Honda Insight Forum banner

1 - 20 of 82 Posts

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #1
FINAL VERSION 8.31.08 - Added positive recal definition

Minor additional edits 3.11.07 to reflect newer MCM & BCM logic and refine verbiage of other points


After participating in several threads in regard to IMA battery performance issues and seeing a similar performance loss in my own Insight I began monitoring the IMA system with the above four performance points in mind. I believe I am seeing a pattern of IMA thermal management that has been falsely blamed on deteriorating IMA batteries.


To help standardize the terms used I will add my definitions to the fray:

IMA, Integrated Motor Assist, the electric engine of a Honda Hybrid.
IMA System:

BCM (Battery Condition Module)
MCM (Motor Control Module)
IMA battery pack (144v)

SoC, State of Charge as it relates to the IMA battery pack.

Since the focus of this post is in regard to the IMA functions of a Honda hybrid when the term battery is used it should be understood that it is a reference to the 144v IMA battery pack and not the 12v lead acid battery.

As shown on the SoC gauge adding to the battery is noted as CHRG (charge) and loading the battery (discharging) is called ASST (assist).

To remain consistent with what we see behind the wheel every day I will use the above terms.


1) Recal or battery recalibration.
(Easily and not to be confused with the term recall)

Common variety a "negative" recal:

This refers to a spontaneous loss of battery charge as shown on the SoC gauge. Which begins as a rapid drop of battery SoC to 2-4 bars _without_ a sustained assist to explain the loss. A Forced Charge (see definition below) occurs immediately after. This happens because battery SoC calculations as shown on the gauge eventually become out of sync with the real SoC of the battery. The only solution is to force feed the battery to a known full level. In other words to recalibrate the the BCM's "understanding" of the battery's SoC with a known level of charge in the battery.

Very uncommon a "positive" variety:

This refers to a spontaneous GAIN of battery charge to near full as shown on the SoC gauge. There has been no defined pattern to the event. Like a negative recal the BCM has lost track of SoC and resets the gauge. "Partial" spontaneous gains of SoC have not been reported or observed and would be inconsistant with this recal event.

Both are due to NiMH battery chemistry. Voltage as a function of SoC is virtually flat across the range of SoC, therefore not useable as an indicator of such. The BCM tracks and counts the flow of electricity both in and out of the battery. With _any_ such system there is an error factor, and we "see" this cumulative error as a recal event. As the batteries age there are increased losses internal to the 120 batteries themselves further adding to the frequency of recal events. Primairly the negative ones.


2) Forced Charge.

This refers to the response of the IMA system when the battery's SoC drops below a determined threshold. This begins with a 2-4 bar charging event displayed on the SoC gauge. The charging continues even during light acceleration. And depending on several variables will increasingly limit assist in favor of charging even up to near full throttle acceleration. This occurs after a negative Recal event or a sustained Assist that the normal BCM hidden charge (see definition below) cannot readily recover. Unlike a Recal event its occurrence can be anticipated based on the amount of assist and battery temperature.

CVT exception:

Recals generally only occurs with 5 speed Insights. The CVT transmission by design is integrated with BCM battery management logic and will simply "shift" the transmission to both prevent excess assist or increase charging. There are reliable reports of CVT IMA recals, but the frequencey compaired to their 5 speed cousins is rare.

Hidden charging / Alternator function:

Alternator "charging" functions are analogous to a non hybrid car and not shown on the SoC gauge (-0- bars). The current varies based on the 12v systems electrical load. The amount of hidden charging of the Insight can be increased by turning on accessories, e.g. headlights or AC, etc. [Thanks for that info Armin]. And can be used to minimize Forced Charge events, anticipated or not. - NOTE: Appears to be updated with the latest software, the headlights on trick is reduced to prevent overcharging damage. (04 and up factory preloaded)

3) Battery Deterioration.

The "hot" topic of all hybrid owners. From my reading here even more so than low MPG. And as we all know and dread an unavoidable eventuality.

