2nd Gen Prius PHEV Conversion (Enginer plug-in lithium ion battery kit)

[puddleglum]

Now that a few of you have these kits working, what kind of speed and range can you get on battery power only (assuming 70%DOD)? I"m curious if you could realistically expect to be able to stay in EV only mode if you were only short tripping in the city?

[Daox]

Well, in EV mode the Prius is limited to 34 mph. If you go above that it kicks the engine in and goes through the warmup cycle and you're in hybrid mode again.

As for range, I'm not absolutely sure how far the 4kWh pack will go. I've never tried to deplete it with just city driving. Most people estimate ~250Wh/mile and at 70% dod I would have 2.8 kWh, so that gives us 11.2 miles. That is probably a bit on the conservative side, but roughly accurate. The other range issue is that the dc-dc converter is only putting out ~2kw or 2.6hp continuously. Cruising at 25 mph it will pretty much keep up with you for a long time. However, if you kick it up to 33 mph or so, it simply can't keep up with how much power you're pulling from the OEM pack. About the longest I've been able to go is 5 miles in a 35 mph zone, and that is really putting along and squeezing as much as I can out of it in summer. In winter, no way. In fall I would say I am down ~to 75% of the range. I haven't been using the kit in winter so far since its out for upgrades.

[Daox]

I guess with the bump of this thread I'll also add in what I've been up to with the kit. Its still out of the car and I'm waiting to get the batteries back.

I have been using my own BMS for a while now, it only worked for protection while charging the batteries. I have since added functionality for protection from over discharge. You can read more about the system here:

http://ecomodder.com/forum/showthrea...bms-20445.html

[GeneralAnarchy]

Originally Posted by puddleglum

Now that a few of you have these kits working, what kind of speed and range can you get on battery power only (assuming 70%DOD)? I"m curious if you could realistically expect to be able to stay in EV only mode if you were only short tripping in the city?

I've been using my Enginer kit heavily in cold weather. It's been installed over a year. It seems to work pretty well, although my converter has spontaneously started dropping its cutoff voltage. Today it puts out 12+ amps at 220V but drops down to 2 amps after I get to 230V. It seems too low. Last summer that cutoff would happen at 237V or so. It could be cold weather, I don't know. I still get the "red triangle of death" if the amps are too high. So it's an odd mixture: probably too many amps, but too low voltage. Anyway, so far so good.

Because of this voltage cutoff, I only get decent gains once the OEM battery drops below 6 bars. Probably at 25 mph I can carefully go 5 miles before hitting 2 bars and the Prius kicks the engine on.

Range on the highway is much more, like 120 miles before the kit depletes. But that is because the voltage is too high for the kit to do much good. Over that distance on a pure 65 mph highway use I average 58 mpg instead of 50, which I guess saves me over a quart of gas. It's short highway trips where I can't get much gain.

[puddleglum]

Sounds like the 20miles in EV mode that they are claiming on their website is pretty unrealistic. Seems like they have some quality issues to work out too. Thanks for sharing your experiences.

[GeneralAnarchy]

You can do 20 miles, just not all at once. I've done 5 miles bursts through towns at low speed, interrupted by highway with no assist. In that case I probably exceeded 20 miles total EV travel.

Like owning an old car, it has to be partly a hobby. The technical issues of any PHEV car seem to mandate some amount of do-it-yourself. When warranties expire on the Volt or GM goes under, those owners will be in the same situation. I see it all as opportunity to save gas, not necessarily time.

[Daox]

I got my batteries back last night and threw them all together to discharge and balance them. They should be back in the car before the weekend (when I get to take a trip to pickup a Prius for a friend)!

I did want to elaborate on the BMS a bit. The first version of it had one feature, over-charging protection. This 2nd version will be adding a few additional features including: over-discharge protection, SOC gauge, Prius off PHEV operation. Over discharge protection is pretty self explanitory, stops the kit when the batteries get down to a programmed DOD. The SOC gauge is an LED bar graph display that will act like a fuel gauge for the PHEV batteries. The Prius off PHEV operation will allow the PHEV kit to charge the OEM pack even when the Prius is turned off. This allows you to park the Prius with a partially discharged pack and not have to sit there with the Prius on while the PHEV charges the OEM pack. The PHEV will automatically shut off once the OEM pack has reached a programmed SOC.

[bennelson]

Originally Posted by Daox

This allows you to park the Prius with a partially discharged pack and not have to sit there with the Prius on while the PHEV charges the OEM pack.

Ooooo! That's a really good idea.

That allows you to recharge BOTH the Enginer AND the Prius stock battery from wall power.

If you wanted to get really crazy, you would watch your display and drive in such a way that your Prius battery was most of the way down just as you pull into your garage at home.

[GeneralAnarchy]

Originally Posted by Daox

The Prius off PHEV operation will allow the PHEV kit to charge the OEM pack even when the Prius is turned off. This allows you to park the Prius with a partially discharged pack and not have to sit there with the Prius on while the PHEV charges the OEM pack. The PHEV will automatically shut off once the OEM pack has reached a programmed SOC.

I thought it was for safety. The HV relays turn off, so you need to bypass them or activate them independently, correct? I also thought the Prius regulates the rate of charge by dissipating to the engine spin and/or MG2 as much as needed to keep amps within Toyota's spec. The OEM pack is about 0.5 kWh, and I kind of use it to deplete my kit a little more.

Mostly I return home with plenty of Enginer juice left. Probably my voltage cutoff is too low. I usually set the parking brake and leave the kit on while plugging in, cleaning the car interior, kicking mudflap stalactites, and brushing away snow. While driving I would like to find some other way to take advantage of the 50V DC from the kit directly without passing it through the converter, such as heated seats and/or powering an electric defroster directly off the Enginer pack. Maybe four cheap 12V defroster fans "in series", but probably there is no elegant way to mount them.

[Daox]

I do plan on bypassing the HV relay. I don't see it being unsafe though. It'll have built in protection to prevent OEM battery damage. I won't be charging the batteries anywhere near as fast as regen braking so there shouldn't be any issues there. The only problem would be if somehow the dc-dc went crazy and created a short which is incredibly unlikely. If I was really concerned about that I could just add a ~15A fuse to take care of things.