RV.Net Open Roads Forum: Tech Issues: Wiring neutral/ground when splitting panel for MultiPlus?

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Wiring neutral/ground when splitting panel for MultiPlus?

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 8  
Prev  |  Next
Sponsored By:
3 tons

CA.

Senior Member

Joined: 03/13/2009

View Profile


Offline
Posted: 11/03/19 07:24pm Link  |  Quote  |  Print  |  Notify Moderator

joe6789 wrote:

time2roll wrote:

dropping 1 or 2 volts is too much for no load. Dropping to 1 or 2 volts is a defective battery or open connection. Where exactly are you measuring the voltage? Inverter should pull no more than 2 amps at idle that might show 0.1 volt drop in battery voltage.


Yes, I believe it's some sort of open connection, possibly between the ground of the inverter and the ground of the DC load bus bar.

When only the inverter is hooked to the battery, the battery stays at ~13 volts and 0.7 amps are drawn by the inverter at idle.

The problem is only when I hook up both the inverter and the normal DC loads -- then the voltage essentially drops to 0. I'm measuring voltage between the positive and negative terminal of the battery. As soon as I hook all the cables up, the multimeter actually shows about 6 volts, but then a second later drops to 5 volts, and continues dropping to 4 volts, 3 volts... and settles at 1 or 2 volts after about 10 seconds.

If I disconnect the inverter or disconnect the DC loads, the battery voltage jumps back up to 13 volts and everything functions normally.


How are you measuring the voltage, via victron meter??...Have you installed a shunt (in neg cable), and if so is it wired correctly??

On edit I believe your battery is toast... The auto parts store can do a carbon pile-load test to verify...

* This post was edited 11/03/19 07:31pm by 3 tons *

joe6789

TX

New Member

Joined: 10/10/2019

View Profile


Offline
Posted: 11/03/19 07:41pm Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

How are you measuring the voltage, via victron meter??...Have you installed a shunt (in neg cable), and if so is it wired correctly??

On edit I believe your battery is toast... The auto parts store can do a carbon pile-load test to verify...


I have two ways to measure the voltage: a multimeter and a Victron battery monitor shunt. I'm pretty sure the shunt is installed correctly, as I've been using it for a week with no issues (before attempting to install this inverter/charger).

I believe the battery is still good. When I disconnect the inverter/charger, the battery returns to the normal 13 volts and powers all my DC loads perfectly. Alternatively, if I disconnect the DC loads and connect ONLY the inverter/charger to the battery, the inverter/charger powers on and shows 120V across its AC out.

So in summary, I really think the components are working fine, but there's some sort of issue happening between the inverter/charger and the DC load circuit, perhaps something related to common grounds.

3 tons

CA.

Senior Member

Joined: 03/13/2009

View Profile


Offline
Posted: 11/03/19 09:02pm Link  |  Quote  |  Print  |  Notify Moderator

Well, per your previous (after hooking up the inverter dc side cabling only - ac side not yet connected) and with the battery voltage initially reading 6v then rapidly dropping to 1 or 2 volts within 10 seconds dropping, that seems like a whole bunch of current going somewhere??

How much current does the victron read when doing this, and does this only occur when you hook up to the dc bussbar ??...(just trying to isolate this a bit).

joe6789

TX

New Member

Joined: 10/10/2019

View Profile


Offline
Posted: 11/03/19 10:12pm Link  |  Quote  |  Print  |  Notify Moderator

3 tons wrote:

Well, per your previous (after hooking up the inverter dc side cabling only - ac side not yet connected) and with the battery voltage initially reading 6v then rapidly dropping to 1 or 2 volts within 10 seconds dropping, that seems like a whole bunch of current going somewhere??

How much current does the victron read when doing this, and does this only occur when you hook up to the dc bussbar ??...(just trying to isolate this a bit).


Unfortunately, the Victron shunt does not give a reading when the voltage is at 1-2 volts (nor when the voltage is rapidly dropping from 6, 5, 4...) because the shunt requires some minimum voltage to operate, so it just turns off.

Yes, this problem only occurs when I hook up the DC bus bar AND the inverter simultaneously. With only the DC bus bar hooked up (and no inverter), everything looks and works normally. So when either the inverter or the DC bus bar are hooked up, all is good, but when both are hooked up something causes the voltage to drop to almost zero.

My understanding is that the negative DC bus bar is connected to the chassis for grounding, and the inverter/charger is also grounded to the chassis. Maybe that common ground is causing an issue.

Also, while the DC bus are is connected, as soon as I hook up the inverter, about a quarter of a second later I hear a click from inside the inverter, like a relay or switch is tripping. This could simply be the inverter recognizing that it has too low of voltage (requires minimum of ~10 volts to power on), or maybe it could be a relay that's diverting the power to ground/chassis.

