# Smart Fortwo Electric BMS



## brian_ (Feb 7, 2017)

What generation of Smart ForTwo ED is this?


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## remy_martian (Feb 4, 2019)

How does that fix the drained "cells to zero volts"?

Unless you have that fix, you're giving CPR to a brain dead horse.


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## Cornwallav8r (Dec 28, 2021)

Let's back up and explain a bit better. This is for a 2014 and similar Electric with an N82/2 BMS. I think it's 2008-2016? You'll have to clarify that, it's applicable to 2014 and all similar versions. Somebody please chime in here. On the battery repair, yes it's a little more involved. You'll drop the HV battery, which is actually quite easy, using 4 jack stands to support the car, a floor jack (2 is easier) , and a dolly to hold the battery on and move it around, once it's down. Remove a bunch of nuts, drill out a few soft aluminum rivets, some additional screws and a coolant fitting, and then separate the cover carefully, as there is sealant between the flanges. I used a hammer and a sturdy putty knife to slice the sealant, it was easier than it looks. Pop the cover, and disconnect the current sensor immediately (just the data connector). BE CAREFUL OF HIGH VOLTAGE - don't do this if you aren't knowledgeable of high DC voltage- use rubber gloves, etc. Now slowly recharge the cells, preferably using a constant current/constant voltage benchtop lab supply or similar, so you have total control over the max voltage, and current, starting with no more than 100mA, till they're above 2.0v or better. Then increase to 200mA, up to say, 3v, and much higher amps are permissible near the working voltage. The cells are very robust, and likely they will all come back up to normal voltage. Mine did, so did those of most others I spoke with. On the rare occasion one or two cells don't, you've either a pile of spare parts, or you'll want to source some spare cells. Note that unlike Tesla, or Prius, and similar batteries, these cells are a bit difficult to remove, and they're ultrasonically welded with flexible copper/aluminum ribbons, so it's a bit tricky. I understand some are having success with it, I have no experience yet, mine recharged just fine. There's a guy on Youtube doing solar storage stuff, I know he took some apart successfully, so I'd start there. Remember, the current sensor is very susceptible to failure, because the DC-DC converter loses its cotton picking mind and spits our large overvoltages, when the 12v drops excessively. This is the cause of the failures in the first place. It's a Mercedes Benz "feature" (ugh). So there's a chance the sensor may be toast, along with possible parts inside the BMS itself and the aforementioned cells perhaps. Thus far we've been able to fix most BMS issues, and a friend in Germany is almost done cloning these current sensors, using similar (but with different firmware inside) Bosch sensor. So soon nearly all will be repairable ourselves, and the rest, with spare parts from wrecked Smarts, will also be repairable. I know of one owner with a wrecked Smart, she's got spare good cells right now for sale. Hit me up if you need more information. Or you cam start the well deserved class action lawsuit against MB.


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## brian_ (Feb 7, 2017)

Cornwallav8r said:


> Let's back up and explain a bit better. This is for a 2014 and similar Electric with an N82/2 BMS. I think it's 2008-2016? You'll have to clarify that, it's applicable to 2014 and all similar versions. Somebody please chime in here.


That's the Smart ForTwo ED3, which is the electric variant of the W452 generation of the ForTwo, for model years 2012 through 2016, with the Deutsche ACCUmotive/Li-Tec battery. Before that there were

ED1 (W450, up to 2007) with Zebra sodium nickel-chloride battery
ED2 (W451, 2008-2011) with Tesla lithium-ion battery using Panasonic NCR18650 cells
and after that there is 

ED4/EQ (W453, 2017+) with Deutsche Accumotive battery apparently using LG Chem cells
Yes, that's four generations with four unrelated batteries, which is why I asked. 

This is the report for the US Department of Energy Vehicle Technology Office's Advanced Vehicle Testing Activity for this generation (ED3):
BEV Battery Testing Results for the 2014 Smart Electric Drive



Cornwallav8r said:


> The cells are very robust, and likely they will all come back up to normal voltage. Mine did, so did those of most others I spoke with. On the rare occasion one or two cells don't, you've either a pile of spare parts, or you'll want to source some spare cells. Note that unlike Tesla, or Prius, and similar batteries, these cells are a bit difficult to remove, and they're ultrasonically welded with flexible copper/aluminum ribbons, so it's a bit tricky.


Tesla cells are very difficult to remove from the modules - it can't be done without destroying the modules. Most cells (including Tesla) are welded together into modules now. Repair is normally limited to replacement of entire modules; there are three 31S1P modules in this pack.


