How is SOC measured?

Coulomb counter. A chip counts electrons going in and out of the battery. For example:

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Yes, though it helps if the battery is captive or if interchangeable, then serialized. You want to keep the history of a particular battery. Some algorithms try to factor in the number of cycles.

Basically an unhealthy battery has poor charge efficiency.

Thanks.

I thought it had to be something like that but was unaware that there were ICs that handled the whole job.

Jeff

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Jeffry Wisnia 
(W1BSV + Brass Rat '57 EE) 
The speed of light is 1.8*10^12 furlongs per fortnight.

"jeff_wisnia"

** There is no way to measure or determine remaining capacity other than by discharging the battery.

So equipment makers resort to predicting it by keeping track of the charging time and discharge energy since last charge.

Bit like predicting the weather .........

.... Phil

Ok, so, instead of rating them as 10 AH (10 amp hours) we can now use the term 10 AH = 36000 C(coulombs)/H, not to be confused with light speed :) Sounds like a marketing scheme!

Jamie

Smart Battery Specification

Battery Firmware Hacking: Welcome to the dark side.

Someone probably wanted to call it an electron counter, until someone else noticed that the electrons were going the wrong direction. Counting holes didn't sound very impressive. So, what was left was counting coulombs.

As a joke, I once suggested that a client rate their portable radio batteries in terms of horsepower in order to give the buyer a more familiar term for the "power" of the radio. For example, the NiCd battery pack of the day was about 12V * 0.600A = 7.2 watts

1 watt = 0.00134 horsepower Therefore, this would be roughly a 0.01 horsepower battery. Unfortunately, management seriously considered my horsepower rating, where it might become some kind of sales advantage. However, they were not thrilled by the resultant small numbers. So, I suggested millihps, where 0.01 hp = 10 millihp. Fortunately, that killed the idea before anyone else took it seriously.

Since then, the auto industry has gone the other direction, starting with small hp numbers, and translating engine power into much larger horsepower numbers. (Bigger numbers are better).

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Coulombs, but not /H.

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John

Threshold (Nelson Pass's old company) used to make a one horsepower audio amplifier. I can't find it on the interwebs due to too many people talking about horsepower in a general rather than literal sense. That is, too many false positives from google.