Isolation Monitor - Suggestions?

[EV_Builder]

and if 600volts dc is enough.

[P.S.Mangelsdorf]

I think you can buy it here in USA. Note the differences. The "-1" version has 2 digital outputs with which you can switch your lights directly.

https://store.neweagle.net/shop/our-mar ... evice-imd/

Thank you! I hadn't seen that supplier.

[RetroZero]

In the EU you can buy it for €290 if the version without digital outputs and with 250 kBaud is sufficient.
I was also wondering if one of the two voltage inputs can be used to monitor the DC charging port
https://www.conrad.de/de/p/bender-iso16 ... 6+Haushalt

Thanks for the link. I have had a reply from the sales department and am waiting on a quote for 20 units (mininmum requirements)
It is for the Bender IR155-3204 B91068139CV4 unit.

[Zieg]

Hm, I'll probably want one if: 1. The price is good, and 2. The SCCA follows through on requiring them for EVs in SOLO events...

[RetroZero]

I've been doing some 'research' into the subject, and find this component nearly obligatory from a safety point of view. EV's for mucking about off road is one thing, using them as daily commuting is another.
Firstly - safe charging requires monitoring for leaks to chassis, and no one is there at 2am when the overnight charging is done. Second is in case of accidents. Legislations are tightening up all over, so better find a viable solution before someone gets injured (or worse). Putting an isolation monitor before hv contactors solves the problem I think. Provides proof of safer charging and when connected directly to a pyrofuse for example, in case of an accident where a leak to chassis ground is detected (and there is no safe way of disconnecting the HV relays....), the isometer can trigger the pyrofuse.

[jrbe]

Thanks for the link. I have had a reply from the sales department and am waiting on a quote for 20 units (mininmum requirements)
It is for the Bender IR155-3204 B91068139CV4 unit.

Documents is behind a login. Curious if they are well documented - to make this almost plug and play for swaps.

[nickyivyca]

IR155-3204 datasheet is here just from their website: https://www.benderinc.com/fileadmin/con ... D_XXEN.pdf

I used this same model when doing Formula SAE in college - Bender would donate one per team per year for cost of shipping. At a minimum, you hook it to your HV bus (battery side) and chassis referenced potential, then it has a status output signal that we set up (as competition required) so it could open the main battery contactors if isolation failure was detected. This was enough for the competition's specs, we never took advantage of the PWM output for diagnostics.

I am interested in adding constant isolation monitoring myself to my project, for now I have just been borrowing an insulation tester from work every once in a while, which is better than nothing but still not great. I don't think I would make it open the contactors/fuse the moment it trips though - sounds like a recipe for getting stuck in the middle of the road in an unsafe place before you are able to pull off in a safe place. I would just do a light on the dash, or maybe also prevent the contactors from closing in the first place but just not open them automatically once they're closed. I do have a crash sensor though, that the contactor coil power runs through such that if I do get in a crash the battery contactors still automatically open.

[jrbe]

IR155-3204 datasheet is here just from their website: https://www.benderinc.com/fileadmin/con ... D_XXEN.pdf

Thanks for the link.

Snipped...
I don't think I would make it open the contactors/fuse the moment it trips though - sounds like a recipe for getting stuck in the middle of the road in an unsafe place before you are able to pull off in a safe place. I would just do a light on the dash, or maybe also prevent the contactors from closing in the first place but just not open them automatically once they're closed. I do have a crash sensor though, that the contactor coil power runs through such that if I do get in a crash the battery contactors still automatically open.

Some crash sensors (inertia switches) are overly sensitive and could be triggered from hitting a big pothole. Seems the newer versions are better though.

Agreed on delaying opening the contactors until it's safe to stop is likely ideal. Using CAN communications and some code could make adding one like this (or an oe solution) a fairly simple add on that would up safety a lot. The manual version seems to be more of a pita to integrate well, might not be worth the cost savings.

[P.S.Mangelsdorf]

Ok so I've got a potentially dumb question:

When driving, what's the actual danger from an isolation fault?

