Need Battery Monitoring IC Advice

[elcrcp]

Hello, I may in need of a 1-S li-ion battery monitoring IC (Charger IC might have this function but not clear yet). Circuit will work on battery so I would like to get battery level as digital data, prefably i2c and with low power consuming . Can anyone advice one?
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There is nothing you can't do if you try

[Ttelmah]

Understand, that using battery voltage to assess the charge in the battery is
basically close to useless. The way things like modern phones work is
by 'coulomb counting'. They measure the voltage when the battery is not
loaded, and reset their internal counters when the voltage is at the 'full'
level, and then measure the current being used, and the time, to calculate
how much has actually been 'used' from the battery. The chip using
this data knows the battery capacity.
Texas, Maxim, and SgS Thompson all do coulomb counting IC's.
Look at the STC3100.
I've done purely PIC based systems, using a 'hybrid' approach, where when
the current is down to only a few mA, the cell voltage is read, while when
current is drawn the coulomb counting method is used.

[temtronic]

general comments....

3 decades ago for the energy control systems I checked the batteries every 20 minutes+- using a 'dummy load' for a fixed time. I was using Gates Sealed lead acid batteries( as used in nuke powered subs). I got the specs of 'how to do it' from Gates themselves. The BIG issue to understand is what effect temperature has on battery capacity ! Get too cold or too hot for too long and battery dies......
The easy 'cure' is to at least double up on the capacity of the battery. Usually, a small increase in size yields a 'better' battery. Also follot THAT batteries manufacturer for charge,discharge and monitoring specs !!! Don't think all '1S' batteries are the same !!
Also be sure to use EVERY energy saving trick in the book ! There's at least 12 'must do' tricks that overall could save you 1/2 the coulombs !

Jay

[elcrcp]

Thanks for advice, I knew about coulomb counters but haven't used any before so I wanted to hear the voice of experience =) . I took a look and STC3100 seems ok for me, I'll buy and try one.

Thanks Jay, I'll check the book for sure =)
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There is nothing you can't do if you try

[Ttelmah]

Dead right on just how large the effect of temperature is.
I have a number of sites where we use wind/solar and batteries to
power instruments. The 'guide' we use when assessing the battery
size needed, is to use 60% rated capacity.
I have a PHEV, and in the summer, you easily get 25% more range
than in the winter from the battery. Also, if the battery is cold, and you
plug it in to charge, the system will actually use electric power to warm
the battery before attempting to charge it. The Lithium rechargeable
batteries don't like to be charged below about 4 to 5C....

[elcrcp]

[Ttelmah]

Yes, LiFePO4 batteries are a much more rugged technology throughout.
On LiPo, you can charge down to 0C, but the charge rate has to be reduced
below 5C.
However LiFePO4 batteries have a lot lower power density than LiPo. The
'best' current battery is Lithium Nickel Manganese Cobalt oxide. This will
charge down to -20C, and has better capacities than LiFePO4. Look for
G-NMC which is the 'name' for the Leclanche original versions of these use.