Carthago hab panel displays low battery 10v but shunt reading over 13v. Solar readings similar. Where to check next ?

[MarkHoughton]

Hi,
So ignoring the B2B / SCR issue and trying to test the rest of the install, I have configured the inverter and confirmed it sends power to the sockets ok. So that bit works and i can turn it on/off from the panel inside the van.
But my main control panel is only showing a HAB battery voltage of 10v and flashing low volts on the ALDE panel even though the fogstar and shunt are showing 13.2v , they are identical solar of 88w so those appear to be in-sync.

Plugged in mains and the charger panel reads ok and fogstar shows nearly 800w input.

So where do i check now to sort the low volts on the hab panel ?
Had fitted 2 new earths, one from the inverter (earth) and one from the negative busbar. All cleaned and shiny new holes/bolts/washers etc.

Everything else is connected and tight. Had not touched the existing earths.

Any thoughts ?
Cheers

 

[Rollingwheels]

Just checking if you have a shunt fitted I am sure only the negative from the shunt should be connected to the negative on the battery or the panel won’t see it, if this is correct turn everything off disconnect solar panels if you have any, remove ehu and leave a few hours they reconnect battery first then solar, it may just need a reboot

 

[AdrianChen]

If you measure the voltage between B2 and GND in the DS470, you should get the hab battery voltage. If you only get 10v, then follow the Pos/Neg cables back to check fuses/connections etc. If you get the full 13.5v, then there is an issue between the panel and DS (which I doubt!).

 

[MarkHoughton]

Hi, only negative from shunt (battery minus right hand end) is connected to the negative post on the battery.

Just checking if you have a shunt fitted I am sure only the negative from the shunt should be connected to the negative on the battery or the panel won’t see it, if this is correct turn everything off disconnect solar panels if you have any, remove ehu and leave a few hours they reconnect battery first then solar, it may just need a reboot

 

[MarkHoughton]

If you measure the voltage between B2 and GND in the DS470, you should get the hab battery voltage. If you only get 10v, then follow the Pos/Neg cables back to check fuses/connections etc. If you get the full 13.5v, then there is an issue between the panel and DS (which I doubt!).

Left the charger running on mains whilst I have been watching Burnley play at home this afternoon, just got back and Fogstar shows battery full, checked control panel and that is now displaying 13.7v ( ehu disconnected and inverter off too). Voltmeter between B2 and GND showing 11.8v (though ALDE is running…so some draw). Will run heating up in van as a drain test then try again.

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[Lenny HB]

I would expect the voltage between B2 and ground to be the same as the control panel voltage.
Check the voltage directly on your batteries.

 

[MarkHoughton]

I would expect the voltage between B2 and ground to be the same as the control panel voltage.
Check the voltage directly on your batteries.

Just tried again and B2 to GND is showing 12.9 and the hab panel now showing 13.5 , inverter off, ehu unplugged, ALDE off ( all turned off about 15 minutes ago). Fogstar shows 13.3 and Victron shunt 14.1
Which is better I guess but not aligned. I followed volt settings from Fogstar and Inverter settings from Roamer web reply.
All that is remaining is sorting the SCR situation with the B2B !

 

[Guigsy]

It sounds like there's a break between the battery and the hab electrics. Maybe a blown fuse? Are your hab electrics being supplied purely by the solar panel?

 

[Lenny HB]

Normally the shunt is very accurate still best to measure direct on battery.

 

[MichaelT]

Normally the shunt is very accurate still best to measure direct on battery.

But you have to start off with fully charged battery's.

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[Lenny HB]

But you have to start off with fully charged battery's.

Didn't mater we are talking about voltage not percentage of charge.

 

[AdrianChen]

Just tried again and B2 to GND is showing 12.9 and the hab panel now showing 13.5 , inverter off, ehu unplugged, ALDE off ( all turned off about 15 minutes ago). Fogstar shows 13.3 and Victron shunt 14.1
Which is better I guess but not aligned. I followed volt settings from Fogstar and Inverter settings from Roamer web reply.
All that is remaining is sorting the SCR situation with the B2B !

So can you switch everything off, including the ALDE etc, so there are no loads on the system at all, and then switch off all the chargers EHU, solar etc.

B2 - GND should be the same as the battery ideally measured at the battery, it should be spot on with the shunt. The CBE panel is adjustable, and may be a volt or two out, so ignore it for now. In fact I would turn the panel off, just in case it is paralleling the cab and hab batteries, which it will if it thinks the hab is 13.5v or above, this only happens when the panel is switched on, so to remove any effect it has, turn it off.

