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Genny/solar charging mystery

jenevers

By jenevers
in Boat Equipment

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jenevers Rising Star

jenevers

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No sun today. Episolar MPPT 40 reading 15 volts/1A on the input side. 400W panels.  6 Trojans wired for 12 volts.

Mastervolt MICC reading was 12.9 volts before I turned Genny on.

Fired up the Genny and noticed that the reading on the MPPT went up to 76 volts input!

Why????

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Tony Brooks Veteran II

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Posted
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Remember the voltage produced by any generating source is likely to be depressed are the current rises. My guess is that the 15 volts was all the panels could supply at 1 amp given the light levels. When you started the generator the battery voltage would probably have risen so reducing the current the solar could supply at that light level so the panel voltage went up.

It would be interesting to know the current the panels were supplying to the battery with the genny on.

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WotEver Veteran II

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10 minutes ago, Tony Brooks said:

My guess is that the 15 volts was all the panels could supply at 1 amp given the light levels. When you started the generator the battery voltage would probably have risen so reducing the current the solar could supply at that light level so the panel voltage went up.

Exactly this :)

11 minutes ago, Tony Brooks said:

It would be interesting to know the current the panels were supplying to the battery with the genny on.

My guess would be 0A

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nicknorman Veteran II

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Yes it’s simply because the battery charger (supplied by the genny) has raised the battery voltage to above the setting that the solar regulator is set to, so the solar regulator shuts right off effectively making the panels open circuit. So their voltage rises to the panel open circuit voltage!

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jenevers Rising Star

jenevers

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Phew! So I can relax. I thought something was flowing the wrong way. Never noticed this before....probably cos I’ve never looked before.

2 hours ago, Tony Brooks said:

It would be interesting to know the current the panels were supplying to the battery with the genny on.

I’ll let you know next time I fire the Genny up.

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nicknorman Veteran II

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3 minutes ago, jenevers said:

Phew! So I can relax. I thought something was flowing the wrong way. Never noticed this before....probably cos I’ve never looked before.

I’ll let you know next time I fire the Genny up.

If you fire the genny up in the pitch dark, I'm sure the panel voltage won't go up.

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jenevers Rising Star

jenevers

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Next mystery....... Genny off, inverter off, no 240v or 12v items running, just Mastervolt MICC display lit. Display shows -2.9A. Where’s it going?

7 minutes ago, nicknorman said:

If you fire the genny up in the pitch dark, I'm sure the panel voltage won't go up.

I’ll try that.

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jenevers Rising Star

jenevers

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26 minutes ago, nicknorman said:

Something is still switched on / drawing power. But we are not psychic!

Could it be the MPPT 40s ? I’ve got 2 each linked to 4 x100w panel’s.

26 minutes ago, rusty69 said:

I am.........its the tunnel light

Nope.

 

23 minutes ago, WotEver said:

Fridge

Nope.

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WotEver Veteran II

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9 minutes ago, Dr Bob said:

I must buy one! Anyone got a good recommendation?

....but will it need calibrating?

https://m.ebay.co.uk/itm/UNI-T-UT203-Digital-Handheld-Clamp-Multimeter-Tester-Meter-DMM-CE-AC-DC-Volt-Amp/172994785231?epid=633590249&hash=item28474aefcf:g:zIUAAOSwnTdaFTzn

Yes, it will need calibrating although it will probably drift so I wouldn’t bother. You don’t need test bench accuracy for the kinds of things you’ll use it for. 

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rusty69 Veteran II

rusty69

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8 hours ago, WotEver said:

https://m.ebay.co.uk/itm/UNI-T-UT203-Digital-Handheld-Clamp-Multimeter-Tester-Meter-DMM-CE-AC-DC-Volt-Amp/172994785231?epid=633590249&hash=item28474aefcf:g:zIUAAOSwnTdaFTzn

Yes, it will need calibrating although it will probably drift so I wouldn’t bother. You don’t need test bench accuracy for the kinds of things you’ll use it for. 

That's cheap. I paid a lot more for mine. 

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jenevers Rising Star

jenevers

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12 hours ago, WotEver said:

Phone chargers

Bilge pump

 

 

12 hours ago, WotEver said:

Phone chargers

Bilge pump

No no

12 hours ago, rusty69 said:

If you have circuit breakers, try pulling them one at a time 

All switches on the board are off

9 hours ago, Dr Bob said:

If none of your breakers show you the 2.9A drain, then what is connected to the shunt with no breaker? The eberspacher?

Mine is wired directly to the batteries! Not by me!

Haven’t got an Eberspacher

9 hours ago, WotEver said:

A clamp meter would soon find it. 

How?:mellow:

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