[ausev] Cold weather and lead acid batteries

[Ken Thomas]

The charger input is a cord that plugs into a 120 VAC mains wall 
outlet. The heater wire system is connected directly across the 120 VAC 
mains input to the charger from the wall outlet. There is a junction 
connection inside the vehicle between the 120 VAC plug on the vehicle 
and the charger inside the vehicle. The heater wire system is connected 
at that junction.

"Parallel" simply means that the two wires from the heater is connected 
to the two wires going to the charger. The two wires in question are 
the Neutral (white) and Hot (black). That is, one heater wire connects 
to the black wire and the other heater wire connects to the white wire 
- along with the charger.

Hope that helps!

Ken

PS. IMPORTANT: If you are using a charger that runs off of a 240 VAC 
input, the heater wire will need to be 50' long. 25 feet at 120 VAC is 
about 9 Watts per foot, which will warm the wire to the touch. 25' at 
240 VAC would be about 18 Watts per foot, which would be hot enough to 
melt plastics and burn you if you touched it. 50' at 240 VAC will 
maintain the 9 watts per foot.




-----Original Message-----
From: JohnFM <johnfm101 at gmail.com>
To: AustinEV News Announcements and General Discussion 
<ausev at austinev.org>
Sent: Wed, 17 Dec 2008 8:16 pm
Subject: Re: [ausev] Cold weather and lead acid batteries



That's a pretty good trick. One question, what do you mean by
paralleling it across the charger "input"?


On Wed, Dec 17, 2008 at 8:01 AM, Ken Thomas <kenscircus at aol.com> wrote:
> I got some resistance wire, 25' of HWR-21168 from
> www.refrigeratorparts.com and a couple pop-switch thermostats, stock
> number 802-STO-60, from www.mouser.com.
>
> All 25' of the resistance wire was snaked around the batteries. The
> batteries are split into two compartments so a thermostat is installed
> in series with each section of resistance wire. Each compartment gets
> 1/2 of the 25' but it is all wired in series. So, either thermostat
> will turn the whole thing off.
>
> The heater wire system draws 1.9 amps at 120 volts or 228 Watts. The
> wire is 2.5 Ohms per foot. The thermostats will keep the compartments
> at about 50 degrees Fahrenheit. Still a bit cool but much better than
> 30 degrees. It will never turn on above 50 degrees.
>
> The 1.9 Amps is low enough that it can be paralleled across the 
charger
> input without undue mains load while charging. I just leave it plugged
> in all night (which I always do anyway) and it keeps the batteries 
from
> getting lethargically cold.
>
> Thanks,
>
> Ken
> _______________________________________________
> AusEV mailing list
> AusEV at austinev.org
> http://www.austinev.org/mailman/listinfo/ausev
>
_______________________________________________
AusEV mailing list
AusEV at austinev.org
http://www.austinev.org/mailman/listinfo/ausev