Electronics

fancy nospam tunes · Guest

Thinking of buying a variable DC power supply to recharge an electric
scooter's sealed gel lead acid battery. However, when trying out two
models from the same manufacturer, their voltage displays aren't
consistent:

The less powerful model (0-3amps) shows actual voltage, as it rises
from actual voltage, until it stops at the target voltage [using
Constant Voltage mode.] Whereas the more powerful model (0-10 amps)
shows only the target voltage; requiring the user to use a multimeter
to view the actual, rising, voltages. I personally prefer to see the
actual voltage.

Can someone explain why these power supplies' displays differ?

Second newbie question: Is the more 0-10 amp unit a more
"professional" design? I'd like to have a power supply that doesn't
self-destruct as soon as the warranty expires.

All perspectives totally appreciated. Cheers!

Re a layman's question: Digital display of power supply supposed to
show actual or target voltage?

. · Guest

Greetings..

There's this wonderful FREE Search engine portal called Google
(http://www.google.com/) which you can either go to directly OR
through online services like Yahoo.com. Why do I mention this? Because
questions such as yours can be answered by doing simple Google
searches! For example, doing a few searches on charging circuits and
or battery chargers yields the following:

http://www.ragebattery.com/power_sonic_chargers.html
http://www.batterystuff.com/
http://www.jcwhitney.com/webapp/wcs/stores/servlet/Product?storeId=10101&Pr=p_Product.CATENTRY_ID%3A2006100&TID=1544&productId=2006100&langId=-1&catalogId=10101
http://www.automotive-battery-chargers.com/

For the Do It Yourself (DIY) folks:

From the simple:
http://www.electronicsforu.com/EFYLinux/circuit/Mar2003/cir4-lead-acid.pdf

To the more complex:
http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=6389

For the more technically inclined:
http://www.geocities.com/vk3em/sla-charger/sla-charger.html

Then of course there's the good folks at Advanced Auto Parts at a
store near you: (this is not to mention Sears too..)

Advanced Auto Parts
Schumacher SE112S ~ $29.98
Battery Charger: 1.5 Amp Fully Automatic
Onboard Maintainer/Charger

Personally, the first place I would check would be your discount
warehouse type stores. Sam's or the Price Club depending on where you
are in the USA. IF they don't have what you're looking for venture
(often times) next door to Walmart. They usually WILL have a small,
automatic, trickle charger at a price that will be hard to beat.

The point here is it's probably NOT worth the effort, OR your time for
all that you're going through for a simple automatic trickle charger!

Today's automatic trickle and float chargers are [often] based on
specific integrated circuits which anyone can obtain IF you desire to
build your own. IF that's the case, up above, there are some DIY links
that you may want to explore that reveal from simple to more complex
circuits. The batteries in question here DO NOT need to be monitored
voltage or current-wise by the owner. It's available in automated
designs that preclude this these days. AND at a price that most can
afford down at your local discount stores.

IF you look at the DIY circuit section, you will find that the
chargers are often based on either a half-wave or, in some cases, a
bridge rectifier design. That's to say it's merely a DC power supply
with current limiting and the ability to monitor voltage and flip over
to trickle (current) charge once the battery comes up to a
predetermined level. In some cases the current can then be pulsed
every so often to maintain charge OR, shut off completely and once the
voltage drops below a predetermined state, automatically flip back to
trickle charge again. This depends on the design of the circuit and
the sophistication of the charger.

G.

fancy nospam tunes wrote:

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