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Heat is a battery killer... anybody done any mods to the cooling fans?


16vjohn
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I had a 3.3kw EVSE plugged in to my car at home and had to go out to grab something out of the trunk. There was a lot more heat in the car than I anticipated!!! I pulled up the carpet and styrofoam insert and there was no small amount of heat coming out of that cooling fan. Upon investigation, I found that the pack pulls air from inside the car (parcel shelf) and through a tiny hole at the bottom of the trunk from outside the car. In both cases, the hot air is exhausted into the spare tire well of the trunk!!! Honestly, wtf Ford. They had the foresight to install a flap to either pull air from the inside or outside, but not the same for the heat exhaust? I can see this being a benefit in the winter, but heat is unnecessarily kept inside the cabin in the summer. I may devise my own way to exhaust that heat.

 

I'm all about leaving the car/programming alone to manage its own issues, but this seems a bit ridiculous...

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I don't think the charger really puts that much heat into the battery from what I've witnessed. The charger module itself generates quite a bit of heat because its only about 90% efficient. So you're getting 300W+ lost as heat. Thats likely most of the heat. If you think about it only 11A of current approx go into the battery when charging at 3.3kW. If you compare, the motor can pull around 200A at full electric throttle and regen about 120A. Just to maintain 45mph flat pulls roughly 50A! That generates WAY more heat then the charging at 11A.

 

After I drive 23 miles to work in 100 degree weather the HVB is at about 110ºF if it has been sitting all night. I use value charge to let the charge complete around 7am and I leave at 9am. Going home its way too hot and the motor starts kicking in after the first 3-5 miles of my drive home when the HVB hits 113ºF or so.

 

I wish they would run the battery fan while the car was plugged in and not charging. Keeping the HVB cooler would really help when you go to drive later. Just sitting in the heat after the battery is already hot from driving does not help...airflow would help that. I've noticed it will run the fan if its set to value charge and waiting to charge BUT it won't suck air from the outside. Only from the trunk.

 

I've been thinking about making a PWM controller to run the fan the way I want it and just feedingback what the BECM expects the cooling fan to be at. Just gotta be able to open that door too to allow air in from the inlet behind the bumper. If I ever have the time to do it I'll happily sell some to whoever wants better battery cooling.

 

One other note. It may exhaust into the trunk but there are flaps in the trunk to allow air to exit. If there weren't it wouldn't be able to suck any air in from the outside.

Edited by breeves002
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I don't think the charger really puts that much heat into the battery from what I've witnessed. The charger module itself generates quite a bit of heat because its only about 90% efficient. So you're getting 300W+ lost as heat. Thats likely most of the heat. If you think about it only 11A of current approx go into the battery when charging at 3.3kW. If you compare, the motor can pull around 200A at full electric throttle and regen about 120A. Just to maintain 45mph flat pulls roughly 50A! That generates WAY more heat then the charging at 11A.

 

After I drive 23 miles to work in 100 degree weather the HVB is at about 110ºF if it has been sitting all night. I use value charge to let the charge complete around 7am and I leave at 9am. Going home its way too hot and the motor starts kicking in after the first 3-5 miles of my drive home when the HVB hits 113ºF or so.

 

I wish they would run the battery fan while the car was plugged in and not charging. Keeping the HVB cooler would really help when you go to drive later. Just sitting in the heat after the battery is already hot from driving does not help...airflow would help that. I've noticed it will run the fan if its set to value charge and waiting to charge BUT it won't suck air from the outside. Only from the trunk.

 

I've been thinking about making a PWM controller to run the fan the way I want it and just feedingback what the BECM expects the cooling fan to be at. Just gotta be able to open that door too to allow air in from the inlet behind the bumper. If I ever have the time to do it I'll happily sell some to whoever wants better battery cooling.

 

One other note. It may exhaust into the trunk but there are flaps in the trunk to allow air to exit. If there weren't it wouldn't be able to suck any air in from the outside.

 

My thoughts exactly. I also agree on the charging heat... except that, like you already said, the fans are running the entire time the charger is going. If I know I'll need the range I'll use 240v at home. If the car is in the garage for the night, I'll use 120v. Also, over the last several days, I've been doing some testing on how to keep the battery below 105F, yet still do ~41 EV miles/day. It's by far the hottest time of the year here in Utah. The last two weeks have seen 95 degrees + mid-day. At night, the temperatures get down to the 70's usually. I used 120v charging last night, this morning the pack was at 91F (hot from yesterday). Pure EV on the highway all the way to work. Arrived at work with 4% left and a 99F HVB. I plugged it in at work (120v). Torque seems to read the SoC and HVB temp even while the car is off, so long as the car is plugged in. So from my office chair, through the window I could monitor the temps. As the SoC climbed, the temperature actually fell down to about 98F. Battery full just after lunch, ambient air temp is well over 95F as well... I unplug the car and park under a tree and put up the sun shade in the front window. From about 1:00pm to 3:30pm, the HVB temperature climbed from 98F to just over 99f. Now, the interesting part... I left work in EV mode to get out of the business park. Just before I got on the highway, I kicked it over to EV later... let the engine warm up, then blasted the AC while I was getting up to speed on the highway. I ran in EV later mode for probably 4 miles. As soon as the climate wound down to <1kw, I switched back to pure EV. Over the course of the next 16 miles, the pack temperature climbed from 99F to 104F. As I got off the highway, I turned the AC compressor off and regen braked to a complete stop on offramp. I remained in EV mode for another 1 or 2 miles in the city to get home, back in the garage at 105F, which is my max temp goal.