It _is_ happening right now to all our beloved Insights and HCHs as this is read. Time marches on...


4) Thermal Management.

The still murky dark logic of battery management that is only loosely defined for us by Honda. We know that if the battery pack is too cold, hot or SoC is too low then the IMA starting system will backup to the standard 12v battery and starter, and the auto stop function will be disabled. We also know that under defined temperature and load conditions that battery CHRG / ASST is limited or disabled.

We have also learned that as the IMA batteries age and cells begin to deteriorate temperature has a significant effect on their ability to hold a charge. Some of what may appear to be thermal management is probably related to one or more aging cell internally self discharging at a higher rate.

SoC Gauge operation:

We know that the SoC gauge is software driven. [Armin has documented rates of charge / discharge that are displayed differently by the number of bars shown.] The amount of charge shown is necessairly a calculated value since voltage in a NiMh cell is almost flat across its entire range of charge. Its only when a cells SoC reaches near 100% or 0% that voltage spikes or dips in response.

We know that the upper and lower percent of charge available in the battery is not used nor indicated on the SoC gauge (life extending battery management). We believe (hope?) that additional life extending thermal management occurs with only some of the defined points being described for us.

We see unexplained and troubling variations in SoC behavior which could be interpreted as battery deterioration.



My observations:

[edit with updates]

Data collected from my

02 Insight 5spd.
110k+ miles
70.5 LMPG and fluctuating (aging batteries causing more unavoidable forced charging)
78.8 best tank average
99.4 best one way commute
94+ best round trip commute
50 mile avg. commute, 60 mph top speed
purchase date 9/02

This being my first summer with an Insight and armed with my 8/80K IMA warranty I was highly confident that any battery worries were years away for me. In fact battery issues were the sole cause of my delay in purchasing an Insight in 2000. I knew that with such cutting edge technology that Insight owners would be guinea pigs to some degree. Not that I mind, I just didn't want to be a leader of the pack. <g>

I learned of and understood Forced Charging and the eventuality of a Recal event. I understood the defined points of battery thermal management and even experienced two 12v starting events last winter. Peak summer heat was not as intense as in past years so I was confident that I would not see battery thermal cut-off conditions that those in hotter climates have reported here.

I have only experienced three Recal events. Two occurred after multiple heavy CHRG / ASST cycles of the battery. However, I began experiencing regular Forced Charge events mid summer with daytime temperature only in the upper 80's to very low 90's. None clearly associated with any sustained assist. Which is a bit tricky to determine in the terrain of east Tennessee. SoC indications would be 2 - 4 bars from full then easily vs. rapidly (as with a Recal event) under assist fall to 30-50% and begin a Forced Charge. Sometimes Forced Charging began at or near an indicated 70% SOC gauge reading. My initial thoughts were that my very conservative driving style in combination with my commute pattern was not providing enough regenerative braking (CHRG) to balance my ASST (discharging). I frequently had to do the headlights on trick [Hidden charging, thanks Armin, I hope :)] to prevent Forced Charging and the lower MPG suffered as a result. I also rarely used the AC system both to maximize my MPG and that the heat wasn't really that bad this year.

But now that fall and cooler temperatures have arrived the Forced Charge events that I had blamed on my style and commute pattern have disappeared!


My conclusion:

[edit: Proven incorrect read my post on page 4 Final Conclusions]

Battery thermal management, specifically thermal cut-off is done in stages. At no point did I reach total thermal cut-off as has been reported by owners in the Southwest U.S. There appears to be a graduated logic to this aspect of battery thermal management. Specifically, the available range of capacity that the battery operates in appears to narrow with increased temperature. Just like the upper and lower limits of the battery's full capacity are never used, the capacity appears to be intentionally limited as temperature increases.

This narrowing of the battery's capacity is what would be expected with one type of age deterioration. But such a failing pack would not be expected to recover simply because of cooler temperature.
Anyway, I hope this helps in alleviating some of our shared fears in regard to the eventual expense of replacing the IMA battery pack.

