The early iMiEV charging problem

Comments Off on The early iMiEV charging problem

So, as previously mentioned, the early iMiEV can’t charge from modern J1772 or Type 2 chargers. This is because it was built before the protocol that they speak was finalised. Or, to put it another way, The car no-speaka-da-lingo.

The cable that comes with the early iMiEV looks like a J1772 compliant cable, but with an ordinary household plug on the end. And contrary to the standards, the cable is always live. At least when it’s plugged in. This has two unfortunate effects. One, these cables were explicitly designed not to be unplugged when live, to avoid arcing. That’s not going to happen with the early iMiEV. Obviously, best to let it charge all the way before unplugging it, otherwise you’re yanking a lead which is potentially drawing 2.5kW. Arcing may occur.

The other is the one that bugs me the most, the car can’t charge at Type 2, or ‘Fast’, chargers. Take a second. Look at this map and tick only ‘Fast’. See. None of them. Not a one usable with the iMiEV.

Now, in reality, with an early iMiEV you’re a bit buggered, because you’re not going to get a fast charge out of them, the early iMiEV’s charger will only handle 10A. That’s 2.5 kW in the UK. Fast chargers can deliver 30A – or about 7kW (late iMiEV’s can only manage 16A, apparently). But getting anything from them would be awfully handy, if you’re in a bind and no where near the nice DC chargers that are appearing all over the UK motorway network.

Thankfully there are a few solutions, you can spend $40 on a little box that you can hack into the car’s wiring which will allow it to at least talk to the charger and draw 10A from it. You can replace the charger (about £1000) with a charger which will not only talk to the charger but also adds 30A capability. Mmm. Wants. [Edit: It turns out that the company who I thought were offering this were, in fact, not. They just offer what appears to be the equivalent of the $40 module hacked in to the car, but it can still only charge at 10A. However, they never say this outright, they always couch it in terms of ‘You can charge at a 30A charger’. Hrm.]

Or you can do what we did.

See, the iMiEV is not alone in not talking to chargers, the Twizzy apparently doesn’t either. And someone came up this (Locally held copy of that file) which is a fantastically cludgy solution, in which you, the user, manually switch the sensing circuit from ‘connected’ to ‘available to charge’. All it requires is a few quid of parts – a diode, an 880Ω resistor, a 660Ω resistor, a switch, and a ridiculously expensive plug (£85!).

Which is what I spent my afternoon doing.

Hopefully there's a 680ohm and 880ohm resistor in this box somewhere...

This is the overly expensive plug. Yes, it’s quite nicely made, but it’s not £85 worth of plug:


After much routling through the bits box I came up with two 680Ω resistors.


A resistor that said ‘620 Ω’ but was actually about 660Ω and, err, predates colour codes:


And a resistor that’s marked as 680Ω +/- 5% which actually reads 900Ω.

Making up a type2 to commando socket cable

*Looks at it sternly*

You better stay 900Ω. Do I hear John weeping?

Anyhow, I’d also been to RS and got a keyswitch (of appalling quality and of a difficult size – the smallest one I could find in their catalogue was bigger than expected. I’m not sure why).


What I’ve learned from doing this today is that I need to buy some more heat shrink in different sizes, because the size I’ve got is not big enough for several of the jobs I wanted to use it for today. So instead I (as you can no doubt see) ended up using the sheath off the wire I’d used for the 16A cable. Also, it turns out that 1950s resistors are ‘big’ which is inconvenient when the space you want to put them in is ‘small’.


Irritatingly I’ve managed to get a keyswitch that captures the key in one position. This was not intentional, I’m hoping that it’s the ‘off’ position, rather than the ‘charge’ position. I *think* it is, but honestly, I’m a bit vague on the details of the protocol.


Anyway, here it is, my dark and evil piece of hackitude for the day:

Why yes, that is a dark and evil piece of electrical string. Nice, isn't it. Heeeere type 2 charger, nice charger...

Which is handy, because Chargemaster just rang and said they’d like to come and survey the house to install the new charger.


Kate is lord and mistress of all she surveys at