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Old 29-07-2019, 08:09   #1
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My attempt to murder my Firefly Batteries

Just an interesting story.

As I mentioned in other threads, if there is someone who can kill batteries, it will be me. I have a long history of murdering batteries badly! My challenge is to destroy the Firefly batteries in my boat by abuse!

They, however, have a different agenda!

I also have a fuel cell, EFOY 1600, I installed a while ago. After installing the firefly batteries 4 years ago, I decided to change the settings on the fuel cell. I made a big mistake! I changed the turn-on voltage to something like 11.5v or so! I thought I changed it to 11.9v from the default (12.2 or 12.4v, I forget).

The refrigerator has a cut off at 11.7v, so the refrigeration will shut off way before the fuel cell kicks in at 11.5v ooops !

At anchor for like 4 days, I kept watching the Balmart Smartgauge dropping..50%...40..20...6% / (11.8v ) and the EFOY fuel cell was not coming on to recharge the batteries!

Of course I can't find the friggin adapter to check/change the settings on the fuel cell!

The refrigerator just kept humming away.. 95 degrees out.. didn't miss a beat.. everything is nice and cold!

The batteries stayed at 6% for a half day or so. Hovering around 11.8-11.9v

The next day, we did motor 2 hours and got it up to 40% and motored 4 hours the following day. The smartgauge read 95% after resting 24 hours after getting to the mooring.

Those friggin firefly batteries are putting up a fight!! Even with my total incompetence.. they are holding in there! 4 years with these batteries (2x 12v in parallel), they just work. Damn, I am impressed!

Also since going to the FF batteries, I have not gone through 1 methanol refill in 4 years. Then again, it hasn't had a chance to come on due to my fat fingering!

So far they have FAR exceeded the performance of my old Rolls 2x6v batteries. I only got about 4 seasons on my last set. These Firefly batteries are performing like new! Short of any controlled testing, I can see no performance drop since they were new.

Time will tell to see how long they can take my abuse.. I don't baby the batteries. Never have. I don't charge them over the winter. Goes into storage the voltage it was when it was taken out of the water. I never charge to 100% during the season as I am on a mooring. I do charge to 100% in the spring before launch.

But my 4 year impression of the batteries is high.. Nice seeing they have a better selection now, and have increased production. Hope the quality stays up there. I am genuinely impressed
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Old 30-07-2019, 01:42   #2
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Re: My attempt to murder my Firefly Batteries

strange at 6% the voltage should be down much lower then 11.8v. like under 11v. they still drop voltage like a normal battery.
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Old 30-07-2019, 04:46   #3
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Re: My attempt to murder my Firefly Batteries

Paul
Nice simple setup.
  • System: 12v nominal
  • Batteries: Firefly capacity?
  • Fuel Cell:Efoy 1600: 65w, 1600w/day, 130ah/day, 5.4a charging, 7 kg, 435 x 200 x 276
  • Fuel Cell Fuel: M10 Fuel = 2,64 US gal / 10 l, 11.1 kWh / 925 Ah, $66
  • Alternator: ?
  • What are your sailing patterns/use?
Now Efoy has Efoy Comfort 80 140 210 which is the output in ah/day.
The cost is 80 = $3000,140=$4300 ,210=$5900
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Old 30-07-2019, 05:01   #4
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Re: My attempt to murder my Firefly Batteries

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Originally Posted by smac999 View Post
strange at 6% the voltage should be down much lower then 11.8v. like under 11v. they still drop voltage like a normal battery.
Ditto. Your voltage doesn't match your stated SOC number.
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Old 30-07-2019, 05:16   #5
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Re: My attempt to murder my Firefly Batteries

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Also since going to the FF batteries, I have not gone through 1 methanol refill in 4 years. Then again, it hasn't had a chance to come on due to my fat fingering!

What does this mean?

-Chris
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Old 30-07-2019, 07:22   #6
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Re: My attempt to murder my Firefly Batteries

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strange at 6% the voltage should be down much lower then 11.8v. like under 11v. they still drop voltage like a normal battery.
Probably the smartgauge is still learning. I never dropped the batteries very low before.

I am sure if I keep dropping the battery down it will become more accurate over time. But it hit 6% and just hung there for a while.. like it was on a reserve backup battery or something

I was pleasantly surprised they lasted days like that with power to spare!

Just amazing they got to 95% after only about 5-6 hours of running the engine (assuming the SG is accurate) . A lot faster than my old LA batteries!

So far they have lasted as long as my LA batteries did when they died. However these FF are acting like they are new!

I don't have the testing equipment to perfectly calculate the power in the batteries. Be curios to try. Anecdotal evidence is pretty friggin awesome (sorry for using an industry term)
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Old 30-07-2019, 07:29   #7
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Re: My attempt to murder my Firefly Batteries

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Originally Posted by rgleason View Post
Paul
Nice simple setup.
  • System: 12v nominal
  • Batteries: Firefly capacity?
  • Fuel Cell:Efoy 1600: 65w, 1600w/day, 130ah/day, 5.4a charging, 7 kg, 435 x 200 x 276
  • Fuel Cell Fuel: M10 Fuel = 2,64 US gal / 10 l, 11.1 kWh / 925 Ah, $66

  • Alternator: ?
  • What are your sailing patterns/use?
2x group 31 Firefly batteries

Alternator is a Balmar 100 amp, using their alt-belt (10 groove belt) kit using a Balmar 614 regulator. Also use the Balmar Duo-charge - so no more switching the battery switch!

