Daox's 2004 Toyota Prius Build Thread

[Daox]

Wow, I wasn't aware the DC-DC could provide 100A to the 12V.

[Cobb]

The Insights are like that too. They use a dc to dc device that uses the hybrid battery as a source for power. You can easily use up the power by using both defrosters. Also a low or bad starter battery can cause you to see little to no assist and mostly regen as it tries to charge the battery up. Many i2 users have gone to a larger group 51 battery and notice way more assist than before.

Also when you do regen braking it also turns on the dc to dc converter. So, the more braking you do the more it tops off the battery vs it falling before 12.5 volts among other varibles it watches.

Some people go as far as to precharge the 12 volt battery before their trip to help get a boost in mpg. I did that before I purchased my plug in kit. I notice a boost in trips for the first 7-12 miles or so.

[Xringer]

I guess if you were to add on a 144v top-off charger, then it would be smart
to also add a 12v charger/tender for the low voltage side.

Because of low usage, I'm forced to use a 12v charger/tender to keep my old Ford ready for use.
So, I too might be getting a little MPG boost with the Escape..

[bwilson4web]

Originally Posted by Daox

Wow, I wasn't aware the DC-DC could provide 100A to the 12V.

Not quite 100A but close enough from the NHW11:

50A @13.83V ~= 690W
75A @13.75V ~=1,030W
90A @11.48V ~=1,033W

The ZVW30 has a similar voltage roll-off at a slightly higher current. Once I remove the Anderson connectors and 120A @12V circuit breaker, I'm expecting to see our 2010 Prius provide a full kilowatt of sine-wave, 110VAC house power with the aux battery providing 10s of seconds of surge energy.

I've already put a 1.2kW, resistive load on the 2010 inverter and watched as the battery provided the 'make-up' energy. When the current reached ~120A, the circuit breaker tripped around 12.4V. But subsequent tests at 930W, revealed the Anderson connector and 120A @12V circuit breaker were drawing about 100W and getting toasty warm. That is why the next version will use bolted-on, 4 gauge, cables.

Bob Wilson

[Xringer]

High current is a big problem. Wasted wattage is equal to the current squared x the resistance. P=I(squared)xR

If they could make a DC to AC(sinewave) converter that worked at 144vdc,
You could use much lower current.

I've used a small switching power supply (120-240Vac in / 12Vdc out) on a 144 Volt PV array and it worked fine. Turns out that DC input didn't hurt it.

Most of the Switching power supplies convert the AC right to DC, at the input.
Chop off the DC output section, and I could see a design like this being used to convert 144Vdc right into 230Vac (or 120Vac) for my house..
It would only take about 7 amps to make 230Vac at 1kW.



Of course, these designs save weight by using high-frequency transformers. 60Hz transformers weight a lot more.

[Cobb]

I was considering getting some type of grid tie inverter that works on 100 volts dc to use my newer insight in conjunction with a generator or inverter for emergency power.

[bwilson4web]

Although I agree in theory:

Originally Posted by Xringer

High current is a big problem. Wasted wattage is equal to the current squared x the resistance. P=I(squared)xR

If they could make a DC to AC(sinewave) converter that worked at 144vdc,
You could use much lower current.
. . .

There are two practical problems:

• tapping the traction battery HV - although not insurmountable, there is a ground-fault circuit built into the battery controller. If the plug and/or electronics doesn't keep this high-frequency isolated, it could throw a false, ground fault code. Also, this is the sort of thing a skilled owner needs to do whereas most semi-technical types can deal with 12V and not 'let the smoke out' too badly.
• creating a 110 VAC sine-wave - pulse width modulation allows much smaller transformers that feeding into some 'starter caps' can generate a usable sine wave. But other than the photo-array vendors, such inverters are both rare and expensive compared to the 12V ones.

In the back of my mind is this approach:

• AC power tap/plug on MG2 - the main motor, this is already driven by a water cooled, high power inverter already in the car. So instead of driving the wheels, the tap provides AC, house power.
• spoof encoder signal - may also require spoofing the antilock brake sensors so the car thinks it running down the highway at 60 Hz.

This approach allows the existing power electronics already integrated into the car to provide external AC power. The car is put in 'AC power mode' and the parking brake set. Then the car 'drives' providing external AC power.

Another variation would simply 'spoof' the MG2 inverter signals so it begins 'driving' MG2 at 60 Hz. There is still the challenge of defeating the ground fault detector and making sure the HV ECU doesn't see an error.

The microcontroller and glue-logic should be fairly small as all of the power electronics are already in the car. We're looking at up to 18 kW, the amount of power MG1 can provide on its own.

Bob Wilson

[Daox]

I suggest starting a new thread on using your hybrid for A/C power. Its not going to get much attention in my build thread. I know I'd like to hear more about your improved design Bob.

[Xist]

I am trying to find an old post and thoroughly enjoyed skimming this build thread. I was sorry to see how it ended. How does the second 2004 Prius compare with this one?

[Daox]

They are virtually the same car. I think they're even the same trim level. I did prefer the Ecopia tires vs the ones I have on the second Prius. Also, the second Prius is a salvage title vehicle and has new front panels and a hood. The replacement hood is steel vs the OE aluminum which I don't love as it is heavier and also rusting pretty bad (holes recently developed). However, that really is the extent of the differences.