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Garry Kemp avatar image
Garry Kemp asked

Converting 48v battery to 46v for off grid system?

I have a problem with a 48v battery used on an off-grid power system - one 2v cell has failed. The battery has actually only been cycled 12 times and the other cells seem ok so it stings a bit to replace a £7000 battery, that has been worked fairly lightly. I know best practice would be to replace all cells, but I am going to try swapping out the dead cell. Unfortunately there is a 16 week delivery time for the replacement cell. I would be interested to know if I could temporarily run as a 46v system to preserve the integrity of the remaining cells until my replacement cell is available. My battery pack is 700ahr 24 x 2v gel cells. I have a Victron Quattro 48v/10000/140 inverter - can the settings be adjusted to compensate for the missing cell and if so can anyone help me out with some suggested settings please? I purchased my off-grid system as a pre-wired package, so I don’t the experience of assembling it and setting the initial parameters.

I hope you can help!

Garry

MultiPlus Quattro Inverter Charger
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2 Answers
Patrick avatar image
Patrick answered ·

The answer is yes and its one of the benefits of using 2v cells. Calculating the new set points for the battery bank with just 23 cell are easy to figure out

Take your current Absorb voltage divide by 24 and then multiply the result by 23.

Absorb example (57.6v / 24 = 2.40vpc) x 23 = 55.20v

Float example (54.4 / 24 = 2.2666vpc) x 23 = 52.13v

Reuse this math (/24 x 23) to figure you Low voltage pre alarm, Shutdown etc.

If you're using temperature compensation on any of you charging sources be sure to change it to to reflect 23 cells vs 24 cells. or disable the setting until you get replacement cell connected.

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Garry Kemp answered ·

Thank you for the advice, I will try that.

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