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## Cornwallav8r (Dec 28, 2021)

Thanks for the detail. So it's an ED3. Most will been to replace modules only, though I know single cells can be replaced, with some skill, I've seen it done.
I do wonder whether the other parts are identical, those being the BMS and the current sensor. They seem to be the parts that fail, and if we can fix other years, that'd be great.


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## Seb34567 (10 mo ago)

Hi,
I'm from QC, Canada and I just found a 2015 smart ED3 with a broken battery (removed, open) and another battery salvaged from another smart. Guy will accept 5300$CAD for the kit. I'd like to use the drivetrain for another project with the included sealed battery, and salvage what i can or repare the 3 defective module, with new generic BMS.

Since you seems to know a lot on these vehicules, could you tell me if what I want to do should be possible or not ?

Thank you very much!

Seb


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## bill.kichman (Dec 28, 2021)

Seb, can you message me direct? Lots to talk about. bill dot kichman at gmail dot com


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## remy_martian (Feb 4, 2019)

"Lots to talk about". This is not a one on one help line. We post stuff in the open here so someone in the future has a knowledgebase to look at. Can't do that with PM.

Seb - With the new generic bms you'll be halfway there. You've said nothing about the inverter to run the traction motor...afaik, nobody has cracked the SMART's inverter which means you'll need to run a different one. Doable.


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## bill.kichman (Dec 28, 2021)

For starters:
1. It is nearly impossible to break into the firmware and ECUs and make them interface in a DIY project, unless you happen to be a Mercedes tech or other extremely knowledgeable tech. The motor itself isn't really large enough in hp to merit reuse, unless you have a really small project car. 75hp IIRC.
2. That's way too much to pay for a bricked car, unless one of the batteries is in great shape, in which case it wouldn't be apart.
3. The BMS is likely bricked, I can help with that, I have 3 on my bench right now being fixed.
4. I have a whole drivetrain here I can sell a whole lot cheaper than that, but re-read #1 above.
5. There are likely other trashed parts, beyond a few cells in those batteries, likely the near impossible to replace current sensors are likely missing or burnt.
6. You can't just swap a BMS in there and expect it to run. The pc boards across each bank need to talk code to the system, or be entirely replaced with another BMS. A job itself.
7. The included "Sealed" battery will most definitely be another bricked battery. I bought one like this, and all but 10 of the 103 cells were toast, zero volts. So I am still in a bind with too few cells to repair my car. Will likely scrap my original bricked car. The other parts paid for the purchase, I'll get my money back, but I only paid US$1200 for the whole parts car.
8. Till you're done, you will have been able to re-use almost nothing from the Smart.
I can go on and on....


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## remy_martian (Feb 4, 2019)

1. It's been done. That's what most projects here do. The Smart is a donor car.
2. The purchase price is when seller's value and buyer's value is the same number
3. He specifically said he was using a third party bms
4. Yes, you're selling. This isn't the classifieds section of the site
5. You're selling again, using amateur-hour FUD tactics
6. Yeah, you actually can with a third party BMS. He's after the battery modules, so it's legit.

6/6 wrong. I hope your mom and dad don't see that I graded your post with an F.


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## bill.kichman (Dec 28, 2021)

remy_martian said:


> 1. It's been done
> 2. The purchase price is when seller's value and buyer's value is the same number
> 3. He specifically said he was using a third party bms
> 4. Yes, you're selling. This isn't the classifieds section of the site
> ...


I don't know where you get your information. What system do you have that will communicate with the PCM? The DC-DC converter? The throttle and other parts? They all need to communicate and it's proprietary and all interlocked. Maybe you've a lot more coding and firmware experience than average. I work with a German EE on this stuff, with contact with the original manufacturer's coders, and he wouldn't attempt it either. I'm not selling shit, just sharing what the car is worth, he's not coming to lower US to buy parts. I don;t know what cars cost up there, but I couldn't sell my good running cabrio for that much down here. $4k to $6k seems the norm around here for a working car. Good luck.


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## remy_martian (Feb 4, 2019)

The Smart is a donor car. He's using the battery and drive unit from it, maybe the pedal and other misc pieces. Period. Shit's scarce in Canada, and expensive...he's working with what he can get.

You have a bunch of reading to do on this site to catch up, my friend.


