Sensor Selection for Electric Vehicle Monitoring

I am in initial stages of selecting sensors to monitor and record electric vehicle performance.

MONEY We do not have a huge budget so we must buy good equipment only ONCE - price while important is second to quality, durability and reliability

Again because of money we are going to use what we got. I suppose Labview or other software and computer installed in vehicle would be better but the budget,,,,,,,

All sensors will more than likely be removed and installed on multiple vehicles so they must be hardy ie boob proof - OK OK resistant.

Will use Fluke Hydra Bucket 21 channel data logger. This unit accepts voltage inputs only both DC and AC thermocouple and RTD and maybe pulse (gotta read the manual on this)
I do not want battery line voltage in the cab where data logger will most likely be located to prevent someone contacting 144 or more (allow for 400 VDC)

I am only asking for help to select good manufacturers to contact for brochures. I have Branom Instrument in Seattle to talk with and will of course. But I want to tap the brains of the guys who use and repair on a daily basis.

I do not know how or where sensors will be mounted so assume worst case -- under the vehicle not enclosed exposed to water mud splash etc. Yes I am smart enough to not mount instruments in these conditions but I may not be the only one doing this so allow for a boob factor.

Initial vehicle to measure is a Datsum pickup with 124 lead acid battery, driving a series DC motor via a 4 speed transmission. Will be looking at vehicle this Sat and get dimensional details etc.

FUTURE VEHICLES
Battery voltage up to 325 (allow to 400 for charging)

MEASURED & RECORDED PARAMATERS
Relative wind velocity (have instrument)

Need insight and recommended mfr for the below
Motor RPM 0 to 5,000 -- use encoder??
Vehicle speed (driveline RPM maybe) or a bicycle wheel off back end with tach gen or encoder??
Motor amps -- using Hall effect "shunt" 0 to 500 amp
Battery amps (both charge and discharge) 0 to 500

DC line voltage both charge and discharge 0 to 400. This is the one that I am scratching my head on. Need suggestion on how to sense and have an output at a low voltage ie 0 to 10 VDC.

We will do testing on varying slopes possibly up to 21%. This will have to be hand recorded.
Transmission gear selection will also be hand recorded (should be able to get this if we have record of vehicle speed and motor speed but will worry about that later)

Data will be used to calculate
Torque vs RPM at varying grade
Kw per mile, Kw vs speed at varying speeds
Kw vs speed vs slope of road
Kw vs speed and wind at various speeds.

Thank you guys for the help. Will report results and share data if you want.

Last and most important to ensure I am PC and I get all the various cultures covered

Seasonal and other factor appropriate Felicitiations.
Aw nuts to all that
Merry Christmass and a Happy New Year.

Dan Bentler

400 VDC Transducer

"DC line voltage both charge and discharge 0 to 400. This is the one that I am scratching my head on. Need suggestion on how to sense and have an output at a low voltage ie 0 to 10 VDC."

Check out Ohio Semitronics- They have a 0-400VDC transducer that outputs 0-10VDC or 4-20MA.

DC voltage is easy, all you need is a voltage divider corcuit into a signal isolator.
Roy

>Vehicle speed (driveline RPM maybe) or a bicycle wheel off back end with tach gen or encoder??

If the vehicle is all electric, you might have a vehicle speed sensor (VSS) 'left over' from the original design.

All vehicle speed sensors I'm aware of generate pulses from rotor wheels (an exception is the reed switch pulled closed by a rotating magnet).
They can be located in the transaxle, or commonly at the output shaft of the transmission.

Find the location of the VSS sensor for that vehicle and see if one isn't already there. If you need analog for recording purposes there are I/O signal conditioners that will convert pulse to 0-5V or whatever.

>motor amps using Hall effect "shunt" 0 to 500 amp

What's wrong with precision copper shunts? The specs here:
http://www.crmagnetics.com/newprod/ProductView.asp?ProdName=CR5210
for Hall effect DC shunts are not overwhelming
- 1% accuracy ?
- 1/4 sec response?
I'm not sure what you're looking for but the shunts in a lab I worked in were far better than 1%.

