Electrathon America Forum

Josh5 · Newbie

Battery Cooling

Nitoragro · Senior Member

I have heard cooling batteries will let them hold a charge longer, such as in storage. But how useful would that be if you "top off" your batteries right before the race. But I think a problem will come up in a safety view point. In these cars there is not much room to put the dry ice and it could be very close to the driver and cause some problems in a serious collision or a rollover. If you want to keep the batteries cool you can start with something simple such as a fan or extra venting to the batteries.

However it seems like your goal is to get more from your batteries, and there are several ways to do that. Heating is fairly common in Electrathon, however the best way to see what works best is testing. You could always build a battery tester.

This post has an example of how to build a battery tester: electrathonamerica.activeboard.com/t60750752/simple-battery-workstation-build/

This link has an interesting picture of a graph of capacity and temperature
www.tawaki-battery.com/how-temperature-affects-batteries/

A meter to monitor batteries on a workbench, I used this in all my testing where I pulled 20-35 amps and it worked great
powerwerx.com/watt-meter-analyzer-inline-dc-bare-wire

Get your batteries and label them all then charge them normal, discharge them, then find how much power is in them. Then do the same thing but cool them down. Just keep a log of everything.

In short If you want to try cooling your batteries with dry ice go for it, just be safe. Just don't let the first time you do it be on the track. Bench testing using a system like the one above helped my car a ton and you might find something that no one else has found. Good Luck

ProEV · Senior Member

Formula E use lithium batteries. They can be damaged and lose capacity if over heated. The batteries are delivered to the teams as a `black box` meaning they are not allowed to open them up and change anything. The manufacture sets the temperature limits and the packs automatically cut power if they reach a certain temperature. To avoid hitting the limits, the teams use fans and dry ice.

Lead acid batteries have greater capacity if they are warmer and less capacity when cold within limits. To get the best results requires adjusting your charging voltage as well. But even keeping your batteries in a warm building the night before a race will help if you are racing on a cold day.

My understanding is that motors lose efficiency as they get hotter, so maybe dry ice on the motor might offer an advantage.

mhodgertt · EA President

We used to race in Eastern Oregon in the high desert in late July. As I was leaving the town about 3 hours after the race one year, I saw a bank thermometer that was reading 109. The high was 114 that day. For our races there we often would make expanded metal 'cages' to hold dry ice on top of our motors and controllers. Both are more efficient when they are cooler from what we found.

One especially hot year my controller would shut down every 10 to 25 minutes of driving as it was too hot...which is why we started using dry ice there. We have used it at a couple of other races when the temp was going to be in the 100s as well.