Fox D1 Battery Monitor

[JumbleDuck]

My boat came with a Fox D1 battery monitor which is supposed to show voltage or, at the press of a button, current.

http://www.svb24.com/en/sunware-battery-display-fox-d1.html

It's neat but doesn't work, and it doesn't work in an odd way. If the batteries are discharging the monitor shows a steadily decreasing voltage way below reality (checked with DVM) and if the batteries are charging it shows a steadily increasing wrong voltage in the same way.

So, for example, if the battery is reading 12.6V and I switch on a couple of cabin lights (1A, ish), the indicated voltage will be 12.1V after half an hour, 11.6V after an hour, 11.1V after 90 minutes, 10.6V ...

For the mathematically minded, V_disp ~ V_actual - I_discharge * hours.

This is all a bit unsatisfactory. The easiest solution would be to replace the Fox (€60 or so) and the more complicated one (£100 or so) would be to fit a NASA monitor and shunt instead. I'll probably do the latter, but I'd be interested to know if anyone else has experience of the Fox and might be able to shed light on its odd behaviour.

 

[pvb]

I wonder whether it's correctly wired.

 

[typhoonNige]

I have one for monitoring the output from solar / wind turbine and it behaves as expected most of the time BUT if the wiring into the back is touched, the readings jump, suggesting to me that the internal connections are not the best. Maybe yours is suffering a variant of the same problem.

 

[JumbleDuck]

I wonder whether it's correctly wired.

I have downloaded the installation manual and will check, but it's a pretty simple three-wire setup (battery+, battery-, out) as it doesn't use a shunt. On the other hand, there is a solar panel controller as well which I suppose might be jiggering things somehow.

I have one for monitoring the output from solar / wind turbine and it behaves as expected most of the time BUT if the wiring into the back is touched, the readings jump, suggesting to me that the internal connections are not the best. Maybe yours is suffering a variant of the same problem.

Ah, thanks. Might be worth whipping it off and having a poke round inside with a hot soldering iron.

 

[William_H]

If it does not use a shunt (well actually it must have a shunt but it is internal to the meter unless it uses some sort of magnetic field detector around the current carrying wire) In any case high current wiiring must pass through the meter box. This could be a recipe for trouble as any resistance in the connections internally or externally will cause all sorts of odd voltage drops.
As said check all the connections internal and external . You call also check with your multimeter the voltage representing battery voltage at the meter itself. May be some wiring volt drop between meter and battery. good luck olewill

 

[JumbleDuck]

If it does not use a shunt (well actually it must have a shunt but it is internal to the meter unless it uses some sort of magnetic field detector around the current carrying wire) In any case high current wiiring must pass through the meter box. This could be a recipe for trouble as any resistance in the connections internally or externally will cause all sorts of odd voltage drops.
As said check all the connections internal and external . You call also check with your multimeter the voltage representing battery voltage at the meter itself. May be some wiring volt drop between meter and battery. good luck olewill

Thanks. Yes, I should have said that it has no external shunt. I've check with a DVM at the Fox connections and the volts are getting there just fine, so it's something in the Fox going funny. I'm surprised, by the way, that marine systems still use shunts and not hall-effect sensors. Perhaps their power draw is the disadvantage.

 

[halcyon]

Thanks. Yes, I should have said that it has no external shunt. I've check with a DVM at the Fox connections and the volts are getting there just fine, so it's something in the Fox going funny. I'm surprised, by the way, that marine systems still use shunts and not hall-effect sensors. Perhaps their power draw is the disadvantage.

What are you using it for ? looks like a solar regulator and they use the volt drop across a MOSFET for current value.

Re Hall effect sensors, we have been supplying them for over 20 years to the marine trade.

Brian

 

[vyv_cox]

I had a Fox solar panel regulator. It never worked very well and in the end I dumped it and bought a Sunworks http://www.sunworks.co.uk/ That too has had its problems but sorted by the manufacturer at minimal cost.

 

[JumbleDuck]

What are you using it for ? looks like a solar regulator and they use the volt drop across a MOSFET for current value.

