Battery life and stat conversion

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eatkabab
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Joined: Sun Sep 27, 2009 2:56 pm

Battery life and stat conversion

Post by eatkabab » Sun Sep 27, 2009 3:04 pm

I'm looking to use a Sony infolithium Battery NP-FP90 / NPFP90 (http://www.monoprice.com/products/produ ... escription" onclick="window.open(this.href);return false;) to power a mod but I need to run it at a different voltage/current or better yet the same voltage/different current. PLEASE tell me if this will work and how long it will last.

Stats on the batt: 7.2v 2250mAh
Stats I need to run at: ~3v 700ma

also, can I just slap power leads on to the batt and start using it?
What kind of current/voltage can I use to charge the batt?
Is there anywhere I can find a connector for the power terminal on the batt?

I'm not sure if I'm doing these calculations correctly, but I calculate the watt hour of the batt to be 16.2 (2.25ah x 7.2v), and my power draw to be 2.1 (.7a x 3v). If this is correct, then my batt life should be about 7.7hrs (16.2/2.1).

Thank you very much to whoever can tell me I'm right or wrong.

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XCVG
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Re: Battery life and stat conversion

Post by XCVG » Sun Sep 27, 2009 4:27 pm

:facepalm:

First, if you connect your 3V-requiring device straight to your battery you will fry it. You need a voltage regulator. Preferably a switching voltage regulator; WAY more efficient. A lot of people use the TI PTH08080 or PTH08000. I'm using the PTH08080 in my N64 project.

Second, to charge a 7.4V lithium battery you should ideally use a smart charger. But if you want to go the "pump power in and cross fingers" approach, use an 8.5V or so power source.

eatkabab
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Re: Battery life and stat conversion

Post by eatkabab » Sun Sep 27, 2009 4:42 pm

XCVG wrote::facepalm:

First, if you connect your 3V-requiring device straight to your battery you will fry it. You need a voltage regulator. Preferably a switching voltage regulator; WAY more efficient. A lot of people use the TI PTH08080 or PTH08000. I'm using the PTH08080 in my N64 project.

Second, to charge a 7.4V lithium battery you should ideally use a smart charger. But if you want to go the "pump power in and cross fingers" approach, use an 8.5V or so power source.
well I actually am going to be using a power controller. http://www.luxeonstar.com/buckpuck-700m ... s-p-35.php" onclick="window.open(this.href);return false; It accepts anywhere from 5-32v. however whatever I'm going to be powering only uses 3v 700ma. and I think I'll just keep it simple and use the stock charger for the battery.

My real question is if I can just attach leads to the +/- of the battery and use it and if there is anywhere I can find an plug to attach to the batt power terminal.

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XCVG
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Re: Battery life and stat conversion

Post by XCVG » Sun Sep 27, 2009 6:41 pm

Yeah, I don't think that will work. The stock charger is fine, just use a switch. Like I said, use a voltage regulator to get 3V.

eatkabab
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Joined: Sun Sep 27, 2009 2:56 pm

Re: Battery life and stat conversion

Post by eatkabab » Sun Sep 27, 2009 6:43 pm

XCVG wrote:Yeah, I don't think that will work. The stock charger is fine, just use a switch. Like I said, use a voltage regulator to get 3V.

http://www.luxeonstar.com/buckpuck-700m ... s-p-35.php" onclick="window.open(this.href);return false;

well it better work since it was made to run the lights I'm trying to power...

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XCVG
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Re: Battery life and stat conversion

Post by XCVG » Sun Sep 27, 2009 8:27 pm

Oh, you're trying to power lights? I was assuming you wanted 3.3V for your N64p. I don't know where that came from...

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