KanoMaster22
Posts: 168
Joined: Wed Oct 05, 2016 6:06 pm

Using lipo out of power banks

Wed Jun 13, 2018 8:48 pm

Hello everyone I am looking and have read that this (https://www.amazon.co.uk/20000mAh-Porta ... op?ie=UTF8) power bank contains two 10000mah lipo batteries. Is it a good idea to use these with something like a Zero Lipo board to power a Pi?

W. H. Heydt
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Location: Vallejo, CA (US)

Re: Using lipo out of power banks

Wed Jun 13, 2018 10:29 pm

So long as they're still in the powerbank, probably. I'd be rather more certain of that if the actual output specifications were given (and were suitable). I'm basing the "probably" on the assumption that the output is 5v. I wouldn't recommend disassembling a powerbank unless you are experienced at doing so and intimately familiar with working with raw LiPo cells.

Bear in mind that a Pi0 has not input power protection, so if your PSU (or battery pack, in this case) is out of spec, you could get fireworks.

KanoMaster22
Posts: 168
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Re: Using lipo out of power banks

Wed Jun 13, 2018 11:10 pm

Okay thanks for the help. Maybe it is best to keep the batteries inside the power bank and use like a normal person.

W. H. Heydt
Posts: 8634
Joined: Fri Mar 09, 2012 7:36 pm
Location: Vallejo, CA (US)

Re: Using lipo out of power banks

Thu Jun 14, 2018 1:28 am

KanoMaster22 wrote:
Wed Jun 13, 2018 11:10 pm
Okay thanks for the help. Maybe it is best to keep the batteries inside the power bank and use like a normal person.
Good idea.

Now I have a question for you... How long does your Pi0 need to run on a single charge? I can run a Pi0W with a 3.5" LCD attached from a 4Ah powerbank for about 12 hours. The pack you linked to is 20Ah, so to a first approximation, that should run a Pi0 for at least 60 hours.

KanoMaster22
Posts: 168
Joined: Wed Oct 05, 2016 6:06 pm

Re: Using lipo out of power banks

Thu Jun 14, 2018 6:04 am

I am planning for the Pi to last 24 hours.

KanoMaster22
Posts: 168
Joined: Wed Oct 05, 2016 6:06 pm

Re: Using lipo out of power banks

Thu Jun 14, 2018 11:20 am

Okay, so the batteries contained inside this power bank are 3.7V what could go wrong if I connected one of these to a board like the Zero Lipo or an Adafruit Feather?

drgeoff
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Re: Using lipo out of power banks

Thu Jun 14, 2018 11:56 am

KanoMaster22 wrote:
Thu Jun 14, 2018 11:20 am
Okay, so the batteries contained inside this power bank are 3.7V what could go wrong if I connected one of these to a board like the Zero Lipo or an Adafruit Feather?
They are not 3.7 volts. Rechargeable lithiums are 4.1 or 4.2 volts when fully charged. The voltage falls as charge is expended. Typically you should stop taking current from them when the voltage reaches the region of 2.6 to 3.0 volts.

While some RPis may work OK with such low and changing voltage compared to the specified 5 volts, any attached peripherals may not.

An additional advantage of keeping the cells in the powerbank is that contains a circuit for safely charging the cells and a circuit to prevent them being over-discharged. Lithiums are dangerous* if not charged properly and over-discharging damages them.

(* risk to property, limb and life in respect of which your insurance company might refuse to honour a claim.)

KanoMaster22
Posts: 168
Joined: Wed Oct 05, 2016 6:06 pm

Re: Using lipo out of power banks

Thu Jun 14, 2018 2:40 pm

Okay, thanks for the information. I definitely won't be getting the batteries out of a power bank now but power banks still do offer good amount of mah for not much money. Anyone got a recommended power bank for the Pi or do most work fine with the Pi?

W. H. Heydt
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Location: Vallejo, CA (US)

Re: Using lipo out of power banks

Thu Jun 14, 2018 4:19 pm

KanoMaster22 wrote:
Thu Jun 14, 2018 2:40 pm
Okay, thanks for the information. I definitely won't be getting the batteries out of a power bank now but power banks still do offer good amount of mah for not much money. Anyone got a recommended power bank for the Pi or do most work fine with the Pi?
I get mine from Monoprice (they're located near Los Angeles). For "wearable" applications, I usually use a 4Ah unit. For a Pi2B plus 7" RPF display, I use a 10Ah or 10.4Ah. Pretty much any commercial unit will do, so long as it will deliver its specified current while maintaining 5v output. You do have to be alert to the max current rating. Smaller units (like the 4Ah ones I use) tend to be limited to 1A, while larger ones can supply 2A or more. Be sure to read the actual specs. After that, it's just a matter of how long your particular system will run on a given pack.

All of that said...I am intrigued by the one you linked to. That's the first powerbank I've seen (not that I spend a lot of time looking at them) that claims to provide more than 2.4A, making it suitable for a Pi3B+ based portable project.

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Imperf3kt
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Re: Using lipo out of power banks

Thu Jun 14, 2018 11:39 pm

W. H. Heydt wrote:
Thu Jun 14, 2018 4:19 pm
All of that said...I am intrigued by the one you linked to. That's the first powerbank I've seen (not that I spend a lot of time looking at them) that claims to provide more than 2.4A, making it suitable for a Pi3B+ based portable project.
"Total combined output - 3.4A"

This is actually extremely common. Two ports, one at 1A, one at 2.4A
Usually these fail to deliver even 2.4A
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