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## bill.kichman (Dec 28, 2021)

No kidding Sherlock, it's a donor car. He wants the battery and the drive unit. You can buy those parts for less than half that. The rest is worthless, though maybe usable to resell to Smart owners. Just wanted him to know that most of the car's electronics are unusable. I forgot how vile "car guys" were, I'm used to the aviation crowd, where people are more decent to one another.


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## remy_martian (Feb 4, 2019)

I'm used to new people not waltzing in all arrogant about "impossible" when that's what people here do in almost every thread. You came in shooting him out of the sky, then selling him your junk pile of stuff.

Again, Yankee-ass pricing goes out the window in Canada. They pay tax (GST), sales tax, and duty, plus a 25% premium on currency, on everything that comes in from the US, so stuff gets to be 50% higher, if not double, in a hurry. Even if he was to buy your junkpile.

His question wasn't about pricing. It was "can I do"...the answer is yes and afaik, he may need a different traction inverter in the target vehicle. You said "impossible", "gas pedal won't work", blah blah blah. Go read a bunch of stuff here and catch up on how it's done, then say what's impossible without the "Mercedes tech" nonsense. He's fairly new and you could easily derail his plans with nonsense.


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## brian_ (Feb 7, 2017)

bill.kichman said:


> 1. It is nearly impossible to break into the firmware and ECUs and make them interface in a DIY project, unless you happen to be a Mercedes tech or other extremely knowledgeable tech.


There are, in general, three approaches to this problem which is common to use of production EV parts:

Use the entire system (motor, inverter-controller, BMS, charger...) with minimal truncation of unwanted parts, so they they all continue to work together as if they were still in the original car. Of course this is only viable if you have a complete set of working parts.
Front the parts used (typically just the motor and inverter-controller, although is some cases with the battery and BMS as well) with a processor which provides the interface to anything else being used. There are commercially available products to do this with some Tesla and Nissan (Leaf) donors, but a very determined hobbyist could potentially do this with any vehicle.
Replace the controller (or just a logic board of the controller) for the inverter with a replacement that is usable outside of the original vehicle environment. Again, this is only available for Tesla and Leaf.
The issues with any of these approaches limit the range of viable donors in most cases, and it does seem likely that any Smart is outside of that range for most people.


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## Seb34567 (10 mo ago)

So in the light of all your comments, more questions came...

1-Is there a way that I can check if the sealed pack is working or not without installing it in the car?

2-if the 2 packs are dead, is it too difficult to extract the cells, charge them individually and assemble them for a custom pack for a custom use (not in a smart)? I know about high voltage protection, just don't know about Wich type of specialty charger I need for individual cell.

3-if I understand correctly, the inverter driving the motor needs a OEM battery pack to work?

3-i know it's an expensive guess. Here such ev in working condition is more than 16k$cad as Remy explained correctly. So maybe I can buy a new battery pack this summer and make the smart run again for offroad use (on my outfitter, because to put it back on roads it's quite complicated and expensive here, burocrat nation)? If yes, I think this idea is still ok. Does the new packs fixed the trouble or they are the same shit?

I find it strange too that the seller did not fit it's used pack to make it work and sell this car as a good price. It only has 53k km and seems like new.

I can pick it up next Monday, I'll waiting for my flatbed lost ramp.

Thanks again for the comments and in advance for the next ones. I'll stay on this thread, instead of going in private, since your advices can help others later.

Seb


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## brian_ (Feb 7, 2017)

Seb34567 said:


> 3-if I understand correctly, the inverter driving the motor needs a OEM battery pack to work?


On the power side, the inverter (with controller) just needs suitable DC voltage. On the control side, it probably expects communication with the original BMS to function properly.


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## Bruno Sá (9 mo ago)

bill.kichman said:


> There's been a deluge of failed Smart Electrics in the recent past, mine being one of them. For no explained reason other than a weak 12v battery, the high voltage pack commits suicide, draining all its cells to zero volts, throwing an apparently irreversible P code, and quite possible destroying electronics, including the BMS and the current sensor inside the pack. Given that none of these parts are sold or readily available from Mercedes, we were in quite a predicament. But please note that we've learned to correct and repair the BMS for reinstallation. And will very soon have a replacement current sensor available as well. So if you know anybody (there are hundreds at this moment) scrapping a Smart for a bricked HV battery, please pass this along. I offer the reset service on Ebay at the moment. Cheers, hope this is helpful to someone.


