adding extra 4kw battery for more than double plug in miles

all the best kit!

 

THANX

 

I'm looking forward to your reviews of the add on pack.

Cute. It looks like they used a Liftback instead of a Plug-in for the pictures.

 

basically the same

 

I'm not buying one yet, I have a Tesla Model S reservation. Seems much more practical to me.

Go look at the pictures of assembling the 4KW pack.. It's not a product, it's an adventure

 

Wonder if they would fit sideways down in the unused storage container?

 

This is where they fit in the GEN II: http://priuschat.com/attachments/hpim0233-jpg.40276/
(looking at the cargo tray sideways)

 

Are you going to keep the Prius Plug-in for long distance trips?

Link?

 

Probably not, my sister will probably end up with the PiP.
The Model S IS my long distance car, the farthest I go is NYC, thats 215 miles away from Boston. If you have to go farther, you can always rent a car for $30/day, I don't anticpate needing that at all.

The pictures are on the Plug in Supply site: Installation Instructions | 4KW Pack Assembly

 

I had no idea it was that DIY. While I'm pretty sure I could put something like that together, it seems like it would be a nightmare supporting less handy customers. Also, it limits the market for customers significantly. It seems like it could be fun, but if it isn't reliable it would be a terrible time sink.

 

I think you can pay them $500 more to assemble the (2) subpacks, and even more to install it for you, so you can trade money for your labor/skill. I am skilled in electronics, and it doesn't look like a fun project to me, its a repeatative, monotonous task, with a high risk of electrocution, if you are not careful. I could certainly assemble it, with enough time, a clean workspace, and no interuptions, but, its not the kind of project you should tackle in your living room (or bedroom, as can be seen in some of the photos with a bed behind the table/batteries)

it also appears you buy some of the items directly from suppliers, or you can buy the components from them (for an additional fee of course). by the time you add up "just buy it and have them install it", its not a very attrractive price. Is 20 additional EV miles going to be worth$6,000 to $6,500 to you, because thats the "real" price of this kit.

btw, its also going to add to the recharge time, since the original PiP pack is 4.4KW, (only discharged down to about 1.1-1.3KW, so only about 3.1-3.3 KW being added), it will double your recharge time on L1 (3 to 6 hours), and also double it in L2 (1.5 hours to 3 hours). Of course you are getting about 31+ EV miles.

 

I believe you're right about the $500 to assemble the two sub-packs. Considering how much time it took me to do it, I don't think they're making any money doing it. As for fun, it depends on your perspective. I definitely wouldn't want to do it for a living, but as a one-off project it was shall we say...interesting. Regarding my work area...yes, it was the spare bedroom. I don't have a workshop, the kitchen table was definitely out-of-bounds, and the living room wouldn't work either.

I think I would dispute your 'high risk of electrocution if not careful' comment. I would characterize it as closer to 'moderate' risk. That doesn't mean there is no danger at all associated with the project--of course there is. There's danger any time you get out of bed...and even if you don't! A fully charged/assembled subpack measures about 127 volts. Now that voltage is similar to what you get out of your wall socket...Except! It's DC current instead of AC. My admittedly limited knowledge of electricity tells me that DC current can be more dangerous than AC. But, if you never take any risks, you never get any rewards either.

When you start wiring a pack together, you do one side at a time. So you're halfway finished before there is any danger of shorting more than 6.4v at any one time (each individual cell is rated at 3.2v). But that's why you use duct tape or masking tape or something to insulate the surrounding terminals once you start work on the second side.

I wouldn't recommend this project for an absolute klutz, but it doesn't require an advanced degree in electronics either.

 

I think those numbers are a bit off. The unit for energy is kWh; kW is a unit of power. The Prius Plug-in takes about 3.2kWH to charge and with 85% charging efficiency, that means only about 2.8kWh of that is usable battery capacity. I believe the way the add on battery kits are advertised is their usable battery capacity, not their total battery capacity.

As for charging, it takes about 2.5 hours at L1 (120V*12A = 1.44kW) and 1.2 hours at L2(240V*12A = 2.88kW). It takes a little longer than simply dividing 3.2kWh by the power is b/c the current slows when the battery is almost full and takes another 10 minutes to top off the battery. The add-on pack should take an additional 4.7kWh to charge, which corresponds to 5.76 hours (2.5+3.26) to charge at L1 or 2.83 hours (1.2+1.63). So the charging times are a little faster.

 

Um, ok, if that makes you feel better, Mr OCD it basiclly doubles the charging time, in either case.
The Plug in Supply kit is sold with total KW in the pack, not the usable KW, so the add on 4KW is actually smaller than the 4.4KW pack that the PiP comes with from Toyota.
They connect in parallel with the Toyota pack (via a relay), so the same DoD (Depth of Discharge) will be used, as well as the same top end when charging.. And yes, I am aware of the difference between a KW and a KWh.

 

Really, I appreciate being called a name for trying to get things right. You managed to get approximately the right answer, but from the inputs that were slightly off. The OEM battery charges faster than you suggest and the add on battery capacity is larger, so it actually takes a more than twice as long to charge the combined batteries (yet still faster than you suggest).

Their website states that the 4kWh is usable capacity under the "Plug-In Conversion System Specifications" at the bottom:
Plug-In Conversion Features, Specifications, and Warranty | Plug-In Supply

Which means their usable capacity is larger than the OEM battery pack. Assuming the same usable battery capacity to total battery capacity ratio as the OEM battery pack, this means the total battery capacity is about 6.3kWh.

If you say so, but you are still using kW in place of kWh.

 

I wouldn't count on that being true, they use 76 headway cells in their 2 packs (38 cells each)
Each Headway cell is 15000mAh (15AH) X 3.2 Volts, or 48AH per cell
the math works out to 76 cells X 48A, or 3648 AH for their system.
divide by 1,000 to get Kilowatt Hours, 3.648

its actually under 4, not over. at any rate, I am not buying it, but good luck to those that do.
Of course it all depends on what voltage the cells are run at, but 3.2V is considered standard for this chemistry.

References:

76 cells needed: Installation Instructions | DIY Pricing | Step 3
Cell specification, from the PIS website: Installation Instructions | Cells | Step 1
Converting Amp Hours to Kilowatt Hours: How to Convert Amp Hours to Kilowatt Hours | eHow.com

 

DUH!

 

Looking at the Headway spec sheet, "maximum float charge", 3.6V

Using that as a maximum, we get 15AH * 3.6V, or 54AH maximum per cell
54AH * 76 cells = 4104AH, or 4.104KW

So they are not telling an untruth, it's the entire capacity of the pack, 4.1KW it's a little smaller than the factory pack of 4.4KW, they want them close in capacity, since they just parallel the packs, this way they will charge/discharge in tandem.

Mitch