Reply by ●March 10, 20142014-03-10
On Sunday, March 9, 2014 8:09:57 PM UTC-4, Andy K wrote:

> I would like to buy a NP 4-6 Yuasa 6 Volt 4 Amp Hour Battery.
> 
> 
> 
> Would this charger work and how do I determine how long to recharge a discharged battery ?
> 
> 
> 
>   Model: HB-0702-01
> 
>  Input: AC100-240V 50-60Hz 0.2A
> 
>  Output: DC7.2V 1.0A
> 
>  
> 
>  I would be powering some led lights that operate at 3.0 volts, so I would need to find out how to step down the voltage as well.
> 
>  
> 
>  Thanks.


Hello,
In general, if a battery is rated at X Ampere 
Hour, the maximum charging current can be X/10 
Ampere, in this case 0.4 A, or 400 milliAmpere. 
So, an appropriate current limiting resistor at
the output of the 1.0 A power supply would work. The output voltage of the charger is fine, as it has to be slightly above the rated maximum
voltage of the battery, in order to charge it.
As for the LED lamp itself, what is the number 
LEDs to be used, and what is the average number
of hours of use ? Note that as the battery voltage is just 6 V maximum, all the LEDs need
to connected in parallel, each with a series 
dropping resistor of appropriate value. Hope that helps.
Reply by Jeff Liebermann ●March 10, 20142014-03-10
On Sun, 9 Mar 2014 17:09:57 -0700 (PDT), Andy K
<andrewkennedy775@gmail.com> wrote:


>I would like to buy a NP 4-6 Yuasa 6 Volt 4 Amp Hour Battery.


Like this?
<http://www.ebay.com/itm/171258184100>
URL's are always helpful:


>  Model: HB-0702-01
> Input: AC100-240V 50-60Hz 0.2A
> Output: DC7.2V 1.0A
> 
> I would be powering some led lights that operate at 3.0 volts, so I would need to find out how to step down the voltage as well.


Good question.  It's difficult to tell from the advertisements, which
offer no useful numbers or information:
<http://www.tmart.com/HB-0702-01-7.2V-1Ah-US-Standard-2-Flat-Pin-Plug-Charger-for-Lead-Acid-Batteries-Black_p226230.html>
The problem is that it claims to charge "lead-acid" batteries, which
in the common jargon for a flooded lead acid battery.  Those have a
different charging profile from an SLA (sealed lead acid) battery,
such as your proposed Yuasa battery.
<http://batteryuniversity.com/learn/article/lead_based_batteries>


>Would this charger work and how do I determine how long to recharge a discharged battery ?


You do not make that determination.  Presumably, modern chargers have
a way to detect EOC (end of charge) and either turn off or switch to a
low level "float" charge.  If you are counting on running a timer to
determine the EOC, you will need to know the state of charge of the
battery when you start charging, or you could easily overcharge and
kill the battery.  For the prices found, I doubt if the HP-0702-01 has
any intelligence inside.

I suggest you start with a 12V system as components are common and
generally cheaper.  Something like this for a charger:
<http://www.ebay.com/itm/231064439281>
According the above datasheet, it will charge any 12V gel cell from
2.5 to 10Amp-hr.  The common 7Amp-hr gel battery should work.

For driving your LED lights, it would be helpful if you provide some
clues as to how many lights, what type, wattage, how they are wired,
and what you plan to do with them.  You can't just tie a mixed
collection of random LED's in parallel, apply 3.0VDC, and expect them
to light up equally.

-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558
Reply by Tim Wescott ●March 9, 20142014-03-09
On Sun, 09 Mar 2014 17:09:57 -0700, Andy K wrote:


> I would like to buy a NP 4-6 Yuasa 6 Volt 4 Amp Hour Battery.


That's nice.


> Would this charger work and how do I determine how long to recharge a
> discharged battery ?
> 
>   Model: HB-0702-01
>  Input: AC100-240V 50-60Hz 0.2A Output: DC7.2V 1.0A


First, this is an electronics design group, not a consumer devices review 
group.

Second, you don't report on a brand, or what the charger purports itself 
to be.  If it's labeled as being for sealed lead-acid batteries, then it 
may well work.  If it's a name brand then the chances go up higher (but 
not, unfortunately, to 100%).  The "Output:" rating looks more like 
something for a wall-wart, but could conceivably be for a battery charger.

If it's a decent charger, it should tell you when the charge is done, or 
it should automatically go to float charge mode.


>  I would be powering some led lights that operate at 3.0 volts, so I
>  would need to find out how to step down the voltage as well.


This deserves a whole separate thread.  Isn't there anything in your 
"step down a 12V battery voltage" thread that's helpful?

The whole kit and kaboodle belongs in sci.electronics.basics, for that 
matter.

-- 
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
Reply by Andy K ●March 9, 20142014-03-09
I would like to buy a NP 4-6 Yuasa 6 Volt 4 Amp Hour Battery.

Would this charger work and how do I determine how long to recharge a discharged battery ?

  Model: HB-0702-01
 Input: AC100-240V 50-60Hz 0.2A
 Output: DC7.2V 1.0A
 
 I would be powering some led lights that operate at 3.0 volts, so I would need to find out how to step down the voltage as well.
 
 Thanks.