I welcome additional _careful_ observations both in support or contradiction to my above conclusions. :)


John K. Bullock
aka. Insightful Trekker


See my Final conclusions post on page 4 of this thread for the conclusion of this story! :eek: :shock: ;)
 
G

·
Guest
Joined
·
0 Posts
Re: Recal's, Forced charge, IMA Battery and Thermal mgmt - l

Very well explained, Trekker. I have experienced everything you have in my '03 5 speed. I also notice that sometimes regenerative braking is reduced temporarily but assist is not. I doubt this is temperature related, as the cabin temp is usually quite reasonable when this happens.

Also, I used to always get 3 or 4 bars of "trickle charge" when moving at a constant speed until the battery reached about 80% of charge. Now I usually don't, even when the battery is almost completely discharged. The turning on the headlights trick works fine for me, but it also seems that the battery discharges faster under normal assist, and seems "reluctant" to charge when the SOC reads 25% or less. This is possibly due to more agressive driving style now that I'm used to driving the car, but I doubt that. It also could be related to the amplifier I added to the stereo system, but I doubt that as well. These problems started several weeks after the stereo upgrade. Nevertheless I plan on removing the fuse for the amp for a week or so. Or it might just be that the headlights are sucking so much power that the battery charges slower.

At least I haven't experienced forced charging in quite some time. And it is still a blast to drive.
 

·
Premium Member
Joined
·
891 Posts
Why would higher temperatures lead to more forced charging events (which would presumably make the battery hotter, the opposite of what you would expect the car's response to be to heat)?

I wonder if this is why my car does not idle-stop. I thought it was the well-known external air temperature sensor disconnect, but mine is still plugged in. I get rare idle-stop if climate control is on (even in ECON A/C OFF) and I get a generally lower SOC on my meter.
 

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #5
<replies inline>

Kevin Dougherty wrote:

> This concise description should be bookmarked to provide reference for new
> list readers. The only suggestion that I would make is to provide links
> to the issue(s) involved from the InsightCentral encyclopedia.

<tongue firmly planted in cheek>

I'd guess that either being marooned on an island in the middle of the Indian ocean or all the gasoline "fumes" in your area has addled your mind for you to give such praise to my dry technical dissertation. <VBG>

Thanks for your effort in reading! :)



el_vacho wrote:

> Also, I used to always get 3 or 4 bars of "trickle charge" when moving at
> a constant speed until the battery reached about 80% of charge. Now I
> usually don't, even when the battery is almost completely discharged.

3-4 bars of charge is a forced charge, by my wording of the definition anyway. :)

And now you are experiencing no forced charge events even with a low SOC gauge?
Hmmm. A demanding driving style is the only explanation I can think of as an answer.


Tim Maddux wrote:

> Why would higher temperatures lead to more forced charging events (which
> would presumably make the battery hotter, the opposite of what you would
> expect the car's response to be to heat)?

Good question. Limiting the duration (depth) of a cycle maybe overall reduces heat?
Like a blinking light bulb vs. one on continuously. Maybe some other aspect of battery life extension? Maybe my observations do not fit my conclusion. But it appeared to be a clear cause and effect given my specific circumstances. And I posted here specifically for other user feedback, to try and broaden my understanding of what I think I saw. :)

> I wonder if this is why my car does not idle-stop. I thought it was the
> well-known external air temperature sensor disconnect, but mine is still
> plugged in. I get rare idle-stop if climate control is on (even in ECON
> A/C OFF) and I get a generally lower SOC on my meter.

Idle stop will be limited or eliminated if thermal sensors inside the battery module aren't happy about the heat. Is your horn working intermittently along with idle stop? Rickey Suiter had a problem with the under hood fuse box and fuse #6 melting down the female spade connectors. I'd begin on p.23-9 of the ETM and check switch inputs at the ECM. Now that cooler weather is here (there?) temperature issues should not be the cause unless you have a faulty (high) sensor input making the BCM think its too hot for idle cutoff p.32-6.

