[RE Farmer]

I just ordered the AC50 kit and mounting kit for a fiero from grassroots. This is a good bit of capital to spend without ever meeting someone.

Has anyone here had any experience with grassroots?
What did you order?
How quickly did it ship?
Was Jon responsive after the sale?

I ordered the AC31 from Jon and received good service/no problems. It's been a over a year so the details are a little fuzzy, but it pretty much shipped when my check cleared. I suspect the motor/controller was drop shipped from HPEVS and not from stock at GrassRootsEV but I'm not sure. Jon was quite friendly and usually responded to emails w/in a day. I think it took a little over two weeks to receive the kit by motor freight from the time I mailed the check. I'm pretty sure he emailed me when the kit shipped, but I had lots of other things (like putting a new roof on my house) going on at the time.

 

[RE Farmer]

Questions: Hopefully I'll find out soon enough from Curtis... but what were the factory programming variables? Just battery voltage?
I've seen folks use 108 V nominal or greater with the Curtis but I can not find any Curtis documentation to support this... Hate to kill the MOSFET with too much voltage potential across the source/drain.
Also, any idea what must be done if I change the battery level at a later date? Does the controller need to be sent back to factory?

Hope your house has stayed leak free.

My understanding is the 1238 has voltage protection in that it shuts itself down when the pack < 130VDC. Several people has used 120VDC +/- as I'm planning to do.

OT: My house is NOW leak free, but getting out old one off and the new one on before the rains came proved futile ... boy, was that a mess.

 

[RE Farmer]

The 1238-7501 has a voltage shutdown at 130 volts. ... If you had an adjustable charger you could get an extra few cells and only charge them to 3.5 volts per cell and get 37 in there and might pull slightly more power at the higher RPM range but it probably wouldn't be enough to notice but it would a bigger difference with range. Keep in mind that 37 cells might be an issue with heavy regen current when the pack is full, which is why I'm sure people are keeping with 35 or 36 cells.

That's pretty much my plan - to install 38 cells and stay away from the steep parts of the charge/discharge curve to enhance longevity by only charging to 128Vdc. Even if I did end up charging over 130V, I figure briefly turning on the electric heater would "eat up" that surface charge real fast, quickly dropping the pack voltage back under the 130V cut-off.

 

[RE Farmer]

I'd prefer the CALB, but TS are an option. I'd go to higher AH cells, but their increased height start making installation problematic.

Since the nominal voltage is 3.2-3.3V, i could easily charge 39 cells to 3.3 and stay below 130V. 130V/38 cells is 3.42V; well within my parameters. Like I said above, I plan to stay away from the max. capacity of the cells to increase longevity.

 

[RE Farmer]

What do you plan to do for the BMS?
I've only started to look, but most BMSes support 3.6 or 3.8 V for charging.

I don't plan on using a BMS. If cells aren't abused (over/undercharged) several people have reported the cells stay well balanced if they start out that way. If fact, I seen some reports that they tend to balance themselves if the extremes of the charging curve are avoided. This is a highly contentious subject, but that's where I stand.

For more about this issue i recommend the following sites if you haven't already discovered them:

http://media.ev-tv.me/news111309-1280.mov

http://groups.yahoo.com/group/ThunderSky/

 

[RE Farmer]

Since I'm running 36 SE/CALB cells with an AC31 I can give you some feedback. Fully charged I'm resting around 120 volts. Moderate regen of 100 or so amps can drive the voltage to 124, higher regen around 200 amps will hit 126, BUT, if your cells are colder their resistance is higher and voltage will be higher on regen, I've seen 127 so far, my controller is set for 40% regen, (neutral braking).

I live at the bottom of a valley so I have to travel uphill right away and wont' be regen'ing until after I've "burned" a bunch of electrons. Opportuity charging won't be topping off the cells so I'm not too concerned about hitting the cut-off. If CALB' higher AH cell wer the same height as the 100's, I'd use them but their 11-12" height starts giving me fitment issues. China Hi-power's new format is shorter but heavier, and weight is even more critical for me than size.