DIY plugin prius

That's a lot of AC/DC conversion going on there. It seems like you're going head-first with this project. What examples are you trying to follow with this DIY job?

 

I would spend some time on:
Prius PHEV - EAA-PHEV
and on the mailing list associated with that page.

A lot of these sorts of things have been tried, and failed in the process of coming up with a working recipe. Biggest problems I would be worried about with this plan:

1) DC voltage needs to be at least 242V to trigger SOC drift, otherwise controller will not use any of the extra charge you put in.
2) 12V -> 240V conversion means the current out of your batteries will be 10X higher than the current demand by the HV system. This could easily cut the efficiency/capacity of your battery pack in half.
3) To extend EV range, you really need to get somewhere between 40-100 Amps supplied to the HV system. Thats more in the 10-20kW range rather than 2kW.
4) Just because your inverter is rated to 2kW, and rectifier is rated to 1A, doesn't mean that the HV system is only going to pull 1A. If the HV battery is at 180V and you put a 230 or 240V constant voltage source across it your source is going to try and put out enough current to maintain its target voltage. This will either smoke the rectifier, crash the inverter voltage (killing its efficiency), or overheat and smoke the inverter.
5) In order to get the Prius to use electric power more often, you have to manage the apparent SOC of the built in battery pretty precisely. The ideal SOC value is different under different driving conditions. A simple time based charging could easily over charge and damage the HV battery. Trying to determine SOC based on voltage is not very reliable.

Although it may sound complicated/expensive, the cal-cars conversion is really about as simple as it gets. There is a big battery, a switch, and a small computer that decides when to open and close the switch. There are dc:dc converter based conversions (like Manzanita Micro's) out there as well, but they are considerably more expensive.

Rob

 

Hate to stifle your creativity, but I don't think this will work either. As the 12V pack voltage runs down, the built in dc:dc converter will pull more and more current from the HV system to try and recharge the 12V battery. This will in turn pull more and more current out of the 12V system, lowering its voltage further. You basically get a feedback loop and burn all your battery power heating up all the inefficiencies/losses in the system. Then it will start running the gas engine all the time to try and charge the whole thing up back up.

Rob

 

I'm thinking it if was this simple, cheap and got any kind of effective results, someone would have done it by now or Toyota would have incorporated it by now.

 

sounds like a comment about electric light blubs from the 1870's

 

I think this trial is not practical because the PbA cycle life is very short.

You'll need to spin the ICE above 42 mph and require approximately 2 kW to spin it.

Ken@Japan

 

I was saying you can't exceed 42 mph or 67 km/h by motor alone.
However, Toyota factory plug-in Prius can be in EV mode up to 100 km/h.
TOYOTA: News Releases

Ken@Japan

 

My point is that the folks at cal-cars have spent five years coming up with a low cost open source phev conversion process, which is finally just about complete. As an EE, I started out thinking I would just come up with my own design too. I quickly realized I would just be reinventing the same things they had already come up with. They have learned a lot of things the hard way, and made a lot of mistakes that I won't have to repeat by taking advantage of what they are offering.

As a data point the cal-cars packs are 4800 Wh (20x12Vx20Ah) and they seem to be getting 10-12 miles of EV out of them, and that is at much slower speeds than 60mph. Part of the problem is the non-linearity (Peukert Effect) of lead acid batteries. At the ~60A that the pack is discharged at in the cal-cars case you only get about 60% of the ideal pack capacity. On top of that, you can only use about 50-80% of that or you will severely impact the longevity of the batteries. So the usable capacity is probably <2400Wh. So this would probably be in the 200-240Wh/mile range (or maybe a little less), but I believe the speed is <34mph so as to be able to maintain EV mode. The difference is probably just the reality of real driving. You have to accelerate, there are hills, wind etc.

Rob

 

this guy's going to become a negative statistic..
.
_H*