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Ima Battery Saver & Assist/Regen Booster

Ima Battery Saver & Assist/Regen Booster

Old 09-18-2013, 09:48 PM
Thread Starter
Join Date: Nov 2011
Posts: 40
Default Ima Battery Saver & Assist/Regen Booster

I've been working on this gizmo over on IC and some of you might be interested.


Basically it reduces or increases the car commanded assist or regen by upto 100% using two adjustable pots.

Simple four connections in the footwell and can be mounted on the dash.

It can prevent the car stressing (overusing a weak battery with high assist or regen) or it can be used with a good battery to boost assist or regen levels.
Old 11-04-2013, 10:26 AM
Thread Starter
Join Date: Nov 2011
Posts: 40
Default Re: Ima Battery Saver & Assist/Regen Booster

It's now installed and working as described. Quite good fun!

I made one small change to the alpha software after bench testing.

Cheap and simple to build and install (4 wires in the footwell).
Does what it says on the tin.

I tested the pots at all extremes and it increases or reduces any assist/regen requests as described earlier in this thread. It's a simple way of protecting a failing battery as you can turn assist or regen down to nothing.

The Led remains on geen most of the time at the moment as the IMA is always requesting and producing some regen to cover the car background loads.

It changes to red once assist is required. So basically it switches back and forth between green and red.

I might try and adjust the led null (off) point so it ignores the normal background load.
I really only want it coming on when there is a proper regen load on like the hidden background charge, visible background charge, or coasting/brake commanded regen.

Pcb's now available in the usual way.

Some YT Videos showing install, pcb notes and completed device.

Just back from a 40 mile drive.

I think the software needs a few minor enhancements just to make it a bit smoother, ramp up and down the max assist/regen etc. But it certainly works as planned and no ima errors.

If you have the boost button pressed while accelerating and assist is requested then that is boosted to maximum, but if you let your foot off the throttle whilst keeping the button pressed and the assist request becomes a regen request on the overrun, then it switches to max regen in an instant which is the expected action but a bit unsubtle!

As noted in my video the regen with the button pushed is slightly stronger than with the brake activated regen. Perhaps 5A more.

If you don't like the button, the device could be re-programmed to activate the pic ADC and the input attached to the throttle pot so that it simply senses WOT and engages the max assist then. This needs another wire to the ECM connectors though so only for the advanced tinkerer.

The button on the box can be paralleled with another mounted somewhere more convenient if you don't want the box on the dash. Simply connect a momentary push to make button between Pins 4 and 5 on the pcb connector and install where you want.
It's possible to put the button connections through the steering column coil clock spring for a nice button on the steering wheel in exactly the same way as I did with IMAC&C, but this will only be possible with manual cars and a modified manual or cvt clock spring. Again this is for advanced tinkerers. Check my YT channel for videos on this.

Lots of possible variations.

When both pots are in the middle position the assist/regen level is stock except when the button is pressed, when it goes to max assist or regen.

The top pot when looking at the board as mounted in the box is the Assist Pot, the bottom one is the Regen Pot.
Adjust Pot clockwise to increase assist or anticlockwise to reduce.
Ditto for the regen pot.

If you install your bi-colour led the wrong way round I can supply software with the led action reversed so we get the right colours for the actions.

Programming Note

1) Don't forget to remove the jumper when programming the device once installed in the car.

2) The assist/regen pots on the pcb must be adjusted to the mid position when programming, as those pins are used by the pic programmer. If they are adjusted to either extreme the programming will fail. Readjust them to your chosen settings after programming is complete.

Feedback appreciated.


I saw a sustained 90A at 125V on the wifes (standard) car which has a one year old 8ah battery.
That's 11kw from the system and a good 10kw from the motor!
Remember battery temp has to be at least 20C+ and the Soc above 40% before the system will deliver maximum power.


Last edited by RetepSnikrep; 11-04-2013 at 10:29 AM.
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