Cycle Satiator: How Precise Watt Hours?

Each time I charge my lithium battery, I compare the number of watt-hours that the TSDZ2 w/OSF reported used before charging with the number of WH the Grin Satiator says were put back into the battery to get it back up to 80%.

Sometimes the numbers are not even close, as in 49/97, 44/69, and 12/103 (TDSZ2/Grin) for my last 3 discharge/charge cycles.

My money is on Grin but, not knowing squat about electricity, I have to wonder if maybe used WH is somehow an inherantly imprecise figure.

Elucidation from Those Who Know?

Yes coulomb counting is inherently imprecise.

And what you put in charging is to be ignored, always lots more than discharge measured.

That 80% number is also likely very much guesswork too.

john61ct said:

And what you put in charging is to be ignored, always lots more than discharge measured.

Click to expand...

Can somebody elaborate on that?

It is inherent in the physics / chemistry of how all batteries work.

The inevitable inefficiencies result in the Ah going inbound are less than the Ah available discharging from storage.

The ratio is called CEF "coulombic efficiency factor", and can vary widely.

But since cheap grid power is usually used for charger input, it is a relatively unimportant factor in choosing a chemistry.

Since the energy available while discharging is important, that is how Ah capacity is measured.

The mfg rating is usually very exaggerated, based on a super slow C-rate, so that needs to be matched if verifying, say within 85-90%,

discharging at a much higher rate, say 1C, will yield a much lower capacity. See "Peukert coefficient" on that.

Don't want to talk over John he does a good job.

You hear about efficiency's all the time. This just means to turn your amps/watts in to something usable. Not just lost to the void.

Anytime you can detect heat form controllers, motors, batteries or wires this is a loss. If you would monitor the power before your charger the difference would be even greater from charger losses.

Glad you are catching on. This is why people here have all the debates over what is the best setup to use, the least wasteful. Your numbers are all over the place would have expected to see more of a pattern. There is a lot of data not shown that could answer some of it.

by PeteCress » Sep 18 2021 9:36pm

john61ct wrote: ↑Sep 18 2021 8:58pm
And what you put in charging is to be ignored, always lots more than discharge measured.

Click to expand...

Can somebody elaborate on that?

Click to expand...