[Dave Koller]

Originally Posted by dimitri

Dave, I never actually listen to AM radio. For past couple years I don't even listen to FM radio, only XM satellite and my MP3s. My car tuner doesn't even have antenna connected, I only use it as a reciever for XM and MP3s.

I don't think you can do much for AM in close proximity with large DC motor. Can you imagine the noise produced by constant sparking of the commutator? Maybe AC drive would be better, but I am no expert in this kind of thing.

LOL you are right ! But I use a small AM radio to "sniff out" noise in other situations - assumed AM will be a good test of any noise suppression.. relative to just the "Before and after" - instead of using the scope. Got ta love those spark transmitters! ( I do remember tubes as an old "Ham" person here and made some "spark" transmitters as a kid!)

Dave

[jaspersk]

Originally Posted by dimitri

To filter out the noise and smooth out the signal I put 4700 µF capacitor across red and black wires and 0.1 µF capacitor across green and black wires. This was done at the display unit's end of the data cable.

Results are incredible, PakTrakr is absolutely 100% rock solid now, woohoo! I drove around few miles going from zero to full throttle, making battery current jump from 0 to 450 amps back and forth, not a single glitch on the PakTrakr

So, bottom line, twisting battery cables and generally locating them close to each other, putting few ferrite chokes in strategic places and adding capacitors at the display unit makes a huge difference. I hope this helps others as well.

Thanks everyone for the info and suggestions, this has been a great learning experience for me!!!

Very cool! I am impressed and a bit jealous. I tried messing around with capacitors on the line between the remote and the meter but I must not have had the right combination or maybe I put them on the wrong line. Great work!! I tried the ferrite cores as well but they never seemed to help me. It sounds like you really have to attack the problem from all angles to nail it.

Someone asked if I ever scoped mine. Wish I had a scope!!! The answer is no. I am really happy to see Dimitri get some great data and solid results.

Ken is obviously a smart guy to build the product he has. It seems like a couple of small adjustments might provide some real gain. I wonder if he just built so many of them that his inventory is too large to make improvements?

[tj4fa]

Originally Posted by jaspersk

I wonder if he just built so many of them that his inventory is too large to make improvements?

Originally Posted by dimitri

...To filter out the noise and smooth out the signal I put 4700 µF capacitor across red and black wires and 0.1 µF capacitor across green and black wires. This was done at the display unit's end of the data cable...

Maybe Ken could make an inline plug-in modular box?

[Nsharit]

[quote=tj4fa;139807]Maybe Ken could make an inline plug-in modular box?

Wouldn't the entire system be safe from EMF if shielded wires were used? I kinda figured that would be standard for any discrete indication wiring.

[tj4fa]

Originally Posted by Nsharit

Wouldn't the entire system be safe from EMF if shielded wires were used? I kinda figured that would be standard for any discrete indication wiring.

Possibly, but all EV builds components, wiring, ect are not the same and the "dirty" environments have different frequencies and different types of EMI (magnetic/electric). Apparently, some EV builds have no problems at all, while a few others have.

That's why I think a plug-in module that can be easily connected between the existing wiring may be the easier way to go if there has been a lot of the units already fabricated.

It seems like the best cure right now is something filtering the EMI in the final wiring close to the indicator itself whether it be the method Dimitri found earlier in this thread or someone else found in this thread:

http://visforvoltage.org/forum/2987-paktrakr-data-noise

Perhaps shielded twisted pairs installed in the final wire segment inside the passenger compartment from the Paktrakr display unit to the next Paktrakr junction box being may do the trick.

[PJ-box] = Plug-in Passenger compartment J-box

Meter------[ PJ-box ]------shielded pr------[ PJ-box ]--------[ Last battery J-box ]

Unfortunately, I don't have the system to give this a try.

Here is a good article about EMI and filtering that might be of value.

http://www.woodward.com/PDF/IC/50532.PDF

[jaspersk]

[quote=Nsharit;140355]

Originally Posted by tj4fa

Maybe Ken could make an inline plug-in modular box?

Wouldn't the entire system be safe from EMF if shielded wires were used? I kinda figured that would be standard for any discrete indication wiring.

Powering the remote and the meter from a 9V akaline and putting unshielded twisted pair wire as close as possible to the power wiring provided for meters that work perfectly. (Unfortunately this is no good unless you are willing to have a 9V error in your pack voltage reading). I tried shield twisted pairs and it did NOT fix my problems.

The point is that the source of the noise is the power source given that both the meter and the remote are fed from traction batteries. Think about it. We are trying to shield the meters from a signal that is used to power the meter. It doesn't pay to work on EMF when the noise signal is already inside the meter and the circuits powering the communication.

[jaspersk]

Originally Posted by tj4fa

Maybe Ken could make an inline plug-in modular box?

I agree. It is probably would hurt is marketing to have that option listed.

I think the capacitors are a reasonable fix. Personally, if Ken is reading I'd be much more in favor of an optocoupler and power to the final meter coming from the 12V SLI power. And some filtering on top of that.

[ElectriCar]

I'm going to try the capacitors trick. Makes sense the noise could be inductively picked up AND directly from the battery source as well.