BCB Traction Battery Fault

Hi All,
Having a few issues, most things are straight forward to do and sort out.

I’ve an intermittent fault on the 58v system. It had a diagnostic done a while ago before I got it, but can’t seem to get the details from the dealer that did it.
I had a battery health test done at my local dealer who were really good guys. A ‘CLIP’ result showed 5 fault codes. I think they are all related to the charger. Anyone heard of a BCB?!
I also need to get a template for the forward belly pan as mine went ‘missing’ at the last Renault dealer.

BCB is a charger fault or a Traction Battery fault. It is a generic code for Battery Impossible to Charge!

How old is your Twizy? The early ones were recalled to have an extra Earth strap fitted to the charge and Chassis

The under tray provides protection to the charger and all the connections including the earthing strap. Which is why I mentioned it. The Chargers also change in the way they ‘breath’ with the Mk1 charger having a breather pipe.

Luckily the under tray is flat and just shaped with (6 bolts?) to hold it up. So should be easy to fabricate one from a white goods panel. :slight_smile:

It’s a 1st generation charger from 2013. The codes from the clip are:
Battery Tray Current
No BMS Multiplex Signal
Internal Fault
The car has had a new 12v, and charges fine. The 58v warning light, BAT and STOP lights comes on about 15s after plugging it in but does not inhibit charging. It completes charge and then charges the 12v upto 14v as normal.
The warning lights also comes on about 15s after starting the car, and then intermittently whilst driving (normally at slow speed).
Range is around 30-35 odd miles on a full charge (it’s a bit hilly where I am), and charges to 100%
SoH from Renault says 92% but I think this was read wrong from the CLIP under code PR002 (Traction Battery Charge). I am trying to get clarification on this as the cell voltage was 4.1v, and 100% cell voltage is 4.15v, so 92% sounds like SoC rather than capacity.
I’m under the impression and inclined to think it might not be something as straight forward as a charger as it seems to be working fine, but still trying to get to the bottom of the diagnostic it had done from the previous owner a number of months ago!
They say it needs both the BCB and Charger totalling over £2300!!
I’m not convinced.

Sounds like the charger. When you charge can you hear the cooling fans start up?
The error lights after charging starts are sometimes caused by the charger overheating due to the fan not running. I have experienced that.

The warning lights during driving are possibly caused by the 12V not being continuously topped up. Same charger issue. @peter-ss has experienced this issue.

When charging the Twizy it will always reach 100% - That doesn’t mean the SoH is 100% only that the battery is no longer taking any charge as it is full. ie. a SoH battery of 92% will still charge to 100%. only 100% is now only 92% of what it was when new.

BCB error is related to the BMS error. The Battery Management circuit board has an intermittent (dry joint) problem. If you lease the battery then it should be replaced as part of that. But not the charger.

Did you check the earth cable between the charger and the chassis?

Relays clicking away, charger comes on and then 5 seconds later the fans come on. About 10 seconds after that the ‘ping’ and [!] on the dash comes up, however the car charges up perfectly happily to 100%.

So the local dealer is escalating my request to Renault to find out what they actually need to do to get a capacity check. Apparently the Zoe test shows up battery capacity in Kw, where as the Twizy doesnt.
I know the battery charges to 100% and then rolls back a couple of %.
API states that it settles at about 99.2% so that is good enough for me, and indicates that the SoH is 99%. After 14,000 miles, that seems pretty spectacular (unless it has had a battery replacement with previous owner).
I thought the 12v was only charged when plugged in to the mains on the 1st generation. I thought the 2nd generation was different and charged the 12v whilst driving.

Task for this evening is to get it back up on the ramps and have another look under it.

Main question, is there any risk to the car/battery if I continue to drive it with this intermittent fault pinging up?

