mkshuman
Joined: 15 Jun 2007
Posts: 1
|
 Posted:
Fri Jun 15, 2007 7:37 pm Post subject:
Regulating a rechargeable battery pack |
|
|
I have a couple of projects in mind using a NiMH Battery pack but I want to clear up a few things and figure what I need to do to have them provide clean enough power for the application I want.
First I want to make sure that I am clear on the difference of Rechargeable Batteries like those used in RC Battery packs vs your run of the mill alkaline.
First difference is Voltage Rechargeable(RC) are 1.2V cells while Alkaline(Alk) are 1.5V
NOTE***For this discussion I am talking SubC, C, AA, AAA, 2/3, and Ds only! here where there is an alkaline cell and an equivalent physical sized Nicad or NiMH cell.or in the case of 2/3 or Sub Cs they are an offshoot of a normal sized cell. I am not talking any Lipo or odd sizes here which could be a number of different voltage!
Second Difference is discharge. An Alk Battery are used for lower draw applications and the current coming from the battery will not be high and they are naturally regulated in their output they tend not want to release their energy real fast. Where as RC cells are not so regulated and can provide a steady output of higher current they want to release their energy as fast as they can.
In use terms this means:
That if you were to hook either battery type up to a light bulb which is a resistor and you are not overpowering it in voltage the light will last and not burn itself up because it is regulating the output of both battery types. on the alk since it is not a high draw device it will pull out the current it needs. while with an RC which tends to want to release the power the fact that a light is a resistor it will stop the RC from releasing the power real quick.
The above goes for any device that uses power with built in regulation.
But what if your device is relying on a regulated ac/dc brick or could be set up with a power pack that was using alkaline.
If in this case you connected a RC battery pack to the device you would either burn that device out from over amping it or would just really screw it up and not have it work like intended.
If the above is true this is where my problem lies. One item I would like to do is to take a wireless video camera I have and provide more power for it and longer run time also to be able to get away from rep[lacing batteries.
I have a barn that on different days want to watch different horses in the stall out in the field etc.
I have a wireless camera and a receiver. The camera came with a 8vdc AC "Brick" and also an adapter to plug in a 9v Alkaline to the camera. the AC adapter is bulky and limits my range while the 9v Alkaline are short lived and expensive to replace. This is where a 8.4V SubC Battery pack comes in. Portability with longevity and less expense. But when I hook it up I will get a picture for about 10 minutes then I loose picture. if I unplug it and let it sit for a while and use either the 9V or ac brick everything is fine again. The camera is rated for 8v DC. but the 9v works. Therefore the 8.4V pack should work too! But I think that since the SubC rechargeables are as described above the camera has no or limited power regulation and are relying on the alkaline or brick to limit the amps. Therefore the High Drain SubCs are allowing to much power to go to the camera and the camera will pull more and more since it does not have built in regulation and thus stops working.
Am I correct in this theory?
If so what do I need to do? is it is simple as adding a resistor in line between the battery pack and the camera and if so how do I figure what I need
Thank You
Michael
|
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in
