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Discussion Starter #1
Had a range anxiety moment today. While I'm waiting for the rear battery
box to be built, I've currently got only 1/3 of my pack installed under the
hood (120V of 100Ah CALB cells). But it's enough to drive with. So I made
arrangements today to take the car to a shop to put it on a lift and have
some work done. The plan was to let the car charge during the couple of
hours it was being worked on. Due to a miscommunication, however, I ended
up going to the wrong address, and by the time a got to the right place,
they were closing. So I had to drive home with no charge. Round trip:
49.5 miles--and the last 6 miles comprised that grueling 1700-ft. climb back
to my house. I'm happy to report, however, that when I pulled the car into
the garage and popped the hood with my heart racing, the lowest cell still
read above 2.9V, and the mid-pack temperature had climbed to no more than
110 degrees F. I had feared the worst, because the pack had been sagging so
terribly on the last mile of the drive. You really can tell when these
cells start to hit the "knee".

Now that the pack is at a deeper DOD than I ever wanted to take it, maybe
I'll try Jack's bottom balancing to see how that works out. I hadn't
balanced the pack at all yet, and my strongest cell was up at 3.11V, so a
2/10 volt spread.

Bill

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70 Posts
Discussion Starter #2
It's that last mile that will kill you and I suspect that you may have done some damage. Was there any load still on the batteries when you measured them? The voltage starts to rise immediately when they are unloaded. 49.5 miles sounds like a long way to drive on such a small pack. To properly measure each cell after a trip like that you need to leave a load on the traction pack when you measure them. If you have a heater that runs off the traction pack that will work, or if you have a DC/DC you can leave some accessories running. My guess is if you had done this you would have seen some of your cells down at voltage levels you were not very happy with.
I personally never have range anxiety. I fitted some towbar mounts to the front of my truck and have it wired for lights. If I ever find myself short a mile or two it's simple to get the family SUV there and bring the truck home without risking damage to the batteries.

damon

> From: [email protected]
> To: [email protected]
> Date: Fri, 19 Nov 2010 16:15:25 -0700
> Subject: [EVDL] Still Grinning (barely)
>
> Had a range anxiety moment today. While I'm waiting for the rear battery
> box to be built, I've currently got only 1/3 of my pack installed under the
> hood (120V of 100Ah CALB cells). But it's enough to drive with. So I made
> arrangements today to take the car to a shop to put it on a lift and have
> some work done. The plan was to let the car charge during the couple of
> hours it was being worked on. Due to a miscommunication, however, I ended
> up going to the wrong address, and by the time a got to the right place,
> they were closing. So I had to drive home with no charge. Round trip:
> 49.5 miles--and the last 6 miles comprised that grueling 1700-ft. climb back
> to my house. I'm happy to report, however, that when I pulled the car into
> the garage and popped the hood with my heart racing, the lowest cell still
> read above 2.9V, and the mid-pack temperature had climbed to no more than
> 110 degrees F. I had feared the worst, because the pack had been sagging so
> terribly on the last mile of the drive. You really can tell when these
> cells start to hit the "knee".
>
> Now that the pack is at a deeper DOD than I ever wanted to take it, maybe
> I'll try Jack's bottom balancing to see how that works out. I hadn't
> balanced the pack at all yet, and my strongest cell was up at 3.11V, so a
> 2/10 volt spread.
>
> Bill
>
> _______________________________________________
> | REPLYING: address your message to [email protected] only.
> | Multiple-address or CCed messages may be rejected.
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