Traction Battery Preventative Maintenance - Hybrid Automotive Chargers

I'll answer a bit and let Jeff chime in with the rest.

2) You could charge daily as long as you stayed within the cars normal operating state of charge.
You would not want to charge it up to 100% SOC every single day. That'd be too hard on the pack.

3)The balancing happens mainly at the top end of the SOC range. If you don't bring the pack up to the high SOC range it won't balance. Most of the time you would just be balancing if you stay away from the top SOC range.

 

Thanks for that. I think I'll get the current one on offer first and if ever you need a test mule for the charger-only (or dual) module, i'd be more than happy to report on it.

 

What is the purpose of discharging, and cycling ? Is it just to "exercise" the pack ? can someone confirm the benefits of cycling ?

since the balancing is done at the top, when the full cells simple convert added energy to heat while waiting for the lower cells to catch up.

thanks

 

Simplest way to explain it is that the discharging helps regain capacity. The Honda Insight community has used similar chargers/discharger for years.

 

Is there a go-to place in Southern California that could/would install this for me? Installation cost?

 

I have also read that NIMH batteries can form crystals inside and cycling will break these up.

 

Another way to think about it is that when nimh crystals are new they have well-defined facets. Over time the facets become muddled. Discharging can bring back some of the facet's definition. Never as good as new, but better than if it was never cycled at all.

 

Jeff652,
Firstly, I don't doubt your sincerity and the basic rationale behind your product, but I do find claims of "significant" improvement in battery life to be not informative at best. I say this as a person schooled in basic statistics where 'significant' means the improvement is highly unlikely due to chance, but it says nothing about the amount of improvement.

Can you provide quantitative data that can gives a firmer notion of how much longer a battery will last ? I am thinking of data that compares in the lab groups of batteries aged with and without your balancing protocol. This kind of study could start from new batteries, or begin with batteries that had been aged down to say 75% of rated capacity.

I entirely agree that people who buy your product after the battery gives off an alarm have missed a window of opportunity to prolong battery life that will not return. I'm interested in knowing the value of smart battery maintenance over 5 - 10 years.

 

To Jeff652: who wrote, quote, "Sulfation is a well known effect that impacts NiMh battery cells" end of quote.

• Are you serious? Are you selling chargers to cure "sulfation" in NiMH batteries?

Could we suggest that was a typo...

FYI: Sulfation is a chemical reaction found in Lead Acid batteries, not in NiMH.

 

Jeff,
You linked one of my favorite articles.
The three photos at the beginning are the ones I think of when describing battery condition.

 

I like the way you think... FYI -We have already started here in New Zealand...

• There are numerous patents and tons of claims of all sorts of "cure" against aging of everything from face wrinkles :-( to traction batteries in this case.
• There are numerous rejuvenation/reconditioning "proprietary" technologies claimed especially in USA which is famous from the Golden Rush to modern times to be full of inventive people selling “Elixir of Life”.
• For example you can easily find on the net:
  
  - Numerous schematics for devices to recondition and conduct “de-sulfation” of Lead-Acid batteries
  - Numerous articles, patents for asymmetric or sometimes called “burp” or "pulse" chargers to destroy “crystals” formed in NIMH batteries and hence regain capacity

• What is lacking in all those claims, articles and patents is absolute absence of the documented results of the tests conducted in controlled environment.
  
  We at www.hybrids.co.nz have been asked numerous times of whether we think those technologies work or not.
  
  We are open-minded and inquisitive at the same time and extremely curious of the end results ourselves.
  
  Without conducting tests – how do we know? But, wait, we though recently:

• Our High Voltage Battery Analyser is perfectly fit for purpose to prove or otherwise any claim of reconditioning improvements.
  
• We can put few batteries together, charge few with conventional “off the shelf” charger and few with the “magic” charger and discharge simultaneously one and another with the same load applied in controlled manner, graph it, table it and analyse what is going on.
  
  Being curious we have purchased recently two quite expensive Asymmetric Pulse (“Burp”) Chargers for NiMH batteries. Those are claimed to have something similar to NASA technology and reference to previously openly published ideas incorporated into them. It is now up and running in our lab.
  
  We have also invested in some extra testing tools and planning to build our own Lead Acid De-Sulfator following open source design, which was claimed by folks in US and Japan to rejuvenate Storage (Solar) / UPS / Starter and Traction (Golf Carts) Lead Acid batteries.
  
  We have plenty of Lead Acid batteries from our industrial UPSs, plenty of Prius NiMH batteries and NiMH batteries used in RC models to play with in our Lab

Surely we will have a lot of fun in conducting numerous tests.

We are not biased at this stage to object or support those reconditioning ideas. Please continue inventing stuff.

• P.S. Providers of "magic" chargers of all sorts are welcome to send their devices to New Zealand for us to test.
• Even if it is a prototype and requires assembly and soldering - we can add tender loving care to it and put it to the test.

 

X2

Great article and the pictures are worth a thousand words as to why the deep cycling works (ie cycling breaks up crystal growth in NiMH cells).

 

Putting my audit and analyst hat on can't resist to mention folks that that article IS NOT applicable to NiMH Prius batteries. The whole article and deep discharge methodology is applicable to nickel-cadmium batteries. Modules used in Toyota are NOT NICd, they are NiMH.
By the way, applicable to both type of chemistry, the methodology suggested by then was aimed at increasing battery life span and was mostly focused on the way you charge (pulse charging) to Prevent formation of the crystals at the first place by reducing overheating of the plates and formation of crystals during charge, rather then to try and apply reconditioning after-fact when it could be too late.
What we have already found with the our newly build asymmetric pulse charger - versus conventional one is that batteries were experiencing little temperature rise and accepting more charge. But that IS NOT yet an indication of increasing module's capacity. Conventional chargers (aka RC chargers) a lot of forum members have in their possession - they cut off charge based on change in voltage curve (aka delta-v). Pulse charger we use for experiments control the temperature rise - hence not cutting of prematurely. That may give wrong perception of the capacity being increased, whereabouts it is a matter of being able to fully charge vs partially charge by conventional charger.
Cheers,