Battery charger for 12 volt source

[mspirito]

Is it ok to use a battery charger for a 12 v source when testing things like horns clocks, etc?

[Chuck.H]

it's ok for little things, but I've found they have too much voltage/current manipulation within them, that they might not provide good voltage for low current situations. I find it better to use an old battery, or, for indoor stuff I use a radio-shack 12v source that has positive and negative terminals, plus a cigarette lighter charger. This charger has come in handy when all the phone chargers go missing and you resort to charging your phone inside with the car adapter.

Chuck.H
'89 TurboLookTarga, 346k miles

[mreid]

Absolutely! I've use my 10a charger to check the wiring and operation of every car I've wired. Works on everything but the starter.

[hcoles]

sub.
the volt level output will be higher than 12v but may be typical (13.5-14.5v?) for a running engine, I don't see why using it as a source would be an issue. Let's see what others say. It should not hurt anything because e.g. the clock is attached when you charge your battery using the charger and as far as I know there is no damage and the clock continues to work. Some charger may have a "high" charge rate mode, so you might want to use the "low" charge mode or at least check with a volt meter.

[wwest]

Originally Posted by mspirito

Is it ok to use a battery charger for a 12 v source when testing things like horns clocks, etc?

Only if what you have is a "DUMB" charger. Some chargers, even relatively inexpensive ones, will try to detect the current state of charge and go into "fault" mode if it doesn't sense a battery type load.

Stupid inexpensive, <$1.00, microprocessors.

[HawgRyder]

Most chargers have no capacitors inside to keep the "ripple" down.
This means you are not getting true DC...but DC with an AC component.
Depending on the device you are trying to power...it may damage the device.
Better to use a charger connected to a battery to power your setup.
Bob

[wwest]

Originally Posted by HawgRyder

Most chargers have no capacitors inside to keep the "ripple" down.
This means you are not getting true DC...but DC with an AC component.
Depending on the device you are trying to power...it may damage the device.

Better to use a charger connected to a battery to power your setup.

Yes, but NOT a battery with relatively unlimited current "supply".


Bob

I really can't think of anything that might be damaged by "pulsating" (~18 vollt "peak") DC voltage vs an actual DC voltage level. Most solid state devices will have a substantive electrolytic filter capacitor at the "head-in", some even with a proetctive diode.

[timmy2]

I have a 2,10, 50 amp charger I use all the time for testing. Just put a fuse in the line somewhere to protect yourself.

[wwest]

Originally Posted by timmy2

I have a 2,10, 50 amp charger I use all the time for testing. Just put a fuse in the line somewhere to protect yourself.

Most chargers in that "class" have self limiting output current in the 2 and 10 amp position, meter just sets there pegged. In the 50 amp position it has a self-resetting electronic breaker.

[timmy2]

Originally Posted by wwest

Most chargers in that "class" have self limiting output current in the 2 and 10 amp position, meter just sets there pegged. In the 50 amp position it has a self-resetting electronic breaker.

I knew that, the fuse is to prevent me from shorting things out as I fiddle with them!
Been an electrical tech for 30 yrs, been there done that...

[HawgRyder]

I guess I'm spoiled...I have a very big current and voltage limited supply to work with on the bench (capable of more than 50 Amps).
But I still stand by my previous statement...have a battery in the circuit to work as a ripple limiting device just for safety sake.
And...I have tested some battery chargers on a scope...and found that depending on full wave or bridge style recifiers, there can be as much as 4 times the output voltage in ripple.
This means that possibly (not every time) you could have 48Volts of spike on the output of the charger.
In an integrated circuit...once again...dependent on the type...48 volts would destroy the ICs.
Some ICs are so fragile (usually not used in cars) that anything over 5% of rated voltage can turn them to junk.
I remember a new tech testing components one time with an old DVM...and saying all the chips were bad....they wern't before testing...but the 9V battery in the DVM had killed them!
Bob

[anders88]

The 12V battery charger output level is greater than 12V. Check the battery charger voltage before using in any applications. If this voltage is suitable for your application use the charger with ripple capacitor at output of charger.

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