How do you know when your batteries are done? That’s the ‘thousand dollar’ question.
On our last tip out to the islands we started noticing that the batteries didn’t seem to have the same capacity, or rather, looked like they did, but didn’t.
Old Deka 8Ds
On Volare, we have multiple ways to measure the amount of Amps in.. and Amps out. We use a Xantrex LinkLite, our Philippi and the old backup, analog gauges. Reading about the way Amps are measured as they pass over a shunt is interesting to me, but most would probably find it blasé. Ultimately though, power management is the key to all things wonderful on a big sailing boat.
We like to boast about our 1000 watts of solar but really, we only need that much solar because we choose to run 1 refrigerator and 2 freezers. Not to mention the watermaker, navigation equipment, lights, pumps and everything else that makes living aboard fun. Like the stereo and Sirius radio.
Back to the batteries. We noticed reduced capacity from our batteries as well as an increase temperature when charging. This lead us to decide to replace our 3- Deka 8D AGM batteries. After a fair amount of research, we decided to purchase 5- Oasis Firefly Carbon Foam AGM batteries.
New Batteries in San Diego
Bruce Schwab of OceanPlanet Energy ( Oasis Firefly Carbon Foam ) provided great customer service and guidance and eventually pointed us towards Fisheries Supply in Seattle. ( Fisheries Supply )
Fisheries Supply made the process extremely easy. Luckily they had 5 in stock as most places had the batteries on backorder. They shipped them to San Diego for us where they waited as we drove up from La Paz.
The Group 31 Oasis Firefly batteries are much lighter that the 8D’s. 75 pounds versus 160 pounds. Capacity per Firefly is 110 Ah but its ability to operate in a Partial State of Charge PSOC on a long term basis makes this battery pretty unique. Discharging it to 20% or 0% will not hurt the battery. Plus..they’re Nigel Calder approved!
Using topping lift to remove batteries
While we had 740Ah of batteries previously, now we have 550Ah of Firefly power. Yes it’s less, but on Volare, our daily overnight usage is about 100Ah. This level of discharge really lets us operate in the sweet spot of the battery which is somewhere in the 60-80% charge range.
Out with the old
One of the biggest challenges was figuring out how to set our multiple charging sources. We have 9 Genasun solar controllers, the Xantrex charger and a Balmar regulator on the generator.
Adjusting Genasun controller
Per Oasis, the batteries should be bulk/absorption charged to 14.4v (temperature controlled) and although the batteries don’t need a float charge, if one is used it should be set to 13.4v. (For the life of me, I can’t figure out why a battery wouldn’t need a float charge. How else do you get your electrons back in the yellow and blue boxes?)
We’re setting off for a 2 month cruise of the Sea of Cortez this week. I’ll update the website when I have some operational experience with these batteries.
Finished Firefly install
Thanks for reading! Make sure to check out the rest of our website and follow along with our travels at CruisingVolare.
Comments
Totally nerding out with ya right now Adz! Good job 👍
So, how have the Firefly batteries performed since you write this post over 18 months ago? Thank you!
We’ve been pleased with them. Especially when I run my DC genset and push 200A into them. They’ll take pretty much whatever you can throw at them.
They also seen to act very much like AGM’s. Although you can delete them south of 50%… We never do.
Other than the cost, I haven’t found anything I don’t like about them.