Electronics > Projects, Designs, and Technical Stuff
Help with Battery pack and related charger IC
ricko_uk:
Hi,
I spent few hours researching but could not find a battery solution and matching charging IC that I feel comfortable about.
The project is for 80 off units of a portable instrument.
I am looking for both of the following:
1) a battery (pack?) with:
- voltage anywhere from around 3.6 to around 8V (I can work around it with switching regulators to get the 5V and 3v3V I need on the board)
- 2.5Ah minimum but ideally as high as possible (preferred 3.5Ah)
- max discharge current 300mA
- preferably (but NOT an essential requirement!) a chemistry that is safe/allowed to be transported by air as part of the product (i.e. permanently locked inside the product enclosure)
2) related charger IC:
- suitable for that battery specific pack/chemistry
- standalone and as simple as possible. No need to have any microcontroller control. Only a mean for the Micro to read the battery level, but even that not that important.
- the input (only when charging the battery) is a wall adaptor and I can choose any voltage accordingly to whatever is required by the IC/battery. It does not need to be a USB charger NOR a 5V charger. Whatever input voltage the IC accepts I can find a wall-adaptor to work with it.
- I guess for safety it might need some monitoring and cutoff perhaps?
- OPTIONAL (would be nice but no need to have) is means for the charger IC to allow to also supply the system (i.e. feeding whatever the incoming DC voltage is to my onboard switching regulators)
I appreciate any parts suggestions because so far it has been a frustrating process finding them.
Much appreciated! :)
Many thanks :)
tooki:
As someone who is working on a project where I had to select those things, too, you’ll have to provide a lot more requirements with which to narrow it down. Does it need processor control? Or is “standalone” operation needed? Do you need it to be “smart”? What’s it going to be powered by? Does it need to know how to talk USB? Do you need a built in boost converter to provide a guaranteed minimum system voltage?
Martinn:
What's wrong with any decent 18650 Li-Ion cell? If you absolutely need 3.6 V min, you'll need 2S as minimum voltage is around 2.5 - 3.0 V.
Maybe you should explain your application and whether it's one piece DIY only or some small series production.
ricko_uk:
Thank you Martinn and Tooki, much appreciated!! :)
I updated the original post with the additional details you asked, copied here too:
2) related charger IC:
- suitable for that battery specific pack/chemistry
- standalone and as simple as possible. No need to have any microcontroller control. Only a mean for the Micro to read the battery level, but even that not that important.
- the input (only when charging the battery) is a wall adaptor and I can choose any voltage accordingly to whatever is required by the IC/battery. It does not need to be a USB charger NOR a 5V charger. Whatever input voltage the IC accepts I can find a wall-adaptor to work with it.
- I guess for safety it might need some monitoring and cutoff perhaps?
- OPTIONAL (would be nice but no need to have) is means for the charger IC to allow to also supply the system (i.e. feeding whatever the incoming DC voltage is to my onboard switching regulators)
Martinn:
Assuming 100 pcs and a certain level of reliability, I'd use a top brand standard pack like this one https://www.amazon.de/ANSMANN-Li-Ion-Akkupack-7-4V-2-6Ah/dp/B073P9XNCQ.
You could also have one custom made, but that's unlikely to be any different.
Charger: Li-Ion has been around for decades, there are hundreds of choices. For simplicity go to ti.com and select one. For 2s and standalone, switch mode, you get
https://www.ti.com/power-management/battery-management/charger-ics/products.html#p1152=2;2&p338=Li-Ion/Li-Polymer&p273=Switch-Mode%20Boost;Switch-Mode%20Buck;Switch-Mode%20Buck-boost&p1341=Standalone;Standalone%20(RC-Settable)&sort=p1130;asc
Pick one... BQ24133 might be OK.
If you don't want to design your own, adafruit has lots of charger modules, although you'll end up with 1s probably.
You'll also find that there are arbitrarily cheap batteries and chargers (on ebay, Ali, DX...). I'd say you get what you pay for. Top brands (like cells from Panasonic - from official sources, otherwise chances are good they are fake) are a safe bet, but expensive. Anything cheaper might be OK or might be junk and/or fake. Your risk.
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