battery backup for Pi

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greavette
 
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battery backup for Pi

Post by greavette »

Hello,

Does adafruit sell a system whereby I will plug my Raspberry Pi into mains power, but I want to also have attached to my Pi a small battery backup that would allow me to run my Pi for hours (in case of power failure). This battery backup will get continually charged while on mains power but will kick in to take over if mains power fails.

Hopefullly I've described what I'm looking for adequately. Does such a system exist for the Pi?

Thank you.

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adafruit_support_mike
 
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Re: battery backup for Pi

Post by adafruit_support_mike »

Swapping directly like that is a bit complicated, but you can get the same effect using one of our PowerBoosts:

https://www.adafruit.com/products/2030
https://www.adafruit.com/products/2465

The PowerBoost always runs from the battery, converting the 3.7v LiPo voltage to 5v output. If you connect wall power to the LiPo charger, that should keep the LiPo topped up while the wall power is available. If the wall power fails, the PowerBoost won't care, and will continue to convert battery power to 5v for the RasPi.

The PowerBoost 1000C has a built-in LiPo charger, but has an upper limit of 1.1A @ 5v. Anything more will probably damage the LiPo charger. The PowerBoost 1000 Basic doesn't have to worry about protecting a charger, so it can go up to about 2.5A @ 5v.

The PowerBoost Basic does need an external LiPo charger, and you need one large enough to supply all the current the boost circuit needs while generating power for the RasPi. As a rule of thumb, assume that every 100mA @ 5v that goes to the RasPi requires 150mA @ 3.7v from the LiPo.

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lynchmob_lerry
 
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Re: battery backup for Pi

Post by lynchmob_lerry »

So if I wanted to make a battery powered raspberry PI that had the PI camera and Pi touch screen, what battery charger combo would you recommend?

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adafruit_support_mike
 
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Re: battery backup for Pi

Post by adafruit_support_mike »

I'd go with the Basic and an external charger.

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lynchmob_lerry
 
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Re: battery backup for Pi

Post by lynchmob_lerry »

And I can use a standard USB wall charger?

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adafruit_support_mike
 
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Re: battery backup for Pi

Post by adafruit_support_mike »

You can use a wall adapter to power a LiPo charger, but can't charge a LiPo directly from one.

The LiPo charging cycle is kind of complicated, and they have a tendency to catch on fire if they're over-charged. That's the main thing keeping them from replacing all other kinds of battery these days. You always want to use a charger that's designed to work with the cell you have.

LiPos are everywhere these days, so chargers aren't hard to find and don't have to be expensive. We have several over in the shop: https://www.adafruit.com/categories/575

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greavette
 
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Re: battery backup for Pi

Post by greavette »

Thank you for these replies. The PowerBoost 1000C sounds like it would be perfect for my project.

Thank you.

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