# Fan recommendation for Warp9



## sholland (Jan 16, 2012)

I'd like to get some feedback of what cfm is recommended for cooling the Warp9... I will be running up to 1000A for 10 second bursts, but plan on no more than 480A continuous. 

I see EVWest has a cooling kit with a 800cfm fan, but it also is very loud... I have found some 230cfm blowers on eBay that may be better, but only if it's enough airflow...

I'd like to hear your opinions...


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## onegreenev (May 18, 2012)

The motor already has a built in cooling fan. For higher rpms that should do just fine but for lower stop and go speeds the stock fan may not be enough. I have a 9" GE Series motor that has no built in fan. I am using a fan from a VW Bus heater system. It has two outputs and you could have a cover over your brush end that has an opening on both sides of the motor so you can run one output into each end. Mine only has one opening so I only use one output. So far no issues. Did not use it much so long term I can't say but it does pump out some good volume which is what you need and its much quieter than those turbo blowers. You can find them on TheSamba.com


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## dougingraham (Jul 26, 2011)

I don't have any external cooling on my WarP9. It never seems to get all that warm. When under higher loads like highway driving I tend to keep the RPM in the 3-4k range which is where the internal fan seems work pretty well.

And yes I do drive like a teenager from time to time.

Do you have reason to think that the internal fan is inadequate or you just want to be safe?


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## sholland (Jan 16, 2012)

dougingraham said:


> I don't have any external cooling on my WarP9. It never seems to get all that warm. When under higher loads like highway driving I tend to keep the RPM in the 3-4k range which is where the internal fan seems work pretty well.
> 
> And yes I do drive like a teenager from time to time.
> 
> Do you have reason to think that the internal fan is inadequate or you just want to be safe?


I'm still building the car, so I have no idea if I'll need it or not. I know I do like to use the power I've got, so I was just wanting to be safe...

The EVWest cooling kit has a 800cfm fan, which from a video review I've seen sounds like a vacuum cleaner! They race their cars, so maybe they need that level of cooling. 

Maybe I'm just over thinking all of this, but I would not want to be burning up brushes either...


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## dougingraham (Jul 26, 2011)

Forced air cooling to the motor was one of those things I was worried about too. I had room for it at the time I was building and I decided that if I needed it I would add it in later. I go on 30-40 minute drives all the time and there are several fairly long grades I climb at highway speeds. I used to check motor temps but I don't anymore. The brush end shaft would be the warmest thing I could touch and it has never been more than just warm to the touch.

I suggest you delay fitting this until after you see if you need it. A heavier car and different roads or traffic conditions could change everything. So keep it in mind when fitting stuff around the motor but don't worry too much about it either. I would hate to have the sound of a vacuum cleaner under the hood!


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## sholland (Jan 16, 2012)

Thanks Doug! That's exactly the advice I was looking for ☺


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## dladd (Jun 1, 2011)

I have the kit that used to be sold by a few places that has a 105 cfm Jabsco blower (it's a bilge blower I think). It works OK, but is a bit loud to me. I put it on a toggle switch so I can shut it off when I want to. I like to be able to switch the blower off when first driving the car, for that stealth feel. And anytime I'm creeping around parking lots, cause it's just more fun to be silent.  

Personally I'd feel OK about not having cooling, but I like having the shroud with a filter to keep out rain/dust/dirt. And with the shroud, I think it needs the blower cause the vents are almost all covered up. I do think 105 cfm is a bit weak, but I don't have a 'high performance' car so it seems fine. No scientific data to back that up though...

I'd think 800 cfm would be massive overkill. But sometimes overkill is just enough, right? Depends on the use.

this is the kit as installed in my car:


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## Tesseract (Sep 27, 2008)

FWIW, if you have a Soliton 1 that is liquid cooled and 200V+ lithium pack capable of more than 300A or so continuous current (e.g. - 100Ah @ 3C) then I would strongly recommend forced air cooling of the motor (unless it is a GE 13" or two smaller motors always wired in parallel). The reason being that the higher voltage pack and liquid cooling allows the controller to deliver 1000A for a longer period of time.

Also note that waste heat is proportional to the square of current while torque (at these current levels) is linearly proportional to current, so a modest reduction in current will have an equally modest effect on torque, but a much larger effect on waste heat.

For example, reducing motor current from 1000A to 900A results in 10% less torque but 19% less waste heat.


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## Yabert (Feb 7, 2010)

Tesseract said:


> The reason being that the higher voltage pack and liquid cooling allows the controller to deliver 1000A for a longer period of time.


Of course, 1000A to a Warp 9 in a lightweight Civic will quickly give you stupidly fast speed 



sholland said:


> Here's my blog if you want to see my progress.
> [URL]http://1996-civic-ev.blogspot.com[/URL]


Sholland, I've done the same than DougIngraham in my Smart... I've removed the external fan after have notify the motor was only warm in most situations. 
Can be different on hot weather...


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## sholland (Jan 16, 2012)

Tesseract said:


> FWIW, if you have a Soliton 1 that is liquid cooled and 200V+ lithium pack capable of more than 300A or so continuous current (e.g. - 100Ah @ 3C) then I would strongly recommend forced air cooling of the motor (unless it is a GE 13" or two smaller motors always wired in parallel). The reason being that the higher voltage pack and liquid cooling allows the controller to deliver 1000A for a longer period of time.
> 
> Also note that waste heat is proportional to the square of current while torque (at these current levels) is linearly proportional to current, so a modest reduction in current will have an equally modest effect on torque, but a much larger effect on waste heat.
> 
> For example, reducing motor current from 1000A to 900A results in 10% less torque but 19% less waste heat.


Ok... I will have 67 160Ah cells, so I expect to be able to provide almost full power for the SOC range of the pack (motor voltage will drop a bit at low SOC, ~155V at 30% SOC). This is based on the assumed ESR of the cells... obviously I can't know how much voltage sag I will have until I try it out, but I am trying to test ESR myself now...

Can you recommend what kind of cfm might be required though? The only forced air cooling kit I've seen is providing 800cfm, which seems like a lot... It would be nice to know what kind of cfm the built-in fan provides at high rpm, but I can't find that spec. I may try to contact Netgain to see what they recommend...


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## sholland (Jan 16, 2012)

I just got a response from Netgain:

"It is very difficult to measure the cfm provided by the internal fan, but i can tell you that it cools best and is most efficient between 2000-4000RPM.

For an external blower, we recommend 200cfm minimum at low and high RPM as well as during high current draw. However, most applications leave the blower run whenever the motor is in use."

I've ordered a Jabsco 250cfm continuous duty bilge blower, that will on with ignition which should do the job. I also have a temperature switch that I may try later...


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