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Matt avatar image
Matt asked

A odd one for everyone MPPT 100/20 charging car starting battery.

Gday guys so I have a odd one for everyone. I have a 350w Solar panel on my car with the smart 100/20. But I only have one battery in the car which is the cars starting battery also. My question is will the 100/20 be happy if I was to use it to charge the battery directly or should I attach a relay that is Normally closed and then opens once the alternator comes online so it doesn't back feed into the 100/20?

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michaeld answered ·

No need, it'll be fine. Many of us have the same setup :)

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Matt avatar image
Matt answered ·

Ok thanks for the info, what does the unit do when the battery is being charged by the alternator?

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michaeld avatar image michaeld commented ·
@Matt it depends what the voltages are set to. My alternator charges at 14.4v but the MPPT is normally higher due to temperature compensation. If there's no solar the voltage will hold at 14.4v, but with enough sun the MPPT can push it higher to the correct absorption voltage. In that case they'll both be charging the battery together.
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Michelle Konzack avatar image
Michelle Konzack answered ·

If you start the car and the Alternator start producing energy, the MPPT will probably stop charging, since the system voltage is high enough.


Do not worry about it

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kevgermany avatar image kevgermany ♦♦ commented ·
Not necessarily. Depends on the Orion and MPPT settings
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Matt avatar image Matt kevgermany ♦♦ commented ·
I don't have a Orion only MPPT
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kevgermany avatar image kevgermany ♦♦ Matt commented ·

Sorry. That's what happens when I rush.

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