The Fox-D1 isn't a solar regulator. It's a simple battery monitor showing volts and amps. They do make solar regulators as well (Fox-220, Fox-350), but I'm pretty sure the one my boat is another brand.

Re Hall effect sensors, we have been supplying them for over 20 years to the marine trade.

Interesting. Do any of the standalone battery monitors around use them, or do you sell them for use as part of bigger systems?

 

[halcyon]

The Fox-D1 isn't a solar regulator. It's a simple battery monitor showing volts and amps. They do make solar regulators as well (Fox-220, Fox-350), but I'm pretty sure the one my boat is another brand.



Interesting. Do any of the standalone battery monitors around use them, or do you sell them for use as part of bigger systems?

Most confusing instructions, they must have a shunt between the blue ( high side main power return ) in and black out to battery, then use red to black for voltage only.

We used to supply them as part of switch panels to production yards, later stand alone shunts, now we still supply them as part of VSR's and switch panels.

Brian

 

[Nicholas123]

The Fox-D1 isn't a solar regulator. It's a simple battery monitor showing volts and amps. They do make solar regulators as well (Fox-220, Fox-350), but I'm pretty sure the one my boat is another brand.

I have a FOX-D1 on my boat & it is definitely being used to monitor the Solar panel output.I have it at the moment with no batteries attached down the boat & it is ranging between 5/6 volts & 10/15/16 depending on the intensity of the sun.
Not sure what the current ever does,not had the boat long enough & the wiring leaves a lot to be desired.Shall probably get round to sorting it out eventually.

 

[JumbleDuck]

I have a FOX-D1 on my boat & it is definitely being used to monitor the Solar panel output.I have it at the moment with no batteries attached down the boat & it is ranging between 5/6 volts & 10/15/16 depending on the intensity of the sun.
Not sure what the current ever does,not had the boat long enough & the wiring leaves a lot to be desired.Shall probably get round to sorting it out eventually.

They sell them to monitor solar panel output, but they don't control the solar panel. On my boat it seems to have been wired to show full domestic charge/discharge, using surprisingly skinny wires. I may try leaving it in for the solar panel and adding an additional monitor to show what in total is going in and out.

 

[Nicholas123]

They sell them to monitor solar panel output, but they don't control the solar panel. On my boat it seems to have been wired to show full domestic charge/discharge, using surprisingly skinny wires. I may try leaving it in for the solar panel and adding an additional monitor to show what in total is going in and out.

I would have thought that to monitor the domestic charge they would have to be wired between the alternator & the battery & I believe that we are talking about 13 amps on mine so I would'nt like that lot going through what looks like a flimsy instrument.
I have another companion to the FOX-D1 called a FOX-40 which is another mystery but I presume is all part of the solar panel setup.
I don't think I have anything to monitor the alternator input except a red warning light on the instrument panel that I think is supposed to come on if the alternator is'nt charging & a little unit with red amber & green led's to show the battery condition.I also have a similar device that just fits into a cigarette lighter socket & tells you if the alternator is charging & general battery condition which must have cost peanuts.A much simpler solution than spending a 100 quid or so & wiring in a NASA battery monitor?

 

[JumbleDuck]

I would have thought that to monitor the domestic charge they would have to be wired between the alternator & the battery & I believe that we are talking about 13 amps on mine so I would'nt like that lot going through what looks like a flimsy instrument

I think whoever did it has indeed arranged that the flimsy instrument sits in the main house battery line ... it shows -40A discharge when the battery's low and the engine's running. I was really quite surprised, and dismayed, to find that no remote shunt is involved.

I agree about possible over complexity, and you've made me think that perhaps a simple voltmeter/ammeter set up would suit my purposes better than a hundred quid's worth of NASA stuff.

 

[pvb]

I think whoever did it has indeed arranged that the flimsy instrument sits in the main house battery line ... it shows -40A discharge when the battery's low and the engine's running. I was really quite surprised, and dismayed, to find that no remote shunt is involved.

You need to remove it or rewire it ASAP - it's only rated for 20A.