Regardless, I still don't fundamentally understand what can cause voltage between battery terminals to temporarily drop to almost 0, and then have it return to normal 13V as soon as a wire is disconnected.

time2roll

Southern California

Senior Member

Joined: 03/21/2005

View Profile



Good Sam RV Club Member


Posted: 11/03/19 10:53pm Link  |  Quote  |  Print  |  Notify Moderator

May need to post a picture of the batteries.


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

enblethen

Moses Lake, WA

Senior Member

Joined: 01/05/2005

View Profile






Posted: 11/04/19 06:40am Link  |  Quote  |  Print  |  Notify Moderator

Have you verified the polarity?


Bud
USAF Retired
Pace Arrow

2003 Chev Ice Road Tracker


3 tons

CA.

Senior Member

Joined: 03/13/2009

View Profile


Offline
Posted: 11/04/19 11:45am Link  |  Quote  |  Print  |  Notify Moderator

“My understanding is that the negative DC bus bar is connected to the chassis for grounding, and the inverter/charger is also grounded to the chassis. Maybe that common ground is causing an issue.”

No, the inverter AND the dc bussbar grounds both go to the common chassis ground... Something else is amiss...

If you’re empirically confident that the battery is up to snuff, and all the dc loads are easily accommodated via the battery (converter-charger OFF) when inverter is not in the loop, then I would begin to suspect (per Occum’s razor) the inverter...This assumes (??) that everything works just fine until you insert the inverter into the loop...JMWAG

joe6789

TX

New Member

Joined: 10/10/2019

View Profile


Offline
Posted: 11/04/19 10:33pm Link  |  Quote  |  Print  |  Notify Moderator

I'm pretty sure polarity is correct.

After experimenting today, I found a workaround to the issue, and I'm able to run both the inverter/charger and the DC loads simultaneously. But I still have no idea why the issue (drop to 0 voltage) was happening.

There is a master battery disconnect switch connected to the battery positive terminal. Both the inverter/charger and the DC loads were connected to the output of this switch. So when the switch was turned off, there were no loads, no DC current flowed, and the battery terminal voltage was 13V. When the switch was turned on, power should have been supplied to both the inverter/charger and DC loads, but instead the terminal voltage would drop to almost 0 and neither the inverter/charger nor the DC loads would receive power.

What I tried today was to connect the DC loads direct to the positive terminal of the battery instead of the switch, while leaving the inverter/charger connected to the switch -- and the problem went away. Now, when I turn on the switch, the inverter/charger powers on fine, and the DC loads are also running since they are no longer controlled by the switch.

In summary, if the inverter/charger and DC loads are switched on together, neither received current and the terminal voltage drops to 0. But if instead the inverter/charger is switched on while the DC loads are already receiving power, then everything works fine.

What could be causing this? Is it just a fluke? Perhaps some sort of advanced "feature" inside the Victron inverter/charger?

Note the DC loads are only about 0.9 amps and the inverter/charger only draws another 0.9 amps, so the total draw of 1.8 amps is very small.

3 tons

CA.

Senior Member

Joined: 03/13/2009

View Profile


Offline
Posted: 11/05/19 08:28am Link  |  Quote  |  Print  |  Notify Moderator

If you are saying that the battery supply to the inverter passes thru a master switch, I would suspect the switch...Leave dc loads connected to the switch (per former scheme) and connect inverter directly to battery positive terminal...The inverter needs to be connected directly to the battery with a 300a fuse in the positive cable.. Hopefully you’ve chosen cables of an adequate AWG size and a relatively short round trip cable run. It’s doubtful the switch could handle the kind of dc current the inverter will demand.

I’m using 0004 aught AWG for my 2,000w ProSine with a RT cable run of about 7’.

joe6789

TX

New Member

Joined: 10/10/2019

View Profile


Offline
Posted: 11/05/19 09:01am Link  |  Quote  |  Print  |  Notify Moderator

Well the switch is actually rated for 350A, there's a 300A fuse at the positive terminal, and I'm using 0000 cables that are all very short. So theoretically all these components should be able to manage the current just fine. And right now the inverter isn't even hooked up to any AC loads, so it's only idling at about 0.9A draw.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 8  
Prev  |  Next

Open Roads Forum  >  Tech Issues

 > Wiring neutral/ground when splitting panel for MultiPlus?
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2019 CWI, Inc. © 2019 Good Sam Enterprises, LLC. All Rights Reserved. | Terms of Use | PRIVACY POLICY | YOUR PRIVACY RIGHTS