If the shunt is showing 14.2v my guess is it's picking up a charge source - Solar? If all the chargers are switched off, this voltage should drop down to the battery voltage perhaps not instantly, but pretty quickly, if you turn on a load for a few minutes than turn it off the voltage will drop, and recover to a resting voltage more quickly, but 30mins should do it.

Disconnected, well charged and at rest without any load at all the batteries will be around 13.4v. Without a charge source in operation the shunt should agree. If the shunt is lower voltage, there must be some wiring/fuse issue. If the shunt continues to read 14.1v or higher without any charge source, then you have potentially a faulty shunt (which I've never come accross so would be a first for me). You can double check the voltage with a meter at the batteries, which (as long as the meter has a fresh battery installed in it) should confirm the Fogstar app as well.

Assuming you're happy the battery voltage agrees with the meter, Fogstar app, and shunt, B2 to Gnd should also be the same as long as all loads and charge sources are off and there are no wiring issues.

Switching the panel back on should give a panel reading similar to the battery/shunt/meter. If its a little out you can adjust it in the menu system on the panel. If it's reading over 13.5, you may see the symbol that it has connected to the cab battery, and it may show a few amps flowing out to the cab battery.

I'm crap at describing this stuff, but hope that helps!

 

[MarkHoughton]

So can you switch everything off, including the ALDE etc, so there are no loads on the system at all, and then switch off all the chargers EHU, solar etc.

B2 - GND should be the same as the battery ideally measured at the battery, it should be spot on with the shunt. The CBE panel is adjustable, and may be a volt or two out, so ignore it for now. In fact I would turn the panel off, just in case it is paralleling the cab and hab batteries, which it will if it thinks the hab is 13.5v or above, this only happens when the panel is switched on, so to remove any effect it has, turn it off.

If the shunt is showing 14.2v my guess is it's picking up a charge source - Solar? If all the chargers are switched off, this voltage should drop down to the battery voltage perhaps not instantly, but pretty quickly, if you turn on a load for a few minutes than turn it off the voltage will drop, and recover to a resting voltage more quickly, but 30mins should do it.

Disconnected, well charged and at rest without any load at all the batteries will be around 13.4v. Without a charge source in operation the shunt should agree. If the shunt is lower voltage, there must be some wiring/fuse issue. If the shunt continues to read 14.1v or higher without any charge source, then you have potentially a faulty shunt (which I've never come accross so would be a first for me). You can double check the voltage with a meter at the batteries, which (as long as the meter has a fresh battery installed in it) should confirm the Fogstar app as well.

Assuming you're happy the battery voltage agrees with the meter, Fogstar app, and shunt, B2 to Gnd should also be the same as long as all loads and charge sources are off and there are no wiring issues.

Switching the panel back on should give a panel reading similar to the battery/shunt/meter. If its a little out you can adjust it in the menu system on the panel. If it's reading over 13.5, you may see the symbol that it has connected to the cab battery, and it may show a few amps flowing out to the cab battery.

I'm crap at describing this stuff, but hope that helps!

Meter on the battery terminals AND the shunt show 12.76 but B2/GND is 11.8 Fogstar BMS app shows 13.3
Solar is off, EHU been unplugged since 3pm, control panel off. All been sat idle this past 90minutes.
Just tried HAB panel and that is showing only 10.9 , looks like the solar was boosting it earlier. Almost same issue I had when i purchased it, that I only resolved by re-wiring the solar direct to the battery/busbar.

 

[AdrianChen]

Meter on the battery terminals AND the shunt show 12.76 but B2/GND is 11.8 Fogstar BMS app shows 13.3
Solar is off, EHU been unplugged since 3pm, control panel off. All been sat idle this past 90minutes.
Just tried HAB panel and that is showing only 10.9 , looks like the solar was boosting it earlier. Almost same issue I had when i purchased it, that I only resolved by re-wiring the solar direct to the battery/busbar.

Thats odd - will have a think after my supper!

 

[Lenny HB]

Are you measuring to GND on the DS terminal or to the chassis.

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[MarkHoughton]

Are you measuring to GND on the DS terminal or to the chassis.

The GND on the DS circuit board. My multimeter would not reach from chassis to B2

 

[Lenny HB]

Your B2B is not by any chance an isolated one as they are not normally used in Motorhome. If so might cause an earthing problem as normally the only ground on the leisure battery is to the starter battery.