RE: [Paddlewise] A last turn on Global Warning -> exercise and power -> rechargeable batteries for kayak equipment - will they work?

From: Paul Hayward <pdh_at_mmcl.co.nz>
Date: Wed, 21 Oct 2009 14:48:05 +1300
Craig said on Wed, 21 October 2009 07:09:

> Most of the devices that you can buy to charge a device or battery that
needs 
> less than 12vdc from a car (12vdc) are also pretty inefficient; 

 

Mostly, I use what the manufacturer of the device gave me for using in a car
- that way I know it's well-matched. 

 

I bought one dedicated 'smart-charger' for NiMH AA & AAA cells. It works
_only_ from a 'car' socket (it's not an afterthought capability tacked onto
a 110/240 device). As to how efficient the 'from 12v' circuits are, I
haven't done any tests other than the old "Is it real hot ?" hand test and
they all run so cool as to be undetectable.

 

Some of the cables may be 'smart' and some of the devices themselves may
have 'smart' charging circuits - today that doesn't cost a lot. After all,
in a car cigarette-lighter environment, a device's power-supply should be
capable of surviving quite a wide range of voltage - much wider than my
gel-cell puts out. If you make a device that is destined to run from a car
socket (most cellphones, GPS, VHFs, etc) they will "see" from about 7 volts
(when the engine is being cranked) to 15+ (when charging the 'house' battery
at max) - plus some wicked spikes. I believe that many modern devices deal
with that range more 'smartly' than by just using a resistor.

 

I realise that we are talking about mA here - so it may be moot. I agree
that in a camper or on a yacht or launch it makes complete sense to have a
meaty inverter; but on a kayak I don't see the advantage of carrying the
inverter's bulk & weight, unless there's something I just can't get to run
directly from 12v.

 

Best Regards

Paul Hayward, Auckland, New Zealand
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Received on Tue Oct 20 2009 - 18:49:07 PDT

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