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Low voltage cut off

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Low voltage cut off

Postby DG-Unit » Tue Jun 07, 2022 7:21 pm

Right. Finally made my way to the campervan section of this forum and it’s a nerdy one..

I’m getting into the electrics and want something to cut off the load to the leisure battery when it goes down to 50% state of charge to protect it. I’m planning to be in some hot places and want to leave fans and phones charging overnight with the comfort the battery won’t be drained and damaged in the morning.

I’ve got a Ludo McGurk Charge Divider 2L as the split charge relay and a 110Ah Varta wet battery. Ideally want a low voltage cut off to add to that but open to suggestions for DC to DC chargers that have this built in. I don’t think the load will be more than 30A but up to 60A would be great. Had a look at the Vitron Battery Protect but this will only cut out at up to 12v which apparently is less that 25% charge and ideally i need about 12.2/12.3V to avoid going below 50%.

Anyone fitted something that works?
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Re: Low voltage cut off

Postby Noctule » Wed Jun 08, 2022 6:44 pm

You could try a Kemo M148A Battery Guard , it'll switch up to 20a and has an adjustable switching voltage, from 10.4 to 13.3, which gives you lots of scope to find your preferred minimum state of charge.

Don't forget that a battery in use will be at a lower voltage to when it is at rest, you may find 12.3v doesn't give you much scope. I regularly use a Halfords (Yuasa) 115ah leisure battery to run an 500w inverter (running lights, chargers, sometime a 240v fan and coolbox) until the low voltage alarm kicks in at around 11.5v. It's still going strong after 5 years, so I wouldn't have thought a few USB fans and phone chargers should worry a Varta 110ah.
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Re: Low voltage cut off

Postby DG-Unit » Wed Jun 08, 2022 11:29 pm

Noctule wrote:You could try a Kemo M148A Battery Guard , it'll switch up to 20a and has an adjustable switching voltage, from 10.4 to 13.3, which gives you lots of scope to find your preferred minimum state of charge.

Don't forget that a battery in use will be at a lower voltage to when it is at rest, you may find 12.3v doesn't give you much scope. I regularly use a Halfords (Yuasa) 115ah leisure battery to run an 500w inverter (running lights, chargers, sometime a 240v fan and coolbox) until the low voltage alarm kicks in at around 11.5v. It's still going strong after 5 years, so I wouldn't have thought a few USB fans and phone chargers should worry a Varta 110ah.

Excellent shout there. I had just come across the Kemo Battery Guard. 20A should actually be plenty but can always use it to trigger a 30A relay if needed. Good info on the battery voltage too. Thanks
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