# JLD404 AH Meter



## Zappo (Sep 1, 2011)

I've got a problem with my JLD404 that I thought I'd see if anyone else has seen. When I first installed it, it worked great. The only thing I noticed was there seemed to be a loose connection to the LED that indicated when it was showing AH. The LED would blink on and off randomly. 

The AH display was very consistent in returning back to very near zero about the same time the charger was done.

About two months ago, it started losing that accuracy. After a full charge, it would usually read between 2AH and 4AH. Various testing indicated the error was with the meter, not with the actual SOC. This morning on the way to work, I noticed the AH quit counting up. I switched to "amps" and it was near zero when it should have been around 40-50 amps at the time. While watching it, it started working and then started actually showing negative (charging) amps. According to the meter, it only took about half the AH to get to work today (I wish).

Pretty much the same thing happened on the way home. I've checked all the wiring and the output of the DC-DC converter powering the meter. At this point, I'm guessing it is internal to the meter. Just wondering if anyone else has seen this or if I just happened to get a lemon.


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## onegreenev (May 18, 2012)

Sorry but I can't help because I only use mine right now for battery testing. Could be that being in the vehicle could jar something loose. Not sure if you purchased it from Rickards store or not but if you did you can get them much cheaper at the main store in California. Just down the way from me and they deliver fast if you happen to need another one. I have the JDL amp meter and the Volt meter for my setup. Sorry to hear it is being dodgy.


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## Zappo (Sep 1, 2011)

Yeah, I paid the high price the first one but already have ordered a replacement from Lightobject.com for much less.

I did jar it a bit yesterday as I was leaving work. As I was leaving the parking lot, there were a couple of coworkers watching me pull away. I decided to tromp down on the pedal to show them it wasn't gutless. Boy did it surprise me! I'm usually pretty soft on the pedal. The acceleration was way more than I was expecting. 

I have my Zilla battery amp setting down around 270 amps (3c for my 90AH pack). I had the motor amps dialed down to around 400. I completely forgot that I had cranked it up to 800 amps last week. Wow! what a difference.


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## Ziggythewiz (May 16, 2010)

For the first issue, do you read 0A when sitting? One of mine usually says -.01A so numbers while driving will still be quite accurate, but charging numbers will be off. I haven't gotten around to testing but it may be a connection issue. Someone else asked about that and I realized I have one meter fused but not the other.

I previously found my meter always reading ~.2A and replaced a connection or two and it went to 0.

I got the reset issue with my first one. Whoever you got it from, Jack or lightobject will replace it no problem.

It would usually reset while or just after backing out, which I didn't care about, but then it started doing it randomly in the middle of my commute which was unacceptable.


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## Zappo (Sep 1, 2011)

Thanks Ziggy. It had been reading zero with no load. Now it usually shows .04 to.1 amp. Sometimes as high as 1.2 amps with no load. 

After what you said about the reset, I'm convinced even more it is internal to the meter. I forgot about this, but I noticed the "time since last reset" or whatever they are calling it had reset on its own on the way to work also. Usually, you need to hold the "down" button for a few seconds for that to happen.

Unfortunately, I'm sure they won't want to take it back for a refund. I mounted this in the dash over on the passenger side. I made a custom holder so it would face the driver better. The only way I could think of to secure it to the custom holder was with some silicone seal. I will be able to separate it from the holder but it won't look very pretty anymore.


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## Ziggythewiz (May 16, 2010)

On mine the reset was easy to see because I leave it on Amps while driving and when it reset it would switch to AH (which would be zeroed).

I really don't think they'd care if it isn't pretty getting sent back, I don't know if they refurb returns or what but they'd likely replace the plastic case anyway. You could always ask.

If you decide to keep it, open it up and see if there's anything loose. The fact that it generally works but occasionaly trips makes me think there might be something that shorts occasionally or something. I once had a USB drive that would self wipe if I held it a certain way shorting something through my thumb.


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## PStechPaul (May 1, 2012)

If you used silicone sealant to mount the meter, and it was not electrical grade, the acetic acid fumes could have gotten onto the PCB and etched away some tracks or created a conductive path. If so, you might be able to remove the silicone and examine the board, repair any damaged tracks (or thru-holes), and then clean it with alcohol followed by detergent, then clean hot water, and dry thoroughly with a heat gun. You can get PCB coating to protect it from further contamination, if the problem has been fixed.


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## Zappo (Sep 1, 2011)

Ziggythewiz said:


> On mine the reset was easy to see because I leave it on Amps while driving and when it reset it would switch to AH (which would be zeroed).
> 
> I really don't think they'd care if it isn't pretty getting sent back, I don't know if they refurb returns or what but they'd likely replace the plastic case anyway. You could always ask.
> 
> If you decide to keep it, open it up and see if there's anything loose. The fact that it generally works but occasionaly trips makes me think there might be something that shorts occasionally or something. I once had a USB drive that would self wipe if I held it a certain way shorting something through my thumb.


I'm going to check with EVTV to see if they would take it back. If not, I will open it up a check it out. Thanks again.


