Best Plug-in Conversion System - Please Weigh In

[TheForce]

Originally Posted by zcat3

Why is the PICC kit better than the Hymotion kit (disclaimer - I have the Hymotion kit)?

The PICC kit is better because if you try to do too much EV with the Hymotion battery it will start to drain the stock battery. I have found if you draw more than 30-40A continuous you will discharge the stock battery possibly draining too low. With the PICC you can draw 100A continuous and wont have a problem since there is no stock battery to drain.

Since you can draw more amps and not worry about damaging a stock battery the PICC can do its thing to use more electric at higher speeds.

If the PICC was available now with A123 LiOn batteries and has its interface integrated into the MFD I think I would switch to the PICC kit.

I know the NiMh batteries are good enough to get about 80% for the life of the car but I would prefer LiOn since it would be 1. More light weight for the same kWh or 2. You could stuff more kWh in their for longer range. Plus the A123 LiOn have been tested over 9000 charge discharge cycles and still hold over 80% charge.

[hobbit]

As a broad class distinction, at this point I would say that any
system that's contactor-based, i.e. banging two big batteries
together electrically without regulating the current between
them, is not worth looking at. Especially with mixed chemistries.
.
_H*

[ericbecky]

Originally Posted by zcat3

The other downside for PICC has to be the weight of the system. I could not find any information on their site, but this pack has to weigh in the 300 pound range, which means you really need to upgrade the rear suspension with heavier duty shocks and springs - which could easily add another $500 or more to the cost (perhaps PICC includes this in their system price?).
.

I found this on the PICC info sheet from Luscious Garage

Additional Weight: 250 lbs (kit includes upgraded rear springs)

So it's included as part of the cost of the conversion.

I posted a full copy of the info sheet on this post at Prius Chat.

[Creekside]

zcat3 brings up a very good point. The benefit you will see from a PHEV over a stock hybrid is dependent on 3 things: The number of miles you drive each day, your access to plug-in power, and the way you drive.

If you have a 90 mile commute each day and you can't plug in at work you are not going to see much benefit. However, if like me, you drive 20 miles or less each day you will have the ability to do a lot of pure electric only driving which will raise your overall fuel economy. I drive 3 miles to work and total of 18 to 20 miles each day. My mileage on my PICC conversion averages 115 - 130 MPG. However, I have a friend who does more driving each day with a Hymotion conversion who averages 70-75MPG.

Access to plugs is important. I have a plug at work and home and can plug in just about every time I get out of the car. This increases your MPG as you are doing more driving with a "full tank" of electrons. If you can't plug in at work your mileage will decrease.

Finally, how you drive makes a big difference. If you want to just get into your car and hit the gas you won't see the benefits that you would if you spend time mode-switching and planning your route to avoid freeway speed driving. The amount of energy needed to overcome wind resistance at freeway speeds is much greater than at 30-40 MPH. Part of my high MPG average is the result of traveling on surface roads at 25-40MPH instead of on the freeway at 70. As I said, my commute is 3 miles, so this is not much of a hardship. In fact, I quite like it. I am enjoying the slower driving and the increased connection to the neighborhoods I drive through.

Finally, when comparing conversions I think one of the most important factors is regen. Let's not forget that the stock Prius gets all of its electricity (and hence efficiency) from regen. The PICC allows full regen just like the original Prius battery. This "free fill up" can be quite significant. A few nights ago I traveled 8 miles to my friend's house almost all uphill. When I left his house to head back home my battery was at 65% state of charge. Eight miles later at home at the bottom of the hill I was at 73% state of charge. Essentially, I drove 8 EV miles and recharged my battery 8% at the same time for free.

Good luck in your research. Happy driving!

[Creekside]

Just to clarify the PICC weight issue:

The new battery adds 220 pounds to the car. The suspension upgrade id part of the conversion and is included in the price. Luscious Garage adds bigger springs to the car to handle the extra weight. I believe this is 40 pounds more than the Hymotion pack.

Battery weight becomes a bigger factor in your MPG if you drive longer distances each day. If you drive 20-30 miles each day you are going to be doing most of your driving with a full battery and the electric drive will increase your MPG a great deal. However, if you drive 60-80 miles each day, you are going to be doing a lot of driving in depleted battery mode. At this point your conversion will act like a similarly to a stock Prius except it has more battery weight in the back which can decrease your mileage.

[linuxpenguin]

Originally Posted by Creekside

Just to clarify the PICC weight issue:

The new battery adds 220 pounds to the car. The suspension upgrade id part of the conversion and is included in the price. Luscious Garage adds bigger springs to the car to handle the extra weight. I believe this is 40 pounds more than the Hymotion pack.

