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Discussion Starter · #1 · (Edited)
I am planning an EV project for my momma (who's scared of the motorway), and just wanted to get some more informed opinions on whether the battery I'm looking at will be big enough. She drives maybe 30 miles a day, all on surface streets, and lives in Seattle (some hills but nothing crazy). Does a 72V, 100AH, battery pack sound like it would work for her? Or should I look for something higher voltage, or greater capacity, or both? Thanks in advance.
 

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It is going to depend on what vehicle is converted but I would generally recommend a somewhat higher capacity and higher voltage pack. Perhaps 96 volts at 100 amp hour using LiFePO4 cells would manage the desired goals if it was a light vehicle and rarely exceeded 35 mph.
 

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Discussion Starter · #3 ·
I was planning on using lead acid batteries actually. From what I've read they're less finicky and far more forgiving. As far as the car goes, I'm also looking at something like an Escort ZX2 or 2nd gen Probe. Something small but not ugly looking. With all that in mind, does 96V and 130-150AH sound more reasonable?
 

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I was planning on using lead acid batteries actually. From what I've read they're less finicky and far more forgiving. As far as the car goes, I'm also looking at something like an Escort ZX2 or 2nd gen Probe. Something small but not ugly looking. With all that in mind, does 96V and 130-150AH sound more reasonable?
When i got my Yaris, they had 14x12v Optima's giving 168v and they are rated at 50ah each. Best range when new was 25 miles at freeway speeds. When I purchased the car the batteries were only giving 10 miles, so Lead acid do not last long and Lithium are more economical in the long run. Gottdi here on the forum has some new 100ah High Power (not the best maker), but I certainly would put money into those as opposed to buying leadies. And his price may even compare to be about the same as good quality lead.

francis
 
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120 volts of at least 100 amp hour cells will do very well. Just don't drive the cells hard and they will do you well. I took mine into town with 8 miles total at 55 mph and the cells did real nice. About 2 or 3 miles around town just to drive then back home. 4 miles to town on the Hwy. 55 is the speed limits but most drive faster.

Pete :)

72 volts would be too hard on the Hi-Power 100 amp hour cells. The higher the voltage the the easier on the amp draw. So 120 minimum and you will have a pretty peppy little car too.
 

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Discussion Starter · #6 ·
My mother is actually scared of the motorway (probably has something to do with some jack-hole rearending her at 60), so being able to reach motorway speeds isn't necessary. The highest speed roads around here are 40mph. I'm not sure I want to spend all the extra money on a higher voltage pack and ancillary bits to make it motorway capable if she never goes on the motorway.
 

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I'm in seattle. I live in Georgetown (a south seattle neighborhood surrounded by industrial areas, boeing field, the duwamish river, and I-5), so many of my destinations are close by and don't have much if any hills on the route.

I have 126V, 200AH unheated flooded lead in my 1985 MR2. That battery pack will allow about 50 miles at freeway speeds under the best conditions (temperature, elevation, wind, etc) but for running around town in the rain and winter with all the stop and go, 30-35 miles is max. That is using about 8KwH.

A 120V, 100AH LiFePo4 pack would have at least the same 8kwH usable as what I can get under less-than-nominal conditions for lead acid pack, and would also weigh about a third as much (my FLA's weigh over 1200lbs) which would increase overall efficiency especially in city driving with more stop and go.

Strongly recommend 120V, 100AH. Your mom won't have to go fast, but the car will be able to if she wants. If you must stay with 72V, use 160AH cells and design the car with enough room to upsize the battery pack to at least 96V or preferably 120V, for future upgrade potential.

Been to any SEVA meetings yet? (next one: march 8th)
 
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