Powerboost 1000C low voltage when on battery power [Solved]

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SteadyShift
 
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Powerboost 1000C low voltage when on battery power [Solved]

Post by SteadyShift »

I am having an issue powering my raspberry pi 3 when running off of battery (4000mah), via the powerboost. It works fine when plugged in, but if i disconnect main power, the low battery led lights up and my screen starts flickering. I am seeing only 3V at the pi, when running on battery. 5.2V when plugged in. Is there something wrong with my powerboost or what? Can I get a replacement if so? I bought it a month or 2 ago.

Im doing a handheld/portable build. Im using a raspberry pi 3, a 5 inch hdmi lcd screen, and the 3.7w stereo amp. I am sure the battery is good. Its reading about 4V on its own.
Last edited by SteadyShift on Thu Jul 28, 2016 6:33 am, edited 1 time in total.

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Re: Powerboost 1000C low voltage when on battery power

Post by adafruit_support_mike »

Post a photo showing your hardware and connections and we'll take a look. 800x600 images usually work best.

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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

It's a bit of a mess at the moment. EN and GND are wired to a switch. G is wired to GND and 5V is wired to the 5V in testpad, on the raspberry pi, (via a breadboard currently). I have tried without the screen hooked up as well and still get the same result.
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Re: Powerboost 1000C low voltage when on battery power

Post by adafruit_support_mike »

Thank you.

If you disconnect the RasPi and measure the voltage between the + and - pads where the USB jack would mount, do you see the same low voltage?

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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

I just probed the + and - on the USB connector vias, with the rpi disconnected (on battery power) and got 5.2V. I also probed between G and 5V pin and got same.

Edit: (update)

OK so I fully disconnected the screen from the pi, both at the GPIO's and the HDMI. I get no low battery and the pi is powered. However, if I try and connect the screen to the pi, and power it via the 5V in pad on the pi, or through the screen, using its on-board USB connector, I get the low voltage and the pi craps out. If I plug power directly into the powerboost, the charge LED lights up, the low power indicator LED goes off and all is well.

It powers/boots fine if I plug the pi straight into the wall, using the supplied adapter. It seems the powerboost cannot supply enough power to power both the rpi, and the 5 inch LCD, when operating on battery alone. Wondering what the deal is.

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Re: Powerboost 1000C low voltage when on battery power

Post by adafruit_support_mike »

How much current does the circuit draw? The 1000C has a hard upper limit of 1000mA @ 5v.

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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

Not sure, whats the best way to go about determining mAh being drawn?

By the way, I hooked the screen up to the powerboost (by itself) and I still get the low power inidication. Pretty sure I've seen other projects use this same screen with the powerboost.

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Re: Powerboost 1000C low voltage when on battery power

Post by adafruit_support_mike »

Disconnect the PowerBoost's 5v output and put your ammeter in the gap.. red probe connected to the PowerBoost, black probe connected to the free end of the 5v wire.

Start with the ammeter set to the highest current level it can measure, and step down as necessary to get a good measurement. The lower current levels are usually protected by fuses, and it's easy to blow one by connecting it to a circuit that uses more current than you expected. Starting high and working lower keeps that from happening.

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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

It's a pretty cheap meter. The only setting I managed to get an accurate reading was @ the 10ADC setting. I am getting roughly 270 mA. This is with just the screen connected to the powerboost. Probes connected between screen and powerboost (positive to powerboost side).

As you can see I am getting the low power warning. The battery is fully charged.

Thanks.
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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

Bump. Anything else I should try? I really need to get this going. Thanks.

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Re: Powerboost 1000C low voltage when on battery power

Post by adafruit_support_mike »

Sorry for the delay.

270mA is well within the PowerBoost 1000C's limits, but the problem seems to be associated with the display. My guess is that the LED backlight is using burst current high enough to make the PowerBoost's output seem unstable.

Try putting a large capacitor (at least 1000uF) between VCC and GND near the display. That should smooth out any fast ripples in the current load.

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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

Hi, thanks for the response. I placed a 1200uF capacitor in parallel between 5V and GND between screen and powerboost which seemed to help and add some stability. However, I probed the battery posts while running the RPI and screen both (draws about 380mA together) and got a reading at about 4V which quickly started dropping until around 3.3V and then the low power LED comes on. This leads me to believe I have a faulty battery, that won't hold a charge at all.

I am ordering a 3.7 4000mAh li on off of Amazon and will be testing again with that. This project is on hold for the time being.

Will report back with my findings.

Thanks for all your help.

Steve

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Re: Powerboost 1000C low voltage when on battery power

Post by SteadyShift »

Update: I got a bit impatient and ended up ripping apart an old HP laptop battery I had laying around. I wired a couple of its 3.7V cells (about 2400mAh) up to the powerboost. Is this safe? No issues whatsoever powering both the screen, and the rpi3. Marked thread as solved.

Thanks!

Steve
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Re: Powerboost 1000C low voltage when on battery power [Solv

Post by adafruit_support_mike »

If the cells were paired originally, they should be fine. Glad to hear it's working for you.

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