congratulations.... and best of luck.
Quote:
Originally Posted by crx_rogus
I also plan to use a connector harness to get each subpack paired up with its twin across the two packs to maximize balancing, minimize cell overheating, restore the effective total capacity to about what it was to when the BCM allowed a 20 - 80% SOC range from a single pack,
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That would not be easy.
The second pack could end up being asked for ~1/2 the assist or regen during IMA usage.
A cable for ~50 Amps for each of the 20 subpacks... would have significant design issues.
Quote:
Originally Posted by crx_rogus
Per my much earlier PHEV-Light thread, I'd then like to go for at least occasional home-based charging, which the 2nd pack would make more worthwhile. It looks like 172V is about the maximum the pack should be kept at I gather, with 1.43V/cell leaving a 0.3V or so inter-cell variation allowance margin at 8.6V max per subpack.
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Voltage alone is the most basic / least accurate option when it comes to NiMH SoC determination... it increases the risk of over charging and over discharging.
Remember there is an artificial voltage elevation that happens during charging and a artificial voltage depression that happens during discharging.
It can take several hours after the charging or discharging event ends before the NiMH cell terminal Voltage settles.
Quote:
Originally Posted by crx_rogus
I understand NiMH internal resistance doesn't vary across most of the SOC range, until dipping at full charge and then climbing steeply (which is where the zener-based voltage limiting would kick in). That should (in theory at least) allow balanced and safe but full subpack recharging.
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There is a difference between battery cell internal resistance and battery cell impedance.
It does vary significantly between Discharging and Charging... and it Varies depending on SoC... and on Temperature... and on Pressure.
See picture here for various SoC:
http://www.geocities.com/ian_p_georg...Resistance.jpg
and here for a few various temperatures:
http://www.geocities.com/ian_p_georg...emperature.jpg
