BeginnerKid
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Battery for Raspberry Pi

Thu May 23, 2019 6:57 am

Hi guys,

need some help on wheel robot with raspberry pi battery. Current I am using 4000mah, 7.4V lithium battery.

Is it possible for me to shift my lithium battery to double A battery with the same specification?

Thank you! :D

W. H. Heydt
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Re: Battery for Raspberry Pi

Thu May 23, 2019 2:40 pm

It's certainly possible. How many AA batteries (cells, really) it will take will depend on what type they are. For instance, the nominal cell voltage for zinc-carbon/alkaline is 1.5v. For NiCad it's 1.2v per cell.

Getting the same stored energy is trickier as Li Ion has a relatively high energy density.

cspan
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Re: Battery for Raspberry Pi

Thu May 23, 2019 9:04 pm

W. H. Heydt wrote:
Thu May 23, 2019 2:40 pm
For instance, the nominal cell voltage for zinc-carbon/alkaline is 1.5v. For NiCad it's 1.2v per cell.
1.2V for NiMH too ....

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Imperf3kt
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Re: Battery for Raspberry Pi

Thu May 23, 2019 10:47 pm

Be careful not to draw too much current through that AA battery.
I once used a cheap torch that had lots of high power LEDs and ran from 3 AA batteries in series
After about 5 minutes, one of the batteries got so hot that it melted the plastic casing of the torch and burnt me.


Make sure the battery you use, can handle the current.
https://batteryuniversity.com/learn/art ... the_c_rate
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BeginnerKid
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Re: Battery for Raspberry Pi

Wed May 29, 2019 5:57 am

Hi guys,

Thank you for your reply.

I was thinking to use an Alkaline battery (1.5V) and connect them in series to get 7.5V. As for the capacity (milliamp hours /mah), I am not sure how should I parallel those batteries.

I saw some people did use 4 AA batteries and voltage regulator to run the raspberry pi for a long time but I need to use the battery for a wheel robot so it will consume more power.

I have read regarding the discharge rate but still not sure the comparison between AA and lithium battery discharge rate as both have different range of discharge rate.

I am hoping to get some clues from you guys.

Thank you guys!

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Imperf3kt
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Re: Battery for Raspberry Pi

Wed May 29, 2019 7:34 am

This test appears to show a Duracell 'Ultra Plus' alkaline battery can safely maintain a 3 ampere load for approximately 12 minutes. It will reach about 54°C during this time.
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BeginnerKid
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Re: Battery for Raspberry Pi

Thu May 30, 2019 7:56 am

Hi guys,

If let say, I used 4 series double A batteries and then parallel it with another 4 series double A batteries. So the voltage will be 1.5v x 4 = 6 volt and 1300mah x 4 = 5900mah.

Then is it possible for those 8 batteries to be charge will a charge that has an output of 8.4volt, 2Amp current?

Thanks guys

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Imperf3kt
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Re: Battery for Raspberry Pi

Thu May 30, 2019 8:17 am

BeginnerKid wrote:
Thu May 30, 2019 7:56 am
Then is it possible for those 8 batteries to be charge will a charge that has an output of 8.4volt, 2Amp current?

Thanks guys
I'm not sure what you're asking as your sentence structure is a bit broken, but if you're asking can you charge them, no, 1.5v AA cells are non rechargeable and any attempt to do so will result in a potential fire.

If you simply meant how much charge can you get from them, I'm not sure. It would highly depend on the battery, most are not the same as each other. One AA battery might give 1C just fine, whereas another of the same capacity might only be okay to use at 0.2C due to internal resistances.

To get an answer, look up the datasheet for the specific battery (brand and model) you wish to use.

At an educated guess, I would personally believe that setup should work fine (just remember a Pi only wants 5 - 5.25v)
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sharperalison6
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Re: Battery for Raspberry Pi

Thu May 30, 2019 10:01 am

Hi,

i used this kind of solution for a ratBox, but it is not reliable, the battery drain so fast that you can't launch long operations..
Mine was a 10000mA.

I know that nowadays there are a myriads of battery that are really better, so maybe you could take a look at those battery.
Let me know if you get some informations about that, i'm interested :)

For information i was hosting my website on my raspberry pi, so yes i know it is not the best solution, but at this time i did not have electrical plug available in my room

W. H. Heydt
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Re: Battery for Raspberry Pi

Thu May 30, 2019 2:28 pm

BeginnerKid wrote:
Thu May 30, 2019 7:56 am
Hi guys,

If let say, I used 4 series double A batteries and then parallel it with another 4 series double A batteries. So the voltage will be 1.5v x 4 = 6 volt and 1300mah x 4 = 5900mah.

Then is it possible for those 8 batteries to be charge will a charge that has an output of 8.4volt, 2Amp current?

Thanks guys
It would be simpler to put all 8 in series, supplying 12v to your voltage converter (you are planning to use a voltage converter, aren't you?) and reducing the required current. Using two banks of 4 cells each is very likely to run into problems with not all cells being identical and the two banks having a slightly different output voltage leading to all sorts of grief.

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