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## Zappo (Sep 1, 2011)

PStechPaul said:


> If you used silicone sealant to mount the meter, and it was not electrical grade, the acetic acid fumes could have gotten onto the PCB and etched away some tracks or created a conductive path. If so, you might be able to remove the silicone and examine the board, repair any damaged tracks (or thru-holes), and then clean it with alcohol followed by detergent, then clean hot water, and dry thoroughly with a heat gun. You can get PCB coating to protect it from further contamination, if the problem has been fixed.


Good point Paul. In this case, it happened to be electrical grade only because that is what is usually in my tool box. I carry the box to and from work and electrical grade is what we carry at work.

That mention about detergent and hot water sure brought back memories. Way back when I repaired TVs, Some circuit boards would be so covered in greasy dirt that I had to clean them that way before I did any troubleshooting. My wife wanted to kill me when she would find me cleaning one in the bathtub. As long as I dried everything completely before applying power, it worked great.


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## simat (Mar 25, 2013)

Could some please confirm whether or not the JLD404 is able to measure current in both directions.

The instruction manual on one page says 0~9999A, and on another says 75mv (shunt value -15~75mV).

I want it to increment the AH counter when a battery bank is being discharged and decrement the AH counter when it is being charged.

Thanks


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## grip911 (Dec 14, 2011)

Yes it does ,but make sure that your negative lead from the charger is at the uttermost part of the battery pack including and past the shunt. I don`t know if I said that right, and If I didn`t maybe someone else could elaborate


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## simat (Mar 25, 2013)

Thanks for the reply, 

Do you mean that the shunt should be between the charger negative lead and the negative battery terminal?

If the shunt is not between the battery terminal and the charger, the current from the charger will not be flowing through the shunt resistor and will not be registered.

To measure current going into or out of the battery i think one terminal of the shunt should be connected to the negative battery terminal and the other to the load and charger negative leads.


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## Ziggythewiz (May 16, 2010)

The shunt will read fine as long it's between the charge leads. 

It only has to be at between the negative most battery and the charge lead to read full pack voltage.


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## Lopezjm2001 (Nov 22, 2011)

Ziggythewiz said:


> The shunt will read fine as long it's between the charge leads.
> 
> It only has to be at between the negative most battery and the charge lead to read full pack voltage.


I am planning on using one of these where the cable between the display and 75mV shunt is about 25 metres. Does somebody know whether it uses the four wire mV measuring method to cancel out any noise induced into the measuring cable. Maybe any induction can be calibrated out.


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## onegreenev (May 18, 2012)

With long runs you need to twist your wires from end to end.


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## Roy Von Rogers (Mar 21, 2009)

The one thing one needs to realize that if you use the meter to read amps forward and reverse there will be a discrepancy, the reason for that is that your using a 75mv shunt which reads 75mv at 500 amps, but when you hook the charger up, your only putting in a small amount of amperage compared to the shunts maximum of 500 amps, which brings the millivolts down to a fraction.

So the amps hours used will not show the same when you charge the cells back up.

The only work around is to use two shunts, one for amps out (500a), and another shunt as close as the chargers amperage you can get, and then use a relay to switch shunts when charging.

And of course when working with millivolts, the leads need to be short and solid.

Roy


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## Ziggythewiz (May 16, 2010)

The main source of charge discrepancy is the longer time frame. I have inline fuses in mine which introduce a slight error in the reading. While driving (30-40 min/day) this error is insignificant but while charging or if left on 10+ hours even a .01A misread adds up.


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## Roy Von Rogers (Mar 21, 2009)

Your just stating what I have already said, what is your point. Its about the resistance of the connection from shunt to the metering device. But what your missing is the relationship of voltage versus the resistance.

If you take a 500a shunt with 75 millivolts coming out going to the meter, and then attempting to read lets say 50 amps of charging through the same shunt, your voltage will be one tenth, 7.5 millivolts.

But if you took a 50a shunt and read the 50a charging voltage the millivolt out of that shunt would be equal to what the 500a would give.

It should be obvious that the relationship of amps used and amps returned via charging would be lot more accurate.

Not to mention the impedance of the meter and how much of a loading it would put on the shunt voltage, which when the millivolt is very low, amplifies the error even more.

The larger the sampling of anything, the better the resolution will be, its a well known fact.

Roy


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## PStechPaul (May 1, 2012)

I use a 1000A/100mV shunt in my Ortmasters to measure currents from about 50 amps to 10,000 amps with a resolution of about 0.02% and accuracy of better than 1%. But I have very short leads from the shunt to the PCB, and the signal is amplified by an instrumentation amplifier and a selectable gain amplifier which boosts the voltage in 8 ranges from 1x to 200x. The input of the amplifier is 2k ohms so the lead resistance has negligible effect on the reading. If I had current flow in the shunt leads for power, and if the leads were longer, there could be enough voltage drop to skew the readings.

