Hi Jim,
Now my interest is really piqued!
There is zero chance your batteries would be sitting at 29 volts in a partial charged state. Even at 100% soc they would fall below 29v within a minute after taken off the charger and they would keep falling 26ish volts. While often not followed, Lithium batteries are supposed to be shipped at no more than 30% soc, fyi.
The specs on the link you sent seem perfectly in line with 8s lifepo4. Click on the "Download the Lithium Battery Spec Sheet" link. Scroll down to the Battery Management System. This is where things get weird. They say per cell "over voltage protection" is 4.3v. This would be a correct (even a little high) for an NMC chemistry battery. I have seen manufactures put in high upper limits to make up for bottom of the barrel cells, but never this high. What's even more concerning is the "over charge release voltage" of 4.1. This means the cell will cycle between 4.1 and 4.3. It should never go above 3.65.
I would say they just put the wrong specs on this page, but this does not explain your abnormally high voltage. You either have an unusual number of cells in series (highly doubtful) or these cells are actually NMC or some other chemistry.
I would get them on the phone ASAP and not charge these until they can explain. If they give you a run around I would gladly talk to them for you.
Matt Foley
Sunlight Conversions
Perpetual Energy, LLC
201-914-0466
On Tuesday, September 13, 2022 at 06:35:17 PM EDT, James Jones <jgjones252@gmail.com> wrote:
Thank you all for the info and suggestions!
Turns out that it wasn't the meter (I checked with two different meters), and the batteries themselves are within spec (no extra cells, etc.): Their documented fully charged voltage is 29.4 volts, and each one currently reads 29.1. Which adds up to what I see on the meter for the whole bank: 58.3. Here are the particular ones I'm using: https://www.lithiumbatterypower.com/collections/marine-batteries/products/24v-75ah-lithium-ion-battery
They haven't even been plugged into a charger yet; they're still in the "partially charged" shipping condition.
So I guess either these batteries have an atypically high voltage, or the Karvin outboard has a unusually low maximum voltage. Or both. :)
And to answer bobkart's question: I'll definitely post info about how it works when I finally launch the boat in, hopefully, a week or two. And yup, I'm near Lake Washington and will probably launch at Magnuson Park.
Thanks again,
Jim
Turns out that it wasn't the meter (I checked with two different meters), and the batteries themselves are within spec (no extra cells, etc.): Their documented fully charged voltage is 29.4 volts, and each one currently reads 29.1. Which adds up to what I see on the meter for the whole bank: 58.3. Here are the particular ones I'm using: https://www.lithiumbatterypower.com/collections/marine-batteries/products/24v-75ah-lithium-ion-battery
They haven't even been plugged into a charger yet; they're still in the "partially charged" shipping condition.
So I guess either these batteries have an atypically high voltage, or the Karvin outboard has a unusually low maximum voltage. Or both. :)
And to answer bobkart's question: I'll definitely post info about how it works when I finally launch the boat in, hopefully, a week or two. And yup, I'm near Lake Washington and will probably launch at Magnuson Park.
Thanks again,
Jim
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