Herm
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Re: Accurately Measuring Battery Amperage Draw

Sun May 29, 2011 4:14 am

Tony, I think we need this.. eventually we will get a programmable display driven by the can bus for the Leaf, in a matter of months. What you really want is a KWh meter, an instant and an integrating one to keep track of the energy going in/out of the battery pack, this meter should also keep working while the battery is charging.. an amp meter would also work since the pack voltage is relatively constant for lithium ion cells, so the error would be small.

it would be nice to display the full pack capacity with a 1% granularity, and have a couple of programmable range guesstimators driven by the data. An instant one, one that averages over the last couple of days and a best case guesstimator.

DaveinOlyWA
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Re: Accurately Measuring Battery Amperage Draw

Sun May 29, 2011 6:03 am

i would like (if there is enough memory) for a program that can determine based on NAV'd routes and previous performance on said route.

i could make it work for me (although i have zero range anxiety) since a lot of my life is routine and repeatable.

but would be a complicated program that would have to integrate tightly with the GPS...but i find that it is plausible and allows the car to "learn" our needs.
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 15,000 miles, 478 GIDs, 37.0 kwh 109.81 Ahr , SOH 94.61, Hx 120.15
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garygid
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Re: Accurately Measuring Battery Amperage Draw

Sun May 29, 2011 7:53 am

The LEAF's Battery Pack voltage drops from around 400v down to about 300v during usage, and more when current extraction is high.

So, measuring Pack current ONLY will not give you accurate power usage, off by as much as 25%, or even more.

(*) Each Cell-Pair is roughly 3v to 4v in normal operation, and 96 in series are used to make the LEAF's Battery Pack.
Last edited by garygid on Mon Apr 30, 2012 9:13 am, edited 1 time in total.
See SOC/GID-Meter and CAN-Do Info
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TimeHorse
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Re: Accurately Measuring Battery Amperage Draw

Sun Apr 29, 2012 3:07 pm

I have my CARWINGS data logged every 5 minutes at the moment, not that that helps. The info and limited interface of CARWINGS seems too primitive for what you describe here by far; it can't even force the car to stop charging!
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Levenkay
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Re: Accurately Measuring Battery Amperage Draw

Mon Apr 30, 2012 8:38 am

garygid wrote:The LEAF's battery voltage drops from around 4v down to about 3v during usage, and more when current extraction is high.

So, measuring current only will not give you accurate power usage, off by as much as 25%, or even more.

You must mean the *cell* voltage, not the battery voltage, yes?

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garygid
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Re: Accurately Measuring Battery Amperage Draw

Mon Apr 30, 2012 9:09 am

Right, I meant the "cell-pair" voltage.

There are 96 in c-series to make the Battery Pack,
so around 300v to 400v for the pack.

I fixed my post, Thanks.
See SOC/GID-Meter and CAN-Do Info
2010 Prius, now for sale
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2018 Tesla Model 3
2014 Tesla S, Model 3 in 2019
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Solar PV: 33 x 225W -> 7 kW max AC
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