But the greatest source of error is likely to be the number of bits used by the A/D converter, as well as the accuracy of the ADC and the DC offset error. If you have a typical 10 bit ADC with 5V reference as found on most microcontrollers, a 500A/50mV shunt would supply only 1/100 of the dynamic range of 1024 counts, or 0.05*1024/5 = 10 counts, so your precision would be 5 mV or 10%. There is almost certainly a preamplifier to boost the signal as much as 100x, or the reference could be set to 50mV or 100mV. Either way may introduce offset error, noise, nonlinearity, and accuracy issues, but good components and some trim adjustment should bring the error down to close to the precision, which is 1/1024 or 0.01%.

That is for a full scale current of 500 amps. If you use the same shunt and amplifier for a 10 amp charging current, the precision drops to about 0.2%. If the bit transition voltages are very accurate, it is possible to achieve greater precision by "dithering", which adds just enough noise to produce a statistical sampling that spans one bit and by averaging a large number of samples the effective resolution improves.

But it is even better to amplify the lower millivolt signal to get the full dynamic range, which can achieve the full 0.01% resolution if needed. Adding a precision amplifier for the low current range may be better and less expensive than adding a separate shunt and a switch.


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## Lopezjm2001 (Nov 22, 2011)

Thanks for the replies. Just one more question. Can the 75mV shunt be used in the positive leg. I know it is standard to put the shunt on the negative side but will it work in the positive side? It may seem to be a strange question, it's just that I have good access to install the shunt in series with a fuse on the positive side whereas I have no access on the negative side since most of the connections are made with Anderson plugs. To install the shunt on the negative side I need to cut the cable and crimp lugs. It is just a lot easier to install on the positive side in my case.


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## PStechPaul (May 1, 2012)

I doubt that it will work, and it may damage the meter. There are high-side current monitors, however:
http://m.eet.com/media/1135137/72204di.pdf
http://www.analog.com/library/analogDialogue/archives/44-12/high_side.html
http://www.analog.com/library/analogdialogue/archives/42-01/high_side_current_sensing.html
http://www.supertex.com/pdf/datasheets/HV7800.pdf

You can get isolation amplifiers for high-side shunt measurements:
http://www.knick.de/?/en/Products/M...olation-Amplifiers-for-Shunt-Applications(513)
http://www.ti.com/lit/ds/symlink/amc1200.pdf

You may be able to get a free sample of the TI part:
http://www.ti.com/product/amc1200#samples

Or pay $6 from Mouser:
http://www.mouser.com/Cart/Cart.aspx?GUID=7478ee81-bc25-4f1f-8176-59dd0c624d66

From the datasheet I downloaded, it appears that the JLD404 uses a common ground and the shunt must be at ground potential. It should use a differential amplifier input which has some common mode voltage spec, but I don't see it.


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## Lopezjm2001 (Nov 22, 2011)

I have tested if it measures on the positive leg using the 5amp (terminal 7). It measures the current accurately but it is negative, the voltage is also negative and the AH is also negative just using a 12Vdc fan as a load. Whereas when connecting the negative the values are positive.

I just do not have a 75mV shunt available at this time to see if it works.

It appears to me that the common terminal 10 could either be negative or positive.


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## Ziggythewiz (May 16, 2010)

Lopezjm2001 said:


> Can the 75mV shunt be used in the positive leg.
> 
> To install the shunt on the negative side I need to cut the cable and crimp lugs. It is just a lot easier to install on the positive side in my case.


It works anywhere as an AH counter. The voltage is designed to be read from bottom to top, so you won't get full performance if you connect it in reverse. I have one on the neg leg of my booster pack and one in the upper middle of my regular pack because it started there as an experiment and is not convenient to relocate.

What kind of battery connections do you have? If they're bolt on you could just add it on the neg batt end with 1 additional cable.


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## Lopezjm2001 (Nov 22, 2011)

Ziggythewiz said:


> It works anywhere as an AH counter. The voltage is designed to be read from bottom to top, so you won't get full performance if you connect it in reverse. I have one on the neg leg of my booster pack and one in the upper middle of my regular pack because it started there as an experiment and is not convenient to relocate.
> 
> What kind of battery connections do you have? If they're bolt on you could just add it on the neg batt end with 1 additional cable.


I expect that if I just connect the 75mV shunt terminal 9 and negative to common (no connection to terminal 5 or 6) I should be able to get a current reading as all it should do is measure the voltage across the shunt to determine the current. Am I correct in assuming that the meter does not need to measure volts between the common terminal 10 and terminal 5 or 6 in order to measure current?

I am planning to use this meter to measure AH in and out of a Enginer PHEV kit which I am using as a off-grid solar power system on my house. All the cable connections are Anderson plugs except for the circuit breaker. The only place I can easily connect the shunt is in series with the 100amp circuit breaker.


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## Roy Von Rogers (Mar 21, 2009)

The amps are read from the two terminals at the shunt, and go to 9 and 10 on the meter, which wire you connect to common will determine if you want to read the amps negative or positive.


You have to power up the meter from 1 and 2 usually 12v from your vehicle. 

Negative on the meter is not the same as common on the 75mv.

Roy


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