Building a grid-charged A123 20ah pack. PP50 Project

[ericbecky]

There has been some discussion off list about building a duplicate of Peter Perkins' original design for a replacement pack for his Generation 1 Insight out of fifty A123 20ah prismatic pouch cells.

I have dubbed this project the PP50. (Peter Perkins, 50 cells)

Peter has been running his original PP50 (lets call it Version 1.0) since 2010 with zero issues.

I will work on building a single Version 1.0 PP50 here in the US.

(It will actually be Version 1.5 PP50, since it will have a minor BMS board update)

We can share the process of that buildup with everyone.

By the time we have it completed we will be that much closer to Peter creating Version 2.0 which will have a consolidated Master/Fooler/Interceptor/Charge Controller and other updates.

After that, THEN, we could move forward with a distributed group build of a bunch of these systems.

***************************
Some basics about PP50:
The PP50 replaces the original battery pack with a hand-built lithium pack that retains the stock case and weighs about the same, but has more energy density.

It is intended to be grid chargable.

Everyone should read and look at every one of Peter's pictures in his original build thread. It will give you a high level view of what is involved as well as some great visuals of what the end result will be. A123 20ah Lithium Install

We will need fifty (50) of A123's 20ah prismatic pouch cells with full tabs.
Image of one cell Data Sheet: 20Ah Prismatic Pouch Cell
Currently, cells cost between $25.50-$40 apiece depending on vendor, shipping costs, and availability. ~$30 is most common.
So 50 cells would run between $1,275 - $2,000

Rough estimate of additional items required $2,000 which includes:
- Original Insight battery casing
- Peter's custom BMS
- An appropriate charger to grid charge the pack regularly
- *Peter's BCM Interceptor
- *Peter's BCM Foolers
Lots of other little bits, bolts, connectors, etc
The original casing is modified/cut and will not be able to be turned to its original form factor.

*Peter is looking at combining these separate boards into single board. The system works fine with them separate, but combining them would ease installations.)
Optional. Having Mike Dabrowski's MIMA system will greatly increase your ability to get the most out of having the PP50 in your vehicle.

We are lucky to have Peter as the original trailblazer on this project and his initial work will help give us a head start.
But we don't underestimate the time, effort, and money involved.
It will take several months and several thousand dollars.
Prices are subject to change.

We are doing this for the enjoyment of it and the ability to avoid having having to mess around with the stock batteries.

Parts List in work for all boards

Mini BCM Interceptor
Mini BCM Interceptor thread
Mini BCM Interceptor Parts List
9-10-12 Mini BCM Interceptor parts list with prices. Compiled by rothnic

25 Cell Slave Board
25 Cell Slave Board Thread
Full Size Schematic
Note: Schematic is wrong, use 12F683 PIC

Master Board
We will be using the V2 Master Board .

BCM Fooler
BCM Fooler Post

Remote Receiver option (optional)
Picture1 http://www.solarvan.co.uk/bms/Pcbs011.jpg
Picture2 http://www.solarvan.co.uk/bms/250809007.jpg
Schematics for switch could not be uploaded since I can only put 4 attachments on this post. See this post for the schematic.

[IamIan]

Are we still open to the two different directions of battery box design or have we picked just one?

The two I recall reading about were ... hand customizations of the OEM stock pack ... similar to how Peter did his prototype ... and I think Mike mentioned the possibility of a new battery box designed and built for the PP50 v2.0.

[ericbecky]

For this thread, for now I am going to stay focused only on hand customizations of the OEM stock pack similar to how Peter did his prototype.

So as a differentiator I could say it is a PP50 SC. To clarify that it uses the Stock Case to hold the cells.

Yes, I mentioned that Mike D will likely be working on his own custom setup of a A123 pack based off of the original PP50. (Custom box, integrated cooling, Mike D special sauce, etc)

I get the impression that even with a custom case, there still may be parts that can only be harvested from a stock insight case. I'm not sure about that, so it is my pure speculation for now.

Since it will be a different project than the true PP50 SC, I expect Mike will start a new thread about his A123 project when the time is right. That way this thread can be focused on the PP50 SC only.

I imagine that it will be quite a while before Mike's A123 project gets moved to the front burner. He still is completing other projects like the last of the Plug & Play MIMA, and the battery chargers.

[Rush]

Eric,

I followed your suggestion and did go back and read the orig build thread. There really is a good amount of info in it. I really hate reading long threads, I find that the format is just not conductive to seeing the whole picture.

So I copied Peter's posts only and his pics and made it into a pdf. It is not too big, 1,639KB, I was going to put it up on this thread, but don't know how to put up pdf's. If you want I can send it to you and let you do it.

[ericbecky]

Originally Posted by Rush

So I copied Peter's posts only and his pics and made it into a pdf. It is not too big, 1,639KB, I was going to put it up on this thread, but don't know how to put up pdf's. If you want I can send it to you and let you do it.

Great!
This is exactly what I was thinking needed to happen; a tidier summary.

Send it my way and I'll work with it.

[retepsnikrep]

Bizarely I seem to have lost the ability to solder the A123 tabs, I was trying today to solder a 12 cells together for my bicycle test pack with the same flux etc I used before, but I failed miserably to get it to stick to the aluminium tabs. I think the goo I used had a fairly short (6 month) shelf life and is clearly past it's best. I also think my 100w iron is also a bit too hot and oxidising the surface very quickly. I need to run it through a dimmer to cool it down a bit.

Very strange when I had no major problems doing 50 two years ago.

I wouldn't have believed the in date flux goo was so important until today.

[talonmike]

Can you use a spot welder?


CUSTOM BUILT BATTERY TAB SPOT WELDER 2 - YouTube

[ericbecky]

I've seen some people try spot welding A123 packs, but the margin of error is too tight.

It's way to easy to burn through them and essentially destroy a pack.

If you had a bunch of dead packs to play with to get all your setting exactly right first, then maybe it might be feasible.

[retepsnikrep]

Perhaps riveting is an answer with some copper or aluminium washers and some noalox?

[Rush]

Peter, I know that you've already worked with the tabs, but let me put an email in here by Bill Dube, who works with A123 Pouches extensively for battery pack on the Killacycle.

The pouches can get too warm under harsh cycling (like a hybrid, or
fast repeated recharges in a BEV.) You still should pay attention to
pouch temp. The tab temp will likely be greater or equal to pouch
temp typically.

Laser (or resistance) welded connections are what is
recommended because they are the most reliable and have the lowest resistance.

If you are clamping, the oxidation of the aluminum tab is
likely to be a serious problem. A quick polish and a thin coat of
NoAlOx might be prudent before applying clamp type connections. The
expansion and contraction of the aluminum clamps might also be an issue.
Bill D.

I'm sure that he has had many conversations with the A123 engineers about how to connect tab to tab...