powerboost 500 charger problems

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bbusch
 
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powerboost 500 charger problems

Post by bbusch »

I'm using a 2700 mAh lipo from Adafruit and a Raspi B drawing 400-500 mA per my charge doctor. The battery is always in a state of discharge. No matter what I do short of unplugging the pi, the battery eventually drains. I've verified the voltage coming in at 5.2vdc. Any suggestions?

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Franklin97355
 
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Re: powerboost 500 charger problems

Post by Franklin97355 »

What is the draw on the usb input port?

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bbusch
 
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Re: powerboost 500 charger problems

Post by bbusch »

about .25 - .26 amps input to the powerboost without the Pi plugged in. Interestingly, it drops to .20 amps when the Pi is plugged in.

I'm trying to use this as a battery backup but it's useless if the only way to fully charge the battery is remove the pi.

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Franklin97355
 
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Re: powerboost 500 charger problems

Post by Franklin97355 »

If your USB port is providing 200ma and your Pi is using 500ma your battery will drain. You should try a different USB supply and cable.

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bbusch
 
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Re: powerboost 500 charger problems

Post by bbusch »

I understand your logic so i bought a 3A power supply. The powerboost, battery and Pi are drawing .42A from the power supply. The Pi only draws .40A from the powerboost so the battery should be charging right? right now I'm watching the battery slowly drain. What's next to check?

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Franklin97355
 
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Re: powerboost 500 charger problems

Post by Franklin97355 »

Could you post clear pictures of your board and the connections to it?

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bbusch
 
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Re: powerboost 500 charger problems

Post by bbusch »

FullSizeRender.gif
FullSizeRender.gif (552.66 KiB) Viewed 582 times
The red and green wires are disconnected. i dont see where i could have messed anything up. maybe you will see something.

Edit: forgot the picture. ;-)

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adafruit_support_bill
 
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Re: powerboost 500 charger problems

Post by adafruit_support_bill »

You have to also account for charge efficiency (~80%) and the fact that 420mA @5v is equivalent to close to 600 mA @3.7v once you account for the voltage difference and the boost efficiency. So a net battery discharge would be expected with that load.

From the tutorial: https://learn.adafruit.com/adafruit-pow ... us-charger
Just be aware that the charge rate is 500mA max, so if you're drawing more than ~300mA continuously from the 5V output side, the battery will slowly drain since the charge rate is less than the dis-charge rate.

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bbusch
 
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Re: powerboost 500 charger problems

Post by bbusch »

So this product will not work for my application. It probably won't work for any running raspberry pi project since my B is drawing 400mA at idle.

Thanks.

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adafruit2
 
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Re: powerboost 500 charger problems

Post by adafruit2 »

400mA idle is *a lot* - we have a B+ here and it draws 150mA idle. we didnt specifically design this for the Pi, so it may not work for you...

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mrcw
 
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Re: powerboost 500 charger problems

Post by mrcw »

Seems like it's not a good fit for the Pi at all as common Pi models draw more power than this unit can keep up with and much more w/ typical use. The description seems to be leading people (including myself) to believe otherwise.

I think the first sentence gives people the wrong sense of how this device works and how the power flows:
PowerBoost 500C is the perfect power supply for your portable project! With a built-in battery charger circuit, you'll be able to keep your project running even while recharging the battery!
a Pi works fine ... to act like a UPS.
However both my PiB and Pi2 with all USB devices removed drained the battery while plugged in. I would add with a 300mA current draw it looks like the efficiency is below 80% not the "90%+ operating efficiency in most cases" ... so again not well suited as a UPS.
Solder in the USB connector and you can plug in any iPhone or iPod for 500mA charge rate
... just be aware (or surprised in my case) that even though it's plugged into the wall it will drain the device's battery.

I'm sure this nicely packaged board works fine for someone who is typically running off batteries or drawing closer to 100mA continuously but most of the Pi models use much more (original B uses over 400 idle and Pi2 with only ethernet uses 350, wifi dongle runs over 450) which is why they Pi manual recommends at least a 700mA power supply.

Please update the product description as it seems (from reading forums) this has been going on for months and a lot of people are finding themselves BANNED with the wrong product. Sure it's only $15 but with a $10 battery it was $38 to get it to my door... and much time lost. Next time I'll spend more time decoding the description or better yet check forums first.

Has anyone come up with a mod for this board to route the 5v supply side directly to the output while keeping the rest functional?

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bbusch
 
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Re: powerboost 500 charger problems

Post by bbusch »

Thank you. Well said. Hopefully adafruit will take some action.

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