Re: liquid vs direct air heaters

[Seth <vze3v25q@verizon.net>]

I might start with 220V electric water heater elements. I am not sure
how short they can get though. Also for a magnetic blow out relay, I
assume a DC rated contactor like an EV 200 with a magnet for snuffing
the arc would be what they had in mind. If the inrush on the element
isn't too bad, the contacts might survive, otherwise you might need
secondary switching after the contactor, like a pwm circuit.

Seth

Gary Graunke wrote:
> 
> David Roden wrote:
> 
> > If you are going to heat the air in the vehicle, the more efficient way is
> to
> > heat the air directly with a heating element of some kind. IMO, the only
> advantage
> > to a liquid heater is that it's easier to install because you can leave
> the old
> > heater core in place. But it heats up more slowly, and (potentially)
> wastes
> > more energy through losses in the tank and plumbing.
> 
> I noted that some of the EV suppliers sell 1500W ceramic heater cores as
> well--at least one person has presumably thought about approriateness for an
> EV (vs general use).
> 
> I also had some notes from an OEVA meeting on heater relays--the note said
> to use magnetic blowout relays--the others are a fire hazard. However, I
> haven't really found any that have the appropriate DC voltage rating,
> especially for a higher voltage (>200V) pack.
> 
> Since I in the middle of an insight conversion, the heater is on the list of
> things to do. Wayland recommended that, due to the complexity of the insight
> climate control, I use a small liquid system rather than the easier
> replacement ceramic heater under the dash as he normally does. Currently,
> the insight uses a "mix" motor to move a valve to allow varying amounts of
> heat in to the system.
> 
> My US Electricar S10 truck also has a 1500W liquid system, which works well.
> However, it uses 10" by 5" by 8" black box, a 4" x 4" x 7" electrical box,
> and a small fluid resevoir. I'll have to take it apart next time I have the
> pack apart.
> 
> Has anyone else done a liquid system?
> 
> Do you need a pump to circulate the water?
> 
> Is the electrical isolation more of a problem, given the liquid conductor vs
> air?
> 
> Gary

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