Search found 103 matches

by bobc
Mon Oct 18, 2010 5:43 pm
Forum: General
Topic: Greenpower Finals Yesterday
Replies: 2
Views: 3717

Greenpower Finals Yesterday

Bad timing for those who missed it, the BVS had a stall and some demo EVs at the Greenpower national finals yesterday. Thought I'd post 'cos we won again (yee Hah), both races & broke the all time lap record - yes we had a very good day! Quite apart from that, it was a really nice day (apart fro...
by bobc
Wed Aug 18, 2010 8:14 pm
Forum: All things battery related
Topic: Experiment with li- poly batteries in a greenpower racecar
Replies: 16
Views: 17704

Re: Experiment with li- poly batteries in a greenpower racecar

interesting, you've gone the individual cell charger route too. There's a couple of downsides with the fixed voltage charger; allegedly you charge to 4.2 but should then pull the power - the dedicated li charger chips have this state machine built in. Plus they flash indicator LEDs at you to tell yo...
by bobc
Wed Aug 18, 2010 12:39 pm
Forum: All things battery related
Topic: Experiment with li- poly batteries in a greenpower racecar
Replies: 16
Views: 17704

Re: Experiment with li- poly batteries in a greenpower racecar

Jeremy - once again, great spot with that hobbyking battery monitor thing. I was going to build in a stack of LCD DPMs - one for each battery, but this thing is better, cheaper & ready made to do exactly what I want - excellent! PS I should clearly spend much more time browsing the hobbyking cat...
by bobc
Wed Aug 18, 2010 12:29 pm
Forum: All things battery related
Topic: Experiment with li- poly batteries in a greenpower racecar
Replies: 16
Views: 17704

Re: Experiment with li- poly batteries in a greenpower racecar

I've not got onto endless sphere, maybe I should take a browse.... I read the "horror stories" on an RC forum, some guy had compiled all the "my lipos just blew up" he could find, and there did seem to be quite a few. Typically there would be an unstoppable fireball 20 minutes af...
by bobc
Tue Aug 17, 2010 8:04 pm
Forum: All things battery related
Topic: Experiment with li- poly batteries in a greenpower racecar
Replies: 16
Views: 17704

Experiment with li- poly batteries in a greenpower racecar

Hi Gents, been a while since I posted. We tried some 20C 2.2Ah model aircraft batteries in our greenpower racecar in place of the lead acid standard batteries. I was particularly interested in the performance at high discharge rates for my current project. Anyway here is a photo of the "install...
by bobc
Tue Oct 13, 2009 11:21 pm
Forum: General
Topic: Greenpower final this weekend
Replies: 1
Views: 3732

Greenpower final this weekend

The national final of the greenpower electric race series for schools is happening this Sunday at Goodwood racing circuit near Chichester. Check http://www.greenpower.co.uk Some good exhibits this year (bloodhound mockup, IoM TT winning electric bike, Lynch motors) plus the 2 races. First in a.m. th...
by bobc
Tue Jun 02, 2009 11:54 am
Forum: General
Topic: ac motor
Replies: 1
Views: 3425

OK I have my calculator handy.... 240V x 5.3A = 1272VA it's less watts going in because of "power factor" - the phase angle of the current. Wild guess power factor = 0.75, that's 954W into the motor. How efficient is it? who knows - guess at 75% again - that's 715W mechanical output. 715W ...
by bobc
Mon Jun 01, 2009 8:02 pm
Forum: General
Topic: 10kW BLDC outrunner drive
Replies: 18
Views: 23952

I really appreciate your continued help Jeremy - that could have been an expensive thing to find out the hard way! This is the solder side of the board; it's just a bit of logic, gate drives and a switchmode chip. I've steered clear of micros because those projects can acquire a life of their own......
by bobc
Sun May 31, 2009 10:54 pm
Forum: General
Topic: 10kW BLDC outrunner drive
Replies: 18
Views: 23952

I'm aiming to make a set of 10kW drives for this project, that's 4 of the motors above on a single shaft. As Jeremy said in the other thread, the outrunners seem to have the best mix of cost and manageable rpm! His comment about the bearings is interesting: if that's real then I should replace all t...
by bobc
Fri May 29, 2009 9:24 pm
Forum: General
Topic: 10kW BLDC outrunner drive
Replies: 18
Views: 23952

here's the motor going
Image
and the inverter topside (you can't see the SMD stuff)
Image

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