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Discussion Starter #1
I was just wondering what mods had you considered to improve performance?

It seems one bad apple spoils the whole pack. What if the cells had heat fins to remove heat better? What if the wires were heavier? What if the cooling blower was moving more air?

Just wondering.......
 

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I was just wondering what mods had you considered to improve performance?

It seems one bad apple spoils the whole pack. What if the cells had heat fins to remove heat better? What if the wires were heavier? What if the cooling blower was moving more air?

Just wondering.......
1. The cylindrical shape is optimal for heat removal as air is sucked through the pack. Fins would cause turbulance and this would result in uneven cooling.
2. The wires are almost 1/2" thick now
3. The cooling fan at 9V is enough to dissipate 30 amps of discharge down to about 1 degree over ambient. The car can run the fan at 12V, so it is adequate. I do modify the fan by sealing it to the shroud with foil tape.
 

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There are a few things that can be done ... but don't expect any massive benefits though.

You can:

Increase the air flow rate... either by adding small fan to the inlet or modding the OEM fan to run sooner / more often.

Duct some or all of the AC directly to the battery inlet... you suffer from higher cabin heat ... MPG suffers from running AC ... batteries benefit from cooler air.

Re-design the entire battery box to improve air flow ... a rather involved task ... but the battery pack does not heat evenly ... see picture attached bellow ... Some parts of the battery pack could obviously do with more thermal regulation in order to be better in sync with the rest.

re-design entire battery box to make use of a more advanced liquid cooling type of system.

Limit the current flow flow into or out of the battery pack that is making the heat in the first place.

Change / upgrade battery type to one that produces less heat.

Some combination of the above.

- - - - - - - - - - - -

Although I have toyed with some of these ideas ... it is pretty low of my list of projects.
 

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Discussion Starter #4
Thanks. I know many people of their trade see stuff and do it for increase of performance and thought the same here.

I am interested in the increased cooling as its my experience as one who needs to drive some days for hours on end and hundreds of miles the changes in the ima system.

It seems when I first start one I get half assist from the start if not full for part throttle. Then lifting from the gas petal I get half regen, then pressing the brakes just enough to trigger the brake lights I get full regen.

Later on the assist/regen meter doesnt swing as wildly and stays near the center mark. In many cases after a few hours of driving the only way to peg the regen meter is to engine brake at 4 grand while riding the brakes. The assist is rather lacking and the engine just revs up and the cvt goes to work.

I have found regardless of ac settings and day light or lack of at night the trunk area is warm as well as the items in that area. So far the only thing I have found to help was to use outside air and set the blower to at least half its speed setting. After 30 minutes or so rather outside or ac air the ima system comes back to life like when I first start up.

I am interested in the adding fans thing. I am guessing since it has the dual vent and a good side blower in the back I should start off with a squirlcage blower from an economy car to begin with to get sucificent air flow.
 

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Cooling off the Pack at the end of the Drive

I'm intending to Cool the pack by running the Pack fan on a timer at the end of the journey to reduce heatsoak effects

This is the device I will use:

2-Channel RF Remote Control Set (VM130)

It is 2- channel RF keyfob transmitter and a receiver with Relays as outputs, I paid £29.99 for the unit at Maplins in the UK

The smart thing about this device is the channels are settable to switch the relays on for fixed period of time, 15/ 30/45/60 minutes.

I have already purchased one and tested it on the bench.

You can probably see my idea already.

After Parking the Car. press the button on the remote and walk away, the fan will run and switch off at the end of the selected period.
 

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It seems when I first start one I get half assist from the start if not full for part throttle. Then lifting from the gas petal I get half regen, then pressing the brakes just enough to trigger the brake lights I get full regen.

Later on the assist/regen meter doesnt swing as wildly and stays near the center mark. In many cases after a few hours of driving the only way to peg the regen meter is to engine brake at 4 grand while riding the brakes. The assist is rather lacking and the engine just revs up and the cvt goes to work.
Amount of regen and assist can be manually controlled / tweaked with MIMA... even some CVTs are running MIMA.

I have found regardless of ac settings and day light or lack of at night the trunk area is warm as well as the items in that area. So far the only thing I have found to help was to use outside air and set the blower to at least half its speed setting. After 30 minutes or so rather outside or ac air the ima system comes back to life like when I first start up.

I am interested in the adding fans thing. I am guessing since it has the dual vent and a good side blower in the back I should start off with a squirlcage blower from an economy car to begin with to get sucificent air flow.
The temperature of the rear / hatch area has more effect on people comfort ... and hardly any effect on the batteries temperature.

The air inlet for the IMA batteries is behind the passenger seat... and the exhaust air coming out of the battery box goes out of the car... and there is no direct path for air to go from the rear hatch area to the IMA batteries.

If you are going to add additional fans ... I would recommend the inlet behind the passenger seat ... as it is the only air inlet for the IMA batteries ... then you could add manual control of the existing IMA exhaust fan so you are both pushing and pulling air.

Adding exhaust fans to the 2 vents in the rear hatch area isn't a bad idea ... especially for those times when you park in a sunny spot ... but those would be more for occupant comfort than IMA battery temperature.

A complete redesign of the battery box is a rather involved task ... I would generally recommend trying other less involved things first.

You might want to add a temperature display of what the actual IMA batteries temperature is... a in-door / out-door thermometer might work for this.
 

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Monitoring of Pack Temperature

I'd like to attempt this using the PTC strip as an indicator.

I placed a scope on the Strip to look at the signals but it was inconclusive, the PTC strip is pulsed (or polled )by the BCM, I do not understand how it works.

Wish list is an extra meter on the console which displays the Battery temp or PTC resistance so I can keep a eye on how the pack is reacting
 

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I'd like to attempt this using the PTC strip as an indicator.

I placed a scope on the Strip to look at the signals but it was inconclusive, the PTC strip is pulsed (or polled )by the BCM, I do not understand how it works.

Wish list is an extra meter on the console which displays the Battery temp or PTC resistance so I can keep a eye on how the pack is reacting
It would be significantly easier to use a single temperature probe placed into the center of the battery pack.

You could tap off of one of the four individual temperature probes already in the pack or just place the temperature probe from a in-door out-door thermometer in the pack.

The PTC strip is not a linear response ... it is exponential ... the PTC strip is nice because it makes thermal contact for each individual cell ... but it is not really a particularly good method of determining temperatures accurately ... it is mostly used in the car as a inexpensive way of detecting if an individual cell is potentially getting over heated.

Attached bellow is a graph of a few PTC strips from individual sub-packs that I tests a while ago.
 

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Discussion Starter #9
I was thinking of getting a remote start system with alarm and using the turbo timmer feature for that. So, I would set it to let the car run for a few minutes once a button is pressed to cool things down, but not sure the savings would out weigh the fuel used.

Seems Ian says the cabin temp would not effect them.

I'm intending to Cool the pack by running the Pack fan on a timer at the end of the journey to reduce heatsoak effects
 
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