Can we charge a 12V battery with a 9v supply?

[pateljayam]

Hey guys,
I wanted to figure out whether we can charge a 12V 2000MAh battery using a simple 9V charger with 500mAH????
Please help me out

 

[ronv]

What kind of battery?

 

[pateljayam]

Battery 12V, 5Ah
https://www.google.co.in/imgres?um=...w=132&start=0&ndsp=15&ved=1t:429,r:0,s:0,i:70

 

[Reloadron]

Nope:

Minimum voltage
Anything above 2.15 volts per cell will charge a lead acid battery, this is the voltage of the basic chemistry. However, most of the time a higher voltage is used because it forces the charging reaction at a higher rate. The voltage to avoid is the gassing voltage, which limits how high the voltage can go before undesirable chemical reactions take place. The typical charging voltage is between 2.15 volts per cell (12.9 volts for a 6 cell battery) and 2.35 volts per cell (14.1 volts for a 6 cell battery). These voltages are appropriate to apply to a fully charged battery without overcharging or damage. If the battery is not fully charged you can use much higher voltages without damage because the charging reaction takes precedence over any over-charge chemical reactions until the battery is fully charged. This is why a battery charger can operate at 14.4 to 15 volts during the bulk-charge phase of the charge cycle.

The above quote taken from here. That pretty much covered it.

Ron

 

[ronsimpson]

If you had two 9 volt chargers then maybe. (connect in series to get 18 volts)

 

[IntelGent]

As a confirmation of Reloadron's quote and more information than any single person could ever want about batteries....
https://batteryuniversity.com/

And specifically lead acid batteries....

 

[ronv]

I thought I saw some little boost regulators on E-bay that have current limit, but I can't find them now. If you can find one you could set the current limit to C/10 and the voltage just below the gassing voltage and away you go.

 

[pateljayam]

thank you guys!
really learnt a lot.
i had a doubt! can we use a step up transformer with the 9V source and then charge the battery????

 

[colin55]

Can you get to the AC side of the 9v section of the charger?

 

[bountyhunter]

Hey guys,
I wanted to figure out whether we can charge a 12V 2000MAh battery using a simple 9V charger with 500mAH????
Please help me out

There are lots of small boost regs that could be used to do this, but the thing will only put out maybe 300mA so it will take a while to charge the battery.

 

[Mr RB]

Here is a two-transistor boost converter that will convert 9v DC to 12v DC, and has the benefit of being input-current regulated so it will charge at a relatively constant power.

If you tweak a couple of resistor values it should be fine for 9v input at 500mA. For a proper battery charger you should monitor the output voltage, but there are plenty of options for that.

 

[colin55]

Here is a two-transistor boost converter that will convert 9v DC to 12v DC

I could not find the DC to DC converter on your site but the explanation of the 2-transistor SMPS is incorrect.
[MODNOTE]Deleted Off Topic[/MODNOTE]

 

[ronv]

Knew I had seen it somewhere.
This will work. If you have questions just ask.

**broken link removed**

 

[Mr RB]

I could not find the DC to DC converter on your site...
...

Sorry that was my fault!

I forgot to add the link to the 5v->13v converter, here it is;
https://www.romanblack.com/smps/conv.htm