# JLD404 issues



## Ziggythewiz (May 16, 2010)

I'm sure there's a bunch of us using the JLD404 by now, I'm having some issues and hoping someone has more experience.

I started out with it connected to my AUX battery and got good readings of each of my systems, I was surprised how low the usage was, and was able to verify the readings using a DVM.

I now have it connected to the traction pack (124V lead), and the first weird thing was that I got negative readings with it connected in the same way as with the 12V (COM connected to negative end of shunt, 75mv to the other). I swapped it around to what seems backwards to me and it seems to work fine.

The next weird thing is today when I got home I planned to let it run while charging to check my charger's efficiency, but for some reason when I turned the car off the JLD still read 3 A. It had gone to 0 the whole time I was driving whenever letting up on throttle, but not after I got home. So with the charger running (10A quickcharger) it was reading -1.8A, as opposed to the -8-10 I expected. The kill-a-watt showed the charger pulling much less than usual, so I swapped for a fatter extension cord that usually trips breakers. The kill-a-watt then read normal draw (~850 watts) but the now JLD showed even less, -0.5A

Any thoughts?


----------



## Roy Von Rogers (Mar 21, 2009)

Ziggythewiz said:


> I'm sure there's a bunch of us using the JLD404 by now, I'm having some issues and hoping someone has more experience.
> 
> I started out with it connected to my AUX battery and got good readings of each of my systems, I was surprised how low the usage was, and was able to verify the readings using a DVM.
> 
> ...


Are you using the 12v/12v dc converter for isolation ??


Roy


----------



## Ziggythewiz (May 16, 2010)

Not right now. I had one hooked up but it got fried so I ran the JLD off a separate battery when testing the 12V, and now off the 12V.


----------



## spturnip (Nov 18, 2013)

If the JLD404 meter is drawing power from the always-on pin from a DC-DC converter, don't you still need a 2 or 3-watt DC-DC converter brick to isolate the meter and prevent it from possibly shunting current to the common ground via the 0 to 75mV lead wires connected to the shunt? If there is current flow, couldn't this also contribute to amp reading inaccuracy due to the voltage drop across the lead wire? In the Feb 24, 2012 EVTV episode at 80 minutes, Jack talks about installing a DC-DC converter to isolate the meter.


----------



## Ziggythewiz (May 16, 2010)

JLD404 is isolated, so no need for DC-DC. Jack just assumed it needed one because many other meters do and once he assumes something it becomes gospel.

As for the issues I was (am) seeing, any bit of resistance in the lines can cause slight misreadings, such as a loose or dirty connection, or the inline fuses that I use on all my connections. I just live with it, and don't pay attention to overnight readings.


----------



## rwaudio (May 22, 2008)

Since you switched from a lower voltage to higher voltage measurement are you still in the right ranges for voltage/current?

Have you gone through the chinglish set up sheet and gotten things configured properly? What you said about the shunt leads me to believe something is up. Is your shunt attached to the most negative cell?


----------



## frodus (Apr 12, 2008)

Draw it out for me for a second. I think you've got the shunt wires backwards.

Is it wired like this:
http://www.thunderstruck-ev.com/images/JLD404Manual3.pdf

or do you have the shunt on the positive terminal of the traction pack?


----------



## Ziggythewiz (May 16, 2010)

Thanks for the responses guys. Honestly I don't recall how exactly it was hooked up 2 years ago, but it's been working fine (aside from the slight line resistance issues) for a long long time.


----------



## z_power (Dec 17, 2011)

I had similar issues - offset reading when zero expected etc. - when measuring relatively small (<3A) current during charging experiments. The reason was meter/shunt combined accuracy; I used 300A/60mV shunt declared in settings as 375/75, it seems like JLD has some trouble measuring shunt voltages near zero, playing with settings could help with this issue but messed any measurments at higher than 5A currents.
Just calculated: 300A/60mV gives 3A/0.6mV and this is a bit tricky for JLD.
Moral: use the right shunt for expected current ranges


----------



## Russco (Dec 23, 2008)

Roy Von Rogers said:


> Are you using the 12v/12v dc converter for isolation ??
> Roy


I am using a 12V to 12V DC-DC from the 12V accessory battery to pins 1 and 2 of the JLD.

Is it necessary to use the DC-DC or can pins 1 and 2 connect directly to the accessory battery?


----------



## Weisheimer (May 11, 2009)

The JLD404 has a built in DC/DC converter. (or at least the one I have here does...)
Thus, you should not need to use one externally.


----------



## lou-ace (Jul 21, 2009)

uhmmm loose grounds are always a bitch on DC circuits it sounds like you might have grounding issue. Is your EV on two dedicated circuits? i.e. the accessory system ( everything that runs the rig) should be grounded to earth like the frame and all metal that connects to the frame. And the traction circuit should be isolated and " float" and never connect to the frame, or any metal that connects to the frame. I would take your DVM and check voltage between your "pack"and earth ( frame) , and conversely I would check your accessory system for any " leak" between the systems. THEY MUST NOT COMMUNICATE!!. If you find a problem, always start at the source and work forward. EV 101 but I always try to keep it simple. I hope it helps. buy the way I'm trying to resolve the difference that I'm having between the JLD and a old analog meter that I have in my EV. the analog meter states about 200% more usage than the JLD and I have rechecked my setup in the JLD and the analog meter without any resolution. making me crazy but I tend to believe the JLD more. Other that that I love the JLD it's awesome.


----------



## Ziggythewiz (May 16, 2010)

Lou, do you have a clamp-on ammeter you can use to check while charging?

When I first got mine I had it hooked to my 12V system to check max ACC usage, and was surprised how low it was, but a clamp meter verified the reading.


----------



## dh999 (Dec 23, 2015)

Ziggythewiz said:


> As for the issues I was (am) seeing, any bit of resistance in the lines can cause slight misreadings, such as a loose or dirty connection, or the inline fuses that I use on all my connections. I just live with it, and don't pay attention to overnight readings.


Did anyone figure out a way to eliminate the misreadings? Using a separate 12V power supply for the JLD404, and with *no* 500V connections to the JLD and *no* other connections to the pack, I still see 0.3-5A current. I have twisted pair between the shunt and the JLD. Annoying - I would like to track AH between charges. 

Inaccurate shunt? Dirty/loose connections? Other ideas?


----------

