Re: (ET) Fully charged pack voltage

["David Roden" <etpost drmm net>]

On 23 Apr 2009 at 12:59, Michael S Briggs wrote:

> In principle, this should allow a person to use a Kill-a-Watt meter
> where the charger plugs into 120V to make a decent estimate of when
> the batteries are charged 

Interesting idea!  Of course you'd still have to watch the meter, so I'm 
not 
sure how much you'd gain over having a voltmeter and ammeter on the 
battery 
side of the charger.  But if you're tracking energy in anyway, it could 
serve as a rough approximation.


> Of course, the charger isn't 100% efficient - I would guesstimate maybe
> 90% efficient? 

Hmm.  I'd guess closer to 80-85%, maybe even less.  Ferroresonant chargers 
tend to waste somewhat more energy as heat (and noise!), compared to 
linear 
and switching chargers.

If you have a good DMM, you should be able to measure the charger's output 
and then compare it with your wattmeter's reading.  That would give you a 
rough idea of its efficiency range.  Keep in mind that the efficiency will 
vary with load and mains voltage.


David Roden - Akron, Ohio, USA

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