[MineCooky]

The battery of the smart ED3 very reliable and robust, however, it still can fail some times. In the following I would like to list everything that is available and how to repair or replace it:

• Desiccant cartridge
• Bricked from an accident
• Deep discharge (P18051C)
• Current sensor
• Battery cells & module replacement
• HV contactors

You will also find useful additional information on how to prevent these defects. Should something break, you can find suitable used parts in the Shop, there you will also find the offer to reset the P18051C error.


I'm very prowd of this article, we've been working on it since the start of this year:

smart ED3 17.6kWh battery repair (feat.P18051C / bricked BMS)

 

[Vincent Rapide]

Dropping the hv batt on a 2014:

The large front plastic bottom panel is attached by several ~10mm bolts, however there is one in the center area that has a specially-texted nut instead of a bolt which says to me: "beware". What is this and should it be left alone?? I'm willing to cut across this panel to avoid any issues and give me just enough room to drop the batt, should such an effort be required. Thanks in advance.
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[MineCooky]

We've simply unscrewed the skid plate. There is nothing to worry about.

 

[Vincent Rapide]

That weird nut is just a thin bolt attached to the bottom of the 12v battery tub. LOL

The mult-connector and the orange hv connectors are no problem but how to remove the connector located just below the hv?? The sleeve turns freely but no engagement.

edit- Needed to turn everything to release the balls, no problem! Now ready to drop the batt.
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[Vincent Rapide]

Replacing hv battery in a 2014:

I threw all the bolts into one container

edit: to answer my own question:

The hv battery is supported by 14 short bolts - M8x20mm
and 6 long bolts - M8x36mm

The long bolts go thru the side brackets as well as the battery flange.
The shorts bolts, 3 per side, are underneath the brackets; be sure to
put them in their correct positions.
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[Vincent Rapide]

My battery measures almost exactly 10v + 10v +10v = 30vdc. It suffered a slow death over a 6 month period. Should I bother measuring all the cells, or likely they will all be the same voltage. This battery cannot be saved, right?
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[MineCooky]

I would try recharging it to 60V per module and then check if every cell has got >1,5V. If they do, I would assume the cells are fine. If one is remaining at about 0,0V, I would assume it's dead.
Right now, with 0,3V per cell, it's to close to 0V to tell if they will survive the recharging attempt.

For recharging I would use a current of 0,5A or less. Let it take its time, rushing it, could damage the cells.

 

[Vincent Rapide]

Yes, they all seem to have the same voltage; no empty cells. I'm encouraged.
But now to open up the battery that I paid for, I hope it has more voltage.
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[illanvoyager]

All usual safety precautions and “proceed at your own risk disclaimer” aside, (and while monitoring temperatures and individual cell voltages, once the bus bars and current sensor are disconnected)—-module level charging can be done on a budget, without spending hundreds on dc charger/s.

12v automotive battery charger, modified pc power supply putting out 12v, or 30v adjustable dc lab power supply ——->

feeding 120v dc-dc adjustable boost converter "900w step-up boost converter” (eBay amazon or Ali express $20-35usd)


And for balancing cell voltages, (if necessary) , imax b6 hobby charger is one option (for charge/discharge single cell manual balancing or upto 6s balancing), other sizes of “active balance boards” are a possibility, OR 32s “ant” Bluetooth bms from China is another option.


Balance wire leads can be pushed in to the copper battery cell top terminals with a small screwdriver without removing the CSE boards or etc.

 

[Vincent Rapide]

or 30v adjustable dc lab power supply

This is the only one I would suggest using for a Smart battery that the car can no longer charge - dash will show various complaints such as 'mechanical' or logo of red motor etc.
Do NOT begin your salvage operation with any of the others listed since they do not offer dc regulated current below 0.5a, initially at 0.3a. Recovery is a slow process!

There is a supplier in New Jersey that sells a 60v version that will be useful as the recovery process reaches level2. I just ordered one.
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[illanvoyager]

I thought it would be clear I was referring to module level charging (qty3 x 31cell /31s modules in the Smart Fortwo hv battery). With the bus bars disconnected. There is no possible way anyone could or should do any module level charging with the hv battery hooked to the car.

The ~340v+ dc adjustable charger that could be used to charge all 3 modules together is fairly expensive especially if it’s a one time use scenario. And it may be necessary to isolate the modules anyway. So this is just one possibility to build an adjustable 113v+ capable dc charger/power supply that could be used to charge a smart for two 31s module. There might be other/better options out there.

But for about 30$for the dc-dc boost converter and ~$50+ for a 1-30v or 1-60v lab power supply, it’s not a bad option. Some people with more electrical knowledge probably already have a suitable adjustable dc power supply, or could determine if they have something suitable to build one with laying around already.

All common sense safety precautions should be followed any time you’re working around hv dc current. and I suggest YouTube to familiarize with the battery internals before proceeding.

The lab power supply, or other dc ~12v+ input is feeding the boost converter.
The dc-dc boost converter I mentioned is adjustable, (you can see in photo, for example .05a ) and the options for a adjustable dc power supply to feed the dc-dc boost converter that I listed do/can work. Basic electrical knowledge and familiarity with a multimeter is necessary as well as common sense to determine if a low voltage dc power supply is appropriate to feed the dc-dc boost converter OR how to adjust/set it up.

 

[Vincent Rapide]

Confused about what you are doing. Does your car no longer charge the hv battery since the hv battery cannibalized itself due to a dying 12v battery? Or are you faced with a dead dc-dc unit?

Maybe better to separate into individual failures that you can solve by doing such-n-such using xx equipment.

I was hoping you might launch into open-source inverter board use.
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[MineCooky]

Small update from my side:
The reset we offer also works for BMS, which have been bricked by an car accident.

 

[Vincent Rapide]

With the bus bars disconnected. [illanvoyager]

Why would you need to disconnect the bus bars?? You simply connect to the module you want to charge. If the cell voltages within that module are reasonably close to one another you can apply a current controlled matching voltage (+ to +) starting at zero current, then very slowly increasing the voltage so that current starts to flow. With luck the module will begin to slowly charge over time. This will be a slow process over hours/days.

You need a lab grade power supply that you will operate in current controlled mode = or > the module voltage. You do not use voltage controlled mode for this operation; read and understand the documentation.

Ebay has 60v versions available that ship from California. If you charge each module up to 60v then you could use a second matching 60v power supply in series to raise the charge level to that which the car can maintain on its own. If anyone knows what this voltage is for the Smart EV please advise. My guess would be ~90v.

For recharging I would use a current of 0,5A or less. Let it take its time, rushing it, could damage the cells. [MineCooky]

I would emphasize the "or less"!!
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[MineCooky]

You remove the bus bar to not damage the current sensor. I don't exactly know why, but it get's damaged, if it isn't completely removed.


Yes, definitely less. I've now stepped down to 0.25 A.


The voltage of the whole battery is between 310 V and 390 V. So each module needs to be at 105 V or more.

 

[Vincent Rapide]

And the current sensor is in series with??

Why is it not possible to avoid sending (your test currents) thru this device?

Is it attached to one of the bus bars? I've seen photo of the sensor itself but where is it inside the battery box? I looked around for it but could not find.
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[MineCooky]

The current Sensor is in series with the 3 modules, it's covered by the orange covering.

• current sensor

Source: EQpassion.com

 

[Vincent Rapide]

Once you open the box lid you connect directly to the conductors you need to connect to, should be no need to go thru this Current Sensor. But now that you've shown me where it is I'll make damned sure I don't send any charging current thru it!! Maybe just stick to charging each module separately. Thanks for the photo.
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