Charge management chip?

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

MCP73831 ?

-Lasse

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

Battery watchdog chip?

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

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

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

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

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

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.

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.

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

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.

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

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

-Lasse

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.

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

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

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.

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

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