Building battery packs - Dewalt lion (a123), NiMH RC packs, PrivateNrg etc..

[Atari]

PriusChat user mwbueno made (6) battery packs for the prius out of 28 off the shelf NIMH RC car batteries:

Photo below shows the first Priu


Others are have been harvesting LION batteries (made by A123 systems) from Dewalt DC9360 36v electric drill packs... here's an example:

Porsche 914 EV Conversion: Visiting Gary of the OEVA to get a Crimper
Dissecting DeWalt 36V Packs (A123 Systems)
How To Build a Battery Pack from A123 Cells - RC Groups


Does anyone have any plans or schematics on how a Prius could use these homegrown packs?

I would really love to be able to do whatever mwbueno is doing. On his site he reports that he's been using those 6 homemade NIMH battery packs for many, many miles.

[bwilson4web]

Originally Posted by Atari

. . .
How To Build a Battery Pack from A123 Cells - RC Groups

Does anyone have any plans or schematics on how a Prius could use these homegrown packs?

Thanks! This matches a problem I've been mulling over, how to handle keeping the battery packs equalized in a plug-in lite. There is a 24 pair, connector that should work just fine for what I want to do.

Originally Posted by Atari

I would really love to be able to do whatever mwbueno is doing. On his site he reports that he's been using those 6 homemade NIMH battery packs for many, many miles.

Battery engineering is not a trivial problem. I've only started working with batteries, mostly to try and refurbish weak modules:

I've also seen photos of what happens when batteries are overcharged and it isn't a pretty sight. The biggest problem is the flat charging and discharge profile means there is no voltage clue to the state of charge.

Bob Wilson

[krousdb]

Originally Posted by Atari

PriusChat user mwbueno made (6) battery packs for the prius out of 28 off the shelf NIMH RC car batteries:

Photo below shows the first Priu

Does anyone have any plans or schematics on how a Prius could use these homegrown packs?


I would really love to be able to do whatever mwbueno is doing. On his site he reports that he's been using those 6 homemade NIMH battery packs for many, many miles.

Atari,
From the link provided:
"Early in 2004, when I had finished assembling the NiMH array, a friend & I put the whole array in the spare-tire wheel-well and you can see for yourself, 18Ah & more can fit down there."

In late 2005, that same friend helped me install the same 18Ah setup in my Prius. I also built a low cost grid charging system. For very short trips, the setup had some merit. But for my (at the time) 25 mile commute, I found no real difference in FE. I removed everything in early 2006 and sold off the components. For me, the $3000 cost would have never paid itself back.

Also note from that link:
"I know a lot of people can get this kind of mileage without extra batteries but, I don't have the patience to go the slow speeds required to do that ... Yet!"

I currently have a 135 mile round trip commute. I drive 60mph for 100 of those miles and 25-45 for the other 35 miles. My MFD currently shows 68 MPG at 400 miles, which is better than the 64.5 mpg shown in the link provided. Just food for thought.

[Atari]

Originally Posted by krousdb

Atari,
From the link provided:
"Early in 2004, when I had finished assembling the NiMH array, a friend & I put the whole array in the spare-tire wheel-well and you can see for yourself, 18Ah & more can fit down there."

In late 2005, that same friend helped me install the same 18Ah setup in my Prius. I also built a low cost grid charging system. For very short trips, the setup had some merit. But for my (at the time) 25 mile commute, I found no real difference in FE. I removed everything in early 2006 and sold off the components. For me, the $3000 cost would have never paid itself back.

Also note from that link:
"I know a lot of people can get this kind of mileage without extra batteries but, I don't have the patience to go the slow speeds required to do that ... Yet!"

I currently have a 135 mile round trip commute. I drive 60mph for 100 of those miles and 25-45 for the other 35 miles. My MFD currently shows 68 MPG at 400 miles, which is better than the 64.5 mpg shown in the link provided. Just food for thought.

doh. Missed that.

[Atari]

Anyone know how many A123 cells are in the Hybrid-Plus PHEV-30 pack?

[iLLa Prius]

I've looked at this. Its not very cost effective right now. A123 and some of their suppliers do custom battery packs. The EV Nova drag car had a custom pack which is probably one we could use or need. I dunno how much it cost though.

[Atari]

Depending on how many A123 cells you need.... you can get 10 cells per dewalt battery pack for about $110. So $11 per cell. Curious how many are in the PHEV-30. Those are big C or D sized cells... 100 for $1100 may not be a bad deal. Even if you needed 400 cells, that would be a lithium pack for under $5k. But maybe you need more than 400? :shrugs: Was hoping someone here would know.

