9-volt battery question.


Active Member
Can you power 9-volt cameras directly from batteries besides standard 9-volt alkaline/nicad/NiMH? For example, my camera power box has a lead acid 7amp hour backup battery. Could I wire a camera directly to it?

Background is for my rover project. The 9-volt on the wireless camera drains too quickly. The rover has enough power to carry some additional weight. I saw a y-splitter that will let the wireless camera run off of 2 standard 9-volt batteries, but I was still hoping for double that.

Is there a not-to-complicated way of running like 4 standard 9-volts together?

I'm not an EE, and you don't mention the voltage of your lead acid battery (guessing 12v) , but most low voltage DC equipment has a pretty wide tolerance . . .

. . . you can wire 9v batteries in parallel (ie: all + on one wire, all - on another) to increase amp rating . . . batteries in series (+ to -, like multi-cell flashlights) ups the voltage . . .

Pete C
Perfect! The Series vs Parallel is what I was looking for, I thought it should be easy, but was worried about raising the voltage.

Yes my led acid batteries are 12v and most my camera take that. I did not mention it because I figured they cam in 9-volt too...


(I have a volt-meter, but then I wouldn't have anything to post about on here =)

. . . as far as your rover goes, I'd bet you could run it all on one battery . . . use the diodes as Paul H suggested for each set of power wires to the different loads , but again, most of this equipment is pretty tolerant . . . the diodes are also a 'load' and using them will shorten battery life . . .

Paul H,

. . . just what kind of bad things might happpen running a 9v motor or camera on 12v, I figure a little overheating and subsequent shortening of lifespan . . . but in real terms, any idea ? . . .

. . . anybody ?

Pete C
You can use a 7809 regulator which will not need any additional components. Or a just a zener diode.

The power loss with either will be minimal

Keep it simple and there will be less gremlins
You can't use a zener diode alone to regulate a voltage unless the load you are powering uses very little power (less then 50 mA). Zeners are normally used to generate a reference voltage that is then used with a regulator circuit. The easiest way is to use a 7809 regulator as previously mentioned. If you can't get that easily but you have a bunch regular rectifier diodes handy (eg: 1N4001) then you can put several of them in series to produce the required voltage drop. Each diode will drop about 0.6 volts so to drop a 12 volt source down to 9 volts, five such diodes in series will give you approximately the 3 volt drop that you want.
Digger said:
You can use a 7809 regulator which will not need any additional components.
True Digger, but I was a little worried about its one amp rating in this application (might have misread the original OP's specs). Anyway HERE is a good schematic showing it in action if needed.
I thought the 9V was for a small camera. Most cameras dont need that much current but that should be verified.
The tank is 7.2v, the camera is 9volt.

It is all I am running of it at the moment. Most of my 9-volt cameras will take 12-volts, but I have also burned up a few of the little wireless ones, so I am hesitant on the 12-volts, but could always get another camera.

Now that I think about it, some of my wireless cameras use 8-volt ac adapters, so I wonder if the 7.2 volt RC battery is close enough to run the camera. Or what if I had an RC car that used a 9.6volt battery, then I could run the camera straight off of the RC car. hmmmm

I love my tank and have contemplated getting another one for spare parts and allow me to cut open my current one. I have also contemplated moving to a professional RC truck and gear it down. So this will affect that descision as to what voltage I get in the new vehicle or whether I can stay with 7.2v.

Anyways, thanks for all of your input guys.