[ausev] Simple charger, was ROI on sustainable technologies

[Rob]

Chris,

Erik and I talked about this a while a ago - he suggested that because 120
VAC is RMS, the actual peak voltage is 170 volts.  Since this is a minimal,
emergency charger then I could take advantage of the >144 volts part of the
waves to charge the battery.  No boosting would be required.

Rob

RMS: http://www.ee.unb.ca/tervo/ee2791/vrms.htm

-----Original Message-----
From: ausev-bounces at austinev.org [mailto:ausev-bounces at austinev.org] On
Behalf Of Chris Robison
Sent: Wednesday, August 13, 2008 3:14 PM
To: AustinEV News Announcements and General Discussion
Subject: [ausev] Simple charger, was ROI on sustainable technologies


A dumb charger is often implemented with a variac, a bridge rectifier, 
and an ammeter and voltmeter. It has no brains, so you have to "be the 
brains" in the sense that you'll need to control voltage with the variac 
knob to prevent the batteries from drawing too much current. And as the 
pack charges, you may have to move the dial to maintain current and/or 
transition from current-limited to voltage-limited charging, as the 
batteries get full. The higher your pack voltage, the more likely you'll 
have to do this.

Most variacs (variable transformers) have some boost on the high end of 
the dial, but I haven't seen one that will produce more than 140VAC on 
120VAC input so you'll probably also need a boost transformer if you 
want to go that route.  I'd suggest getting a 240VAC rated variac, if 
your intended charging context would allow for it.  240VAC variacs are 
much harder to find used (there aren't any on eBay as I write this) but 
they can be found. I bought one a couple years ago for peanuts.

  --chris




Roy Holder wrote:
> At 10:54 AM 8/13/2008 -0500, you wrote:
>   
>> Scott,
>>
>>  I love driving the RAVolt and am always glad that I put in the 
>> effort to create it.
>>
>>  Batteries are stable @ a comfortable 20 mile range (meaning I 
>> don'
>> No leaks.
>>
>> I'd like to build an oh-sh!t charger: one w/o any brains that 
>> just dumps rectified 120 RMS VAC into my 144 VDC pack while I monitor 
>> it- does anyone have some ideas or plans?
>>     
>
> The 'no brains'  charger I think would quiclky cause a breaker trip. 
> you would typically be limited to 16 to 18 amps on the 120vac side w/o 
> power correction(more brains..), maby less depending or the state of 
> the core and coil inverter.
>
> I use a russco 120vac charger as my main charger.  I specifically 
> chose the 120vac version so I could charge anywhere.  It works real 
> nice and I can adjust the amps to match what is available.  I know it 
> cost a lot more than a basic rectifier, but I think the batteries are 
> worth it.
>
> My trojan J150 batts are 2 years old now and I still drive 20 miles a 
> day, with accasional trips of 25 to 28.  I hope you have as good a use 
> out of your batts as mine.
>
>
>   
>> Rob
>> & EValbum 995
>>
>>
>> On Tue, Aug 12, 2008 at 4:03 PM, Wieser Scott <Scott.Wieser at irs.gov>
wrote:
>>       & proactive. Also, how is  the ravolt&#39;s batteries doing?  
>> We&#39;re all in this  together,   Scott  
>>  No virus found in this incoming message. Checked by AVG - 
>> http://www.avg.com  Version: 8.0.138 / Virus Database: 270.6.2/1609 - 
>> Release Date: 8/13/2008 6:43 AM 
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