[dtbaker]

Originally Posted by bruceme

I directly tapped the battery with a small NEMA-5 female plug (w/5a fuse) and I do run it both on my 144vdc and plug it into the 120vac. When I run it on ac, it does just fine. On DC after a few hours it smells very slightly of hot plastic. So I try to only run on DC when I'm out and it's very cold (below 20).

-Bruce

really bad idea to run AC soil heating cable w/ DC. The AC switches WILL melt, and there are several reports of smouldering and even fires.... the thermostats don't work terribly well unless buried in DIRT to even out the temp fluctuations as intended.

I got some 'heattape' from canada with is variable resistance based on temp 1 to 8 watts per foot and no switches so it is fine on either DC or AC.

[bruceme]

Originally Posted by dtbaker

really bad idea to run AC soil heating cable w/ DC. The AC switches WILL melt, and there are several reports of smouldering and even fires.... the thermostats don't work terribly well unless buried in DIRT to even out the temp fluctuations as intended.

I got some 'heattape' from canada with is variable resistance based on temp 1 to 8 watts per foot and no switches so it is fine on either DC or AC.

You're dead on. 90% of the time I run it AC (overnight heating while charging). When I'm out and it's -20F and I need it warmed up, I'll hit it with the 144vdc off the pack, it does smell when I get done with that, so I humbly agree.

When next I pull the batteries out, I'll replace the thermal switch with a 70f AC/DC switch I purchased that's rated for this purpose.

-Bruce

[bruceme]

Originally Posted by PeterH

If you have only one box then it is well worth a try. I have five boxes and tend to complicate things... So I have all the sensors in place and all of the wiring in place and will soon work on the arduino program to monitor and control the individual boxes.

But hard to really test it till the temps in my area head south for the winter.

Please let us know how it works for you!

Pete

'Tis the gift to be simple'

I wrote software for a living... Go to Makers fairs, love cool mc projects (interested in knowing more about yours). But when it comes to my EV, the systems that aren't there, never fail me. One battery box is hard enough to get right.

[mharvey]

As promised, this job is complete. I did order the heat tape 11" from Beanfarm as well as their Herpstat thermostat. It all worked out nicely. Build pics are located at http://www.harveyev.com/gallery.html?galAlbum=6. Dont mind the site as I am still redoing it. I have not time to add all my builds for other projects. There are many shots of the battery box build including the biscuit fans with 140F thermistor to drive them under extreme heat situations. They never actually came on during my test runs @ 40 miles in the dead of summer, but they were cheap and a nice insurance policy.

[jeremyjs]

Not sure if anyone's mentioned it yet, but it seems seedling heat mats should work exceptionally well. They come in tons of different sizes and are gentle enough not to cook seedlings, so no need for a heat spreader. Some of them were as big as 2 ft by 8 ft. to under a foot square and in a variety of wattage's.

[DIYguy]

Originally Posted by mharvey

As promised, this job is complete. I did order the heat tape 11" from Beanfarm as well as their Herpstat thermostat. It all worked out nicely. Build pics are located at http://www.harveyev.com/gallery.html?galAlbum=6. Dont mind the site as I am still redoing it. I have not time to add all my builds for other projects. There are many shots of the battery box build including the biscuit fans with 140F thermistor to drive them under extreme heat situations. They never actually came on during my test runs @ 40 miles in the dead of summer, but they were cheap and a nice insurance policy.

Nice job. I like the wood mock ups, it really makes for a good fit and exposes those potential interference/fit problems.

[JRP3]

Originally Posted by jeremyjs

Not sure if anyone's mentioned it yet, but it seems seedling heat mats should work exceptionally well. They come in tons of different sizes and are gentle enough not to cook seedlings, so no need for a heat spreader. Some of them were as big as 2 ft by 8 ft. to under a foot square and in a variety of wattage's.

The quick look I had at them said they would "warm the root area" 10-20 degrees above ambient, which does not sound like enough to warm up a battery pack in sub freezing temps.

[mharvey]

Originally Posted by DIYguy

Nice job. I like the wood mock ups, it really makes for a good fit and exposes those potential interference/fit problems.

Thanks. Luan and hot glue are a surprisingly strong mockup tool. I actually had the full pack in the wooden mockup and was turning the whole thing on the bench w/o the box torquing at all. And yes, when your paying a guy to fabricate the whole thing, it's nice to say "Make me this exactly." and know it will work

[Caps18]

This is the next step for me now I believe. I know I am going to use 45 LiFePO4 batteries (144V, 100Ah) under the bed of the S-10.

Everything else I have to come up with a good design with the experience of other people have found to work well.

I am thinking about using a sheet of Aluminum, cut & bent, bolted to the frame, painted on the outside, with some insulation around the batteries. Some type of battery warmer (do the batteries just have to get to temp a few seconds before you start driving, or do they always need to be at room temp?), and a 12V industrial computer fan with some water proof vents.

I also would need a protective cover on top of the batteries, some way to keep anything from shorting them out, and a good way to balance the weight (~360 lbs).

Here is a good description of lead acid ones, I would like to find someone who has done LiFePO4 boxes and put something to deflect the air instead of a flat box.
http://waynesev.com/ev/battery_boxes.html

I am hoping to be done with this after the next two to three weekends.

[dougingraham]

Originally Posted by Caps18

This is the next step for me now I believe. I know I am going to use 45 LiFePO4 batteries (144V, 100Ah) under the bed of the S-10.

I am thinking about using a sheet of Aluminum, cut & bent, bolted to the frame, painted on the outside, with some insulation around the batteries. Some type of battery warmer (do the batteries just have to get to temp a few seconds before you start driving, or do they always need to be at room temp?), and a 12V industrial computer fan with some water proof vents.

I also would need a protective cover on top of the batteries, some way to keep anything from shorting them out, and a good way to balance the weight (~360 lbs).

The general consensus is you dont need to cool LiFePo4 cells as long as you aren't exceeding the ratings. With your 100Ah cells as long as you keep the average crusing current under the continuous C rating you should be ok. This would be 300 amps on a 3C battery (around 58 horsepower with your listed system). And I dont think a simple fan arrangement will cool them in the situation where you are exceeding the C rating for extended periods.

If the batteries are really cold your range and performance will be reduced so warming to something above freezing would be a good idea. And to charge they need to be above freezing or they won't accept a charge. A charger that has a typical charging cutoff will turn off almost immediately.

I dont know what you mean by "balance the weight."