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

[hybriddriveguy]

Hi Bill,
Thanks for the compliments. We are working toward making other major components like the inverters available as remanufactured as well.

We have found that the Gen1 cells are always going to have the issue of leaking. They leak around the negative terminals as well and we have found more corrosion problems with packs that had the Toyota goop recall done than the ones that did not. With that said, given some upgrades to components, the leaking takes a long time to cause any failures and we still sell some with refurbished Gen1 cells. The Gen2 cells are much more durable as you already know. They still have some leaking around the terminals, but nothing on the scale of the Gen1. Currently, we only have a few of the Gen2 cells that have failed, so we are doing our own testing to see what happened to them. In one instance, it was an internal connection issue between the cells that caused the failure, so you could say it was a factory defect that took over 30k to occur.
This cell came from a 07 Prius that was still under warranty, but we were able to buy the pack from the dealer.
I think the heat and extreme cold have a lot to do with early failures.

[bwilson4web]

Originally Posted by hybriddriveguy

. . .
We have found that the Gen1 cells are always going to have the issue of leaking. They leak around the negative terminals as well and we have found more corrosion problems with packs that had the Toyota goop recall done than the ones that did not. With that said, given some upgrades to components, the leaking takes a long time to cause any failures and we still sell some with refurbished Gen1 cells. . . .

This is good news! I knew the salvage rate, something less than 3%, was providing a steady stream of recycle NHW11s but without module refurbishment, eventually that stream would fail to meet the long term demand. But the NHW20 failure rate is so low and there are so many, I figured the gap could be made up from them.

Have you found any modules with evidence of the pressure relief valve operating? I bought one failed battery pack in Columbia SC and none of the modules showed evidence of the pressure relief valve operating.

My experiments were aimed at adding a hydration port to the modules. My thought being rehydration could be done every two years to restore capacity. But I was never able to come up with a good anchor scheme for the stainless steel nut-plate.

BTW, last year I helped someone who had a failed traction battery get it picked up by Toyota. It took about two months including some private communications with some Toyota folks. What I'd like to suggest is add a 'standing offer' for failed traction batteries and/or modules. IMHO, fair market price: $200/40 ~= $5/module on top of shipping. Just a thought.

I started a thread over at PriusChat in their NHW11 forum, "Gen I", with your URL. I would also recommend a posting in the YahooGroups, "Prius Technical Stuff" and "Prius." Since the YahooGroup postings are first post moderated, I'd be happy to start a thread in each.

Eventually I'll have to retire from my current employer but we have this RV. I've had this 'brain fart' about putting a lift on the back, tool rack and spare NHW11 parts ... a shade tree, Prius mechanic who makes 'house calls.' <grins>

Bob Wilson

[hybriddriveguy]

I have found very little evidence of pressure relief valve opening on any of the packs I have worked with. I do have a module that was exploded inside the case and then caught fire. The customer was totally unaware of it happening other than the car stopped.

Looks like you understand these packs more than most people. Good job!
I think a mobile setup would work well. I spend many hours a week helping Prius owners who have their cars stuck in dealerships who just want to throw expensive parts at them. I understand the reasons though. These cars have been so trouble free, that few dealer techs have been able to get really good with them. The Toyota factory diagnostic procedures take too long to find out what is really wrong as well.
I do have a standing offer of $200 for Gen1 packs with all electronics included or for bad Gen2 packs.
Thanks for starting these threads. The moderators will not allow me to start them due to what I do.

[Daox]

Originally Posted by hybriddriveguy

The issues with the parallel pairs was needed to help balance the high and low cells. What I would recommend is to separate all cells before any charging and record the static charge on them. Add all voltages together and divide by the total number of cells you have. This will give you a cell average that you are looking for. I would then start matching highs and lows within the cells to match the average as close as possible. This will give you the best pairings for each parallel pair.
The reason we have to do this is because you are charging the whole pack to around 58 volts and the biggest danger to these cells is overcharging. You could have a low cell starting the charge cycle at 2.7v and a high cell at 4.1v.
If they are wired in series they will both continue to receive charge until the total system voltage is achieved. This would in our experience drive the high cell to over 5 volts and damage it before the low cell would be high enough.
Connecting these in parallel, creates a balancer for that high and low cell by using one to balance the other.
We have been fighting this battle since may and my company has been through about 3 complete sets of the batteries, while trying to get all the bugs worked out.

When all of my cells were shipped to me I tested their resting voltage. They were all within .02V of each other. After that, I put them on the balancers to balance them out even further. IMO charging shouldn't be an issue once they are balanced.

Info I'm getting from other users is that it takes some time to brake in the cells until they will charge/discharge uniformly. This doesn't make much sense to me as I don't believe any other battery chemistry has this problem, but I am a bit new to lithium.

[Daox]

I have wired up the cells in their buddy cell setup (I made my own connectors) and hooked up the balancers and let them do their thing before doing anything else. However, when I hooked up my charger, I plugged it into my killawatt to monitor energy usage. In the first few seconds of plugging it in, the charger pulls ~160W or so, but slowly tapers down to 7W over a minute or so. After leaving it plugged in for 10 minutes, it was still only pulling 7W. Sounds like a bad charger...

[bwilson4web]

Originally Posted by hybriddriveguy

. . .
Thanks for starting these threads. The moderators will not allow me to start them due to what I do.

No problem but you know we're out to 'pick your brains.' <grins>

I didn't know about the gold plated sense wires. I bought the used modules.

Bob Wilson

[hybriddriveguy]

The gold plating is only on the ecu end.

[bennelson]

Originally Posted by Daox

.......Sounds like a bad charger...

What were the cell voltages when you started charging?

If they were already charged up, the charger WOULD only pull a few watts.
Do you have access to technical information on the chargers? (Did the kit come with the charger manual, etc.?)

Maybe we should get in touch with Lithium El-Camino Tom?

[hybriddriveguy]

They do not consider these balanced until the are all within .002 of each other. These lithium do react totally different than any other chemistry I have worked with. It is almost like having 16 picky eaters sitting there and trying to get them all to agree on a common meal. The best solution will be to set up a charger that charges each cell based upon it's own needs or go through the long process of balancing with the stock unit. We were getting close on ours a couple weeks ago and lost another dc/dc.
I am working on a charger upgrade now.

Originally Posted by Daox

I have wired up the cells in their buddy cell setup (I made my own connectors) and hooked up the balancers and let them do their thing before doing anything else. However, when I hooked up my charger, I plugged it into my killawatt to monitor energy usage. In the first few seconds of plugging it in, the charger pulls ~160W or so, but slowly tapers down to 7W over a minute or so. After leaving it plugged in for 10 minutes, it was still only pulling 7W. Sounds like a bad charger...

[Daox]

Originally Posted by bennelson

What were the cell voltages when you started charging?

If they were already charged up, the charger WOULD only pull a few watts.
Do you have access to technical information on the chargers? (Did the kit come with the charger manual, etc.?)

Maybe we should get in touch with Lithium El-Camino Tom?

The pack is far from charged. Its resting voltage is ~52V right now, charged is 57ish.

There is no charger manual.