New battery bank size, charging mods... AGM or Carbon Foam

[Maine Sail]

Thanks to everyone for all the great advice. New system is up and running and we love it. 3 x Firefly G31 with a Rolls GR24 Reserve in the settee. Linked with an ACR. Balmar Sg200 monitor and Victron MPPT solar charge controller with smart link battery temp feedback. Perfect for us as we don't have shore power. After a lot of though decided to stay with the original 1-2-both switch for ease of wiring, using only the #1 position. 2 is available if needed. both is marked inop. Its great!

Please be very careful or you can ruin your Firefly's, if you continue taking them to 14.71V as shown in image 3.. I am guessing the 22C, in image #2, is the battery temp?

If this is so, it does not warrant compensating the battery voltage to 14.71V. Be sure your controllers/chargers/regulators have the correct mV per degree C compensation slope programed into them. It should be 4mV per cell, per degree C change, or 24mV, per 12V battery, per degree C change. 14.4V is the maximum voltage for absorption @ 25C/77F.

Also while the interconnects are neat and tidy a small arc in the jumpers relieves the strain on the terminals, especially when they are not restrained. They also like a bit of air space between them, unless you are always in cooler waters, but they do heat up if charging them correctly.

 

[Good Vibes]

Please be very careful or you can ruin your Firefly's, if you continue taking them to 14.71V as shown in image 3.. I am guessing the 22C, in image #2, is the battery temp?

If this is so, it does not warrant compensating the battery voltage to 14.71V. Be sure your controllers/chargers/regulators have the correct mV per degree C compensation slope programed into them. It should be 4mV per cell, per degree C change, or 24mV, per 12V battery, per degree C change. 14.4V is the maximum voltage for absorption @ 25C/77F.

Also while the interconnects are neat and tidy a small arc in the jumpers relieves the strain on the terminals, especially when they are not restrained. They also like a bit of air space between them, unless you are always in cooler waters, but they do heat up if charging them correctly.

Thanks for the insight. I’m not sure why the Balmar would show 14.71 and the victron would show a different voltage. The Balmar is set to the default carbon foam setting and the victron controller was set with the charge profile from the battery manufacturer 14.4v for absorption. All I can think of is that this picture was taken right after I got the app working. Maybe a setting changed. I have had difficulty updating the Balmar firmware because both the shunt and the display are on the same network and the software won’t allow Updates when they are both powered. Point taken about the arc and spacing. I didn’t do the installation. The batteries will be secured for the final version. Thanks!

 

[Good Vibes]

I was back at the boat today and confirmed with the meter that the voltage on the solar controller is accurate and the batteries are good. For some reason the Balmar gauge is displaying almost 1.5 V high. I’ve sent the info off to Balmar and they are looking in to it. When I measure the voltage across the shunt it agrees with the solar controller as well. Hmmm

 

[Good Vibes]

Just an update. Balmar Rep advises it is a known issue that will be resolved with a firmware fix for the shunt in a couple of weeks. Excellent customer service.

 

[Good Vibes]

Update on my update. New firmware update For the gateway, shunt and display works like a charm. Balmar voltages match the Victron charge controller and the multi meter perfectly. Again Balmar customer service was great even while dealing with a major IT snag.

 

[tfox2069]

Thanks to everyone for all the great advice. New system is up and running and we love it. 3 x Firefly G31 with a Rolls GR24 Reserve in the settee. Linked with an ACR. Balmar Sg200 monitor and Victron MPPT solar charge controller with smart link battery temp feedback. Perfect for us as we don't have shore power. After a lot of though decided to stay with the original 1-2-both switch for ease of wiring, using only the #1 position. 2 is available if needed. both is marked inop. Its great!

Just wanted to see if you might provide an update on your system follow up on your system at the 9-month mark?

Also, and I'm hoping Mainesail will chime in on this question: Have you noticed any capacity loss by not charging with .4C occasionally that's recommended for the Firefly batteries? It doesn't appear with your standard alternator and solar that you can push the occasional ~139 amps that would be recommended for the three-battery bank of G31 Fireflies you put in place. I'm curious if that's working out fine with those batteries.

I have two Fireflies in one bank with a 60a shore charger and 80a externally regulated alternator and can almost get to .4C if needed on that bank. I'm thinking about adding a 3rd Firefly myself, but have debated wiring as a #2 bank which I can combine with the other two Fireflies on the "both" setting for usage, but can charge either at or close to .4C if needed by charging a selected bank. I know Mainesail advocates one large bank, but without investing a fortune in an alternator and shore charger that can both get to 139 amps I'm wondering if splitting up that way gets you the best of both worlds - ability to combine to one large bank on "Both" setting, and ability to charge with .4C when needed.

 

[Witzend]

$129 4D Duracell's from Sam's Club lasted me (9) seasons being solar trickled.
No reason not to get another set.

 

[Good Vibes]

Thanks to everyone for all the great advice. New system is up and running and we love it. 3 x Firefly G31 with a Rolls GR24 Reserve in the settee. Linked with an ACR. Balmar Sg200 monitor and Victron MPPT solar charge controller with smart link battery temp feedback. Perfect for us as we don't have shore power. After a lot of though decided to stay with the original 1-2-both switch for ease of wiring, using only the #1 position. 2 is available if needed. both is marked inop. Its great!

Just wanted to see if you might provide an update on your system follow up on your system at the 9-month mark?