Battery weight becomes a bigger factor in your MPG if you drive longer distances each day. If you drive 20-30 miles each day you are going to be doing most of your driving with a full battery and the electric drive will increase your MPG a great deal. However, if you drive 60-80 miles each day, you are going to be doing a lot of driving in depleted battery mode. At this point your conversion will act like a similarly to a stock Prius except it has more battery weight in the back which can decrease your mileage.

Yes, this is correct though the extra weight is not as bad as you might expect. Since the PICC conversion battery has a lower internal resistance than the stock battery, the overall efficiency of the battery is higher and less of the energy is burned off as heat (it also allows you to capture more energy on regen-braking than the stock battery does). This helps offset some of the additional weight of the bigger battery pack. The end result is effectively the same mileage you would see with a stock battery once you have depleted (EG: if you are going on a very long trip w/o charging).

Andrew

[docbooks]

Thanks for all the input -- I now have upped my sights to a 2008 and after digesting everything, it seems as though all the systems will work from the standpoint of lessoning the ICE demands. Whether you use the energy in the supplemental battery packs quickly (ie, all EV usage) or over a longer time (with the ICE contributing, but at a reduced load), in the end the gas savings seem to work out to be about the same (except for repeatative, VERY short drives). Though these supplemental systems seem to be a stop gap measure, insofar as pure EV, I am most enthused that at least you can obtain VERY minimal gasoline useage for around town driving in real world conditions. The Enginer system seems to be the one swaying my decision so far. I'll keep you posted as things unfold. Anyone know of a qualified Enginer installer in the Florida area?
Thanks

[linuxpenguin]

Originally Posted by docbooks

Thanks for all the input -- I now have upped my sights to a 2008 and after digesting everything, it seems as though all the systems will work from the standpoint of lessoning the ICE demands. Whether you use the energy in the supplemental battery packs quickly (ie, all EV usage) or over a longer time (with the ICE contributing, but at a reduced load), in the end the gas savings seem to work out to be about the same (except for repeatative, VERY short drives). Though these supplemental systems seem to be a stop gap measure, insofar as pure EV, I am most enthused that at least you can obtain VERY minimal gasoline useage for around town driving in real world conditions. The Enginer system seems to be the one swaying my decision so far. I'll keep you posted as things unfold. Anyone know of a qualified Enginer installer in the Florida area?
Thanks

I disagree that the systems all work out to be the same (I haven't filled up my car since early August and still have over 3 gallons left running the PICC system) but it does really depend on your needs. Good luck with the conversion =).

Andrew

[NWPriusPlus]

I have only driven the BMS+ conversion system (from Norm at hybridinterfaces.ca ) , so I can't say it's the "best", and of course it all depends on your commute, weather, terrain, and mainly on your budget versus DIY abilities.

The BMS+ system as installed in my 2007 Prius cost me only $2200, and has performed perfectly for well over a year now. But my drives are short, and I can stay in ev most of the time, under 34 mph. I built my own charging system and cables. You have to be very careful with all of this high-voltage equipment and with the safety controls when charging NiMh batteries.

The BMS+ system has many advantages--if it fits your situation, I would certainly consider it. For more information, see my thread at http://priuschat.com/forums/prius-phev-plug-in-modifications/65501-one-year-driving-our-bms-plug-in-prius.html or at One Year of Operation in a Plug-in Prius with Norm’s BMS+ System (slightly more detail).

NW BMS+ Driver

[linuxpenguin]

Originally Posted by NWPriusPlus

I have only driven the BMS+ conversion system (from Norm at hybridinterfaces.ca ) , so I can't say it's the "best", and of course it all depends on your commute, weather, terrain, and mainly on your budget versus DIY abilities.

The BMS+ system as installed in my 2007 Prius cost me only $2200, and has performed perfectly for well over a year now. But my drives are short, and I can stay in ev most of the time, under 34 mph. I built my own charging system and cables. You have to be very careful with all of this high-voltage equipment and with the safety controls when charging NiMh batteries.

The BMS+ system has many advantages--if it fits your situation, I would certainly consider it. For more information, see my thread at http://priuschat.com/forums/prius-phev-plug-in-modifications/65501-one-year-driving-our-bms-plug-in-prius.html or at One Year of Operation in a Plug-in Prius with Norm’s BMS+ System (slightly more detail).

NW BMS+ Driver

I would add a note to this, if you do go BMS+ route make sure you routinely check the voltages on the extra Prius battery packs both at the high end and low end. BMS+ does not (when I last examined one) check the voltages of the two additional battery packs and if they get out of balance (happens over time) it can lead to overcharging or undercharging the batteries (inflicting permanent damage to them or worse). As long as you get the batteries balanced when you put them in and they are roughly the same calendar age you should be OK.

It's probably more of a hobby do-it-yourself approach (okay, it definitely is) but if that's your cup of tea... =)

Andrew