We do mostly weekend cruises around Buzzards Bay and Martha's Vineyard. We sail as much as we can. use the motor, normally to leave/return to the mooring field/anchorage. Time to time motor when there is no wind like last week.

Highest draw is the refrigerator (frigoboat air cooled) and AP/electronics.

Never had the firefly batteries that low, as they charge freakishly fast!

I do have a small folding portable 35w solar panel I put up when I am on the mooring. Seems to take the battery up to 90-95% (before the solar controller shuts it off as it thinks it is full) between uses.

This was it's first real stress test of the system!

But yes, Nice and simple.
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Old 30-07-2019, 07:31   #8
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Re: My attempt to murder my Firefly Batteries

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Ditto. Your voltage doesn't match your stated SOC number.
Yes I agree. Just stating what the SG read.

Probably still learning, as the batteries have never been that low.

I would rather it be conservative and say the batteries are lower than they are, than the opposite!
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Old 30-07-2019, 07:32   #9
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Re: My attempt to murder my Firefly Batteries

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What does this mean?

-Chris
I assume you mean fat fingering? just another way of saying typing an error. I typed the wrong setting into the configuration program!
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Old 30-07-2019, 08:20   #10
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Re: My attempt to murder my Firefly Batteries

Going on year two full time cruising, with two firefly batteries wired in parallel. They get charged by two one hundred watt solar panels, each has there own MPPT controller, and when we motor, 70 amp alternator. The BALMAR smart gauge has not been below 85% SOC that we have seen, we basically ignore them for the most part.

On our boat the big amp draw items are the B&G Zeus 2,7”, an Engle fridge, a S/H vhf w/ AIS receiver, and a Pelagic tiller pilot that hooks up to our Monitor steering vane, the rest is recharging phones, laptop etc, all the lights are LEDs. We have two hundred and thirty two amp hours total, being that the firefly’s can be run down to 20% SOC they give us a lot more available amps than our previous AGMs, that and price per available amp is why we chose the firefly batteries.

We have read many positive reports of those, (like the OP) who have been using these batteries longer than we have, and they do seem to be living up to their advertising. We are currently, although slowly, starting our second trip to the Bahamas.

Fair winds,
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Old 30-07-2019, 08:33   #11
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Re: My attempt to murder my Firefly Batteries

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strange at 6% the voltage should be down much lower then 11.8v. like under 11v. they still drop voltage like a normal battery.
Not necessarily.

If the battery had been discharged below 11.8V under load, and that was a no-load resting voltage, the 6% may still very well be in the ball park. It is not uncommon for a battery just off a 10.5V 100% discharge capacity test to rebound close to 11.8V....

As an example, from actual lab data, if we discharge a 110Ah Firefly at the 20 hour rate (5.5A) non-stop with a cut off of 11.7V we will have pulled approx 85.5Ah out of it leaving the battery at about 22% SoC. Once the load is removed the battery will rebound above 12V. The 6% SoC is certainly within range especially if it went lower than 11.7V under load, which it sounds like it did...
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Old 30-07-2019, 09:05   #12
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Re: My attempt to murder my Firefly Batteries

I'm glad to hear the real world report on the FireFlys. I just installed 4X 12v -110 AH G31 for the house bank.



Thanks for the post.

Jim


edit: consider switching to the new Balmar SG200 gauge. It provides more information than the original smartgage. I think it is more accurate but haven't a way to test that assumption.
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Old 30-07-2019, 09:51   #13
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Re: My attempt to murder my Firefly Batteries

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I'm glad to hear the real world report on the FireFlys. I just installed 4X 12v -110 AH G31 for the house bank.



Thanks for the post.

Jim


edit: consider switching to the new Balmar SG200 gauge. It provides more information than the original smartgage. I think it is more accurate but haven't a way to test that assumption.
Maine Sail has writeups on both. the new one uses a shunt. the old one seems to work just fine. I don't know the difference. Maybe Maine Sail can discuss any difference.
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Old 30-07-2019, 10:00   #14
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Re: My attempt to murder my Firefly Batteries

I am pleased that you "tried to murder your fireflies" and did not succeed, although it was not so bad because you noticed it. ...think of having such an accident with an even more expensive LiFePo installation. These good user reports are very helpful. Thanks.
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Old 30-07-2019, 10:06   #15
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Re: My attempt to murder my Firefly Batteries

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I am pleased that you "tried to murder your fireflies" and did not succeed, although it was not so bad because you noticed it. ...think of having such an accident with an even more expensive LiFePo installation. These good user reports are very helpful. Thanks.
Obviously I am no intentionally trying to murder $1000 worth of batteries!

OTOH, I really was curious to see how resistant to abuse really was.

Kinda like the rush running on empty in your car, low gas light on, no gas station in sight.. wondering if you are going to make it with the last gallon or so in the tank

I figure I am on borrowed time, as I never got more than 4 years on expensive Rolls LA batteries due to my insanely bad charging regiment! Being on a mooring, it is next to impossible to get it up to 100%
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