The other day as I changed out cardiac monitor/defibrillator batteries at work I made an observation. Our batteries are NiCad and are frequently charged and discharged, similar to hybrid batteries. At intervals automatically determined by the charging station based on the detected battery condition, the individual batteries are "conditioned" (whatever is involved in that). This does appear to aid in extending their service life. While hybrid batteries are a different material (NiMH) I do wonder if a conditioning device, external or built-in, would make a difference in extending hybrid battery life? Just a thought FWIW.

 

I think that it does this to itself sometimes.
Some people think they may be experiencing it here:
https://www.greenhybrid.com/discuss/...97/#post145649

and here:
https://www.greenhybrid.com/discuss/...ehavior-15552/

 

Those people are experiencing the car recalibrating its battery meter. The car doesn't directly measure the state of charge, so it needs to be recalibrated every once in a while to make the battery meter accurate again.

From the inaccuracies over time, the battery meter will say full or near full, when in reality it is near empty. So the car will shut down IMA, and charge the battery and recalibrate the meter. The car isn't conditioning the battery, it's simply recharging it because it is empty. I've never heard of the Honda Civic Hybrid conditioning its batteries, but maybe it does. Or maybe, the car has the battery meter inaccuracy on purpose as a way to periodically condition the battery?

Is the conditioning of the NiCads you talk about the full charge-discharge you do to the battery so it doesn't have the memory effect?

 

Mike;
The NiMH chemistry does not exhibit the same profile/behavior as other chemistries (ie: NiCad, etc) and as such, it does not require the level of "specific conditioning" as those other chemistries do for longer life.

However, there are some prerequisites for a longer lived NiMH cell/module.

-The first is a life composed of smaller amplitude charge cycles.
-The second is a set of suitable operating temperature ranges.

Because all the current economy hybrids on the market today perform some form of aggressive charge and thermal management routines, I guess you could count as "conditioning". If that is what you were trying to refer to then, you do not need additional procedures or equipment to ensure the long life of your second gen HCH.

Cheers;

MSantos

 

On average I stay in the 5-7 SoC bar range with an occasional drop to 4 bars with forced regen, and the very rare sudden SoC loss issue (3 times). But in the last 2,000 miles, I have discharged or nearly discharged the battery (1-2 bars) and recharged it to as full as it can get (8 bars with no regen capability) at least 30 times or so. Mountain driving can really turn the SoC into a roller coaster! So will this reduce the life of the NiMH battery? What about those that drive the mountains everyday and probably drop to 2 bars on the inclines and charge up to 7 or 8 on the decents... will they have issues with the batteries sooner than those that drive mostly flat roads?

 

Indeed.

Frequent mountain driving can really kill a NiMH pack.

We've had many owners of older cvt HCH's that have experienced shorter than expected battery life when driven in demanding topographies.

While I believe the HCH2 will do better in similar circumstances, I feel the management routines are still not aggressive enough and some of the mountain driven HCH2's are likely to have battery issues earlier than other HCH2's in flatter topographies.

In this case, I really do wish to be wrong. That is in part why I did not get an extended warranty since I live in a featureless topography, but I would have gotten one if I lived in the rockies.

Cheers,

MSantos

 

Well, I hope you are wrong Msantos, I live in the area you are talking about. I did buy the extended warranty package however. I was more concerned about the darn PC than the HiMH pack. H

 

MSantos,

Interesting. I figured the vehicles had some form of conditioning built into them but I was wondering about it. Our NiCad batteries will still show a decrease in the amount of time they hold a charge even after conditioning. My own HCH II seems to hang out around the 5-6 bar range, occaisionally getting up to an almost full or full charge. I guess that's probably best for it though in terms of battery life.

 

Mike:

I really do not wish to blow this issue out of proportion and cause people to fear the batteries they've got. However, this should also be something that we should all be aware of... since this issue is not without precedents. If there's a chance to manage the SoC in regular mountain driving then much of this fear is trivial and almost insignificant. But, if the climbs are prolonged to such an extend that the SoC is depleted at the top or even earlier then IMO the best recourse is to have a solid extended warranty at hand.


Harold:

There's nothing more that I would like than to be wrong on this issue.
Sadly, I fear history may continue to prove that folks who live and drive in mountainous areas may experience battery failures well before those of us who live in flatter regions. As a matter of fact, I do not expect a single failure out of my batteries on any of my cars, and yes, I intend to keep them for a long time.

Looking forward though, the most that hybrid manufacturers can do is:

1- Increase the aggressiveness of the NiMH management routines at the expense of fuel economy. I don't know if Honda really wants to do this. They could have done it already, but I believe they are playing with statistics and the numbers favor the fuel economy side.

2- Increase the size of the battery packs. For instance, the Prius II is less susceptible to SoC depletion than the HCH-II in part because its battery pack is much deeper. However, Honda and Ford are being forced to compete for the leftovers from Panasonic and whatever cherry picked yieds both can get from Sanyo. So, I would say we're very unlikely to see a Honda hybrid with a deep battery pack in the near future on the account of this "supply/yield" issue.

3- Embrace a different more flexible battery chemistry. This one is very unlikely in the short run as there's nothing really as reliable/safe/effective as the NiMH packs we have today.


Cheers;

MSantos

 

Very interesting comments, thank you msantos,H