DC/DC negative reads 11v positive

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Val Vechnyak asked May 5, '24

DC/DC negative reads 11v positive

I've identified a strange problem and possibly my NON-isolated dc/dc tr orion has gone bad? when battery 1 is connected to 'IN', the voltmeter is showing about 11v between boat negative and the negative/common (middle connector) on the controller. could anyone try to explain why is this happening?

The other side of the voltmeter is connected to the negative buss on the boat.

orion dc-dc

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Answer 1 · 2024-05-05T06:09:14Z

pwfarnell answered · May 05 at 06:09 AM

But you have not connected the negative side to the battery, just the positive, so there is nothing to drain the positive voltage, the positive voltage goes into the unit but can not come out so the whole unit gets to close to the supply voltage.

Nothing wrong here.

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Val Vechnyak commented · May 05 at 01:44 PM

That's the point. The battery negative already connected to the common buss. why would positive voltage read on negative connection of the Orion? Is my controller bad?

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pwfarnell Val Vechnyak commented · May 05 at 02:58 PM

You are not understanding, you MUST connect the negative port of the Orion to the common negative bus bar. Current is trying to flow through the Orion from the positive input to th negative terminal and back to the battery. Because you have not connected the negative to the battery, the voltage builds up on the negative terminal because it has no where to go. Consider the inside of the Orion to be a resistor from positive terminal to negative terminal, if you only connect the 12V positive to one side of the resistor the other side will read 12V also. The Orion can not generate the same voltage as the battery when only connected.

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Val Vechnyak pwfarnell commented · May 05 at 03:26 PM

ok thank you, i get it but then the original issue that led me to this finding... i still need to solve that somehow! when i disconnect ground wire from the engine, the engine becomes (-) negative and the disconnected ground is now (+) pos. The voltage between ground and the engine will read about 11v. I should not have any voltage reading between disconnected ground and the engine! all of this goes away once i disconnect the negative on the Orion.

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Val Vechnyak pwfarnell commented · May 05 at 03:34 PM

I dont know if this is the issue but could it be that this is happening because the negative path between Orion and the battery is somehow going through the engine in the link chain? it sounds like the Orion should be connected directly to the battery instead of just anywhere on the negative buss...

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pwfarnell Val Vechnyak commented · May 05 at 04:09 PM

Yes, it all depends on how the negative paths and ground work if the engine is part of the negative path for starter battery and alter which can be different for vehicles, grp boats, steel hulled boats.

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