Battery question

goodie · Post by **goodie** » Tue Mar 01, 2005 5:33 pm

In which method would the batteries last longer?:

Using a 6v 4000mah battery and connecting directly to your device, or
using a 7.2v 4000mah battery and going through a regulator to lower it to 5 or 6 volts, and sending that into the device.

Post by **SpongeBuell** » Tue Mar 01, 2005 5:37 pm

use a regulator. Anything else will likely fry the board

goodie · Post by **goodie** » Tue Mar 01, 2005 5:38 pm

Even if the device takes 6v?

Post by **gannon** » Tue Mar 01, 2005 5:43 pm

They'd last the same time, but using a direct battery connection would still be bad. (Mainly because voltage in a battery isn't a constant)

goodie · Post by **goodie** » Tue Mar 01, 2005 5:46 pm

Well, my "device" is a pocket tv. It has some sort of regulator built-in doesn't it? Would 7.2 volts be safe for it, or do I need another regulator?

Post by **SpongeBuell** » Tue Mar 01, 2005 6:01 pm

In that case, it probably does have a regulator, and 6v would be fine.

goodie · Post by **goodie** » Wed Mar 02, 2005 3:49 pm

If I tried to put 7.2 volts into the TV, do you think its regulator could handle it? Or would I need another regulator? Also, does anyone know of a non-online place that sells ldo regulators?

HK-47 · Post by **HK-47** » Wed Mar 02, 2005 3:57 pm

goodie wrote:If I tried to put 7.2 volts into the TV, do you think its regulator could handle it? Or would I need another regulator? Also, does anyone know of a non-online place that sells ldo regulators?

If it has a 7805 yes. Also, why a ldo? A 7.2 will run a 7805 fine... Or is this for a 6v sorce powering a ldo 5v reg. ? Though Im not sure where you'de find the reg. Radio-shack if you're really lucky, but Im pretty sure your gonna have to go online...

goodie · Post by **goodie** » Wed Mar 02, 2005 4:12 pm

Okay, it seems that Ben put 7.2 volts into the pocket tv in the cnc Nes, so I guess it has a 7805. One more question: Lets say I have a 7.2 volt battery. I put it through a 7805 to power my system. On a full charge, about how long would it last before the voltage gets too low and the regulator shuts off? (I'm using this information to determine what type of battery and regulator to get.)

HK-47 · Post by **HK-47** » Wed Mar 02, 2005 4:15 pm

goodie wrote:Okay, it seems that Ben put 7.2 volts into the pocket tv in the cnc Nes, so I guess it has a 7805. One more question: Lets say I have a 7.2 volt battery. I put it through a 7805 to power my system. On a full charge, about how long would it last before the voltage gets too low and the regulator shuts off? (I'm using this information to determine what type of battery and regulator to get.)

Well the best battery/reg combo would be lithium batteries with a switching reg. Unfortunatly both are relativly expensive. If you can figure out a switching reg though, Id recommend it. (Though you'de have to order it through digikey or something.)

goodie · Post by **goodie** » Wed Mar 02, 2005 4:25 pm

Hmm, I think I will use this one from Radioshack that I mentioned in another thread, along with a 7805. And if it doesn't last long enough, I could switch to an ldo. I just might try one of those switching regulators on a future portable though, COUGH*snesp*COUGH. But I just wanna get this thing done.

I'm so close......

HK-47 · Post by **HK-47** » Wed Mar 02, 2005 4:27 pm

As you wish...