Adding an additional fan to the Traction Hybrid Battery?

Hello guys!

I've spent the last month reading up on recommendations to help your traction battery last longer and operate more efficiently. Heat is battery's enemy. I already took the battery cover and fan off to clean it as the car had dog hair from the previous owner. I wanted to make sure the fans and battery were clean. I used my air compressor to clean out the battery and took a brush to the fan. There was hair but not much. More dust than anything.

Anyways I was thinking of adding another fan to the hybrid cooling air duct for summer use (Phoenix AZ temps are usually 105-110F). Something like this:

The idea is that this fan would sit in the duct with the cable routed under the back seat connected to a usb->lighter 12v inside the middle console. This fan would aid in cooling the traction battery especially when you turn on the car for the first time. It takes the AC a while to cool off the car in the summer so this could help.

Has anyone here tried this? Any drawbacks?

I have also thought of routing the floor A/C vent to the Hybrid vent.

Let me know what you guys think!

 

I installed the additional fan about 2 weeks ago. First let me show you the tools.

Total: Estimated $50.00

Goal: Lower the traction battery heat by providing additional cooling. This will also aid the traction battery cooling by not having to run the air conditioner colder to keep the traction battery cooler. I like to feel comfortable in the car not frigid. This alone will boost MPG's. The fan will also aid in pulling cooler air into the air vent so more cooler air reaches the battery faster. One of the most important features is when you turn your car off you can leave this fan on for a few minutes so that it continues to cool your battery down. The cars traction battery fan doesn't do this as it turns off right after you turn your car off. Heat is the hybrid batteries enemy so this is a plus.

Details:I decided to buy a battery pack so I wouldn't use any of the cars power for this. The cables are tucked underneath the back seat, into the side rails, back out from underneath the passenger seat up to the middle center console. The fan is mounted externally. I can mount the fan internally which would make it completely clean but I want to make sure I can see the fan just in case it would happen to fail. Eventually it will mount inside the air vent. In the future I will route the cable underneath the rug and will make a small hole to route the cable through the center console just to make it cleaner.Fan noise is minimal. I can also adjust the fan speed. The battery has lasted the whole 2 weeks on 1 full charge. Im still at 50% power running the fan at full power.

Test: Phoenix AZ to Flagstaff AZ. About 300 miles round trip. Elevation that was climbed was equally lost coming back. Estimated 1,100 ft Phoenix and 7,000 Flagstaff (about 6000 ft difference. Same gas. Speed 65 Miles per hour except down hills were I glide. First trip without the fan 50.2 Mpg's. With the fan 53.4 Mpg's. Any variables i could have controlled I did. 2011 Prius III Hatchback 40,000. Tires are shitty Primewell Valera at 44 PSI front and back (came with the vehicle).

Outcome: Very happy with the results. I gained a bit over 3 Mpg's on this trip. As you can see in the pictures and videos the air flow is strong. I tested this with both the car off and also with the car on. The airflow which is passing through the inlet vent, battery and the the outlet is still strong enough to blow out a lighter. I really like that I can cool the battery faster when the car is off after using it for a while.

Alright.....You guys can start the bashing now....




By the way I have videos of this but I cant figure out how to load them.

Thanks

 

It wouldn't work nearly as well. You would have to somehow fit a fan in the outlet vent for the battery which is too narrow. Also putting a fan anywhere in the trunk is inefficient as there too much air to move. It would be pulling air from all directions instead of concentrating its power to only pull air from the battery. Its easier to push air in the battery than pull air out because of the battery vent designs. Using the 12V cigarette lighter outlet doesn't work as the outlets turn off when you turn the car off eliminating the benefit of cooling the battery when you turn off your car. You can probably modify the lighter outlet so it is always hot but then you run the risk of depleting power from you 12V battery if you leave it plugged in. The 2011 Prius III doesnt have a 12V in the rear panel.

 

Thank God there are not any recalls to date right..those engineers get everything right from the start.....even when you get the recall done a new problem arises... The fan on the car is made to fit a balance of efficiency and low noise. Seems to be it favors low noise over keeping the temps low.

 

Quick update. Its been a month since I installed the fan. Before my avg was 50-51 mpg's. Now its 53-54 mpgs. The temps are still in the 100's here in Phoenix, AZ. I havent changed anything else on the car that would help boost the numbers. I really think that the extra cooling works.

One thing to notice is that I leave this fan on running at least 30 minutes after I turn the car off to help cool off the battery faster. If Im doing short trips where Ill get back in the car in 15-20 minutes I just leave it on. Ive read threads in the Priuschat community where the excessive heat will prevent the battery from charging fast (even drain it a bar or 2). The normal fan stops cooling when you turn off the car which leaves the battery "cooking" in heat. When you get back to your car the battery is hotter than when it was on 15 minutes ago. I beleive that aiding the cooling post battery operation helps it cool faster keeping it in a better charging enviroment for the next time you turn on your car as well as when you use the car in EV mode. A cool battery (not cold) will operate and charge better.

Ive been doing the same 50 mile route everyday. The only change is that I routed call the cables under the rug and made a small hole inside the center console to keep the portable battery in there. The fan is no longer at the exterior of the vent. I moved it inside the vent and removed the metal covers. I can charge the battery in about 8 hours with a 3.5 amp charger and it will last me about 2 weeks of everyday use. If you have questions let me know. I can provide pictures if necessary.

 

Hi Kenny
Using your example would equal about 5 bucks a month granted I drive more or less (10 months to pay itself off). By the way wouldn't it be nice to save an extra 5 bucks of gas when you fill up ? This modification wouldn't make sense if your keeping your car for a short period like a lease. But what if your planning on keeping it for the next 8-10 years? Prius owners in this forum (those that are planning on owning their cars for a long time) change the transmission oil every 30,000 miles just to give them a piece of mind that their transmission wont give them issues in the LONG RUN. Isn't that a huge jump vs the 100,000 miles Toyota recommends? What about the benefits of keeping your hybrid battery in better conditions? Doesnt that matter? Doing what you can to keep your battery functioning beyond 250,000 miles. Fuel savings aren't the only things we are looking for. We are looking for anything that will make our vehicle run like new for longer. In this case keeping the battery in best shape possible to make it last longer. From this long term point of view it makes good sense.

 

Charging it isn't the bad part for me. The bad part is remembering to go back to the car and turn it off after 30 minutes. Sometimes I forget and its on for a few hours. Still the battery last me more than a week on a single charge. It all depends on the battery you decide to buy. I'm convinced its efficient so I'm keeping the fan installed.