[iLLa Prius]

the price sounds about right. i just figured out that prius oem battery is 6.5ah, and this one guy running his own set up in that one link, is using something like 18ah with limh. you could do 8 packs to get you up to 19.2ah at 288v if you wanted to. you would still need chargers but, it wouldnt weigh very much, about 20lbs.

i wonder if anyone will just use the dewalt packs as is, make some sort of config, so that you can have them all hooked up to be used and charged. even rig up the dewalt 1 hour chargers. it would be golden. just rig up your two custom two adapters, instead of actually having to mess with the battery packs. a battery pack goes bad, just replace it. use dewalts battery packs and chargers.

i think there are two problems though. i believe i read that there is some sort of low voltage cut off electronic device in the battery pack and there is also a fuse made into dewalts tabs that connect all the batteries together. both of these will hinder using it as only a battery pack (more electronics and saftey precautions to cause a problem).

[miscrms]

In general putting the batteries in is the easy part. Unfortunately, just adding more battery capacity will do very little for MPGs. As an example, the US gov. ran some Gen I Prius to 160k miles. At that point they found the battery capacity was down 50%, but the mileage was unchanged. Under most driving conditions you are not even remotely limited by battery capacity. Adding a grid charger is a crucial first step to better performance, but still in of itself will not result in greatly improved MPGs. In order to really get good numbers from a PHEV conversion you have to get the battery controller to acknowledge that extra charge is available, and the HV controller to use that extra charge. Neither of these is trivial, and really to pull it off requires a custom micro-controller.

In my opinion it makes no sense to go fancy with your batteries and skimp on your control, as the biggest bang for the buck by far is your control algorithm. You are probably much better off with a small lead acid pack with a good controller than a nice Li-ion pack and a switch on the dash.

From the numbers I have seen, a 30 mile PHEV take ~8 kWh of battery. The numbers I've seen for the A123 18650 cells was 3.2V, 1.1Ah. For a 30 miles pack you would need ~2272 cells, at a cost of ~$25,000 at $11/cell. Thats an unfairly low cost, as you will need some sort of sophisticated battery management system to monitor, balance, and protect each and every cell! Incidentally, the Tesla Roadster uses over 6800 of these same cells.

If you are trying to do this on the cheap, I honestly don't think you can do much better than the cal-cars open source recipe. You should be able to get ~10 miles EV, or ~15-20 miles at 100mpg+ for $3-6k. In the long run you might be better off with the Nilar NimH version they are working on, as the batteries should last a lot longer although they cost more up front. This is really about as simple as you can get. There is a big contractor (basically a switch) that connects and disconnects the secondary battery to the primary. There is a controller that monitors all the traffic on the CAN bus between the battery controller and the HV controller and decides when to close the switch to optimize SOC to use as much electric drive as possible. Theres a big lead battery pack, a battery box, some low voltage electronics to keep the car happy about what you're going to it, and a charger.

Its really hard to see where you would get it much cheaper than that, at a guess you're talking about $1000 for the batteries, $800-$1000 for a charger, $500 for the controller, ~$500 for the HV electronics, and another $500-$1000 for low voltage electronics and the materials and hardware to put the whole thing together and have it be safely secured. That would put you in the $3300-$4000 range (ignoring tax, shipping etc). You can also buy the whole kit ready to install with a nice box and retaining spare tire access for ~$6k. You could skimp a bit on batteries, but you'd loose range. You could design your own controller, but that would take a lot of time. Skimping on the HV electronics, low voltage electronics or battery boxes could result in putting the vehicle or its occupants at greater danger.

PriusPlus - EAA-PHEV

Rob

[Atari]

Originally Posted by miscrms

From the numbers I have seen, a 30 mile PHEV take ~8 kWh of battery. The numbers I've seen for the A123 18650 cells was 3.2V, 1.1Ah. For a 30 miles pack you would need ~2272 cells, at a cost of ~$25,000 at $11/cell. Thats an unfairly low cost, as you will need some sort of sophisticated battery management system to monitor, balance, and protect each and every cell! Incidentally, the Tesla Roadster uses over 6800 of these same cells.

Haven't read your whole post yet, but I think 18650 are close to "AA" sized batteries. The ones in the dewalt look like "C" or "D" sized. But maybe they are neither. I'm pretty sure they are bigger than the 18650 package though. I think they are 26650 sized actually. I'd imagine you need less.

However, I think the tesla uses ~6500 of the 18650 cells. :sigh: