On 06/04/18 10:37, Dave Plowman (News) wrote:
In article ,
Tim Watts wrote:
£100 for a simple PSU - and they still couldn't make it properly? Jesus
wept

Sounds like a good application for a 200VA transformer, bridge rectifier
and nice lumpy heatsink.

Think you'd be hard pressed to make a 20 amp limear supply to retail at
about 100 quid?


There are some switch mode ones around which aren't bad, mainly for the
amateur radio market BUT they are power supplies not chargers- which is
(hopefully) what was being used to charge the battery in the motorhome.
A proper charger will help ensure the battery/batteries are not over
heated etc and, assuming the motorhome has a proper smart controller,
interface with it to ensure the vehicle battery is also charged when on
mains, the leisure battery/batteries are charged by the vehicle when the
engine is running, and interface to any solar system.

I think the charger in mine is about £140. Allowing for the extra
functions it has, over and about a basic switch mode PSU, and its
quality, it isn't a bad price. I'm not sure how expensive the main
control unit is- several hundred at a guess.


Sticking in just a transformer, rectifier, etc is a sure fire way to
ruin a leisure battery BDQ.


'Ready made' conversions seem to come with integrated 'smart'
electronic/electrical systems these days. Mine has a unit which controls
the 12V and mains- well the breakers for the mains- and interfaces with
the vehicle system and a battery charger. It does everything from
controlling the 12V master switches to sensing water levels in fresh and
waste tanks. Later ones even interface with your phone.


Those who do their own conversions seem to go for discrete
sub-subsystems- you can buy sensors and displays for water levels etc. -
and simply install a domestic consumer unit and a battery charger etc.

To comply with the 'construction and use' regs, much of the 'domestic'
electrics should be disabled when the vehicle is in motion- the
commercial control boxes do this but I suspect most self builds don't
bother. No doubt, in time, someone will decide this needs to be checked
as part of the MOT ;-(