DoD vs. battery life

Hi Darell,
Yes, thank you for your comments.

I have my own questions about your battery charging/discharging schemes.

Do you let the batteries cool down after charging or before charging?

How long after use do they wait until they are recharged?

 

It doesn't come with a good one, that's for sure. Here's the Palm application that we use. The big number at the top is SOC. This image shows just some of the information available to us. Slick, eh? http://www.darelldd.com/ev/images/rav4/rav..._palm_front.jpg

My fault for making this confusing. I don't actually "set" anything. By my comment, I meant "where you say zero is." When my SOC meter reads 0%, then I'm at zero (under 10V per module average). I can still drive after that... and have. I just meant that we could call 100% DoD 10V, or 9V... or... I agree that 10V is good, yet I've gone below that.

Yes. 98% to 100% is where the heat becomes an issue.

I do that for two reasons. One is self-discharge. If I'm paying to charge that last 10%, but it discharges before I can use it, why bother going there? The other reason is when the ambeint temp is around 100 degrees, I try not to cook the batteries at the top. The official instructions with the car are to charge to 100% every time. But I've found more than once that I'm smarter than the owner's manual.

Nobody has the time to dicharge to 0% every time. That would be AT LEAST 100 miles of driving every day = 36500 miles/year. No, I don't take it down that low every time. I do get down there quite regularly, however (4-5 times per month). We use the whole SOC of these batteries.

 

Nope. In fact, if I come back from a hot drive with hot batteries, one of the quickest ways to cool them off is to plug in and have the battery fans come on full blast. After charging all the way up on a hot day, the best thing you could do is start driving which will also keep the cooling fans on. Letting it sit after charging will just allow the batteries to sit there and bake.

Covered above. Unless it is some extreme situation, there's little reason to wait. During driving, we add large amounts of charge with regen as well, so from one second to the next you can have a huge draw and then a huge charge (by "huge" I mean maybe 150A out and 250A in.)

 

Yup, 46 Wh/kg in the Prius vs 65 Wh/kg in the Rav4, quite different designs.

The early Prius had a bigger battery (1.9kWh), and it was the reliability of this that gave them the confidence to move to a smaller battery with deeper cycling (the current 40-80% range) and higher power density, for the '04 Prius.