 

Here are the takeaways:

 

- Even in scorching hot desert air, the HVB cooled down while charging 120v, presumably due to the continuously running cooling fan

- Parking the car in the shade makes a HUGE difference, both in creature comfort as well as HVB heat soak.

- Extreme amperage draw, like getting on highway, max HVAC seems to disproportionately heat the HVB. (temp increase not linear to amp increase)

- From ~90% SoC to ~30% SoC, the HVB seem to climb in temp very slowly as long as the cabin temperature is below ~83F. (ie, use your AC). Below ~30%, the pack heats up more quickly due to lower HVB voltage... more amps to do the same work.

 

I plan to chart some data points with Torque over the next several days. I want to compare amps at the inverter, to ambient air temp, to HVB temp, to SoC, to cabin air temp. I think it's possible to do 40 or even 60 pure EV miles every day, including highway speeds, if care is taken. All that said... this car lives to serve me. If I have to heat the pack north of 105 or even 115, I will do so. I'll probably end up trading the car for a second-hand Tesla in 3 or 4 years anyway. I'll report back on any data I collect.

 

Cheers.

Edited by 16vjohn
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Wow, that's awesome EV mileage. The most I've been able to squeeze out is 27 EV miles with 2.6 Regen. My battery is down to 4.5kw for EV mode after almost 3yrs and 60k miles.

I just bought the Kobra wireless OBD reader and downloaded some apps for my iPhone and I don't see any of them that show the HV battery voltage. I'm also looking for the watts being used.

Does the Torque also read watts ?

I have a Android tablet and can use that if Torque gives that data.

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I mentioned this idea in another thread but I just saw something that kind of works the way I was thinking. Use a long hose to take AC from the rear vents to the parcel shelf air intake for the battery

 

https://www.amazon.com/Noggle-Backseat-Conditioning-Comfortable-Traveling/dp/B00LXT23RA/ref=sr_1_30_a_it?ie=UTF8&qid=1532061572&sr=8-30&keywords=ac%2Bpro%2Brecharge%2Bkit&th=1

 

Maybe get a longer one?

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So... interesting thing I discovered this week. If the battery is warmer than it should be, the cooling fans stay ON when the car is plugged in, even if I have it set to value charge later. My intention was to let the batteries cool down in the driveway, then charge after 11:30pm. The cooling fans seemed to run from about 4:00pm to 8:00pm, even though it wasn't charging. I have an ammeter to track Kw/h usage for the outlet, and it was pulling about 0.5a at 120v even though it wasn't charging. If I'm not lazy, I may try to figure out at what temperatures the cooling fans will run when value charge is enabled. 

 

I pay the same rate 24/7, but I figure the value charge option is an easy way to delay charging in extreme summer weather.

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Wow, that's awesome EV mileage. The most I've been able to squeeze out is 27 EV miles with 2.6 Regen. My battery is down to 4.5kw for EV mode after almost 3yrs and 60k miles.

I just bought the Kobra wireless OBD reader and downloaded some apps for my iPhone and I don't see any of them that show the HV battery voltage. I'm also looking for the watts being used.

Does the Torque also read watts ?

I have a Android tablet and can use that if Torque gives that data.

 

 

By EV miles, I meant to say that I can do a full charge 2 - 3 times daily if you are strategic about charging and parking your car in the shade and still keep the battery at a sane temperature (goal of less than 105F)... Not that I am getting 40-60 EV miles per charge. I drive a good amount of highway, so I'm getting the standard 18-22 miles depending on speed and HVAC use. :)

 

Edit, Torque doesn't read watts, but it does read amps. If you got crafty with Torque, you can make a custom tile that takes the HVB voltage and multiply by amps at the inverter. That'd probably give you a good idea of kw usage. You will have to install the custom PIDs... takes a bit of reading but it's not too complicated. Found it on the CMAX forum... might be here too.

 

http://fordcmaxenergiforum.com/topic/3934-is-there-one-area-for-all-torquepro-pids/

Edited by 16vjohn
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