I fully understand that when charging, there is a danger because the grounds are connected to earth ground, leading to an energy potential between the car and the earth. I fully understand that when working on the car, an isolation fault is a danger because it makes the entire car one battery terminal, and touching the other would be deadly.

But under normal use, an isolation fault still wouldn't create a potential energy difference to earth ground. The potential energy is still just between battery terminals, but now the whole car is one terminal. I get that that is sketchy, but I'm somehow missing the immediate danger.

(I know, I know, this is probably something I should know already, but it's an area where I know enough to know I don't know things)

[jrbe]

Ok so I've got a potentially dumb question:

When driving, what's the actual danger from an isolation fault?

This could have been the driver at speed.

It's hard to predict what happens if a short or 2 happen. What gets energized? If there are 2 points of failure / 2 shorts in an isolated system or 1 fault on a grounded system then you have a potential shock hazard if you touch those 2 points.

My real world example of this is that I once got electrocuted touching ductwork and a suspended furnace while I was 5 rungs up on a ladder. I had climbed up the ladder between the 2, put a hand on top of the furnace to steady myself, then put the other on top of the ductwork. As soon as my second arm touched I was getting electrocuted and was kind of trapped up there, arms on top of and across 120vac. I had to try many times to let my legs go to fall off the ladder. It was very unexpected and I got lucky.
I dug into why the ductwork was energized. There was a metal flex electrical cable (BX) resting on top of the ductwork that was reading 120vac to ground. This old style cable had no ground wire, it relied on the wound metal jacket as a "ground." That cable ran into a metal light fixture. The wire going back to the panel that would have supplied ground had pulled out of the box cable clamp, so no ground connection. In that metal box there was an extra long ceiling light mounting screw that extended far into the metal box and poked into the 120v line wire. That energized the metal box and what should have been a ground, sending 120v out the cable jacket and where it ran across the top of the duct, it energized that too.

These things can happen in unexpected ways, failures, places, times, etc. Having a device to watch for shorts is definitely something I want in any swap I'm involved in. Getting shocked by high voltage dc you don't get to keep trying to let go and luck out on timing, the shock is constant if you don't get thrown.

[P.S.Mangelsdorf]

It's hard to predict what happens if a short or 2 happen. What gets energized? If there are 2 points of failure / 2 shorts in an isolated system or 1 fault on a grounded system then you have a potential shock hazard if you touch those 2 points.

Fair point.

Getting shocked by high voltage dc you don't get to keep trying to let go and luck out on timing, the shock is constant if you don't get thrown.

I certainly get the danger. I've been shocked by pack voltage, and fortunately it was to the back of my hand so the shock pulled my hand away. (this led to my "no working on the car at night or when tired" rule)

[Galileo241]

I recently visited the Battery show in Stuttgart, Germany and there, Isabellenhuette displayed a new current and voltage sensor with integrated insulation monitoring.
Unfortunately, I only saw it w/o taking a picture.

https://www.isabellenhuetteusa.com/prod ... -0-series/

Curious if anyone has already experienced this product?!

[arber333]

Fair point.



I certainly get the danger. I've been shocked by pack voltage, and fortunately it was to the back of my hand so the shock pulled my hand away. (this led to my "no working on the car at night or when tired" rule)

Well if we talk about casual glancing of the full 400v dc rail against gnd or negative it is survivable. It happened to me (as will to anyone playing evs). The trick is to wear at least some protection like thin gloves or fabric so as the resistance is high enough. No harm done but i had sore musles on that hand for some time.
Always wear skin protection when dealing with HV!!!

[RetroZero]

I,ve been contacted by Bender Germany asking for more details regarding our conversions. I am making up a little presentation explaining that if we find a component that can monitor isolation with CAN bus communication, we would be interested in bulk orders (at the right price). Basically, an option as apposed to the Isabellenhutte Shunt which does Current, Voltage and Temperature sensing, but NOT Isolation detection.

[Bigpie]

It would be good if one device could support split packs or was cheap enough to use multiple

[bigmotherwhale]

There is a separate isolation detection module in the imiev and outlander phev, i don't know whether they are CAN based or outputs an analogue signal.

