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Simon asked

65a battery protect

Hi again everyone, my dads system now has a 65A disconnect on the inverter, set at 24v cut off.

Could anyone help me with the relay trigger function please?

I'm my previous post I was asking about the mppt 100/20 triggering a battery charger, would the alarm trigger stay active until the battery bank has recovered to 26v or is it a momentary alarm?


The idea of the system is to have it automated so my parents have minimal interaction in the winter for recharging.


They have a 24/8 blue charger from victron but unfortunately it isn't bluetooth, so I'm thinking a coil relay triggered by the alarm output would cover recharging if it's possible?


Many thanks for reading


Simon

battery chargingBattery Protect
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2 Answers
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ben answered ·

You don't want to put a BP between a battery and an inverter/charger. It's not a good idea, and it will fail eventually. Possibly quietly, without you knowing that it's no longer "protecting."

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Simon answered ·

Why would this happen? Sorry I thought this is what it was for?

I thought it would turn the inverter off in a low battery voltage situation?


Thank you for replying

Simon

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ben avatar image ben ♦ commented ·

Many inverters have large buffer capacitors on their DC input side. These demand huge current for a millisecond or so when they are first connected. That current can exceed the rating of any BP.

When a BP's gates are overloaded, they can fail in a silent and dangerous way: closed. Then the BP continues "working," except it can't actually open the switch. You might not find out until worst possible time to find out.

Finally, most modern inverters also double as chargers. The BP device can only stop current flowing in one direction, and it may heat more in reverse flow as well. So it can only provide its protection (subject to the limitation described above) in one direction.

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