Prolonging operation of battery powered device

I need more power!

Ok, so, I got a decent portable Video player, but, from what I read, it can only take about 2 hours of use before it needs a recharge... I wouldn't of bought it if I knew that, but, then again, it was on sale. It houses a Lithium Polymer battery, and, unless I take the unit apart, and void the warranty, I need a 'charger' unit.

So, my question is: is it at all likely that I can take advantage of a 9v battery, hook up something like a Voltage Regulator such as the LM317T, a couple of resistors, and have the output to be around 5v, what you'd normally get from a USB port, as that's it's power source.

This way, when I am on the Greyhound likely later in the month to Florida from Montana, I don't have to go without my player for long periods of time, I just swap batteries out.

Any ideas, schematics, or suggestions you have to share will be welcome!

-Haz

Re: Power supply creation.

whatz the charger specification ?? y u want to charge it via a 9 volt battery ??
whatz ur aim??

Re: Power supply creation.

hameeds01 said:

whatz the charger specification ?? y u want to charge it via a 9 volt battery ??
whatz ur aim??

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I replied to your inbox with my AIM address, but, I am looking to 'charge' the unit with a 9v battery, yes... increase it's life span until the internal battery drains.

-Haz

I need more power!

A little 9V alkaline battery has a very low amount of power. Its voltage quickly drops lower than the minimum input voltage (7V) of an LM317 that is set to 5V. You should use a low-dropout 5V regulator that works perfectly until its input drops to 5.5V for low power projects powered from a 9V alkaline battery needing 5V, but still a little 9V battery does not have enough power to charge another battery.

My daughter's portable DVD player uses a 2200mAh lithium battery that has as much power as 15 little 9V alkaline batteries. Its battery lasts for about 2 hours for 1 charge.

Re: I need more power!

Audioguru said:

A little 9V alkaline battery has a very low amount of power. Its voltage quickly drops lower than the minimum input voltage (7V) of an LM317 that is set to 5V. You should use a low-dropout 5V regulator that works perfectly until its input drops to 5.5V for low power projects powered from a 9V alkaline battery needing 5V, but still a little 9V battery does not have enough power to charge another battery.

My daughter's portable DVD player uses a 2200mAh lithium battery that has as much power as 15 little 9V alkaline batteries. Its battery lasts for about 2 hours for 1 charge.

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What would you suggest, then? Bigger battery? Also, I was thinking 'bout the LM7805

-Haz

I need more power!

Both the LM317 and the LM7805 need a minimum input of 7V.

Every semiconductor manufacturer on Earth and maybe on also on Mars make low dropout voltage regulators so you can use them when your battery voltage drops too low. But a little 9V alkaline battery does not have enough power for your application.

I think you need spare battery packs that are exactly like the original. Hopefully the first one can be easily replaced.

Re: I need more power!

Audioguru said:

Both the LM317 and the LM7805 need a minimum input of 7V.

Every semiconductor manufacturer on Earth and maybe on also on Mars make low dropout voltage regulators so you can use them when your battery voltage drops too low. But a little 9V alkaline battery does not have enough power for your application.

I think you need spare battery packs that are exactly like the original. Hopefully the first one can be easily replaced.

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Sadly, not an option. This thing is fully internal. I am just gonna try just connecting it to 4 AA batteries, see how well that works. I mean, with no power regulator, it'll just take at least most of the battery power, and put it into the unit, right?

-Haz

I need more power!

Four AA alkaline cells are 6.4V when brand new. Their voltage quickly drops to about 4.8V when they won't charge your lithium battery.

Energizer make lithium AA disposeable cells and four will stay near 6V when powering things for a fairly long time. Stock up.

Re: I need more power!

Audioguru said:

Four AA alkaline cells are 6.4V when brand new. Their voltage quickly drops to about 4.8V when they won't charge your lithium battery.

Energizer make lithium AA disposeable cells and four will stay near 6V when powering things for a fairly long time. Stock up.

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Sounds good... I just hope I don't have to buy, like, 4 packs of 4. x.x

Any other ideas you may have is greatly appreciated!

Re: I need more power!

1) U can charge ur video player via car cigarette lighter slot.
2) U can use a 5 volt power supply 120/240v.
3) U can use ur laptop USB port.
4) U can use ur laptop battery, my laptop has 14v lithium ion battery slim & light weight + 7805

Re: I need more power!

hameeds01 said:

1) U can charge ur video player via car cigarette lighter slot.
2) U can use a 5 volt power supply 120/240v.
3) U can use ur laptop USB port.
4) U can use ur laptop battery, my laptop has 14v lithium ion battery slim & light weight + 7805

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Thanks fort the reply, but, Greyhound doesn't come standard with any of those, and if I owned a laptop, I wouldn't be asking 'bout this.

-Haz