Also, and I'm hoping Mainesail will chime in on this question: Have you noticed any capacity loss by not charging with .4C occasionally that's recommended for the Firefly batteries? It doesn't appear with your standard alternator and solar that you can push the occasional ~139 amps that would be recommended for the three-battery bank of G31 Fireflies you put in place. I'm curious if that's working out fine with those batteries.

I have two Fireflies in one bank with a 60a shore charger and 80a externally regulated alternator and can almost get to .4C if needed on that bank. I'm thinking about adding a 3rd Firefly myself, but have debated wiring as a #2 bank which I can combine with the other two Fireflies on the "both" setting for usage, but can charge either at or close to .4C if needed by charging a selected bank. I know Mainesail advocates one large bank, but without investing a fortune in an alternator and shore charger that can both get to 139 amps I'm wondering if splitting up that way gets you the best of both worlds - ability to combine to one large bank on "Both" setting, and ability to charge with .4C when needed.

Sorry no update as the boat is on the hard for the winter. One major difference between our setup and yours is that we are essentially all solar. No shore power and I hardly motor. They did great last season and I hope to condition them and have them good as new soon.

 

[stephen_i_w]

I am trying to understand what the advantage of Firefly Carbon Foam batteries have over LiFePO4 batteries. From what I can tell they are only slightly less expensive. But, on the other hand they are an unusual technology with only one source. Firefly Carbon Foam batteries are also bigger and much heavier that LiFePO4 batteries with a similar capacity. LiFePO4 batteries are pretty commonly available now from several different manufacturers. This gives me more comfort that my charging equipment will work well with them.

 

[Good Vibes]

For me it was about not changing technology for the charger and alternator which, while we don't use them often, are still installed. also here in Ottawa where we sail the price of LifePO4 is about double the Firefly. What We wanted was a large bank that can handle being partially charged and can handle a winter in the boat. Don't get me wrong, LifePO4 would be great but it is a bit too much for our daysail, weekend and occasional week away usage style.

 

[stephen_i_w]

For me it was about not changing technology for the charger and alternator which, while we don't use them often, are still installed. also here in Ottawa where we sail the price of LifePO4 is about double the Firefly. What We wanted was a large bank that can handle being partially charged and can handle a winter in the boat. Don't get me wrong, LifePO4 would be great but it is a bit too much for our daysail, weekend and occasional week away usage style.

Yes I can see that. I initially wanted to get the Fireflies. But, when I asked the forum (on another thread) the impression I got, from various posters, was that I would not be able to simply drop in the Fireflies and would need to make major modifications on my charging system. With LiFePO4's available at about 1 1/2 times the cost of the Fireflies and the Fireflies seemingly needing the same modifications as the LiFePO4s , it appeared easier to go the LiFePO4 route. I suspect that I got poor advice. In any case, I am happy with what I did.

 

[Maine Sail]

Yes I can see that. I initially wanted to get the Fireflies. But, when I asked the forum (on another thread) the impression I got, from various posters, was that I would not be able to simply drop in the Fireflies and would need to make major modifications on my charging system. With LiFePO4's available at about 1 1/2 times the cost of the Fireflies and the Fireflies seemingly needing the same modifications as the LiFePO4s , it appeared easier to go the LiFePO4 route. I suspect that I got poor advice. In any case, I am happy with what I did.

If you want your moneys worth out of any high quality battery it is typically going to require changes/upgrades to charge equipment. Changes such as all sources being temp compensated, being able to be set them for the specific charge voltages of the battery chosen, temp protection for the alternator and in the case of Firefly (recommended .4C bare min .2C), Odyessy TPPL AGM, Northstar TPPL AGM's (recommended .4C) or Lifeline AGM's (bare minimum .2C) they all want to see high charge currents for optimal cycle life.

Be very, very, very careful buying LiFePO4 batteries as there is a ton of junk being fed into the US market right now and some of it is just plain scary.

 

[Witzend]

Sorry no update as the boat is on the hard for the winter. One major difference between our setup and yours is that we are essentially all solar. No shore power and I hardly motor. They did great last season and I hope to condition them and have them good as new soon.

Mine lasted 10yrs with solar

 

[tfox2069]

If you want your moneys worth out of any high quality battery it is typically going to require changes/upgrades to charge equipment. Changes such as all sources being temp compensated, being able to be set them for the specific charge voltages of the battery chosen, temp protection for the alternator and in the case of Firefly (recommended .4C bare min .2C), Odyessy TPPL AGM, Northstar TPPL AGM's (recommended .4C) or Lifeline AGM's (bare minimum .2C) they all want to see high charge currents for optimal cycle life.

Be very, very, very careful buying LiFePO4 batteries as there is a ton of junk being fed into the US market right now and some of it is just plain scary.

Maine Sail - interested in this bit of your comment "...in the case of Firefly (recommended .4C bare min .2C)...". If I have 3 Group 31 Fireflies (just installed the 3rd one) and a 60 amp shore charger (Sterling Pro 60 amp), would I be better off setting up my charging system so I could charge 2 of them to float, and then switch to the 3rd and charge it separately to ensure I'm charging at .2C or greater? While away from the dock I have an 80 amp externally regulated alternator (your AMP-IT-80-ER and Wakespeed WS100) and solar and would use/charge on "Both" to take advantage of the whole bank combined.