T-Pain Is On A Boat: Re: [Electric Boats] lithium management question

Wednesday, January 25, 2017

Re: [Electric Boats] lithium management question

Steve-

yes I get power to the Orion from the propulsion pack (small DC/DC converter to 12V). It is the only battery I have on the sailboat. All house loads are also from the propulsion pack with DC/DC converters.

The Orion has a very minimal power draw, but over the winter I still disconnect it as I am still hurting from my first years experience. During the summer when I am away I simply switch off the power to the Orion and also all the house breakers are off. I only charge with shorepower when I am there. Typically for a full charge is 8 to 10 hours at 15 Amps from the shorepower.

On Jan 25, 2017, at 2:58 PM, 'Steve' sdolan@scannersllc.com [electricboats] <electricboats@yahoogroups.com> wrote:

[Attachment(s) from Steve included below]

George,

Sounds like we have similar systems, I've got the Calb 180's and the Orion BMS as well.

I'm interested in how your feeding power to the Orion, are you running power from the Propulsion pack to power it or from a house bank? I'm using the house bank to run the Orion and have had no perasitic voltage drop on the Ppack. The Orion has a fail safe that will shut the BMS down if there was a loss of power so I don't disconnect it, that way I can monitor the state of the batteries at a glance with the Andromeda monitoring system. Ther is NO loads on the Propulsion bank.

Lets see if a picture of the monitor comes through. I have a vid that shows it in a test mode if I can figure out how to load it.

Steve in Solomons MD

Lagoon 410 S2 E

John-

here is my experience with lithium on my Tartan 34C sailboat

Original battery pack was (16) cells, 260AH and a distributed BMS. I made the mistake of not disconnecting everything over the first winters storage and completely drained and wrecked my Thundersky cells. I think the little circuit boards for the BMS had a slow drain all winter.

I had the system redesigned with (20) CALB 180AH cells and a centralized BMS (Orion). The first winter I disconnected the BMS, removed the jumper between my (2) ten cell battery boxes— totally isolating the batteries. I took voltage measurements in October. In May, absolutely nothing had changed. Connected things, dropped the boat in the water and motored to my slip.

I have heard it is recommended to leave the cells at 50% SOC more or less, but I left them closer to 90 to 95% SOC.

Second winter- same

Third winter (now)- same and I will expect the cells to be healthy in May when I get back to the boat.

I have not been able to measure any self discharge over these 7 months of cold storage. The spec is less than 3% per month which would be like 21% discharge over 7 months. I really don't think I've seen more than a couple of percent- at least by the basically unvarying voltage measurements. And I can roughly confirm the battery capacity by the time required to recharge the pack- example- if the BMS says I have discharged 40% capacity, I find it takes about 4.5 to 5 hours at 15 amps to recharge.

The boat is on Lake Superior- extremely cold and long winters (sub zero)

Regarding the original 16 Thundersky cells- last summer I decided to try to revive them with a charging protocol recommended by the manufacturer. They were basically at zero voltage. To my surprise I believe all but three or four of the cells are now good. I will know better in the spring when I return to them and measure their voltage. If they prove good I'll be trying to find someone who wants some high capacity cells at essentially give away cost.

George O.

On Jan 24, 2017, at 10:31 AM, John Acord jcacord@gmail.com [electricboats] <electricboats@yahoogroups.com> wrote:

I'm making the move to lithium. I'm OK with charging & BMS, and it will be a 100 AH stack.

What I would like to know is how to manage the batteries when the boat is idle for periods of time. We tend to park the boat for three or four months in the winter.

What is the best practice when the batteries are idle for periods of time?

thanks,

John A.

Flatwater Electronics
www.flatwaterfarm.com
"Neurosurgery for computer looms."

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Posted by: George Ojdrovich <go@springsips.com>

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