booster battery for imiev and outlander

[CeeJay09]

Today at 7:47 AM
Mickey asked for all outlander topics to be discussed outside of the Imiev upgrade thread so I started this conversation.
I acquired 80 used outlander cells for storage, I do not have an outlander.
I do know Brendan McCarrol that did a booster pack successfully in his outlander to boost the range and I will look for that thread link and post in here soon.
I have also got a booster in my imiev which Brendan also did, the range stays the same sort of but the distance travelled actually increases. by this I mean as 3km comes off the GOM i have actually driven 5km in distance.
this is due to the booster not being part of the current sensor circuit, rather the car reads a low current draw all the time like driving slightly downhill

 

[kiev]

this is due to the booster not being part of the current sensor circuit, rather the car reads a low current draw all the tim

That sounds interesting--would you care to go into some details of how this is done?

[edit: i followed Mickey's link below and found the description--that's quite amazing]

 

[MickeyS70]

I did remember reading about this (end of page 29)

https://www.forums.aeva.asn.au/viewtopic.php?t=5515&start=700

 

[CeeJay09]

yes that leaf pack in the images of that thread is my car now, I have the bms units (yes plural more on that later) to install in the booster to keep it safer and easier to monitor cell voltages. it would also allow me to close the cells in to make hv safe too

 

[CeeJay09]

I have inspected the best place to tee in to the HV on my other silver Imiev and ill likely go straight into the inverter battery connection point rather than splicing the cables, the boosters will need their own bms and be able to handle the same current as the pack, the problem is the voltage range of the boosters with new cells does not match the cars lev 50 cells. A work around for this is under development through mine and Matt Laceys business. Or just use cells from an i3 or leaf where the curves are close enough to the lev50.

 

[CeeJay09]

I have successfully fitted a booster to my vectrix (electric scooter) which doubled the range and can easily be removed when not needed, or to charge at university at my desk. (I got a fine for charging the bike at a power point and this was my work around), I live 120 km round trip from my old uni

 

[MickeyS70]

the boosters will need their own bms and be able to handle the same current as the pack, the problem is the voltage range of the boosters with new cells does not match the cars lev 50 cells.

Does it need to match? The GOM will be inaccurate regardless. The booster’s BMS will handle safe limits therefore as long as its pack voltage remains higher and current flows ‘out’ it shouldn’t matter.

Though you may need some sort of a pre-charge circuit when you turn on the car to prevent excessive equalisation currents due to different pack voltages.

 

[CeeJay09]

You dont want the booster pack higher than the 88 (or 80) cells can reach (88×4.1v), that can be limited by the booster BMS. The problem i find is that NCM has a much wider voltage range and as a lot of other sources of information have shown, roughly 60% of the NCM capacity of the booster is useable.
There is a lot of stored energy that cannot be accessed in the booster when the car has standard LEV cells remaining.
I did find that 100-106 headway LFP cells are not too far off the mark for an imiev booster but theyre not very energy dense.

 

[CeeJay09]

The idea with my booster is that i can lift it out and use it as storage when I dont need the range in the car, this prevents me lugging it around all the time. I also want to build a long range booster for use on my trailer with my other EV. So it serves a purpose for many applications. I would love to upgrade one of my imiev packs to NCM and still have a booster that I can lift into the boot space for reaching my holiday house 280km away, and the NCM booster would match a lot better in that instance.

 

[CeeJay09]

On the precharge circuit topic, the imiev already has that covered. The boosters contactor opens after the main pack contactor is triggered in both "charging" and in "ready" modes

 

[MickeyS70]

You dont want the booster pack higher than the 88 (or 80) cells can reach (88×4.1v), that can be limited by the booster BMS.

True, if your LEVs are charged to 100% but you could have a higher Booster voltage if your custom BMS disconnects the pack in that instance. I think Prius boosters worked on a similar principle; kick in at a certain voltage and then disconnect at another level.

The problem i find is that NCM has a much wider voltage range and as a lot of other sources of information have shown, roughly 60% of the NCM capacity of the booster is useable. There is a lot of stored energy that cannot be accessed in the booster when the car has standard LEV cells remaining.

Might be even worse depending on the capacity of the NMC pack used. David (ODBZero developer) calculated the LEV50 equivaled of NMC60 cells to about 36Ah while NMC90 were around 55Ah if I remember correctly.

The idea with my booster is that i can lift it out and use it as storage when I dont need the range in the car, this prevents me lugging it around all the time.

At a weight of 0.33kgs per cell (headway LFP) that won't be too easy? Do you have a 400V inverter to make use of the storage outside of the car?

On the precharge circuit topic, the imiev already has that covered. The boosters contactor opens after the main pack contactor is triggered in both "charging" and in "ready" modes

I was assuming you were going to charge the booster externally, hence the different voltage reference.