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778 Posts
Discussion Starter · #1 · (Edited)
Completely removing the IMA battery pack and running on 12V.

1) You can theoretically completely remove the OEM IMA stuff in the back and run the car on 12V only.
2) You will get loads of errors and warnings from the car about the missing IMA. (If you don't care about them that's fine read on)
3) You may find certain driving modes and/or performance are restricted/inoperative. Sport/Eco/Cruise/Normal etc etc. (I have not tested what works/doesn't on the CR-Z.)
4) Your 12v starter and battery will get a serious workout and there will be no more start/stop etc (They need to be perfect.)


The IMA motor is also a highly efficient permanent magnet 3 phase generator, and will spin merrily away without loading the engine if simply left disconnected.
It can therefore be used as an excellent integrated alternator in a car without an IMA pack.
This avoids the need for tricky fabrication to add belts, pulley's, and extra weight with a heavy standard IC alternator bolted on the engine.

You add a cheap 3 phase to 1 phase bridge rectifier of about 400/600V rating. (Something like the below $10)

This converts the variable IMA motor AC voltage into variable DC which you feed into a Meanwell 12/15V type switching power supply.


I used an HRP 600-15 on the Insight G1, but there are hundreds of different possible PSU variations. (~$150)
The Meanwell PSU converts the high voltage DC into the standard 13.8V we need for our 12V battery charging.

The CR-Z IMA motor might be a bit lower voltage output so you may need a different psu or some additional smoothing capacitors.
Or you might find it turns off at tickover and you need 1500 rpm or so minimum engine speed.

This old video shows the basic setup on an Insight G1 with no IMA.
Sorry it was filmed on a terrible phone (Potato). But you get the idea.

You need a 70A 12V ignition switched relay or beefy (Schottky) diode as well so the 12V battery is disconnected from the psu
when the car is off to stop parasitic drain/reverse flow, but that's about it. (Nore the relay/diode is not shown in this video)

Note. In the Insight G1 we were able to remove the error codes and warnings so the setup could pass emissions testing as the IMA system is much simpler.
That is not easily doable asfaik in the CR-Z due to the complicated CAN messaging and large amounts of data passing back and forth between the ECM and IMA. Sorry.

Let me say I don't personally recommend this idea as the car will be emasculated, gutless, and have a xmas tree lights warning dash.
But for those with no money, a bad IMA, and no hope of selling or fixing the car, it can be a workable solution.

The legality of this modification will also depend on your own country and local regulations.

If you want to ask more feel free. (y)

1,709 Posts
Yet another detailed and highly informational post PeterPerkins! There's been talk around here over the years of Insight owners who've had problems running this way while things get sorted out/saving for replacement of IMA battery so it's awesome to see some detailed info with the actual procedure and necessary changes to accomplish this.

What are the details of the wiring of the relay to prevent the drain while off?

778 Posts
Discussion Starter · #3 ·
Route the PSU 12V+ output to the 12V battery + through the relay change over contacts.

The relay 12V coil is driven from an ignition switched 12V supply in the IMA harness...
The relay coil will need a reverse emf diode across it.

The car chassis is the gnd for the relay coil and the PSU negative - output.

Here is a very quick video with more info.

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