HTH!

And thanks to all for the feedback. :))

Initial post edited for additional clairity, feedback welcome.

John K. Bullock
aka. Insightful Trekker.
 

·
Premium Member
Joined
·
498 Posts
Re: Recal's, Forced charge, IMA Battery and Thermal mgmt - l

Insightful Trekker said:
BCM Alternator function:
BCM trickle charge is not shown on the SOC gauge (-0- bars) and varies based on the 12v systems electrical load. Its function is analogous to a 12v system alternator in a non hybrid car. The amount of trickle charge of the Insight can be increased by turning on accessories, e.g. headlights or AC, etc. [Thanks for that info Armin]. And can be used to minimize Forced Charge events.
Hi, Trekker!

Great Summary!

Ohhh.. I got quoted... how exciting :cool:

Anyway, just one comment I would make on the "alternator function": The alternator function is really not charging the battery at all. It's just generating enough power in the motor/generator to feed the 12V demand. In my opinion it is entirely separated from the battery management with the exception that you noted.
Also, I really don't see any difference between what you call "trickle-charging" and "force-charging", other than in the second case the little green bars light up. The current is the same. When it happens is somewhat unpredicable. But one thing is very predictable: The charge bars will light, if the SoC is 14 bars or less at the time the car has decided to force-charge.
 
G

·
Guest
Joined
·
0 Posts
Insightful Trekker said:
<replies inline>
el_vacho wrote:

> Also, I used to always get 3 or 4 bars of "trickle charge" when moving at
> a constant speed until the battery reached about 80% of charge. Now I
> usually don't, even when the battery is almost completely discharged.

3-4 bars of charge is a forced charge, by my wording of the definition anyway. :)

And now you are experiencing no forced charge events even with a low SOC gauge?
Hmmm. A demanding driving style is the only explanation I can think of as an answer.
But moving at a constant speed is hardly demanding. I accellerate pretty aggressively usually, but I"m also very concious of fuel usage and maintaining lean burn as much as possible.

Armin said:
I really don't see any difference between what you call "trickle-charging" and "force-charging", other than in the second case the little green bars light up. The current is the same. When it happens is somewhat unpredicable. But one thing is very predictable: The charge bars will light, if the SoC is 14 bars or less at the time the car has decided to force-charge.
Ditto. I must confess I didn't read your definition of forced charging at first, because I've always considered it to be the charging that takes place while recovering from a nearly dead battery or recal event where one loses IMA and auto-stop entirely while the BCM gets the battery back up to a reasonable level. Perhaps "phantom charge" would be a better term for the trickle charging that does NOT show on the meter, and "trickle charge" for that which does. Then "forced charge" could be defined as I have above.

My car used to be VERY predictable about trickle charging. If the SOC was less than about 75-80% and I was moving at a constant speed, it would always trickle charge (with 4 bars showing on the charge meter). Always. Now it almost never does, even when I'm down to 3 or 4 bars on the battery meter. And when the battery is this low, I'm surprized that it does NOT go into forced charging as I've described it. Something has changed but I have no idea what.
 

·
Registered
Joined
·
1,819 Posts
Noticed what seems to be a bit of thermal management going on this morning - the first one I've had to scrape frost off the windshield. Battery charge was also a bit lower than it usually is when I leave home, maybe 4 bars down. Anyway, cruising on level or slight downhills, I'd see it intermittently go to 3-4 bars of charge. Charging usually happens only if I'm decelerating. I suppose it was trying to warm the batteries?
 
G

·
Guest
Joined
·
0 Posts
james said:
Noticed what seems to be a bit of thermal management going on this morning - the first one I've had to scrape frost off the windshield. Battery charge was also a bit lower than it usually is when I leave home, maybe 4 bars down. Anyway, cruising on level or slight downhills, I'd see it intermittently go to 3-4 bars of charge. Charging usually happens only if I'm decelerating. I suppose it was trying to warm the batteries?
Quite likely. Which actually isn't very good for them.

