Plugin but without adding batteries??

It would have limited appeal because of the short range. It sounds like it would work for you, but I think the market isn't big enough for a 3rd party to introduce the charging hardware & whatever other changes they need to make.

I believe Hymotion and other plug-in companies only recharge their own battery, they don't charge the existing traction (HV) battery, that one functions as Toyota set it up, and they fake out the system so the electric power first comes from the new battery pack. Once that's depleted, it's back to the normal system. I'm not sure anybody's looked into how easy or hard it is to recharge only the Toyota traction battery. There has been some solar panel conversions that charge up the small 12V battery, but there's debate on how effective that is.

 

No, it's not just you; it's everyone. It's unusual to see 8 bars because the car is programmed to aim for 6 bars as an optimal level. This allows headroom for upcoming opportunities for regeneration -- such as hills. Otherwise, that energy would be wasted. Then when it hits 8 bars it uses that energy at its first opportunity -- again to make room for more -- until SOC (state of charge) settles in again at 6 or so.

 

I ofen park my car with 7 bars so a plug in charger would have little value.

 

You know a Prius with 8 bars charge uses more gas don't you?

 

It is addressed in many threads, but it boils down to this: For maximum fuel economy, avoid using the battery. (I know, it seems counterintuitive.) All energy ultimately comes from the ICE, whether to move the vehicle or recharge the battery. Best from a fuel economy standpoint is to use as much of that energy as possible to move the vehicle. That avoids the inevitable losses as energy is converted from one form to another -- i.e., kinetic energy from the moving vehicle converted to electrical energy converted to stored chemical energy in the battery, then reversal of the process to use that energy.

Now, on the other hand, if a plug-in was practical without adding batteries, that would change the picture. But as Nerfer suggests, range would be too short and the battery control algorithm likely too complex to make that viable.

 

Jimbo,

For what it's worth you probably wouldn't want to spend the money on a charger (mine cost me £600GBP) specifically designed for the Prius battery pack without having another battery to put the power into.

I'm doing a three battery setup - this should give me about 10 miles EV range. The cost should be about £2,000 GBP in total. I'd advise saving up and getting more than one battery!

Nikki.

 

What charger is it? A genuine Toyota one, a modified one from a gen 1 Prius or a custom made delta V charger?

I am sure that the internal battery would satisfy 90% of my car needs and I will get round to doing this when time permits.

I don't understand why Toyota only run the battery between 40 and 80 % (or whatever the % are). Nothing I read about NiMH seems to suggest much gain from doing so except to say that over charging kills them and leaving them flat seriously affects capacity. From what I read the reduction in life doesn't seem to justify not using more of the battery's capacity.

A 3 hour charge and 2 miles from that would keep me happy as long as I didn't sacrifice the hybrid capability.

It's just an NiMH anyway so trickle charging at 1/10 C should be good for ever without damage so no need for an expensive charger if you have the time to wait. If you don't have the time to wait then provided you monitor it yourself and are careful you only have yourself to blame if you fry it, make a high current charger and buy a good alarm clock.

 

Several studies, including one at a prestigious federal lab, have shown that battery capacity has very little effect on mpg in the Prius, once you get over a threshold. This is because the battery is used only to deliver short bursts of power, and to absorb small amounts of power during regenerative braking.

To use more battery, as in a plug-in conversion, requires that the battery be cycled more severely. NiMH batteries can run though large numbers of small cycles, but only a limited number of large cycles. Using more of the battery's capacity would result in marginal mileage gains while greatly reducing the life of the battery.

Tom

 

I think it is all about longevity of the battery. Extending the usable capacity to range from 10% to 90% would probably shorten the life significantly.
Please note that average NiMH battery life span is quite low, only around 500 to 1000 full charge/discharge cycles. Panasonic probably improved on this, but smart battery management, which allows only capacity range of 40-80% to be used, has extended battery life for several times to quite some thousands of partial charge/discharge cycles. We are probably talking about tens of thousands of partial charge/discharge cycles.
So it was all about life versus capacity.

The ideal battery would be a capacitor. They have almost limitless life span measured in cycles, they can charge and discharge very quickly and they have efficiency second to none. The only problem is, they have almost no capacity compared to its size and weight.

Ogo

 

Other people's explanations of why the traction battery is kept in its given limited range of charge are spot-on.

However, the bigger issue is that as mentioned, the computer is going to try and keep the traction battery in its "sweet spot" where it can contribute a good amount of charge, but also absorb some charge in the event of a large hill. You would, at some point towards the end of your journey, want to intentionally deplete down to three bars, and then be left alone after that. Because as someone already pointed out, there's no point in plugging the battery in if there's not much room left to charge it.

Has any company ever successfully modified the hybrid power system logic? My understanding was that current plug-in retrofits merely lie to it about how much charge is remaining, rather than actually manipulating the logic.

 

So even without messing with the 40 - 80 % thing you could get 2 miles from it without ICU. If you could easily charge it then it is enough for an awful lot of journeys.

Apparently the battery seems good for 100k miles or more. I usually buy cars at a few years old and run them until they decompose and I have never done over probably 70k miles so personally I could stand some loss of battery life.

It certainly seems to make sense to me, though probably isn't that useful for a lot of drivers, it all depends how you use the car.

 

This no doubt explains why the 2010 car continues to use the same battery, with the same capacity, as the 2004-2009 car.

 

In my experience, when you start the Prius on a green battery; the acceleration is MUCH better; in addition to obviously being able to enter into EV mode more often and for longer. That alone makes me want to do the whole plugin thing so I can start off the day with a green battery.

But I have always wanted to do a plugin simply because, most of the year where I live, its hot; and whenever it gets above 75, I have the A/C on full at the coldest setting. In city driving, this destroys my mpg because the battery runs down fast what with all the gliding I do. I would like to plug in my Prius so that I can start it up with a green battery; then leave the A/C on for a few minutes, then get in a nice cool car and still have battery power to drive normally. I think thats reasonable, isn't it?

In addition, there are supermarkets and restaurants much less than a mile from where I live, if I could do this I would probably seriously reduce my fuel usage at least 40%.