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Changing SG-200 Advanced Settings.

Nov 6, 2020
Mariner 36 California
So I have a new Firefly battery in my reserve bank and an SG-200 monitoring it. Its been through maybe 10-12 charge cycles since I connected them. I used the SG-200's factory 'CarbonFoam' setting in the menu for battery chemistry and set Ah's to 116 (single battery).

Since the Firefly battery specs still seem to be evolving slightly ie...Firefly has recently updated the Ah capacity of the G-31, as well as bulk and float voltage from what they were several years ago, I wonder if the Balmar default settings for the Carbon Foam option need to be tweaked? Specifically the SG-200 has the option of setting the charge voltage, the taper current and the Peukert value.

Has anyone reset those values with a Firefly battery bank and seen an improvement in accuracy or is everyone pretty much leaving them at stock settings?

Last edited:
Feb 26, 2004
Catalina 34 224 Maple Bay, BC, Canada
So I have a new Firefly battery in my reserve bank and an SG-200 monitoring it.
I'm surprised. Most folks use the SG200 to deal with their house banks. Could you explain a bit more?

One of the developers of that tool, witzgall, is active there, post #33. I'd go there fore more info, even post your question on their electrical section. Most likely get more there than here. Good luck.

Nov 6, 2020
Mariner 36 California
Thanks, my house bank is not installed yet. The Firefly currently is my house/start battery but will become my reserve battery once the house bank gets installed. I had the SG-200 so decided to use it on the single Firefly so i could monitor the battery but also get to know how the SG-200 works.

Its useful so when the house bank gets installed i'll add another SG-200 to monitor that.
Feb 6, 1998
Canadian Sailcraft 36T Casco Bay, ME
Set Ah, set chemistry and use it. For optimal Firefly cycle life 13.2 Float and 14.4V Absorption..