Do you mean 4 bars down from full, or 4 bars down from where it normally is? Is this a 5 speed or CVT?
 

·
Registered
Joined
·
1,819 Posts
"Do you mean 4 bars down from full, or 4 bars down from where it normally is?"

Yes - it's normally at full charge, or nearly so, when I get home from the places I usually go. Today was an exception 'cause I went somewhere different the last time I drove it, and it didn't have time to get back to full.

It's a 5 spd. This morning was a bit chilly, with overnight lows in the low 20s, but I have several months of similar to look forward to, since teens to 20s is usual winter weather here.
 

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #11
<replies inline>

Armin wrote:

> Hi, Trekker!

> Great Summary!

> Ohhh.. I got quoted... how exciting :cool:


> Anyway, just one comment I would make on the "alternator function": The
> alternator function is really not charging the battery at all. It's just
> generating enough power in the motor/generator to feed the 12V demand. In
> my opinion it is entirely separated from the battery management with the
> exception that you noted.

Hmmm, then why does this hidden charging effectively increase with accessories on? And is an effective way to prevent forced charging. Separate from thermal management, maybe. But it could be a thermal management technique in that if this minimal amount of charge is able to recover a low SoC without higher current Forced Charge which presumably also causes greater heating of the cells.

> Also, I really don't see any difference between what you call "trickle-charging"
> and "force-charging", other than in the second case the little green bars light
> up. The current is the same. When it happens is somewhat unpredicable. But one
> thing is very predictable: The charge bars will light, if the SoC is 14 bars or
> less at the time the car has decided to force-charge.

So this is one of your observations? That this hidden charging is 1A accessories off and 1.5A accessories on (if my memory serves me). And that 2-4 bars indicate the same rate of charge? Hmmm.

14 bars on the SoC! so your gonna make me get my magnifying glasses out and go cross eyed counting all the bars?!?? <g>

And I agree with the multiple assessments of trickle charging. Since it's value on the SoC gauge is zero I will call it hidden charging. Original post updated.
 

·
Premium Member
Joined
·
498 Posts
Insightful Trekker said:
Hmmm, then why does this hidden charging effectively increase with accessories on?
Double-hmmm. I don't know. My guess is that Honda thought along these lines: If lots of 12V accessories are on, we'll need to draw more current from the 144V battery if we go into idle-stop. So let's be a little more aggressive at charging the 144V battery ahead of that.

Insightful Trekker said:
And is an effective way to prevent forced charging.
Triple-hmmm. I never observed the forced charging to go off or be less likely to come on due to 12V loads. Quite the opposite! If my SoC is low and there is no charging, I turn on the lights and voila - a minute later the car is charging!

Insightful Trekker said:
So this is one of your observations? That this hidden charging is 1A accessories off and 1.5A accessories on (if my memory serves me). And that 2-4 bars indicate the same rate of charge? Hmmm.
Actually, depending on other driving conditions, it can be anywhere between 5A and 10A. Usually with some 12V load it's out 1.5 to 2.5 A more than without.

Insightful Trekker said:
14 bars on the SoC! so your gonna make me get my magnifying glasses out and go cross eyed counting all the bars?!?? <g>
No, I'm telling you to get a marker and put little dots at 5, 10, and 15 bars...
 

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #13
Armin quoted what Insightful Trekker wrote:

>> And is an effective way to prevent forced charging.

I think we're agreeing here. If you anticipate a Forced charge event and turn on the headlights for example then the hidden charging increases and prevents a Forced Charge event.

Another observation of a Forced charge event depending on its intensity is the narrowing of the lean burn window.
 

·
Premium Member
Joined
·
498 Posts
Insightful Trekker said:
I think we're agreeing here. If you anticipate a Forced charge event and turn on the headlights for example then the hidden charging increases and prevents a Forced Charge event.
Trekker,

it may seem like splitting hairs, but my point is there is no difference between hidden and forced charging. Charging at cruise is called "hidden" when no green bars are lit and it's called "forced", when green bars are lit. But if the green bars light only depends on the SoC at the time the charging is happening. So you're saying if the car is charging at <14 bars, we call it forced and if it is charging at >14 bars, we call it hidden.

