[ausev] Cold weather and lead acid batteries

[Gil Dawson]

Ah, now I see.  Thanks for the explanation.  My apology. -- Gil

On Dec 18, 2008, at 12:06 P, Ken Thomas wrote:
> I am calculating Watts per foot.
> Adding more feet does increase the total disipated Watts, however, the
> goal is to keep the Watts per foot the same.
>
> Yes, Watts = E squared / R or Volts squared / Resistance.
>
> 120 VAC / 25' = 4.8 Volts per foot.
> 4.8 Volts squared / 2.5 Ohms = 9.216 Watts
>
> Or, 120 VAC squared / (2.5 Ohms * 25 feet) = 230.4 Watts.
> 230.4 Watts / 25 feet = 9.216 Watts per foot.
>
> At 240 VAC and 50 feet:
>
> 240 VAC / 50' = 4.8 Volts per foot.
> 4.8 Volts squared  / 2.5 Ohms = 9.216 Watts
>
> Or, 240VAC squared / (2.5 Ohms * 50 feet) = 460.8 Watts.
> 460.8 Watts / 50 feet = 9.216 Watts per foot.
>
> Ken
>
>
>
>
> -----Original Message-----
> From: Gil Dawson <Gil at Gil.Dawson.name>
> To: AustinEV News Announcements and General Discussion
> <ausev at austinev.org>
> Sent: Thu, 18 Dec 2008 11:23 am
> Subject: Re: [ausev] Cold weather and lead acid batteries
>
>
>
> On Dec 18, 2008, at 7:06 A, Ken Thomas wrote:
>> 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.
>
> Isn't E squared?  Wouldn't that be 36 watts and 100 feet?
>
>> one heater wire connects
>> to the black wire and the other heater wire connects to the white  
>> wire
>
>
> When you touch the warm wire put your other hand in your pocket.  And
> don't lean on the car.
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