7739Re: Lithium voltage sag
- Dec 7, 2011
> Hope to hear from a few more of the owners that have been running the 90 or 100's for awhile. Especially anyone who has some grades's to deal with.I climb 2,600 feet in 17 miles to get home. The first half is 1% ~ 2% uphill grade (45~50 mph speed limit) and the last half is 6% ~ 7% (I keep it between 30 and 35 mph, like most gas cars) on a very curvy road. The Force uses 32 ~ 34 amp hours to get home. I always head home with a full charge. I use Normal mode because if I switch to Power mode I will quickly sag some cells to 2.6v or less. I set my lowest cell under voltage alarm at 2.704 volts and I can quickly trip that alarm in Normal mode if I floor it.
I had to go with Lithium because the fresh Lead pack I bought when I got the car kept going into limp mode on the last mile of the climb before getting home. I really like the Lithium pack. The car feels lighter in the turns, it easily cruises up the hill like a gas car without getting any cells below 2.8 volts. It's a lot more fun to drive without the extra 500+ pounds. Still, if I floor it on the freeway in Normal mode it would sag some cells lower than I want to go.
> This is my major concern with all conversions. I have a friend that put all his batteries in the bed of his S-10 and come the first rain he slid into the rear end of the car in front of him - not enough weight on the front axel.I don't notice the front to rear weight issue when driving the curves in rain. When I hit the brakes to avoid deer, there are lots of them in these mountains, the front end drops and the car stops quickly. Perhaps the S-10 had other braking concerns like narrow or worn tires, extra weight behind the rear axle, low vacuum pressure, glazed pads, etc. I rarely drive the Force when it's snowing because of the heater draw while climbing toward home, but the few times I have it feels fine. I originally had 20 cells in the front box for weight on the front end. Last winter I changed to 8 cells in the front box and can not tell the difference. I would have all 48 in back if they would fit that way while being strapped into the 4 cell compressed bundles.
If I were to build another Force for my wife I'd probably put in 50 of the160Ah cells. She is not as careful as I am with the accelerator pedal (coming out of the steeper turns) and she has tripped the under voltage alarm a few times.
One suggestion for new converters: put the display where you can easily see it while driving. My display is on the cup holder below the radio and I have to look down to glance at it. I only take 1 to 2 seconds to see the voltages as they scroll to show high & low but I recently had a close call with a skunk when I looked up. In city driving it could be dangerous. It's like texting while driving� it's a bad idea.
48 TS 100Ah cells (now have 7,000 miles on them)
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