Charge management chip?

Looking for a charge management chip, thought I'd check here to see if anyone's looked recently.

  • Charge 1 LiPo cell

  • Understands constant C, constant V charging

  • Doesn't pull significant current when disabled.

Less important:

  • Will limit source current to whatever I want (if not I can just limit the battery current and live with slight inaccuracy here).

Thanks.

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Tim Wescott 
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Tim Wescott
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Den mandag den 24. november 2014 22.41.45 UTC+1 skrev Tim Wescott:

MCP73831 ?

-Lasse

Reply to
Lasse Langwadt Christensen

On Mon, 24 Nov 2014 15:41:41 -0600, Tim Wescott Gave us:

Battery watchdog chip?

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Reply to
DecadentLinuxUserNumeroUno

Thanks. If that's not what I want, it's certainly a good starting point.

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Tim Wescott 
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Tim Wescott

These ICs are nice but many have a few shortcomings. Their abs max is

6-7V which precludes solar charging applications. They can also often not be set to 4.1V which may be desirable to increase the number of charge/discharge cycles and battery lifetime while sacrificing capacity.
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Regards, Joerg 

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Joerg

My other option is to roll my own, and is still very much on the table.

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Tim Wescott

Hi, Tim - I have not searched through this, but it might be useful to you. Good luck.

Reply to
John S

Tim,

I can't swear these fit all your requirements, but perhaps one offers a place to start:

LTC4150 -- $13 SparkFun Coulomb Counter Breakout board

DS2740 AN2096: DS2740 High-Precision Coulomb Counter Reference Design

STEVAL-ISB009V1 Li-Ion battery monitoring and gas gauge evaluation board based on STC3100 STC3100 Battery monitor IC with Coulomb counter/gas gauge

BQ26231 Cost-Efficient Coulomb Counter for Battery Capacity Monitoring In Embedded Portable Applications

Enjoy...

Frank McKenney

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  how you make a discovery, only that your claim is true and 
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Reply to
Frnak McKenney

I might have to roll one as well but not sure yet. We need it for solar panel input and the abs max has to go to 8-9V at the least. One challenge with regular LDOs is the tolerance of their internal reference. Li-Ion is very finicky because the difference between fully charged and *KABLAM* followed by a three-alarm fire is very small.

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Regards, Joerg 

http://www.analogconsultants.com/
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Joerg

If you happen to be working with a battery vendor you may want to see if you can talk with their apps engineers.

I was in some discussion with Tenergy about using their LiFe cells, and once we convinced them that -- smart or not -- we weren't going to use their charger, they were very informative about tradeoffs in balancing, cell life vs. final charge voltage, &c.

I'm not sure about the kablam part -- but I fly RC planes, and get to hear stories and see pictures and even the odd video or two of Planes in Flames. So yes, there's certainly a lot of energy that can be released there, to the amusement or horror of bystanders.

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Tim Wescott 
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Tim Wescott

If you're mostly interested in recovering the most energy from the solar cells, you want to go switching anyway, don't you?

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Tim Wescott 
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Tim Wescott

Probably not on this one. A 6V solar cell weighed down to Li-Ion voltage level isn't that far from the MPP under sunny conditions. My client has their hands full with other SW jobs already so I don't want to add an MPPT routine to the pile. Only if we find out we really, really have to.

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Joerg

Huh. Interesting approach -- nice & simple. This seems to be the kind of thing you can do with jelly-bean parts and a precision regulator.

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Tim Wescott 
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Tim Wescott

LTC1734, 8V operating, 9V absmax, 4.1 or 4.2V 1% max 700mA

-Lasse

Reply to
Lasse Langwadt Christensen

Yup. Except that the precision part tends to get expensive. Also, ideally you'd want the words "Li-Ion charging" somewhere in the datasheet for liability reasons.

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Regards, Joerg 

http://www.analogconsultants.com/
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Joerg

It is a good chip. The required external transistor is ok but the price is often a problem. Well over $1 in qties. It also can't do

Reply to
Joerg

Eww. It's the 'L' word. Damn, I think I'll just use a chip.

I'm sensing the battery voltage, so I can always cut of charging myself at

4.1V if I want to, and paint a little target on the chip for the lawyers to aim at in case of fire...
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Tim Wescott 
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Tim Wescott

But you know how it goes. You bake the rolls that are eaten during the design review for the part that went kablouie because some kid stuck mom's sewing needle in there and they'll name you as a defendent.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Yes, and they know to a 'T' how much to settle for so that it's not worth defending yourself.

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Reply to
Tim Wescott

Indeed, nagging fear of the "KABLAM" has forced a lot of us to keep away from these Li-based batteries.

Reply to
dakupoto

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