Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post

wumpus · 10-13-2008, 11:09 PM

Bluebomberman, I hope you understand you are talking a megabucks build...

some other thoughts (since I've let this rattle around in my head a few times...:

1. Microcenter sells huge batches of NiMH AA batteries. Just make a PCB to fit and put several hundred (by buying in batches >50). Before you pull the trigger, make sure you check all the laptop replacement batteries (especially non-name-brand replacements) by Whr/$ I know the homebrew electric bicycle I've seen nearby used laptop batteries (possibly scavenged, I didn't ask), this might be a better deal.

2. You probably want ultracaps. They will take any amount of charging (i.e. regernerative breaking) until full. Expect close enough to perfect efficiency (I'm basing this off of "normal" caps., these are close enough to 100% to ignore the losses in tuning applications, I've hear ultra-caps are chemical based (essentially a hybrid capacitor/battery beast) and might be different)). Note that with lead-acid, pulling any more than half the maximum amount of power out of the battery takes a 50% efficiency hit, if not more. Include the caps.

3. Teh motor: Maxing BSHP at a single RPM seems trivial, but the Chevy Volt PR never seems to mention it. Get a diesel if at all possible (probably not), or a geo metro with custom cams (note that the Atkinson cycle will give you fits...)

4. The body. Ask yourself long and hard why you aren't using either a miata or a Saturn. If you are my size, you don't need to ask (but you might lower the seats in an SC2...). The only way you are going to have modern safety is going the Loremo way (megabucks), but you might accept a little less safety for a lot less weight.

5. Starter engines. Just because they can't power the car doesn't mean they are useless. I suspect a little "e-nitrous" (a lot more power for a very short time) could come in handy (make sure you have the ultracaps charged...).

One final note. Most of these thoughts came from an EE who has never built anything (professionally) with an electric motor. Also most thoughts were generated thinking up ways to soup up my parent's golf-cart (holidays with them are boring, a project would help...).

10-13-2008, 11:09 PM	#23 (permalink)
wumpus EcoModding Lurker Join Date: Feb 2008 Location: Maryland, USA Posts: 39 Thanks: 0 Thanked 0 Times in 0 Posts	Bluebomberman, I hope you understand you are talking a megabucks build... some other thoughts (since I've let this rattle around in my head a few times...: 1. Microcenter sells huge batches of NiMH AA batteries. Just make a PCB to fit and put several hundred (by buying in batches >50). Before you pull the trigger, make sure you check all the laptop replacement batteries (especially non-name-brand replacements) by Whr/$ I know the homebrew electric bicycle I've seen nearby used laptop batteries (possibly scavenged, I didn't ask), this might be a better deal. 2. You probably want ultracaps. They will take any amount of charging (i.e. regernerative breaking) until full. Expect close enough to perfect efficiency (I'm basing this off of "normal" caps., these are close enough to 100% to ignore the losses in tuning applications, I've hear ultra-caps are chemical based (essentially a hybrid capacitor/battery beast) and might be different)). Note that with lead-acid, pulling any more than half the maximum amount of power out of the battery takes a 50% efficiency hit, if not more. Include the caps. 3. Teh motor: Maxing BSHP at a single RPM seems trivial, but the Chevy Volt PR never seems to mention it. Get a diesel if at all possible (probably not), or a geo metro with custom cams (note that the Atkinson cycle will give you fits...) 4. The body. Ask yourself long and hard why you aren't using either a miata or a Saturn. If you are my size, you don't need to ask (but you might lower the seats in an SC2...). The only way you are going to have modern safety is going the Loremo way (megabucks), but you might accept a little less safety for a lot less weight. 5. Starter engines. Just because they can't power the car doesn't mean they are useless. I suspect a little "e-nitrous" (a lot more power for a very short time) could come in handy (make sure you have the ultracaps charged...). One final note. Most of these thoughts came from an EE who has never built anything (professionally) with an electric motor. Also most thoughts were generated thinking up ways to soup up my parent's golf-cart (holidays with them are boring, a project would help...).