Re: (ET) 12 v marine batteries

["David Roden" <etpost drmm net>]

On 30 Jan 2019 at 18:44, Chris Zach wrote:

> remember, twice the voltage means half the amps

I'm not an EE, just a hobbyist, but that's not what I learned.  Ohm's law 
says that I = E/R, so for a given load, current is directly proportional 
to 
voltage.  

The situation is more complicated when the motor is running at normal load 
and speed (back EMF and all that), but my concern would be with what 
happens 
when you get to the end of travel, or have a very heavy load that keeps 
RPM 
way down.  Under stall or near-stall conditions, double the voltage means 
about double the current.   

It's the current that makes the heat that burns out your armature.  That's 
part of what the fuse is supposed to protect against.  But since it's 
still 
current that concerns you, not power, I don't see the need to halve the 
fuse's rating.  I'd think that would just cause nuisance opens.  What am I 
missing here?  


David Roden - Akron, Ohio, USA

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 
Note: mail sent to the "etpost" address will not reach me.  To send 
me a private message, please use the address shown at the bottom
of this page : http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =