[mn23]

Searched the forums and google for an hour, but couldn't find an answer. Please direct me to the correct thread if this question has been asked.

I went to Honda and paid $2500 for a new battery including everything. They claim they are new cells, but I don't know. In order to charge up the battery before delivery they said they disconnected the power steering fuse under the hood and reved the engine to 4000 rpm for 5 minutes.

My question is, can this be used in lieu of battery balancing through Mike D's grid charger? As I understand, the grid charger operates at 350mA, I would imagine that reving the engine would involve much higher amperage. I would like to install Mike's charger, but the price is a little bit high now, so I don't know how much I want to pour into the car. At the same time I would like to develop some strategies to maintain the batteries. One is to drive it all the time I guess, but is reving the engine for 5 minutes gentler on the pack than driving it after a long period of not driving? Thanks in advance for the advice.

 

[TopFuelTim]

Mike D's charger is money well spent

That made me cringe about them revving the engine to 4000 rpm. Also, I don't know what the amperage is, but it is definitely not 350 milliamps.

Whenever I disconnect the 12V battery, and the SOC gets really confused, I still don't rev it. All I do is drive it for a few miles, and it recalibrates.

As for Mike Dabrowski's grid charger, it is a set it and forget it type. You can get a "dumb" charger for much less, but if you forget and leave it on all weekend it can do more harm than good.

I guess my 2001 Insight batteries are on life support now, but I do not think I will have to buy an IMA battery any time soon, as for the time being, I am grid charging with the nine hour soak time cycle afterward once every three months.

One still has the original battery, the other a January 2010 replacement. I think the original battery is in better shape than the replacement.

Just my .02 worth,

Tim Glover

 

[eq1]

I don't have direct experience with your exact situation - a new pack and battery maintenance. But I've worked a bit with the HV battery and read quite a bit around here and other places... The short answer to your short question is "no": grid charging charges the battery beyond what the car can do alone.

The 'battery computer' (BCM) charges the pack up to about 75% state of charge, whereas grid charging will charge the pack to 100%. Additionally, as you suggest, the 'rev charge' is a lot more amps - I've seen around 20 amps at about 4000 rpms, usually in the range of 10 to 20 in my car. It's closer to 10 at around 3100 rpms, closer to 20 at around 4000. So the two strategies/methods - grid charging vs. rev charging - aren't interchangeable.

Given that though, and that you have a new pack, I'm not so sure you need to be charging up to 100%, definitely not frequently. The BCM tries to keep the battery between about 25% and 75% for a reason - mainly because it makes the pack last a lot longer. I've read that overcharging is one of the major detriments to a NiMH battery's capacity, so you don't want to go overboard on charging on the high end...

But anyhow, here's a couple suggestions:

-if you aren't driving the car very often, I'd at least start it once a week, let it warm up, and rev the engine above 3000 rpms until 19 bars are lit on the HV battery gauge. In my car, rev charging stops at 75.6% state of charge, whereas the 20th bar lights at 76.1% - so I'd never see the 20th bar by rev charging alone... But, you can charge more than just up to 19 bars, read on.

-If you already have 19 bars lit, you can still rev charge a bit. If you're careful and hold the rpms steady, you'll be able to feel the engine race - rpms will jump up - when the charging stops. So you'll be holding the rev at about 3100 and then once the battery reaches a certain state of charge, like 75.6% if it's like mine - then the charging will stop, there's no load on the engine, and the rpms will jump up... I'd do higher rpms, like 4000 if my bars were really low, but I'd drop it down to 3000, 3100, once 19 bars are lit...

I guess beyond this I don't have much more to say. In general, my impression is that only shallow, high rate charges and discharges will slowly destroy battery capacity... If you had a clutch switch mod you could disable charge/regen strategically so that you could drain the battery a little more than usual on occasion, and then charge it up only, rather than the shallow in- and out-amps back and forth.

And then if you had a grid charger, after you drained the battery as much as possible by driving with assist, you would plug it in and give it a slow charge overnight - up to 100%. If I had a new pack I might be doing a grid charge, oh, maybe twice a year, maybe once every 3 months. depends on the type of driving I'd been doing... These are just some off-the-cuff notions of mine though. Maybe someone else actually has experience. Put it this way, I have an HV battery with 172k miles on it, I did a stick-level rejuvenation a couple months ago, and I haven't yet needed to do a grid charge. So I would guess a new pack, in a daily driver at least, wouldn't need a grid charge that often. Of course it depends on the kind of driving you're doing. I just wouldn't want to be charging my new pack to 100% very often - as little as possible...

As far as rev charging versus normal drive-charging, my hunch is that a steady controlled rev charge once in a while (once a month maybe?) would be better for the battery than solely relying on the charging that happens day in and day out - if you're one to drive daily yet don't do much to balance the amount of assist versus regen...

Basically, strategically rev charging once in a while is probably a good thing - like when you're pack is low yet you got a commute to do. In terms of battery longevity, it's probably better to rev charge a bit, to get the pack up to 19 bars, when the battery is cool, rather than navigating traffic and having the car try to give you power and charge the battery at the same time, having high amps going out at one moment, and high amps going in the next. The battery heats up, and then if it's warm out it will heat up more, and all the while you're pulling big amps out and pushing big amps in. I think it's probably better for the battery to do a steady 10 amp rev charge and move the battery from say 60% to 75% in one sitting... etc etc...