Hello,
I have a 451 electric smart with the BMS blocked. Can you help me?
Thank you


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## Bruno Sá (9 mo ago)

bill.kichman said:


> There's been a deluge of failed Smart Electrics in the recent past, mine being one of them. For no explained reason other than a weak 12v battery, the high voltage pack commits suicide, draining all its cells to zero volts, throwing an apparently irreversible P code, and quite possible destroying electronics, including the BMS and the current sensor inside the pack. Given that none of these parts are sold or readily available from Mercedes, we were in quite a predicament. But please note that we've learned to correct and repair the BMS for reinstallation. And will very soon have a replacement current sensor available as well. So if you know anybody (there are hundreds at this moment) scrapping a Smart for a bricked HV battery, please pass this along. I offer the reset service on Ebay at the moment. Cheers, hope this is helpful to someone.


Hello,
I have a 451 electric smart with the BMS blocked. Can you help me?
Thank you


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## ElectricTinker (8 mo ago)

remy_martian said:


> I'm used to new people not waltzing in all arrogant about "impossible" when that's what people here do in almost every thread. You came in shooting him out of the sky, then selling him your junk pile of stuff.
> 
> Again, Yankee-ass pricing goes out the window in Canada. They pay tax (GST), sales tax, and duty, plus a 25% premium on currency, on everything that comes in from the US, so stuff gets to be 50% higher, if not double, in a hurry. Even if he was to buy your junkpile.
> 
> His question wasn't about pricing. It was "can I do"...the answer is yes and afaik, he may need a different traction inverter in the target vehicle. You said "impossible", "gas pedal won't work", blah blah blah. Go read a bunch of stuff here and catch up on how it's done, then say what's impossible without the "Mercedes tech" nonsense. He's fairly new and you could easily derail his plans with nonsense.


I've recently had interaction with Bill, found him through eBay. It was HORRIBLE. If you want someone to take advantage of you, stating one thing but doing completely the opposite and who only wants money rather then trying to help you then he is your guy. Didn't even know if I would ever get my property back. I actually had a whole post ready to go to warn others about my experience because he almost made me give up on my smart electric drive project which was a dream project of mine. Seeing this post I had to put in my 2 cents.


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## ElectrifiedMonteSS (Feb 27, 2011)

Hello all. 
As this is about the Smart Battery Pack BMS. I have been seeking assistance in determining which pack I have so I can get the pin out for the blue 35 position Ampseal header I have on the pack I managed to locate for my project. I know they are Tesla packs and contain 6 tesla modules in the pack. I did not get VIN information for the vehicle the pack was pulled from.. So I have nothing to reverse reference to work back to the information I need.

I to open the pack to get a pack voltage measurement as the pack connection plug allows no measurement to be taken. I was told there is something about something that shorts something so the connection is made live.. (Sorry still learning this EV stuff)! I opened the pack and measured the voltage of the pack (6 Tesla modules) which was 360V. So I know I didn't receive a dead pack. Each of the 2 groups of 3 modules measured 180V. I took w reading on a single module. but i didn't note the reading as I was so excited it wasn't DOA that I jumped right to measuring the pack.. LOL

I have searched the internet for every number I could locate for some scrap of info to identify the pack or modules to determine how to get the pin out info or if I could even use the pack as it was built without modification.

EV West has the main two prong connection plug housing and I waiting to hear back from them on the cost of the plug.
I located a plug housing for the blue 35 position Ampseal header. 

I am attaching photos of my pack in hopes that will help someone recognize what I have and hopefully shed some light on my question.


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## oscar.gonzalez (2 mo ago)

bill.kichman said:


> There's been a deluge of failed Smart Electrics in the recent past, mine being one of them. For no explained reason other than a weak 12v battery, the high voltage pack commits suicide, draining all its cells to zero volts, throwing an apparently irreversible P code, and quite possible destroying electronics, including the BMS and the current sensor inside the pack. Given that none of these parts are sold or readily available from Mercedes, we were in quite a predicament. But please note that we've learned to correct and repair the BMS for reinstallation. And will very soon have a replacement current sensor available as well. So if you know anybody (there are hundreds at this moment) scrapping a Smart for a bricked HV battery, please pass this along. I offer the reset service on Ebay at the moment. Cheers, hope this is helpful to someone.


 What is you phone number?


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## autobodysupplycda (17 d ago)

Smart Fortwo Electric drive battery has a federal 10 year warranty. Call me 208 277 7770 Scott


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## Superbirdbuilder (13 d ago)

Bruno Sá said:


> Hello,
> I have a 451 electric smart with the BMS blocked. Can you help me?
> Thank you


In the USA it has a 10 year warranty. Call me 208 208 277 7770 scott


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