Author Options:

9volt Battery overheating.? Answered

hello i have a question.. i have made a usb charger  using a 9 v bat and a 5 v voltage regulator  but the battery  duracell  overheats way to much... same batt  connected to a led strip 12 v. it works but it overheats as well..... any ideas?

my usb charger is on my page.....

anybody have an idea why this happens?   cheers



Best Answer 4 years ago

The diode as you have shown it in the diagram with the anode on the batt pos is acting like a full short and draining the batt.

If you are looking for reverse polarity protection then the neg band of the diode needs to be connected directly onto the voltage regulator not circuit ground.

The radios where these batts are typically used only draw 20~25mA so if
your device uses much more than that it will drain the batt fairly quickly too.

No, its an LED with a resistor in series with it.

I didnt know what was going on there, leds are usually draw with arrows to show light emitting.

True, but this guy WAS using MSpaint by the look of it....

thanx for your reply .... the diode on my drawing is actually a LED i have connected the Gnd directly to the V regulator. like you advised.
electronics are very new to me this is a good learning step....

i have also put a Diode between the battery {pos} and the switch so the current flows from one way only...

the battery still warms up quickly. and that's with the power off.... and nothing connected to it
i measure the diode Left..........======()=...... Right
i get 9 v from the Left side.... and zero V from the Right side.
this tells me that the current is going trough the Ground side..????

Tthe led should have a biasing resistor to stop the main current flowing through it, start with a 1Kohm inseries with the led and maybe raise the values of the data resistors to 1K as well.

If the batt still warms up with nothing connected then something is draining it, remove components to see what it is.

the battery got to 60 on my multimeter.. pictures shows 29. ??????

Too much power being drawn from a little battery.

Your drawing far too much current from the battery if it is getting warm. Have a look at the spec sheet for that type. Measure the current.