Search found 363 matches

by Jeremy
Sat Aug 16, 2008 12:56 pm
Forum: All things battery related
Topic: EV managment module
Replies: 37
Views: 26474

I'm not sure that it's ever truly possible to design out the "numpty factor". No matter how many safeguards you put in, I'm reasonably sure that a truly creative numpty would find a way around them. It could be argued that creating safeguards just adds to the problem, by allowing complacen...
by Jeremy
Sat Aug 16, 2008 7:49 am
Forum: All things battery related
Topic: I have found the ultimate batteries for any EV!!!
Replies: 9
Views: 6094

Re: high selfdisharge for nimh ??

I know they go flat after a day or two with smaller cells - that could be a drag any views to back this up with bigger packs ? I'm not quite sure what you mean above. The self-discharge rate of NiMH is fairly high, but usually less than about 1% or so per day. The useful range of a couple of 1300 w...
by Jeremy
Sat Aug 16, 2008 7:26 am
Forum: Electric Motor Bikes
Topic: Yamaha RD50MX project
Replies: 24
Views: 20721

Kelvin, If you ask for Steve Endersby at the Poole office I'm sure you won't have too much trouble. He's a young chap, fairly new to the job I think, but very helpful indeed. He drove up from Poole to Salisbury specially to inspect my bike.

Jeremy
by Jeremy
Sat Aug 16, 2008 7:21 am
Forum: All things battery related
Topic: WHY USE HIGH VOLTAGE DRIVE SYSTEMS
Replies: 26
Views: 17749

Paul's summed up things well, but it's worth remembering that cables are the really easy bit to reduce resistive loss. It's much, much harder to reduce the resistive losses in the motor, brushes, controller and most importantly the battery cells. To reduce controller losses means, in essence, adding...
by Jeremy
Sat Aug 16, 2008 7:07 am
Forum: All things battery related
Topic: EV managment module
Replies: 37
Views: 26474

To be fair, it's not just lithium cells that need some form of battery management. Nickel chemistry cells can be irreversibly damaged by being allowed to reverse in a series string due to one cell depleting ahead of its colleagues, so some form of BMS is useful. Even lead chemistry cells can be kill...
by Jeremy
Fri Aug 15, 2008 6:18 pm
Forum: Electric Motor Bikes
Topic: Electric motorcycle race in Isle of Man TT
Replies: 53
Views: 31283

Synchronising is a doddle, modern brushless controllers self-synch exceedingly well, even if the motors are locked onto a common shaft, with no pole alignment. Starting performance is dependent on the particular controller start algorithm, but Castle Creations seem to be on the ball and currently ap...
by Jeremy
Fri Aug 15, 2008 5:46 pm
Forum: All things battery related
Topic: EV managment module
Replies: 37
Views: 26474

EVguru wrote:But I do reserve the right to say 'Told you so!'.


I can assure you that I absolutely will not give you that opportunity!

It's worth remembering that we are not all numpties who have a total disregard for the physics and chemistry that underpins our projects............

Jeremy
by Jeremy
Fri Aug 15, 2008 4:33 pm
Forum: Electric Motor Bikes
Topic: Electric motorcycle race in Isle of Man TT
Replies: 53
Views: 31283

The prop actually blocks airflow in the centre, so the slipstream isn't very effective either. This is one reason that aircraft tend to use cooling intakes that are spaced some distance out from the prop centre. The slipstream can be used very effectively to pull air through a cowl, using an extract...
by Jeremy
Fri Aug 15, 2008 4:05 pm
Forum: All things battery related
Topic: EV managment module
Replies: 37
Views: 26474

I appreciate your views, Paul, but it does depend very much on how the cells behave under load, the application vehicle type and the understanding of the operator. In my own case, this is for my own vehicle which will be carefully operated to avoid cell damage. I've incorporated a meter that reads t...
by Jeremy
Fri Aug 15, 2008 6:42 am
Forum: All things battery related
Topic: I have found the ultimate batteries for any EV!!!
Replies: 9
Views: 6094

There are some problems with using Prius cells in a deep discharge application. The NiMH cells in the Prius pack are optimised for very long life and very low cycle depth. They are unable to recombine effectively if charged above about 95% and will gas. Several people who have tried using Prius cell...

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