when compared to true deep cycle flooded or GEL batteries with the exception of the new Firefly AGM, which is still yet unproven over the long haul in the real world of the marine environment....

Right now there is only one AGM I know of that can actually resist sulfation and that is the Firefly AGM. You then have the other premium AGM's like Odyssey, Northstar and Lifeline coming in behind the Firefly in regard to dealing with partial state of charge use and fending off sulfation.

Deka's (which are massively private labeled) deal rather poorly with PSOC operation, which is how we use batteries on boats. In the recent Practical Sailor PSOC AGM testing the Deka AGM lost 30% of its capacity in just 30 PSOC cycles. Deka claims 1000 lab cycles for their GEL and 370 lab cycles for their AGM's so this is not a huge surprise.

Fighting Sulfation In AGM's (LINK)

Maine Sail · Jun 11, 2015

woodster said:
is there a list of sellers ...where some one can purchase these firefly bats

The dealer network is small right now but is growing. These are hand made batteries (not too unlike Rolls in production scale) and demand is sometimes outpacing supply. Best to contact Ocean Planet Energy to get an idea of availability. I think for most folks right now they are mail order...

Here in Maine we have:

Ed's Batteries - (207) 854-9418

Ocean Planet Energy - (207) 370-9112

woodster · Jun 11, 2015

Maine Sail said:
The dealer network is small right now but is growing. These are hand made batteries (not too unlike Rolls in production scale) and demand is sometimes outpacing supply. Best to contact Ocean Planet Energy to get an idea of availability

thanks ms

Rasselas36 · Jun 15, 2015

I am not an expert on Flood vs Gel batteries but this is what I have used in my H36 for the past 11 years. The boat came Trojan batteries and they lasted 3 years. I switched to AUTOZONE batteries because of price. The first set lasted 4 years. Got 4 years on the 2nd set. I am on my third set and will continue to use this brand until they quit making them. AUTOZONE - Duralast/Marine battery two 27DP-DL and one 24MD-DL.

mitiempo · Jun 15, 2015

Rasselas36 said:
I am not an expert on Flood vs Gel batteries but this is what I have used in my H36 for the past 11 years. The boat came Trojan batteries and they lasted 3 years. I switched to AUTOZONE batteries because of price. The first set lasted 4 years. Got 4 years on the 2nd set. I am on my third set and will continue to use this brand until they quit making them. AUTOZONE - Duralast/Marine battery two 27DP-DL and one 24MD-DL.

So you are happy with only 4 years from each set? Many battery banks last 6 to 8 years.

gettinthere · Jun 16, 2015

I am on year 6 with my T-1275 Trojan wet cell batteries. They are still giving full specific gravity reading when fully charged and use very little water. I expect several more good years.
Not uncommon to get 10 years out of trojan wet cell batteries if used properly.

mitiempo · Jun 16, 2015

gettinthere said:
I am on year 6 with my T-1275 Trojan wet cell batteries. They are still giving full specific gravity reading when fully charged and use very little water. I expect several more good years.

While 6 years is good and you may get 8 or 10, specific gravity has nothing to do with capacity.

Johnb · Jun 16, 2015

The specific gravity is a valuable indication of the battery state, especially differences between cells. In my experience it is the easiest and most direct measure of battery condition. Another advantage of flooded batteries. Below is a good read.

http://www.trojanbattery.com/BatteryMaintenance/Testing.aspx

Maine Sail · Jun 16, 2015

Johnb said:
The specific gravity is a valuable indication of the battery state, especially differences between cells.

Yes differences in SG between individual cells can help identify when it is time to equalize the batteries but that is really the only good use for opening the batteries and risking contamination or holes in your clothes.

Johnb;1218551[B said:
]In my experience it is the easiest and most direct measure of battery condition[/B]

Specific gravity can not tell us about the batteries condition, state of health or its current Ah capacity, compared to its Ah rating, until they are well beyond dead. All it can do is tell us the state of charge. Dead for flooded batteries is defined by the battery not being able to deliver at least 80% of the 20 hour rating.

I have tested piles & piles & piles of batteries for Ah capacity using lab grade test equipment. Many of these batteries were down 30-50% of the factory Ah rating yet most all of them were still able to deliver a 100% SOC specific gravity reading after a proper full charge..

Relying on SG readings for battery condition or state of health is just not realistic. SG can tell you SOC but SOC is a lot different than condition or state of health and the batteries ability to deliver the rated Ah capacity. It is entirely possible to have a 100Ah rated battery giving a 100% SOC SG reading yet only be able to deliver say 65Ah's of capacity, I've seen this too many times to count...

Rested open circuit voltage will tell you everything SG will with the exception of individual cell balance. If your batteries won't rest at full voltage charge them more or equalize them.

It is generally best to avoid opening your batteries unless you suspect a problem or they need topping up with distilled water...... If you want to know your batteries true condition you need to conduct a 20 hour capacity test

gettinthere · Jun 16, 2015

There you go again with those darn facts.

You really want me to do that resting voltage test dont you? Uggh

Probably doesn't matter but we're staying above 80% on the victron now that I added 2 more solar panels. This after making all the recommended adjustments to the victron and dialing the bat size down to 800 from the original 900 amp/hr.

Johnb · Jun 16, 2015

What specific gravity is good for is telling you right now whether the battery is DOA or worth persevering with

mitiempo · Jun 17, 2015

Johnb said:
What specific gravity is good for is telling you right now whether the battery is DOA or worth persevering with

Wrong. Re-read post 15

Maine Sail · Jun 17, 2015

Johnb said:
What specific gravity is good for is telling you right now whether the battery is DOA or worth persevering with

All it tells you is the SOC not the condition of the battery. You can still have a battery not worth continuing on with that gives a good SG reading when fully charged.

franst8 · Jun 22, 2015

Greetings Maine Sail, The Firefly batteries are pretty scarce. I just bought the last 2 available in CA. The dealer said they are tooling up to manufacture more very soon to meet demand. My question is...what charger would you recommend I get to go with these batteries? I am redoing me electrical system and want to get it right. I already have heavy duty cables and a couple of as yet unused distribution blocks.