DIY PHEV Upgrades

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  #1  
Old 06-13-2006, 04:05 PM
Schwa's Avatar
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Default DIY PHEV Upgrades

Originally Posted by phoebeisis
Bob,Phil,Ken,Schwa- great stuff.Thanks.
Anyone have any idea of the cheapest way to add a second battery/battery pack?
You guys know that biggest boost in FE would be to add maybe 3000 Watt Hrs (2000 useable, maybe 3000 ) and the EV button with plug in capability. This would give ~ 10 mile low speed all electric (10 cents per 1000 WT HR) capability. You could do 10 miles at 2 cents per mile instead of the 6 cents a mile a 50 mpg Prius gets with $3 gasoline.
I know that there are a couple of expensive ($5000 and $10000) kits, but the cost is too high. Any of you engineers planning to DIY one of the kits? I'm fairly sure the Lead Acid batteries would weigh only 300 lbs and cost just $300. The EV button is just $50 from Coastal. The frame would have to be reinforced to handle 300 lbs of tongue wt.
I would be reluctant to have the batteries in the passenger compartment, so maybe you could add a receiver hitch and carrier and carry them behind the car?
If I was more electrically adept-and the Prius was out of warranty-I would give it a try. For brave souls still in warranty, the batteries on the carrier would allow a quick return to OEM configuration just in case you had to bring it in for warranty work??
Maybe this is the wrong thread to post this in, but this would allow a 1st gen Prius to absolutely KILL all other cars in FE, giving it the equivalent of 100-150 mpg -an Insight Killer. This is the real advantage of Toyota's system over Honda's system.Granted hauling 300 lbs of batteries with them protruding 2.5 ft isn't elegant, but it would certainly help the city FE.A quick D/C could be used to put the Prius back in Hy trim(or warranty trim). A HH would be a natural for this treatment. It would require maybe 500 lbs of batteries to get 10 mile range. I don't see any reason to try to make them rechargable by the ICE or regen-too complicated.Just "trick" the control unit into thinking it is in EV mode, and just draining/using its own battery.
Couple things I can add, 1st gen Prius (2000-2003) doesn't have an EV mode (as far as I know) so extra battery capacity would be used in assist or normal stealth driving mode. You wouldn't really be able to do 10 miles of EV since the engine fires up when you turn the car on, and stays on until it's warmed up the systems.

People have added extra batteries to the Prius, both v1 and v2, and both lead-acid and NiMH. See http://privatenrg.com/PriusBattery.htm for one such example.

The CAN-View data display system now has the ability to control a plug-in battery pack by switching relays that would control the secondary pack's connection to the primary pack. This offers a simple PHEV setup that just tacks on extra capacity until certain conditions are met such as state of charge or temperature.

The biggest 'problem' for the DIY person is dealing with the HV interconnection. Obviously Toyota doesn't want people messing with that part of the system, so there's no easy way to connect / disconnect the secondary battery systems, they have to be (to some extent) hardwired.
 
  #2  
Old 06-13-2006, 06:21 PM
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Default Thanks-Unclear 6.5 AH is OEM- so Volts=230??

Schwa-Thanks for the link-great stuff.I'm a bit unclear on something.He said his 2004's OEM battery was 6.5 AH. My understanding of it is that it is 1500 WHr battery. If this is correct this would make it a 230 V battery? I thought the 2004 had a ~600 V battery?What am I missing here? Thanks,Charlie
PS I didn't realize that parts of the PSD wouldn't get lubrication in the EV mode.He has to kick the ICE on every 7 miles to lube it.No real hardship there, but good to know.
 
  #3  
Old 06-13-2006, 09:15 PM
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Wink Re: DIY PHEV Upgrades

Originally Posted by Schwa
Couple things I can add, 1st gen Prius (2000-2003) doesn't have an EV mode (as far as I know) so extra battery capacity would be used in assist or normal stealth driving mode. You wouldn't really be able to do 10 miles of EV since the engine fires up when you turn the car on, and stays on until it's warmed up the systems.
. . .
The biggest 'problem' for the DIY person is dealing with the HV interconnection. Obviously Toyota doesn't want people messing with that part of the system, so there's no easy way to connect / disconnect the secondary battery systems, they have to be (to some extent) hardwired.
I've been looking at the other end of the speed range, cruise speed. It looks like a turbo-alternator, a turbine driven alternator, could generate serveral kWh, 2-5 hp, of power from the ICE that could be dumped onto the traction battery bus. Sensing the higher voltage as a higher SOC, the extra power would be dumped into MG2 to provide more motive power. This becomes a compound engine where part of the waste heat dumped out the exhaust is turned into motive power. The result would improve highway MPG without having to do 'ugly things' to the existing system.

