[Imkennedy85]

Hi guys i have been trying for the last 6 months to get this car up and running.i pulled the battery it had 30v. Charged it (didnt know i needed to remove current sensor) sent the bms to the guy in pa for removal of the codes permanently. Got it back had the pack up to 385v and this is where im at. I bought a factory scan tool to reset the codes, this is what i start with and then the 3 come up after i erase the 7.



Looks like I need a current sensor?

Any help is appreciated

Thanks
Ian kennedy

 

[Jmk2020]

No you didn't need a current sensor replacement. Check the readout. It was stored but not permanent. This is the reason you didn't see it on the 2. Readout.

But i can help you

Read out the cell voltages via Vediamo and compare it to your measuremens via voltmeter.
You will see there is on connection broken between the CSE PCB and the tap on one cell.

And the failure indicated tells me it should be in the first stack/battery pack.

Could you measure all cells to take charge and beyond 3,0V?
The system says it isn't the case for on cell of the 1st stack.

 

[Vincent Rapide]

You do not need to remove Current Sensor if you charge each of the 3 battery sections (120v) individually, and directly connected thus avoiding the CS completely.

Does the battery hold its voltage overnight? This is a good sign.
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[Jmk2020]

This is not true. It depend if you have still the BMS installed in parallel or not have opened the loop via BMS by removing a busbar. As soon the current loop is closed the broken BMS could cause the death of the current sensor by chance.

Most times to be honest the current sensor died already during discharge of the battery.

 

[Vincent Rapide]

I never removed a busbar while charging the 3 sections, one at a time of course. Did not disconnect the BMS either.

Anyway, is there a simple test for the Current Sensor to see if it is still good. Safest test might be using high resistance scale of your ohmmeter.

Also could you show us which busbar is it that you remove to isolate the CS.

---
Smart, which is an acronym for Swatch Mercedes Art.
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[Jmk2020]

Just imagine the busbars between the stacks/battery packs close the current loop to BMS.
So the negative is the eye ringlet on the current sensor. It is also the minus against current sensor local Vbat of the isolated measurement isle of the BMS.

You act like somebody which use his Television set and external charge the internal standby battery circuit. So the risk to work under bias and damage some circuits is much higher.
This is the reason to open the current loop and take risk out of the task.

 

[Jmk2020]

whould you solder or measure in TV set during operationen?
It could work but the risk is very high you destroy a electronic component if you work under bias.
the BMS close the current loop via ringleteye on minus of current sensor and plus at upper contactor.

The BMS often is broken an the powersupply, means the the current sensor supply could get during charging beyond the allowed supply voltage and die.

 

[Vincent Rapide]

How to safely remove or disconnect the Current Sensor? What does Daimler suggest?

Then you can charge or even try to rebuild the Battery Pack without damaging the CS.
And these 10 year old Battery Packs will need to be rebuilt SOON.
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[Jmk2020]

Ok, this is easy but as i also mentioned. Most times the current sensor already died during discharge. You will see it first after the battery packs are running again and there is enough hv power for a stable supply of the BMS.

So i propose to disconnect just the connector on Sensor. In parallel also disconnect the BMS for a test on the Bench. By this the current sensor is safe and the BMS could not become worse.

 

[Vincent Rapide]

Next time you are into a battery pack how about some PHOTOs.!?
Thanks in advance.
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[Jmk2020]

What photos you looking for?

 

[illanvoyager]

You will see there is on connection broken between the CSE PCB and the tap on one cell.

Any comments in more detail on the optimal re-connection method if this is found to be the case? I was thinking "conductive epoxy" might be best over attempting soldering(/etc)?
Mechanical fastener (small screw down in between the copper plates) should be fine I suppose as one possibility.

But it seems "conductive epoxy" should be well suited for this, I just don't have much experience with the product, personally. Not sure if there is a better option, or a specific "glue" product that would be best suited.

 

[Jmk2020]

You talk about the rectangle part which indeed could be soldered, screwed or glued. If glued you should sink about to fix it somehow.

I talk about the thin lines from the rectangles to the CSE main PCB is broken or interupted.
In this case a easy flexible wire could be soldered onto it but be sure you should never never short some of the solder pins of the CSE PCB. Otherwise the energy of 2 cells will meld down some further PCB tracks or kill some of the devices on it.

 

[Vincent Rapide]

Unlike the top photo where our good friend "D3 Luis" has had a test lead clipped to its bottom bolt, the way I have charged up any one of the 3 hv batt sectors is by direct connection from charger source (a CVCC power supply) to the very ends (+ and -) of those battery sectors themselves. And using lowest voltages as needed and always starting from 0.00 vdc and slowly increasing to the point where charging ensues and the same on the way down. Doing it this way should not affect the Current Sensor in any way at all since all voltages are way below what the CS would normally see.

Each batt sector is max 120vdc but all you need to put into it for testing is 60 - 80v max. But not road testing, LOL.
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[Jmk2020]

The rootcause for the currentsensor breakdown is NOT the current or voltage flow through the sensor but the supply voltage from BMS to the sensor which get disturbed by the low and oscillating hv volate cause the internal power supply get run crazy and sent too high voltage tomthe sensor and part of the BMS which store th known P18051C. They are close related but to store the failure also ignition KL15 need to be on. Without only the currentsensor could die without stored failure and you could see this failure in this case first time when the cells of the stacks recharged again.