EDIT, the detection module grounds the contactor so it should be relatively easy to use.

http://mmc-manuals.ru/manuals/i-miev/on ... 800ENG.HTM

[Ev8]

https://www.ti.com/lit/ug/tidudj6b/tidu ... TIDA-01513

[celeron55]

Isabellenhütte has now published information about IVT 3 Pro which comes with an isolatiom monitoring option: https://www.isabellenhuetteusa.com/dc-c ... vt-series/

Maybe it's worth asking whether it's available, and what's the minimum quantity and price?

[jrbe]

Isabellenhütte has now published informatiom about IVT 3 Pro which comes with an isolatiom monitoring option: https://www.isabellenhuetteusa.com/dc-c ... vt-series/

Maybe it's worth asking whether it's available, and what's the minimum quantity and price?

It's great finding these options but without a way to buy them for the average person it's still a challenge.
Maybe a group buy to help johu get setup with them & stock / drop ship these through the store? (If they're affordable, good, and easy to use..) Not sure his level of interest in this though.

[Ev8]

Was thinking if I get time I may build a simple isolation monitor based on measuring the voltage across a resistor that would be switched on between chassis ground and the battery hv terminals, in turn, using a micro controller with a isolated power supply and a bit of simple logic if the retuned voltage and fixed resistance value adds up to a resistance above 500ohms/volt then light a green led else light a red led, could even add some isolated can in there tooo….

Moving house in 4 week though som everything is getting packed

[jrbe]

Looks like Tom started one but never made a board, https://github.com/Tom-evnut/SimpISO/tree/master

[tom91]

Looks like Tom started one but never made a board, https://github.com/Tom-evnut/SimpISO/tree/master

Yes I drew it and did not get further, possibly good to revisit, also made a isolated 500V HV sense board so it might be good to look at respin this with an STM32 combining the Isolation measurement and HV measurement.

[jrbe]

Yes I drew it and did not get further, possibly good to revisit, also made a isolated 500V HV sense board so it might be good to look at respin this with an STM32 combining the Isolation measurement and HV measurement.

That would be great. I was looking if anyone started one of these. I was thinking along very similar lines when I looked through your schematic. Seems a few people would be willing to help review / design if needed, I would help review and design if using Kicad.

I don't mean to complicate it but my quick thoughts:
- this would make sense to be coupled with a BMS
-add mosfets to control high voltage +, -, and pre charge contactors as part of a safe start up / charge. (Maybe pwm as well for economizer mode?)
- add an accelerometer, pretty cheap - for crash safety
-add some of the other features like a "safe" output some have mentioned here. Maybe just a closed relay circuit to switch the light and let them do the rest externally.
- A current sensor or at least a connector should be easy to add as well.
- pack voltage as you mentioned.

[tom91]

That would be great. I was looking if anyone started one of these. I was thinking along very similar lines when I looked through your schematic. Seems a few people would be willing to help review / design if needed, I would help review and design if using Kicad.

I don't mean to complicate it but my quick thoughts:
- this would make sense to be coupled with a BMS
-add mosfets to control high voltage +, -, and pre charge contactors as part of a safe start up / charge. (Maybe pwm as well for economizer mode?)
- add an accelerometer, pretty cheap - for crash safety
-add some of the other features like a "safe" output some have mentioned here. Maybe just a closed relay circuit to switch the light and let them do the rest externally.
- A current sensor or at least a connector should be easy to add as well.
- pack voltage as you mentioned.

No. This would just be a measurement box to dump info on CAN and then something like a Zombie can do with it what it wants.

Do not make it a big complicated box of tricks.

[RetroZero]

Isabellenhütte has now published information about IVT 3 Pro which comes with an isolatiom monitoring option: https://www.isabellenhuetteusa.com/dc-c ... vt-series/

Maybe it's worth asking whether it's available, and what's the minimum quantity and price?

I'm going to see what Bender can do in regards to this new IVT 3 Pro option.