Re: CANBUS (and a charger wish list)

["David Roden (Akron, Ohio, USA)" <roden@ald.net>]

> The company I am working for is developing a new version of their 
> Can Display unit. ...  common display ...
> estimated range left, battery condition, charge state, diagnostics, 
> trip distance, gps-map data (with charging stations?!), decent 
> speed and rpm displays..    
> 

Much of what you mention for the Can Display is already possible with a 
fully tricked-out E-meter.  If you can do it for about the same money or 
maybe a bit more, and offer greater convenience and robustness (better 
protection for the logic circuitry against careless hookup; one-box 
connection instead of multiple outboard gadgets like DC:DC converters, 
prescalers, and so on) you would have something.

> While we're at it, perhaps there's a market for a good smart charger as
> well?
> 

The conversion sector really needs a flexible smart charger that can be 
programmed by the end user.  The ideal charger would be 

   fully isolated
   light weight
   dual voltage (115/230 volt) 
   independently adjustable input current limit at each voltage
   PF correction standard or optional
   stupidity compensation (reversed output leads, etc.)
   programmable temp compensation (see below)
   at least 4 programmable charge stages, preferably more
   able to move forward or backward through stages
   for charge control, monitors:
      absolute battery temperature (at least 2 probes)
      battery temperature change overall and in current stage
      absolute battery voltage and current
      voltage and current change in current stage
      time in current stage 
      total charge time
      amp-hours charged overall 
      amp-hours charged in current stage
      amp-hours CONSUMED since last charge <= NOTE
   and a way to perform math and comparisons on the above parameters:
      built in add, subtract, multiply, divide operators
      several non-volatile user-accessible memory storage locations
      several volatile run-time user-accessible memory storage locations
   programming software and cables included

Some of these features could be modular (optional at extra cost) for 
those who needed them.  Should be capable of charging packs from 36 to 
360 volts (might require multiple models) and all chemistries, including 
lead, nicad, NiMH and perhaps others (lithium is probably not mature 
enough as a technology to pin down charging specs).

Your benchmark for pricing this charger would be the Brusa range, which 
is out of reach for many hobbyists at over $3,000 ($4,000 if you buy it 
through Solectria).  Build such a charger (using good quality components 
and careful, well-paid labor) for $2,000 to $2,500 fully equipped ($1,200 
to $1,500 stripped) and I think you could sell it.

Does anyone disagree with me?  Flame away!  And thanks for asking.


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1979 General Engines ElectroPed 24vdc
1974 Honda Civic 96vdc
1970 GE Elec-trak 36 vdc