All that is an acceptable, if somewhat awkward, definition. But you cannot prevent forced charging by turning the lights on. I can just coax the car into charging. Actually, on the reverse, it's sometimes true: if I drive with lights on and the car is charging, sometimes I can stop the charging by turning the lights off. But this is true in both cases: forced- and hidden charging.

Oh, I get it. If you are at 15 bars SoC - meaning the car will be forced charging if the SoC drops another bar - you can prevent that by charging more (turning the lights on) and, I guess, driving more carefully. Is that what you meant?
 

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #15
Armin wrote:

<snip>

> Oh, I get it. If you are at 15 bars SoC - meaning the car will be forced
> charging if the SoC drops another bar - you can prevent that by charging
> more (turning the lights on) and, I guess, driving more carefully. Is
> that what you meant?

Well I've never counted bars myself :) Maybe I need to start.

Specifically I have noted that before a Forced Charge reaches your critical 14 bar level it can be nipped in the bud by turning lights on. Driving more conservatively is not an option in the traffic of my neck of the woods. <g> And battery charge / assist / thermal management interactions (?) at higher ambient temperature appear to cause battery SoC to more easily fall. With the 14 bar level you have found as the threshold for hidden charge to become my labeled definition of Forced Charge.

I believe I have observed over many weeks something related to both the duration and intensity of the Forced Charge event (or Hidden charge as the case may be). For more severe events (2 - 4 bars of charge showing) the lean burn window narrows. And my daily measured MPG suffers correspondingly. When I intervene with the headlights on trick before reaching the 14 bar threshold, increasing the hidden charge ( 0 bars still showing) the lean burn window does not feel as narrow, and MPG for this well worn route home measures higher.

I attempt a driving style to keep MPG's in the ultimate high range, 80+. As you are aware this upper range is extremely fragile with virtually everything being an adverse effect. Battery, ambient temperature, SoC and IMA charging / thermal management being one I believe I have observed.

In cooler weather, same route, traffic and comparable MPG, the SoC stays much higher without reaching the 14 bar point or requiring a headlights on intervention.

Thermal management during higher ambient temperatures? A chemical response of the batteries under higher temps? A less anxious to get home right foot? I don't know for sure and it is the point of this thread. :)

Unfortunately with the consistently optimum mild fall weather now turning much cooler further observations this year will not be possible. Cold weather becomes the primary factor in ultimate MPG therefore I cannot correlate battery SoC management vs MPG. Although I am seeing a consistently higher and robust SoC. Now due in part to required additional headlights on time.

Thanks for your responses!

Additional and careful responses from you and others welcome. :)
 

·
Premium Member
Joined
·
498 Posts
Insightful Trekker said:
For more severe events (2 - 4 bars of charge showing) the lean burn window narrows. And my daily measured MPG suffers correspondingly. When I intervene with the headlights on trick before reaching the 14 bar threshold, increasing the hidden charge ( 0 bars still showing) the lean burn window does not feel as narrow, and MPG for this well worn route home measures higher.
Now that you mention it again, I do remember noticing that it's harder (if not impossible) to get lean-burn directly after a recal. Definitely in the 2 - 3 or 4 bars range. I never noticed it at fairly high (>10 bars) SoC levels, though.
 

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #17
Update:

Since cold weather has taken hold I can now broaden my observations.

My primary conclusion appears incorrect; That thermal management appeared to narrow the batteries used capacity and as a result maintaining a high SoC became more "fragile."

The warm weather ended with the loss of daylight savings time. The loss of daylight required routine commuting with my headlights on. Which I believe I have correctly observed increases battery charging current (hidden no bars showing) and maintains an overall higher SoC for my driving pattern / style anyway. Weekends still provide a small "window" of opportunity to observe unassisted charging battery behavior.

