I've been thinking about this a lot lately. if I understand correctly what I've read in these posts, the PHV model has 2 additional battery packs, and it will drain one pack before moving onto the next pack. That is really illogical being that it puts more stress on the batteries to drain them separately than to drain them simultaneously. If you drained them all at the same time, it would distribute the amps evenly between the packs. So.. That brings up the question as to why they would design it in this manner. I suspect that they might be considering offering different versions of the PHV with different amounts of battery capacity. I know I mentioned in a previous thread that it would be cool if they did that, but I didn't really expect it would happen. But once I started thinking about the design, I couldn't think of any other reason why they would design it that way. Unfortunately, based on the current prototype, removing one of the battery packs would give you a dismal 7 miles range. That isn't too terribly useful. But if they could get 10 miles out of a single pack, then that could actually be useful to some people. Heck, I could probably do my daily commute since I am right at 10 miles round-trip. Then another couple of thousand Dollars would get you 20 miles... and who knows, if they could find a way to fit a 3rd pack, and get 30 miles then it would really start to eat into GM's turf!
7 miles would work well for us. When over that, we are usually significantly over that so that the ICE is warm after a single warm up. A bit better CS mode with less weight would be an ok tradeoff for us. Home to work is 1.5 miles. 7 miles would help the price to buy, and still be EV on the little short trips that kill our mpg. Still get the 62+ mph gliding.
Toyota approach does not make much sense in production. It may make it into the 2012 vehicle, but this 3 packs configuration looks like a test configuration from day 1. Expect a different set of batteries for the 2016 my, and I would not be surprised if the 3 packs were not significantly different for the summer 2012 launch. If it was the chosen configuration the question is really what is taking the car so long.
I agree it's obviously easier on a large pack to put out the same amps than a pack half the size, even if it's technically in use half as often (once it's exhausted). There must be a good reason for it, though, if that is indeed how it operates. They can't have separated into two smaller packs just for giggles.
I haven't seen where the new battery packs are physically located. Is there enough space there to put in a single larger pack, or does the space available in the current Prius design require the splitting of the packs due to space availability? If it is a space issue, then it would seem that a redesign of the way the space is allocated could allow for a single larger pack if Toyota so desires.
Since the HV pack is also used in conjunction w/ the EV packs, I'd venture to guess removing one sub pack wouldn't exactly half your range.
"In conjunction" but I'd guess they are not directly connected (not in parallel and cetainly not in series). Toyota uses the term "in tandem", there must be some control electronics between the HV pack and the EV pack in line. The requirements from the HV pack and the sub packs are different! while the HV pack is required to work (alone) in CS mode, each of the sub packs is disconnected after depletion. This may indicate that the sub packs allowed degree of discharge must be much larger than the allowed DoD of the HV pack, to achieve the EV range. I'd assume 70% DoD for sub packs vs. 40% for the HV. What do you think? Giora.
Someone must have the true numbers. I believe that a full charge is 3.56 or 67% of the 5.3kwh pack. Someone please correct these numbers. If we say the ev packs discharge 70% it would probably be a state of charge of 25%-95%. The hybrid pack may discharge like an ev pack to 35% then try to keep it in a range, allowing the brakes to regen to fill it up as high as 95%, but attempting recharge as it gets low. This would hit the 67% re-charge level, but a driver should be able to push it lower if they forced ev at the end of a trip. This would mean removal of one ev pack would leave 65% of ev range (if the number are right, and they aren't) of the three packs. FWIW, I would expect the test fleet would provide toyota with guidance on the charge and discharge range.
14 miles is perfect for me, but i suspect they are going to offer different options for everyone's commute. why else would they do it this way?
One of the demonstrators of the PHV reported about 3.6kWh charge at the wall socket. Allowing for 10-15% losses (contacts, cable and chargers losses, batteries warming-up during charge etc.) we get about 3.1-3.2kWh available charge. I believe you have to start your assumptions based on this range. Giora.
At 3.1kWh, reasonable range for the ev packs would be 25%-90%, which leaves us with the hv pack discharging to about 45% for cs mode. This would have one ev pack and hv going about 63% as far in ev mode, as a car with all three packs.
Here's a potential answer as to why its NOT one big pack: It is so the failure of a single module doesn't brick the entire pack?
Having an option to purchase more EV capacity would be terrific. It would allow one to tune the car for personal use. Such a scenario would likely be fairly limited as there is only so much space (and weight) available. It would be great if you could buy 25 miles of EV or 50 miles of EV, but I think the price/space/weight constraints make this unlikely.