So I had it up on the ramp and took the earth strap off. A good connection all over, but gave it a clean up anyway. Absolutely no difference.
I’ve been having a think about the fault, and actually the more I think about it, the more I think it is the battery itself. All of the faults are directly connected to the traction battery in location and specifics are they not?
What I want to try and avoid is buying a new charger, and then discovering there is still a fault. However, it would appear that 1st generation charger replacement is more like ‘when rather than if’, so is it worth getting one anyway. Not cheap though at best part of £1000!

I asked for a discount and got the charger for £600. My old charger works but is a bit voltage sensitive if you want to try it before replacement or buy mine cheap to limp it along?

Just an update on this HV fault.
I sourced a second hand charger. First generation, so price was right.
Funnily enough, it sorted the issue of the warning lights and beeps. This is brilliant as now the car drives without warnings etc.
Of course, this is a twizy so fix one problem, along comes another.
The replacement charger, even though it’s only had around 150 cycles through it, and has only ever been out in the dry when not garages over the years has an issue with the fans. They don’t turn off when the battery is full!
So without buying another charger, I’m going to have to come up with some timer system to shut off the 230v power so the fans don’t run all day long when it’s plugged in.

They do turn off when it has finished the battery balancing. It can take over 4 hours. It gets shorter the more often it is ran. I thing the mk1 charger makes a better job. I lost range switching to the mk2 where the fans cut out shortly after the chare completes.

It does draw 20w during this period but it is worth it.

That’s really interesting. I didn’t know that.
I’ve ended up turning the power off after about an hour or so of the fans running once charge completed.
I’ve got an issue with my PowerBox after the firmware update, so haven’t been able to check individual traction battery cells.
I might just leave it plugged in for the day and see what happens then.

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If you buy a meross smart plug you (or others) you can monitor the wattage draw real time - so sit inside and see what the Twizy is doing charge wise.
Also with any smart plug - scheduled on and off times etc- so battery is warm in the winter when needed!

Hello OZ
I’m Having a problem on start up, when i turn the key the small red light to the RHS flashes Frantically everything lights up GO and N lights light up but 3 seconds later the STOP light lights and beeps and the twizy wont go.
Ihave changed the 12v battery hoping it was that but it hasnt made any difference, would this be a charger fault its 2012 and probably has a GEN1 charger in it.

let me know your thoughts

thanks Brian

Hi Brian, this will happen if you do not take the Handbrake off first. But sounds more like another fault.
It’s not the Charger if the Twizy will Charge. It doesn’t sound like the 12V battery either but have you checked the voltage when the ignition is on?

the Charger is used to Charge!!! The Sevcon Controller is used to Drive.

tell us about your usage of the Twizy for the past few weeks , is it kept undercover or outside?

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Thanks Everyone
Your correct OZ the charger is still charging the battery to 92% although its not turning off the fan when it turns off the dash when finished.
i haven’t used it much in the last few weeks as the fault has been intermittent and i didn’t want to be stranded somewhere.
A few week ago this problem came up i would try to start it and nothing, then i would leave it an hour and it would go but this week it just won’t go at all. As i said 10000 miles 2012 great fun so i would like to try and repair it if possible


Also forgot to mention since this fault i haven’t had the same regen whilst braking its seems to come in very hard where before you wouldn’t have felt it
Haven’t checked the voltage on the new 12v battery but will do that this evening

I’m wondering if you have something running down the 12V like the hazard light switch, let us know

Regen only cuts in when the traction battery has headroom. I live at the top of a hill and don’t benefit from Regen when I leave. There should be no change in the Regen unless you have reprogrammed the Twizy with say a Powerbox.

The MK1 charger does not keep the 12V battery topped up when parked up. It also doesn’t turn the fans off until it has completed a balancing mode. This can take anywhere between 20 minutes and 4 hours. The more often you cut it short the longer it takes next time.


My BCB issue was resolved when i changed the charger.
I used to get intermittent lights whilst charging and whilst driving.

Hey everyone
So checked the 12v battery it’s reading 13v as it’s brand new checked the hazard switch all seems fine …I can hear a clunk from the rear when I switch the ignition on the beeping starts and the clunk as if the motor has energised and then stopped