Charging is too slow?

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Charging is too slow?

Post by Admin » Wed 20 Dec 2017 11:18

Hey guys,
Got a question about the charging process, and that it was too long. So I wrote a little explanation about the charging process and how to improve it :

Some 5V charger are little bit more than 5V, maybe 5.2V, because most often it helps. But here it does not help. In fact best rating for charging the raspiboy is 4.5V.

The thing is that the lithium battery is between 3.2V and 4.2V. And when charging, the battery charger needs to lower the voltage to the battery voltage. So to 4.2V. So if it is supplied with 5.2V it needs to reduce by 1V the voltage. If it is supplied with 4.5V it only needs to reduce by 0.3V

In order to do so it must dissipate the extra energy into heat, and the more voltage drop the more energy (by the formula P = U x I)

And in order to prevent overheat and give the product a better durability we implemented a overheat protection. So if temperature is going to high the charging process will pause for some time, allowing temperature to drop.

This process can be seen on the LEDs, when LED 3 ON and LED 4 OFF, it's charging. When LED3 ON and LED4 ON it means it's cooling down.

So if your 5V charger voltage is bit high then there's more heat to dissipate so cooling time is longer.

So best is to use charger with bit lower voltage than 5V.

A way to do so could be to use a USB-micro USB cable of low quality. Because in those USB cables they use thin wires to save cost. And that produce a voltage drop. Which is usually bad, that's why they are considered low quality. But in our case the voltage drop will help.

Gorion
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Joined: Thu 7 Dec 2017 12:00

Re: Charging is too slow?

Post by Gorion » Wed 20 Dec 2017 11:27

Thanks for this explanation. I was wondering why my Raspiboy was not fully loaded after 10h of charging. Can you recommend any cheap cable that definitly works like that? Would be very appreciated ;-)

Registry error
Posts: 6
Joined: Tue 5 Dec 2017 17:32

Re: Charging is too slow?

Post by Registry error » Wed 20 Dec 2017 18:10

The past two nights I’ve been using the pi zero w charger however I’ve noticed that it’s charging too slow. This info helps as I’ll look around the house to see if I have any alternative cables before buying one. For those in need of one, These look like viable options. The latter being a more versatile power supply.

Samsung Galaxy J3 Emerge 2017 Home Charger, SOGA Micro USB Travel Wall AC Home Charger for Samsung Galaxy J3 Emerge 2017 Cell Phone Wireless Accessory https://www.amazon.com/dp/B06VXJK87K/re ... oAb3KK461X

[Upgraded Version] SoulBay 30W Universal AC/DC Adapter Switching Power Supply with 8 Selectable Adapter Tips & Micro USB Plug, for 3V to 12V Household Electronics and LED Strip - 2000mA Max https://www.amazon.com/dp/B01N7RS0NG/re ... oAb76S5FN7

Telev
Posts: 17
Joined: Sat 26 Aug 2017 14:45

Re: Charging is too slow?

Post by Telev » Thu 21 Dec 2017 08:05

Admin wrote: This process can be seen on the LEDs, when LED 3 ON and LED 4 OFF, it's charging. When LED3 ON and LED4 ON it means it's cooling down.

So if your 5V charger voltage is bit high then there's more heat to dissipate so cooling time is longer.
So, this is why, in charge, the LED 4 is blinking with a period of 6 or 7 seconds ....

Registry error
Posts: 6
Joined: Tue 5 Dec 2017 17:32

Re: Charging is too slow?

Post by Registry error » Thu 21 Dec 2017 17:32

I’ve been charging mine for 12 hours. The only light that was on was the 3rd led. How long does it take to charge 6000 milliamp with 4.5 v power supply?

finishlast
Posts: 6
Joined: Sun 12 Nov 2017 14:36

Re: Charging is too slow?

Post by finishlast » Fri 22 Dec 2017 15:19

Well you could use a step down converter to get 4.5v out of whatever you plug in (3-40v)

https://www.amazon.com/RioRand-3-01-007 ... cuit+Board

Or you use a simple resistor maybe 0.27Ω for 5v or something, do the math according to your real output, I'm not responsible here...

I would recomment a step down converter to get a "better" 4.5v.

Don't burn down your house, always water the christmas tree too....

GohanX
Posts: 1
Joined: Tue 5 Dec 2017 17:54

Re: Charging is too slow?

Post by GohanX » Sun 24 Dec 2017 02:37

If you have a USB power bank things, try it. I suppose it's because it puts out slightly less juice but it seems to do a better job charging the Raspiboy than plugging it directly into the wall.

roostaar
Posts: 31
Joined: Tue 2 Jan 2018 00:39

Re: Charging is too slow?

Post by roostaar » Tue 2 Jan 2018 00:50

Hi Guys

All the USB sockets and chargers I own are 5-5.2V so slow charging is an issue for me also.

Would a combination of these two items be a good solution to reduce the charging voltage?

https://www.ebay.co.uk/itm/122436407957

https://www.ebay.co.uk/itm/152653292349

:?:

Graylag
Posts: 8
Joined: Tue 12 Dec 2017 12:51

Re: Charging is too slow?

Post by Graylag » Tue 2 Jan 2018 15:03

The combination could work, but unless you are perfectly sure about what you are doing I do not recommend it.

Trouble could be with quality of the power source. Those chap "universal" sources are quite often not or poorly stabilised and filtered, which is perfectly fine for powering of simple devices or electronics with their own stabilisers. But with Raspiboy expecting "exact" 5V you might have more trouble than with USB charger. When set to 5V, you might measure something like 5,5V (which is worse than USB charger), or if not stabilised at all even something like 8V (great way how to instantly destroy precise electronics - personal experience :D ). What is worse, after connecting to Raspiboy voltage could drop to around 4V, not charging your battery at all.

tl;dr might work, but unless measured and tested no guarantees

Graylag
Posts: 8
Joined: Tue 12 Dec 2017 12:51

Re: Charging is too slow?

Post by Graylag » Tue 2 Jan 2018 15:28

If slow charging due to overheating is issue, it might be worth to try some "slower" charger, like 500 mA. Heat dissipation on charging circuit is product of voltage drop and current, so if you reduce current, you reduce the heat. This of course lenghtens the charging but beacuse of how lithium battery charging process works, charging time does not exactly inverse proportionaly increases. Once in CV phase, charging takes roughly same time on both 1A and 500mA charger, meaning 500 mA charger will be only about 1,75 times slower than 1A charger. This means that if your device is half the time in cooling (not charging) state on 1A charger, changing might be faster on slower charger!

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