Quote:
Originally Posted by drmiller100
at what efficiency do your batteries charge? Discharge?
Are you going to the Vetter challenge?
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This was a pretty well considered response from ken:
Quote:
Originally Posted by Ken Fry
...5. Is energy moving through the batteries? There is a level-road, still-wind cruise speed at which the engine has to provide all the energy to more the car. At that condition, all the energy effectively bypasses the battery. In the more typical case, in which the engine comes on for 20 minutes and then shuts off for perhaps a similar time, the the losses in and out of the battery matter. With lead acid, these can be a deal killer. With Lithium X they tend to be small in both directions, often 95% in and 95% out, but worse if you get up to 80% charge... at which point you should not be charging.
Conditions: Mainly temperature, which is why most systems are actively heated and cooled. Secondarily, charge rate, with either way high or way low being not so good.
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so pony up for lithium, but might need to spend energy on heating the pack (engine coolant?) and efficiency takes a dive at roughly 80% SOC (save the rest for regen I recon). 0.95 * 0.95 efficient at best, fairly constant power input for charging so not hard to optimize, driving demands (and if the engine is on or not) will determine actual discharge efficiency.
I looked up a discharge curve for lithium, higher currents do not have a huge effect on capacity like lead, but some energy might be lost in the additional voltage drop (like 7% or so?).
