question

protectyourenergy avatar image
protectyourenergy asked

MPPT 100/15 with a larger fuse than recommended?

The IFU says use max. 25A for the Battery wire.

I use a 6mm2 cable that normally is protected with a 40A fuse.


Can I do it like this or is there another reason for the 25A in the battery wire?


Thanks for the support

MPPT Controllers
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2 Answers
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wkirby answered ·

The IFU would state that if it is deemed necessary to protect the circuit board traces or components from fire in the event of a fault within the device.

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protectyourenergy avatar image protectyourenergy commented ·

I am still confusesd (maybe because of my english skills?!)

The IFU says on page 10


„The battery supply must be protected by a fuse as per below table. This is also the case even if the solar charger has already been been equipped with an external fuse.“


It’s not stating „why“ because if it is to protect the wire then with the 6mm2 a 40A fuse would be fine. Also the MPpT itself is protected with the 25A internal fuse from damage

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wkirby avatar image
wkirby answered ·

I explained why" (sorry, my keyboard does not have an inverted why)
The traces on the circuit board have a certain current carrying capacity. So then the IFU will describe the appropriate fuse size to protect that portion of the circuit. The circuit board traces might be less than 6mm², so the fusing requirement.

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