Re: How to use variable AC/DC power supply

On Sat, 17 May 2008 18:45:15 +0100, Dave Plowman (News) wrote:

In article
<ee259986-a06e-40fb-b75d-c91048ced1e0@xxxxxxxxxxxxxxxxxxxxxxxxxxx>,
CharlesBlackstone <charlesblackstone1@xxxxxxxxxxx> wrote:
Hi, I bought a variable voltage variable amp power supply to use
charging my RC batteries:
http://shop.vendio.com/evan2002/item/857080628/index.html

I don't really understand it much though. First, should I never turn it
on if there is no load?

I will use it with either a nicd/nimh charger or a lipoly charger. In
either case, should I turn the voltage to 12 volts, and the amps to the
maximum (10), then turn on the charger? Should the charger be hooked up
and turned on with a battery connected to be charged, before I turn on
the power supply?

Thanks very much in advance for any guidance.

Seems to be a very expensive way to buy a battery charger. A bench power
supply like this is designed to provide clean stable DC for electronics
use - which you pay dearly for. Nor will it monitor the battery
condition and adjust the charge to suit.

OK, this is what you do. You will need a diode with at least a one ampere
rating. Connect the cathode, that is the lead that is next to the band
around the body, to the positive binding post. If your batter is rated
at, say 12 volts, get a 12volt auto lamp rated at one amp, like one for
the tail light. Hook it to the remaining lead of the diode. Now set the
voltage on power supply to 13.6 volts. Next connect the positive terminal
of the battery to the free lead of the lamp. Connect the negative lead to
the negative binding post.

If the battery is not charged at all, the lamp will glow brightly as the
current flows into the battery. It should dim over time as the battery
charges up. If it doesn't, then the battery may be dead. If you have a
voltmeter, check the voltage of the battery every now and then. If it
reaches 13 volts or so, it will be fairly charged.

If it is a 6 volt battery, get a 6 volt, 1 amp lamp, and set the power
supply to 7.2 volts.

Other battery voltages will take other values for the lamp. If you have a
7.2 battery, put a 6 volt and a 1.5 volt lamp in series. Set the voltage
to 9 volts on the power supply.

What does the lamp do for you? It limits the current inrush to a
discharged battery and gives you a rough idea of the state of charge of
the battery.

The diode prevents a mistake where the voltage on the battery is higher
than that set at your power supply. You don't want the battery to be
pushing current into your power supply.

Experiment and have fun!

Al
.

Relevant Pages

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