Carbon Foam AGM Batteries

ALLOY · October 10, 2017

A friend of mine is installing them in his new boat.....what sold him is there is no need to change the system over to Lithium

The technology is suppose to make lead acid comparable to Lithium

http://fireflyenergy.com/

http://www.trawlerforum.com/forums/s3/carbon-foam-batteries-1-year-later-26233.html

Kirk W · October 10, 2017

It is an interesting technology and bears more research but everything that I could find about them in terms of review is at least 1 year old. I wonder why there isn't something more current?

Al F · October 11, 2017

J-T,

Do you have any info about price?

Looking though the http://fireflyenergy.com/ The batteries seem to be the standard Group 31 batteries, with unsubstantiated claims for long life. The only difference in this battery that I see is the material between the plates is Carbon Foam. They are still lead acid batteries. How much better the carbon foam is than AGM, who knows. The testimonials, (called "case studies") seem to be written by Firefly, not by an independent laboratory.

There is no mention on the website, that I saw, comparing these batteries to Lithium. Additionally discharging lithium to 80% DOD does not significantly reduce the life cycle of the battery. The spec sheet for the carbon foam shows about a 90% decrease in life if you discharge them to 80% DOD. I do have to admit, as long as you accept Firefly's claim of ~10,000 cycles at 30% DOD and ~1000 cycles at 80% DOD, the 1000 cycles compare favorably to Trojan batteries.

The life cycle of the batteries seem to have the same ratio of cycles that Trojan flooded cell batteries do. That is DOD of 30% very long life, DOD of 50% 1/2 the life. One big difference though, Trojan claims that at a DOD of 80% the life is about 25% of the 30% DOD and Firefly shows about 10% of the life of the 30% DOD. Most applications designed for long life of the batteries recommend a DOD of 25% to 30%.

The big question is, Will these batteries really give 9000 to 13,500 cycles at a DOD of 30% when Trojan claims ONLY 3000 cycles. Of course there could be a difference in what the end of life of the batteries is. All batteries have reduced capacity as the number of discharge/charge cycles increases. If one mfg calls the end of life, when the battery provides 70% of capacity (for a 100AH battery that would be 70AH capacity left) and another mfg says end of life is when there is only 30% of capacity left, that would greatly boost the life cycles.

Another very interesting claim is that you can charge these batteries at "1C". I believe Trojan recommends charging at "1/4C". The term "C" is: if you have a 100AH battery, "1C" charging is 100amp charge rate, "1/4C" would be a 25 amp rate for a 100AH battery.

As you might guess I am skeptical. On the other hand if these batteries cost less than Trojan flooded cell batteries I might be tempted to try them. However I tend to lean to very inexpensive flooded cell 6V golf cart batteries, or going straight to expensive Lithium.

For what its worth I installed lithium in my RV.

Itinerant1 · October 12, 2017

$486.00 @ emarine.

Only time will tell if they're as good as they claim. Our lithiums where/ are the same for questionable longevity. <_<

ALLOY · October 14, 2017

Spoke with the dealer that is installing the batteries. Supply is the biggest problem they have. They order 60-80 batteries which take 2 months to be delivered. Before the order arrives all the batteries are sold.

The dealer brings in more 2V volt cell than anything else. This allows them to build 12V-24V-36V banks with no series parallel issues.

The bulk rate is +/-1C but the the float and absorption are the same as other AGM batteries.

They predict that most owners will get 2-3 years more life from a set.

They like to use "4 stage" chargers with no float. Once the batteries reach 98-100% SOC the charge cycles off until SOC drops to 80% and then resumes.

Al F · October 14, 2017

14 hours ago, J-T said:

Spoke with the dealer that is installing the batteries. Supply is the biggest problem they have. They order 60-80 batteries which take 2 months to be delivered. Before the order arrives all the batteries are sold.

The dealer brings in more 2V volt cell than anything else. This allows them to build 12V-24V-36V banks with no series parallel issues.

The bulk rate is +/-1C but the the float and absorption are the same as other AGM batteries.

They predict that most owners will get 2-3 years more life from a set.

They like to use "4 stage" chargers with no float. Once the batteries reach 98-100% SOC the charge cycles off until SOC drops to 80% and then resumes.

I am not following the "no series parallel issues". The 2 volt batteries are wired in series, with external cables or bus bars, until you get to the number of cells need to get the 12/24/36/48 volts needed. The amperage of the resulting battery bank will be the amperage of the 2V cell. I'm sure they have several different 2V cells with different amperage ratings.