Lithium Ion batteries - rant

Hey all,

I've got a project where I'm running Atmega chips on 2S Li Ion cells. Love the power but what a pain in the arse.

To make it robust I need:

Low voltage lock out (BMS or soft latch on the AVR) Charger circuit - IC with high voltage lockout Boost converter - using USB power (slow.. only 5v 500mAH)

this isn't even addressing the drop out on the regulators if i have too many diodes at cut off (5-5.5v)

I'm lost in finding the right parts. Anyone have any advice? No I need the 2S Li ion. They're just great for the end use, I need portable high current source in small package and rechargable is cool.

Wondering if I missed something.

CK

You missed the circuit diagram and description (Web reference) of each part.

wolframore: I've got a project where I'm running Atmega chips on 2S Li Ion cells. Love the power but what a pain in the arse.

Agreed.

I avoid them as much as possible, the pain of using them safely outweighs the advantages.

It's still in my head... I don't like where it's leading me. I'm almost ready to design a battery management chip based on an ATTINY13 and be done with it. What have you guys done with Li Ion?

Here's some of the parts I've been considering - you don't want to see my full list... ugh. It's as bad as shopping for MOSFETs

Charger IC: Microchip MCP73213 and 73244 TP5100

Boost converter LM2621 SX1308

low volt and current lockout TI - BQ2961 HY2120

wolframore: Wondering if I missed something.

Quite a bit. If you run your ?"Atmega chips"? on 8Mhz then you can power them with a single LiPo cell (no regulator). The newer/longer TP4056 charger boards have buildin battery protection. An "Atmega chip" can measure it's own supply internally (code only), to shut down (sleep) before the protection kicks in. Leo..

Wawa - if only I had a micro power project. That would be nice.

That's not what I need the power for... I have a load that requires the 7v (higher the better) thereabouts with with over 5 amps.

wolframore: Wawa - if only I had a micro power project. That would be nice.

That's not what I need the power for... I have a load that requires the 7v (higher the better) thereabouts with with over 5 amps.

See...if you had read the How To Use This Forum near the top of each section, you would have known to provide us this information from the start ;)

Ebay has charge/protection boards for 2S LiPo. Not as many as for 1S but theyre there.

USB power bank might be an alternative in some situations and addresses most of the issues.

wolframore:
Wondering if I missed something.

CK

Betteries like these come with all the protection built-in. Or, you can buy just the protection circuitry.

Sorry guys, kind of new to posting. Been enjoying the forum. Many thanks to all you experts out there!!! Great posts keep it up. Larry wow you have some great ideas in the tips section. I aspire to this kind of level. Have you looked into carbide end mills? They last longer especially with plastic and wood and costs are low on smaller sizes. They're much harder so more brittle so dont try to bend or drop them.

Back to the project on hand. Sorry there's no schematics yet.

the LiPo BMS boards - they would sort of work but most will need a dedicated charge board as well. It's fine for testing and quick prototypes but I need to build something for small scale production.

these are the power sources I'm working with

DEVICE POWER: 1. regulated 5v (LM1117-5) 2. regulated 3.3v (LM1117-3.3) 3. Unregulated battery power for load

CHARGER POWER 4. USB 5v (a little anemic at 0.5A - meaning once it's boosted to 2S charging levels we are at just over 200mA with losses - overnight at best but doable) 5. Charge voltage (9-12v) meaning more stuff like external wall warts or worse AC-DC power supply in device

No external powering required but can be achieved through USB for programming only

Was reading about lithium ceramic (and other solid state batteries) please fast forward time :0

The real problem that I think we can all benefit from is have a simple way to use, charge and maintain lithium ion batteries in our projects safely. Currently it is not a simple solution especially when you go to multiple cells.

so a simple solution to limit threshold levels, temp, balance, and charge from simple source (USB) while draining batteries while system is off is all i ask. :)

wolframore: so a simple solution to limit threshold levels, temp, balance, and charge from simple source (USB) while draining batteries while system is off is all i ask. :)

When you have finished the design, do let us know and post the details.

Perehama: Betteries like these come with all the protection built-in. Or, you can buy just the protection circuitry.

I fixed that first link [above]. You forgot to edit out all that crap the Forum code shoves in there, like the "http://" and the double quotes it puts around the URL.

Here's a little trick: After using the "Insert Link" tool, do a Ctrl+Shift+S [or whatever that is on a MAC], which will take you to the View source mode where you can see these little nocent embellishments. Then, I post from this mode [since it seems the double quotes return when you switch modes]. And, you have to do this every time you use Modify to edit your post!

And if Crtl+Shift+S is not available [like on a smartphone or iPad, etc], then that last little icon, in the tool list--the one that could be interpreted as a sheet of paper with writing on it--that's the View source tool. It looks grayed out, but it isn't ;)

ReverseEMF: I fixed that first link [above].

Thank you. I fixed it in my post.