As for an interface, my plan is to follow Richard's PriUPS approach. I need those connectors for my whole-house UPS but that is another project. The main thing once you have reasonable access to the traction battery bus, power can flow both ways. A turbo-alternator would be a really nice way to improve highway MPG.

This would also allow me to investigate air-metal battery technology. Rather than try to build a 200 or 273 VDC battery pack, I would use a 48 VDC bus system and a step-up, switching power supply. The high voltage, ground isolated interface is fully contained in the switching power supply. Meanwhile, I can deal with the high temperature, less lethal voltages from a smaller set of air-metal cells.

The same switching power supply could be used for those who want to start with a smaller battery pack investment and add cells as needed for more capacity. Properly designed with battery specific control units, mixed chemistries would work just fine. But I don't have much interest in these batteries.

I like air-metal cell chemistries because of the high energy density and their high temperatures support rapid reactions in small, hot packages. There is a heat management and oxide removal challenge but these have already been solved, in reverse, by reduction cells.

In one of the "Back to the Future" movies, the 'Professor' fuels his "Mr. Fusion" by dumping in aluminum cans. Aluminum is high on my list of metal-air cell chemistries.

Bob Wilson
 
  #4  
Old 06-13-2006, 10:22 PM
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Default Re: DIY PHEV Upgrades

the NWH20 had an inverter to step up the voltage, since the classic is lacking that inverter to boost up the voltage wouldn't that be a critical part of the system as well?
 
  #5  
Old 06-13-2006, 10:47 PM
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Default Re: DIY PHEV Upgrades

Originally Posted by philmcneal
the NWH20 had an inverter to step up the voltage, since the classic is lacking that inverter to boost up the voltage wouldn't that be a critical part of the system as well?
All Prius have inverters but the NHW11 and NHW10 didn't have a voltage doubler built into them. The voltage doubler is unique to the NHW20.

Bob Wilson
 
  #6  
Old 06-13-2006, 11:53 PM
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Default Re: DIY PHEV Upgrades

Originally Posted by phoebeisis
Any of you engineers planning to DIY one of the kits? I'm fairly sure the Lead Acid batteries would weigh only 300 lbs and cost just $300. The EV button is just $50 from Coastal. The frame would have to be reinforced to handle 300 lbs of tongue wt.
I would be reluctant to have the batteries in the passenger compartment, so maybe you could add a receiver hitch and carrier and carry them behind the car?
Following is PHEV conversions Fact Sheet of the first CalCar's Prius-plus.
http://www.calcars.org/conversions-factsheet.pdf
The PbA batteries last only 200 cycles in 11 months.
The battery cost was $700 and it drove 10miles/charge. The battery cost was $0.35/mile, so it was not practical.

Ken@Japan
 
  #7  
Old 06-14-2006, 09:33 AM
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Default Ken-thanks!

Ken, thanks for the link. They used sorta expensive electric bike batteries(18 240 W Hr-about $40 each) that apparently couldn't take the deep discharges and high rate of discharge. I was thinking more in terms of much cheaper " car,truck,boat' type batteries that are much cheaper. The boat batteries are kinda bulky, no doubt that is why they went with the bike type batteries.
I noticed that the DIY electric car guy-metric something or other- used lead batteries for his Honda CRX electric car. The weight was not a heck of a lot more than our Prius batteries- maybe 50% more (90 lbs for 1500 W Hr) VS (1300 LBS for 18000 W Hr-14000 watt Hr useable).
Is the actual Prius (2004) battery just ~250 V, and them it is doubled-or is it a 600 V battery to begin with? Thanks,Charlie
 
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Old 06-14-2006, 08:38 PM
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Default Re: Ken-thanks!

Originally Posted by phoebeisis
Is the actual Prius (2004) battery just ~250 V, and them it is doubled-or is it a 600 V battery to begin with? Thanks,Charlie
The NiMH battery voltage depends on charge/discharge current, SOC, temperature, internal resistance and etc, a lot of variables.
Attila saw between 180V and 248V.
http://vassfamily.net/ToyotaPrius/CAN/eveffindex.html

I don't know where your 600V came from, but Prius has DC-DC step up voltage converter up to 500V.
http://john1701a.com/prius/presentat...ntation_32.htm

Have you ever worked with more than 200V DC circuit?
Please be very carfull or you may be killed.

Ken@Japan
 

Last edited by ken1784; 06-14-2006 at 08:42 PM.
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