Even in this much cooler (cold even) weather my SoC regularly exhibits its more fragile behavior. Driving in the maximum MPG style limiting speed and assist, the SoC gauge will easily drop to its mid range and hover there without the headlights on intervention.

One unusual even occurred yesterday. Temps in the upper 50's to low 60's, daylight hours (no headlights or accessories on). My SoC began its now predictable drop into the mid ranges and I decided to observe its behavior. With city stop and go and regular auto stops the SoC continued to drop all the way to three bars (Yes Armin I pulled over got my glasses out and counted <g>) without a forced charge (BCM intervention showing a charging event on the SoC). I began a highway leg of my journey IMA charge and assist behaved normally. Finally, I presume when it was about to drop to two bars, a forced charge of 4 bars began. This continued with little effect on the lean burn window. Average MPG's were easily sustainable in the upper 70's with my best tank average being 78.8. As the SoC reached midway, 11 bars the forced charge ended. After driving several more miles the batteries were apparently not going to reach a near full charge so I intervened with the headlights on trick. At 11 bars on the SoC this caused a forced charge of 4 bars to appear. I cycled this behavior 3 times over then next mile to be sure of what I was seeing. At 14 bars of SoC the forced charge disappeared. No accessory load would make it reappear. I finished the remainder of my trip with headlights on (dusky) and achieved the normal full SoC indication of 18 bars.

The only conclusion that I can think of is that battery management is more tolerant of calibration "drift." And instead of a full blown recal event, allows things similar to what I experienced. Another thought is that while NiMH batteries are tolerant of the memory effect I believe they are not immune. Maybe this "slop" in SoC management is designed to prevent any possibility of a memory effect? And if so any consistent intervention by the driver to override this with the headlights on trick will have detrimental consequences.

I have now forced a recal in the driveway and will report again in the next few weeks.

Other ideas? Observations? Anyone? :)
 

·
Registered
Joined
·
67 Posts
Hi guys,
I owned a cvt for several months (an 02) till it was totalled. It never went below a halve SOC untill a huge hill in WV. Thenm as it went further down it began to charge even though I was still accelerating up the hill. I had to put it to the floor to get any assist and it really wanted to charge.
Now, thanks to you guys I have a five speed 03 and have 200 miles on it. Today while driving on steep short hills, the SOC dropped below 1/2 and again it seemed to really want to charge. The strange thing was that after 30 miles of this the SOC went to 1/4 and when I would come down a hill it would not charge at all. If I hit the gas hafway down the hill and got some assist, then it would begin to charge. This happened several times. Temp about 40. Any ideas? Still averaged over 65mpg.
Thanks
Rick
 

·
Premium Member
Joined
·
4,942 Posts
Discussion Starter #19
RickM said:
Hi guys,
<snip>

Today while driving on steep short hills, the SOC dropped below 1/2 and again it seemed to really want to charge. The strange thing was that after 30 miles of this the SOC went to 1/4 and when I would come down a hill it would not charge at all. If I hit the gas hafway down the hill and got some assist, then it would begin to charge. This happened several times. Temp about 40. Any ideas? Still averaged over 65mpg.
Thanks
Rick
Thermal managment? Its not the outside or cabin air temp but the battery temp. There are sensors in contact with most of the cells and in the case.

Heavy assist / charging will cause battery heating and eventually thermal cutoff. Much more easily achieved when the cabin is in the 90's.

But as you can see the interaction of the known BCM functions appear to produce unexpected results which lends credibility to the existence of additional unknown BCM managment.
 

·
Registered
Joined
·
67 Posts
Rick:

When you say you didn't get any assist going downhill with 1/4 SOC was that with or without the brakes applied? I have found many times, though not with the SOC as low as you describe that I would not get any charging if I downshifted on a downgrade until I stepped on the gas for a second. Before stepping on the gas I won't get charging even with braking. After tweaking the gas pedal I get full charging.
_______
Bill
 
1 - 20 of 82 Posts
Top