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453 ED/EQ Battery Fault

Mod Details
PremiumNo Difficulty Mod ID1500 Creditevilution For453 Fortwo/Forfour Linkhttps://dev.evilution.co.uk/mod/453-edeq-battery-fault.htm Copy to Clipboard

There seems to be a software issue with the 453 ED/EQ which can intermittently bring up a battery fault.

The error can display in 1 of 2 ways.

Malfunction, Visit Workshop

…or

Charging Not possible, Visit Workshop

Either way, the car will not start or drive.

Smart Dealers

Smart dealers will come in 1 of 2 categories. They will either say they can’t find a fault or they’ll say they updated the software. Many people with this problem find that the car doesn’t start or drive but once it’s been recovered to a dealer, it’s ok.

The “Fix”

Many ED/EQ owners have found that waiting 10 minutes (with the car turned off) will allow it to start and drive. Ensure that everything is turned off. No hazard lights, no stereo, no interior light etc. Best thing to do is lock the car up and walk away for a while. When you come back, it’ll usually start fine. Others have stated that disconnecting the 12 volt battery for 10 minutes will also work. Leave that as a last resort.

It’s probably a good idea to have one of those lithium battery boosters.

What’s The Problem?

It’s an issue with the 12 volt battery, not the 400 volt drive battery.

The 12 volt battery (stored under the front service hatch/hood/bonnet) is used to power up all of the electrics. This includes motor relays, contactors, interlocks, controllers, safety systems and the charger. The 400 volt drive battery is used to charge the 12 volt battery. It doesn’t charge it all the time. It doesn’t even charge it continuously when the car is running.

It seems as though the 12 volt battery doesn’t have enough power to initiate the car’s systems. Well, it probably does, it’s just that the car’s electrics have been coded to crap out if the battery capacity goes below a set point. This point is set too high.

Trying and failing to start the car turns on the DC-DC convertor that takes the 400 volts from the HV battery and convertor it down to a more reasonable voltage to charge the 12v battery. Assuming that you have voltage in the 400 volt battery, leaving the ignition in position 1 for a few minutes should give the car enough time to add a reasonable amount of power to the 12 volt battery. Turn the car off, lock, unlock and try starting the car again.

Long Term Fix?

If you keep experiencing this fault. Fit a new 12 volt battery, ideally an AGM type. This should sort it.

Alternatively, carry a jump starter box. This will boost the voltage enough to initiate the car which will start the DC-DC in car 12v battery charging. This helps if you don’t want to sit around waiting for 10 minutes. I have these ones but there are several small lithium Ion booster boxes. You don’t need a super powerful jump starter because you aren’t starting the car, it just need enough power to power up the contactors.

Smart Dealer Software Update

Finally! Smart have rolled out a software update that apparently fixes the issue. This will either bodge the fix and lower the voltage expected by the car for the active systems, or it’ll do things properly and intermittently turn on the DC-DC step-down charger whilst the car is off. This will regularly ensure that the 12v battery is charged.

Any guesses if smart did the fix properly or just bodged it?


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