Adding to and Wiring house bank.....

[NYSail]

Hello all,

So I have been looking to upgrade my house bank...... I can get 4 6 volt T125's in the original engine compartment, however want to add two more. Would also like to do this without ripping up anything. I do have a place which is about 8 feet away and figured I can put two more T125's (in series) there and parallel them as the last in line with the other 4 with the neg going to the neg bus. Right now I am using 2/0 wire.... Is it wise to use the same or should I get a bit larger with wires leading to the 2 remote batteries? Also, would it be wise to fuse this bank (main bank is already appropriately fused)? Does it create a significant issue with some of the batteries of a bank in a different place??

I know it is best to have the bank all together, but this is just not possible unless I move the entire bank about 12 feet away from Alternator (Balmar 150 amp) and main battery switch which would actually be in a cool area with ample room and ventilation and could accommodate the weight easily, however this is in a port aft lazerette not center-line as current bank is.

Any suggestions / better ideas from those of you that know more??

Thanks
Greg

 

[Maine Sail]

Any suggestions / better ideas from those of you that know more??

Consider that when away from the dock your 720Ah bank of 6 GC2 batteries will have only about 30% usable capacity or just 216Ah when cycling between 50% and 80% SoC (due to FLA Coulombic efficiency / charge acceptance). The bank will also weigh nearly 400 pounds. We also don't install the T125's on sailboats because they have maximized the plates and there is less room to heel before the plates uncover. So this typically means T105's which are 225Ah or just 202 usable Ah's for a 675Ah bank...

Now consider that just three 116Ah Firefly Carbon Foam AGM batteries, for a total of 348Ah's, would have a usable capacity of approx 70% of the banks capacity or 20% SoC to 90% SoC. With just three batteries and a 348Ah bank you will have a larger usable capacity of roughly 243Ah's than you will get with a 720Ah bank.

* Firefly's are specifically built to be cycled to 80% DoD
* Firefly's resist sulfation from PSoC use and will have a cycle life that's considerably longer than GC2's.
* Your alternator will be running at peak/bulk output for far longer thus making charging more efficient.
* The bank will also weigh just 225 pounds vs close to 400 pounds.
* Firefly batteries are very efficient and charge much faster than flooded GC2's


Sure, a bit more up front, approx $1500.00 vs. $1200.00 but they will be less expensive in the long run.

 

[dlochner]

Consider that when away from the dock your 720Ah bank of 6 GC2 batteries will have only about 30% usable capacity or just 216Ah when cycling between 50% and 80% SoC (due to FLA Coulombic efficiency / charge acceptance). The bank will also weigh nearly 400 pounds. We also don't install the T125's on sailboats because they have maximized the plates and there is less room to heel before the plates uncover. So this typically means T105's which are 225Ah or just 202 usable Ah's for a 675Ah bank...

Now consider that just three 116Ah Firefly Carbon Foam AGM batteries, for a total of 348Ah's, would have a usable capacity of approx 70% of the banks capacity or 20% SoC to 90% SoC. With just three batteries and a 348Ah bank you will have a larger usable capacity of roughly 243Ah's than you will get with a 720Ah bank.

* Firefly's are specifically built to be cycled to 80% DoD
* Firefly's resist sulfation from PSoC use and will have a cycle life that's considerably longer than GC2's.
* Your alternator will be running at peak/bulk output for far longer thus making charging more efficient.
* The bank will also weigh just 225 pounds vs close to 400 pounds.
* Firefly batteries are very efficient and charge much faster than flooded GC2's


Sure, a bit more up front, approx $1500.00 vs. $1200.00 but they will be less expensive in the long run.

Well, @Maine Sail there you go again getting me thinking. Currently I have 4 GC batteries with about 460 ah capacity when new. I was planning to replace them this spring, however, after reading this post, I'm thinking I might be better off with 2 Fireflys.

If my calculations are correct (sometimes an iffy proposition) I would have 162 usable Ah with the Fireflys and 138 usable Ah with the GCs. With 300 watts of solar and using Calder's estimate of 3 times nominal output for the total output, I'd have 75 ah of charging capacity which just about meets my daily needs of 75-100 ah. (75 at anchor mostly for refrigeration and 100 sailing for refrigeration, instruments, AP). There would also be a weight reduction of about 110 lbs (150 vs 260 lbs) and a bit more space in the battery compartment.

Did I get this right?
Will the Balmar SmartGuage and Victron Battery Monitor work with the Fireflys?

Thanks.

 

[Maine Sail]

Yes, you pretty much have that right. Also the Firefly's really like lots of charge current (.4C or more is recommended) so with two batteries and 75A charge rate your looking at about .32C which is far better than most boaters can achieve..

Do you have the Smargauge or the newer SG200? The SG200 has a carbon foam profile and the Smartgauge can use setting 3. Victron can be custom programmed to work but SoC is usually not very accurate when PSoC cycling..

 

[NYSail]

Consider that when away from the dock your 720Ah bank of 6 GC2 batteries will have only about 30% usable capacity or just 216Ah when cycling between 50% and 80% SoC (due to FLA Coulombic efficiency / charge acceptance). The bank will also weigh nearly 400 pounds. We also don't install the T125's on sailboats because they have maximized the plates and there is less room to heel before the plates uncover. So this typically means T105's which are 225Ah or just 202 usable Ah's for a 675Ah bank...

Now consider that just three 116Ah Firefly Carbon Foam AGM batteries, for a total of 348Ah's, would have a usable capacity of approx 70% of the banks capacity or 20% SoC to 90% SoC. With just three batteries and a 348Ah bank you will have a larger usable capacity of roughly 243Ah's than you will get with a 720Ah bank.

* Firefly's are specifically built to be cycled to 80% DoD
* Firefly's resist sulfation from PSoC use and will have a cycle life that's considerably longer than GC2's.
* Your alternator will be running at peak/bulk output for far longer thus making charging more efficient.
* The bank will also weigh just 225 pounds vs close to 400 pounds.
* Firefly batteries are very efficient and charge much faster than flooded GC2's


Sure, a bit more up front, approx $1500.00 vs. $1200.00 but they will be less expensive in the long run.

well the money thing is not significant so it does make sense. I will definitely like to go that option. However back to original question because I won’t be able to fit three in the same place, having part of the house bank being in a different location and wiring.

thanks as always!
Greg