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jds avatar image
jds asked

Mppt 75/15 motorhome grounding to be able to measure load current AND charge from alternator

Should I ground Battery- or Load- or both in order to be able to monitor load current AND allow the alternator to charge the battery?

I want to be able to put my motorhome domestic loads through the Victon and have it measure the load current, therefore I have wired Load + to the loads and Load - to ground return. Problem is the Vehicle alternator charges the battery when the engine is running, therefore requires the battery - to be grounded. (The alternator + goes direct to battery + in parallel to the Victron battery output +). Unfortunately when BOTH battery - and Load output - are grounded the Victron stops reporting load current in the display.

If I ground the battery - ONLY (Load output - not connected) it still doesn't report the load current. (Not sure why this is?)

If I ground the Load output - ONLY (battery - connected direct to Victron battery - terminal only) it does report the load current ok. But will this cause a problem when I start the engine because the alternator is grounded and the battery isn't. This means that the alternator current would go from alternator + to battery +, and then return *through* the victron to get to ground via the the load output -terminal. Would this harm the victron or affect its operation?

MPPT ControllersGroundingmonitoring
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2 Answers
christyler avatar image
christyler answered ·

Your description is a bit confusing, could you drav a diagram of everything you have and how you have it connected.

Also you say "the Victron". What is it ? What unit do you have.

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jds avatar image
jds answered ·

If I

@Christyler You're right a diagram helps! By "Victron" I meant the charge controller which is an MPPT75/15 as per the title.

If I include wire "Y" the charge controller does not report the load current (with or without wire "Z").

If I omit wire "Y" it DOES report the load current but I am concerned that when I drive the vehicle the alternator will either not charge the battery properly or will damage the victron.



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