Gen II Prius Individual Battery Module Replacement

What do you mean by charging to delta v?

I mean whenever you charge it, you try to charge it fully to balance all the cells inside the module not necessarily delta v(?).

 

"Delta V" is the sudden rise in voltage that occurs as each cell reaches fully charged. The charger can detect this change in voltage and stop the charging process so as to not overcharge the battery. One problem is detecting Delta V with a low charging current can be difficult. The other problem is that if the cells in a module are unbalanced, Delta V happens at different times for each cell.

JeffD

 

I should have been more careful with my terminology, I meant negative delta V. On my own bench my software detects a drop in voltage and terminates the charge by detecting a small drop in pack voltage after it peaks, I only do this when reconditioning packs. When it comes to testing you don't want to start with a fully charged module, weak cells tend to hold a lot more energy fresh off the charger than after a rest period. It's simply a matter of putting in a measured amount of energy into the pack and measuring how much energy you get out, hobby chargers do that, get one that logs/graphs for a much better understanding of what's going on. Start with a cooled down module (1-2 day rest), discharge down to 6v (4.8 is too low), then put in 6000mah charge and discharge down to 6v again, repeat x3. Repeat for every module and write down the results, all the modules should perform equally, with a slight deviation. Modules that are 10% or more off your average tend to be the ones that will fail next.

 

Will you put 6000mah every time? Then you compare the voltages between modules?
Is that right?
Also, why do you think 4.8v is too low?
Sorry for a lot of questions, if you have a link where I can understand fully I will go there.

 

6000mah is a good starting point, it's not too much energy in comparison to total cell capacity, it's not going to overcharge your modules if you're starting by discharging to 6v first. 4.8 is too low because a NIMH cell runs out of capacity around 1-1.1 volts, continuing an aggressive discharge below will cause the polarity to reverse and damage the cell/module but also it will cause your tests to be inconclusive, you will have a lot of bad modules in a functional pack where only a few need to be replaced.

 

Has anyone replaced individual cells on a Highlander? How do you get the individual packs apart, and re-assemble them?

 

Perhaps @MTL_hihy can help you.

 

It is the same process as in a Prius except that the modules have 8 cells in series for 9.6 volts (nominal). It has been done and there are discussions on PC by the owner who did it.

JeffD

 

It's not nearly as easy as the Prius, takes alot of work to get them assembled again.

I think this is the post you are looking for:
Gen II Prius Individual Battery Module Replacement | Page 13 | PriusChat

 

Hello guys, great thread right here, thank you all for sharing your, experience, settings and type of equipment being used to rebuild your packs.

I'm in the journey of rebuilding my pack as well and I have a question for you, more experienced guys. I have a weak module in my pack, yesterday it was discharged the second time to 1009mAH down to 6.1V, and I let it rest overnight. The first charge was @2A and the Delta Peak sensor stopped the cycle soon. It took 2519mAH.

Today I started the second charge cycle @1A, I modified my settings to be a little more gentle on it (I have to cycle the modules "manually" since my charger is acting weird on the DCH>CHG program), I had to stop the charge cycle at 2504mAH and 160 minutes, voltage was too high, it kept at 8.8-8.9V for a while, it's too high... and it swelled around 1.5-2.0mm on each side, measured at the top of the module.

I was trying my best to recondition this module but didn't consider that swelling is too safe to be honest. No apparent heat whatsoever, one of the other modules I'm cycling is generating more heat than this weak one, but no swelling at all, and condition of that one seems pretty good.

What do you guys think? is it safe to keep cycling that module? Do you think it's a hazard? How much swelling would be considered "safe" to continue cycling it?

Any input will be greatly appreciated.

Have a good one.

 

That module you're working with has a bad cell and will never function properly in your car. Under a 1a charge I never see voltages higher than 8.55 to 8.60 on a good module. A module that is rising to 8.9 volts under 1a charge has a bad cell.

Also, wasn't clear from your description but don't do any charging/discharging to module that isn't clamped in the cage or some other way, can ruin a good module this way.

 

Thank you for replying, you're completely right, after just half an hour of sitting after the charge, module voltage dropped to 7.04V, so yeah, dead cell.

I didn't unmount the modules from the case, so they are sitting just as they sit in the car just removed the cover, of course.

Any good reputable online seller that you would recommend to purchase the module from? What's your opinion about Hybrid Automotive? I see on their site they categorize their modules by mileage as well and it seems they test capacity to ensure the state of the module.

My car has 167k mi but seems the pack was already worked on, so not sure about the mileage on the modules but the good ones are averaging 5000+ mAH capacity on the 3rd discharge and I feel that would be enough for a good rebuild (?)