Dan
Dan

Dan

Nothing wrong with the regular brass precision shunts.
Love em -- Have a few

BUT I am not the driver and plan was to have instrument on seat beside him - I did not want anything with battery potential next to the driver - that has changed

Thanks for the help guys

Dan

Yeah, I was thinking the shunt would only drop a low voltage, but the common mode to ground is battery voltage.

So, you'll need isolation regardless, then, huh.

Roy Matson said:

DC voltage is easy, all you need is a voltage divider corcuit into a signal isolator.
Roy

Click to expand...

Roy
Was thinking all in one package
However could as you say build divider then run into the isolator. This setup would be used on different vehicles so must be somewhat hardy to survive the repeated handling.

Suggestions for isolator you have used and know is good unit please ??

Dan

What power is available to power the instrumentation?
Separate carry-along or installed battery?
Tap off the motor power batteries? 12V? 24V?

danw said:

What power is available to power the instrumentation?
Separate carry-along or installed battery?
Tap off the motor power batteries? 12V? 24V?

Click to expand...

Sorry knew there was something I was forgetting.

Vehicle will use original 12V wiring for lites heater fan etc.
So assume 12VDC control power

Dan

Out of curiosity, what's the charging current at 400Vdc?

Dan

Have not got that far. Basically the answer is whatever the supply can handle and how deeply the battery is discharged.
I would guess we would charge at the 4 hour rate (maybe less) so on a 200 AH battery that would be about 50 amp at the start of the charge which then tapers as it charges up.

The exercise at this stage is to get operation data on an existing vehicle to enable us to make predictions / extrapolations to other vehicles. Then we would measure the "extrapolated vehicle" to see how accurate our extrapolatins were.

We intend to do fleet work on trucks 4 to 15,000 GVW starting with the small trucks.

Thanks for the help

Dan
Dan

Weidmuller make a good range, Moore Industries if you want Cadilac
http://signalconditioning.weidmuller.com/signal-isolators.html
The weidmuller will work on 12 VDC. The ones I am most familiar with put out 4-20mA which you can convert to 1-5V with 250 Ohms. They may have one with straight voltage output.
You may be able to pick up speed from the vehicle speed sensor or anti-iock braking system.
Hope this helps
Roy

Dan, you've got continuous 400Vdc common mode to isolate from. I'd recommend that you clarify exactly what any vendor's published specs mean.

Phoenix Contact's isolation modules show a published spec of 1200V for one minute, but are only rated to 250Vdc continuous (not published).

It isn't clear, to me, what isolation the Weidmullers above are rated for.

One statement.
Complete isolation to 1.5kV (AC and DC)
is reassuring.

But further on, the spec sheet says :
Isolation voltage : 2 kV between ports

When I highlighted the line to copy it, it came out:

Isolation voltage {b> for 60 sec.} : 2 kV between ports

OK, so 2Kv port to port. What's a port?
- Is that + or - to ground on any given channel?
- input to output?
- input channel to input channel? (Some models are multiple channel isolators.

Maybe 1500V covers everything, or maybe it doesn't.

Dan

Dan

Many thank yous for showing me I am not alone in being a little uncertain over these specs.

Dan

Dan,
As DanW pointed out you need to be careful with isolation. If the battery is connected to chassis at any point the transducer should also be referencet to that point, that way the input will be < 10VDC.
Instead of a simple voltage divider you may want to consider something like a zenner/s to give you better resolution.
e.g. NTE5105A (200V) & NTE5096A (100V) in series with 10:1 Voltage divider would give you a transducer output equivalent to 300-400 VDC.
If you know for certain that the battery is referenced to chssis you could also just drop the voltage and send the signal to the cab without isolator protected by a series resistor to limit current and perhaps a zenner to clamp voltage at a safe level.
Hope this helps
Regards
Roy