Battery Charger V/Ah - Page 3

 On Thu, 17 Apr 2008 22:13:13 -0700, Dennis Lee Bieber

|>>     I tested some battery chargers last night , and found "as usual"
|>> that the amps and voltages stated on the modules were not the same as what I
|>> found on the Volt and Amp testers....
|>>
|>    HOW did you test? Just hooking a DVM across the leads will not give
|>reasonable readings.
|>
    Right, that's my problem with some of my chargers, since "you can't
believe everything you read on the chargers" that was the best way of
checking the "real" volts/amps, but applying a known  amp load might
help....

|>>     Some 12v charging modules, would say 1.5 amp, whereas the voltage
|>> test was 12-->17v and/or 4-->6amps on the meters....
|>>
|>    A 12V lead-acid battery tends to need >13V to charge, with 14V being
|>a common value.
|>
    There seems to be no other way there, unless you wanna set the
universal Charger to 6-->9v to get a trickle charge, but even trickle
charges tend to sulphate more than just leaving the battery off a
circuit....

 

Most basic chargers have only rectification of the secondary voltage not
smoothing, so the reading with a DMM is likely to be very inaccurate. If you
put an electrolytic capacitor on the output it will charge to the peak
voltage (1.414 x RMS) but as others have stated battery charger transformers
are impedance regulated - that is they have a higher than stated voltage off
load which drops to around 13.8 - 14.4V on load, transformers for general
purpose power supplies (including wall warts) are definitely not suitable
for Pb battery charging unless they have electronic current limiting (like
the LM317 as others have suggested) and then the secondary voltage must be
higher by at least the minimum drop out voltage of the current limit chip.

 On Thu, 17 Apr 2008 22:13:13 -0700, Dennis Lee Bieber

|>    On low-beam (55W I believe), at freeway cruise, my Aprilia only
|>manages 13.5-13.8; on high-beam (35W) it achieves 13.8-14.1 -- according
|>the trip computer voltage display.

That's an interesting observation.....

    That's amazing, I mean the low-beam (55W), unlike the Aprilia, I
have the standard 2 halogens, and they draw 120watts so your system is
different.

     Unless you have a HID lighting system....it's hard to beat the
battery drain from the mains....

    My headlights (mains X2) don't come on till after the scooter is
started, so I'd have a very mission impossible problem to add there....I
suppose your mains work the same way....probably easier to change than a
Majesty400.

Thanx for the nfo.....

 Robert LaCasse wrote:

could you please delete sci.electronics.repair from this thread, as it
seems to be drifting away to a mostly 'motorcycle' issue rather than an
electronic one.  I have no idea what an Aprilia is, nor any desire to know.

Generally speaking, crossposting is frowned upon.

jak

 

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