Thank you in advance

 

Hybrid Automotive would be one of the most well informed sellers out there. They have the expertise and know how to properly store, handle as well as test battery modules. In any case, double check what you buy the same way you're double checking what you have.

When it comes to testing it's important that you don't start with a fully charged module (fully charging is done only during reconditioning). Start by discharging a module down to 6v, put in/charge a metered amount of energy (say 6000mah), then discharge down to 6v and write down the amount taken out. Repeat a few times for each module to obtain an average, then compare your modules with the results.

 

Thanks, I'll definitely check the new module, the first discharge from the DCH>CHG cycle will always be the lowest in my experience, good thing it usually improves with it

Greetings

 

Possibly dumb question: Is an ultrasonic cleaner suitable/ideal for cleaning the copper bus bars?

(ie for a while now I’ve been looking for a good excuse to buy an ultrasonic cleaner…)

 

I bought one for the same purpose, it is absolutely useless.

Hydrochloric acid takes off the corrosion very well and afterwards you can hit it with a brass brush and then polish them or electroplate with nickel.

 

With nickel plating, is there anything special about it? ie can I just take the bus bars to any place that does nickel plating? Or, is there something extra that needs to be done?

Likewise with the nuts - just clean them, or is it worth getting them plated as well?

If the bus bars are nickel plated (and thus won't corrode), is it still worth putting Noalox on there?

 

Any place that does nickel plating will probably know what to do but I suggest doing the prep work beforehand to save on costs/convince them to take such a small job. Acid dip, brass brush each bus bar, then metal wire brush using gloves the entire time and storing the finished product is airtight container.

The nuts cannot be restored since they are 2 pc construction with a plastic ring holding them together. Just buy new ones, 5mm x 0.8mm. I like to use 10.9 steel.

 

Yesterday I received a collection of Hybrid Automotive Prolong equipment.

I bought:
- Prolong Battery Charger for 2006-2017 (ie will charge Prius as well).
- Prolong Battery Discharger for 2003-2017 Prius (ie 2nd and 3rd generation).
- Prolong Battery Discharger for 2006-2017 Camry (ie 1st and 2nd generation).
- Car Harness for 2004-2009 Prius (ie 2nd generation/20-series).
- Car Harness for 2006-2011 Camry (ie 1st generation/40-series).
- Prolong Load Tester.

Although it was an extra expense having to buy two Dischargers, at least each one covers the later generation of Prius and Camry (which I will have in a year or two).

Positives:
- It was well packed, with plenty of bubble wrap.

Negatives:
- Three of the four rubber supports underneath the charger came loose in the bubble wrap. I’ve stuck them back on but they’ll need to be glued back on with some strong glue later.
- Two short US power cords were suppled (I’m in Australia, so US ones are of no use to me). Not a huge problem - I already had some spare power cords in a box of computer junk. Some Prolong green power cables would be a nice touch.
- The shipping quote from Hybrid Automotive was relatively high (just under $US300 to Australia), so I instead had it sent to a nearby freight forwarding company (Shipito), and then sent to me. This cost around half the price.
Note: These are very, very minor issues… measuring 0.00000000001 on the Richter scale.

Now I’ve got to figure out a way of storing this stuff safely (eg a large toolbox with foam inside).

In another box, which is still stuck in California, I have:
- A Hitech X4 AC Pro 44254 Charger (ie four channel, and I like that it doesn’t require an external power supply).
- An iCharger 406 Duo (ie dual channel, with a high discharge rate if I start using regenerative discharge).

I welcome any feedback on the effectiveness of those two chargers.

I’m having trouble getting the freight forwarder to ship that box because it also contains a wall painting, and they’ve decided that the wood frame is an evil substance. Meanwhile, Australian Customs, the Department of Agriculture and Australia Post have absolutely no problem with it (ie it’s classified as a “highly processed timber product”, which is of no threat). Very frustrating.

Photos of the Prolong stuff:

 

1)
Are stainless steel nuts suitable?

2)
If stainless steel is suitable, which grade… 201, 304 or 316?

3)
Does it matter whether the flange is serrated or not?

ie
Local to me: Austain Fasteners | Shop | HEXAGON FLANGE NUTS | METRIC | 304/A2 | Viewing M5 G304/A2 FLANGE NUT

eBay: M3 M4 M5 M6 M8 M10 M12 M16 Stainless Steel Serrated Flange Nuts Hex Lock Nuts | eBay
----------------------------------------------------------------------------
I spoke with one place about nickel plating the bus bars and he put it to me that I have them tin plated.

He does a lot of aircraft stuff and apparently it’s all about tin plating for that.

It’s also a lot cheaper than nickel plating.

Is tin plating a suitable option for bus bars?