Model Forum / Radio Controlled / Air Models / May 2004

Well I tell ya......

I was looking for a battery charger that could be used both at home and on
the field.  I was really more concerned with draining out my cars battery,
but then someone corrected me out at the park and told me that my car
battery has aproximately 450amps, and 550cca, so the .7 that I would draw
out of it would be pretty negligble.

So my LHS had a triton only car charger (hook it up to the car battery) or a
MRC superbrain 969 (yes, yes, I know about them now and lipoly batteries,
but Im not planning on charging lipoly with it), that does both, so I plug
it into the house outlet at night and plug it into the car battery by day.

Now the thing that the LHS owner told me is that if I go with the triton, I
can plug it into the car battery, but buy an adapter for the house at an
additional $80.00 which would have made it $200.00 plus tax, so I opted for
the MRC since it came with both a power adapter for home use and a plug to
attach it to my cars battery.

But if I had it to do over again, I'd probably shell out the extra money and
get one that plugs into the car battery, but buy an adapter for it for home
charging.

The point being that you can get usually find a good one that plugs into
your car battery normally, as well as find a home power adapter so that you
can use it at home, and skip the inverter all together when on the field,
after all one less thing to carry in your car.

One thing to be aware of about inverters . . . many have a true square
wave output, and that tends to drive wall warts and other inductive
types of power converters 'round the bend - the converters (wall
warts) can get _really_ hot when fed square wave "a/c".

Many newer (more recently designed) inverters have an output wave form
which consists of many discrete individual steps up and down, not just
a square positive/negative form - these newer inverters are _much_
easier on inductive loads like wall warts.  The transition from zero
to positive max or zero to negative max looks a lot more like a sine
wave, as in true a/c.

One approach is to get dc input chargers, so you can plug directly
into a cigarette lighter outlet or to the car's battery, and also get
a 12 volt power supply for home use.  The power supply will prove to
have many other uses besides driving chargers.

You can also modify an old PC switching power supply to function as a
bench power supply - several web sites have instructions for doing the
conversion.  Operable used PC power supplies can be had for a couple
of bucks if you look around.

dc input chargers are less expensive, and one decent power supply can
support several chargers concurrently.

   Screwing around with inverters adds both unnecessary expense AND
complexity.
   Why not just get one of the chargers that are designed for 12v use
(Alpha4, Miniron, etc.) and be done with it? The Alpha4 comes with a power
supply, while you have to supply your own power supply with the Miniron.
Other (12v) chargers may or may not come with power supplies, but they're
not that expensive if you shop.
   This way, you've got your power supply to leave at home on the bench and
then you can plug either into your 12v/7a field box battery at the field, or
just plug into your car battery at the field. Either way, it makes things
much simpler.

MJC

Get one that works on 12v then get a power supply to use for it at home.  I
would stay away from using an inverter with your charger.

John VB

I do the other way about: Use a field charger at home on an ex-CB 13.8v
power supply.

Its cheaper than an inverter I think.