 

[eq1]

That made me cringe about them revving the engine to 4000 rpm. Also, I don't know what the amperage is, but it is definitely not 350 milliamps....

Cringe? Why, do you think revving the engine to 4000 rpms does some kind of harm? It certainly doesn't - the car redlines at, what?, 6000. 4000 would do nothing. Also, the grid charger IS 350mA (or the old one was - there's a couple different settings and chargers). Maybe you were thinking OP was saying the rev charging was 350mA...

 

[mn23]

Thanks TopFuelTim and eq1 for the input. This is the sort of discussion I was hoping for and appreciate the long reply eq1 supplied. I have few questions and clarifications though.

When I talked to Honda, they said that there is some sort of trigger at 4000 RPM which charges the battery, not simply that more revs equals higher amperage. What am I missing? Will 2000 RPM charge, but at a slower rate? eq1 states that he can get rev-charging to occur at 3100 RPM with 10 amps. Is there a way to monitor this? ie will the green bars light up? I see that eq1 mentions that you can hear the motor rev freely when the car stops rev-charging and this is the indication. This seems to imply that the green regen bars don't light up. Also, why did the mechanic disconnect the power steering fuse?

When driving normally on the freeway and my SOC is at 60%, and there are no green regen bars, is there actually some battery charging going on behind the scenes? Could I simply drive at 3000 rpm and charge the battery at the beginning of a journey and avoiding braking while in gear to avoid the really big amperage spikes?

Haven't had time to go through the 105 page odyssey of Mike's grid charger, and grid charger strategies, but eq1 seems to provide some crib notes or at least some initial thoughts for my situation. If can paraphrase my understanding, it seems that:
1) I have a new pack that should be balanced
2) Not driving for 2 weeks will result in the sticks or cells all depleting at a similar rate and shouldn't be out of balance
3) Grid charging is more for when sticks/cells are out of balance and is not really applicable to my situation.
4) As the battery ages, balancing will become more of a problem and discharging and then grid charging will be more applicable
5) Rev-charging is an effective strategy for a balanced but depleted battery
6) If I have had my car sitting for 2 weeks I could rev-charge at 3100 RPM until it charges to 19 bars and stop when an audible difference and possible RPM change is noticed in the engine.

Thanks for all the advice.

 

[AClewell]

Let me try to address these one at a time.

1) I have a new pack that should be balanced -YES

2) Not driving for 2 weeks will result in the sticks or cells all depleting at a similar rate and shouldn't be out of balance - Wrong, not driving your car for any length of time causes imbalance.

3) Grid charging is more for when sticks/cells are out of balance and is not really applicable to my situation. - If you are going over 3 or 4 days without driving your car grid charging will help preserve the present good state of your battery.

4) As the battery ages, balancing will become more of a problem and discharging and then grid charging will be more applicable. - Yes, but don't wait for symptoms to show up before doing something about it.

5) Rev-charging is an effective strategy for a balanced but depleted battery - Rev-charging charges at a higher than ideal amperage but will work in a pinch. Not the kind of preventive maintenace I would recomend.

6) If I have had my car sitting for 2 weeks I could rev-charge at 3100 RPM until it charges to 19 bars and stop when an audible difference and possible RPM change is noticed in the engine. - You could but if your planning on letting your car sit for 2 weeks at a time you will be money ahead to buy or build a grid charger. Rev-charging at the higher amperage 10 -20 amps as opposed to 350mA could cause battery venting due to over charging the good cells while trying to bring up the weaker cells.

 

[mn23]

Thanks AClewel,
I may or may not get a grid charger, so I may need to do in a pinch. Does anyone have any advice on my other questions mentioned in an earlier post:

When I talked to Honda, they said that there is some sort of trigger at 4000 RPM which charges the battery, not simply that more revs equals higher amperage. What am I missing? Will 2000 RPM charge, but at a slower rate? eq1 states that he can get rev-charging to occur at 3100 RPM with 10 amps. Is there a way to monitor this? ie will the green bars light up? I see that eq1 mentions that you can hear the motor rev freely when the car stops rev-charging and this is the indication. This seems to imply that the green regen bars don't light up. Also, why did the mechanic disconnect the power steering fuse?

When driving normally on the freeway and my SOC is at 60%, and there are no green regen bars, is there actually some battery charging going on behind the scenes? Could I simply drive at 3000 rpm and charge the battery at the beginning of a journey and avoiding braking while in gear to avoid the really big amperage spikes?

 

[AClewell]

The best way to monitor the IMA system is with an ODBIIC&C gauge, get one from retepsnikrep . Search the site for info on it.

Pulling the PS fuse resets the battery SOC so you can force a charge into it. The RPMs will vary the input charging until the car figures out the true SOC.

 

[AbCaRed00]

Also, why did the mechanic disconnect the power steering fuse?

The power steering fuse is pulled so there is no errant EPS warning on the dash causing a needless diagnostic procedure with the steering.

If the fuse is not removed, and then revving the engine in neutral at several thousand rpm, [which is not a normal operating condition according to the steering's programing], the EPS warning light in the cluster illuminates. No real problem.... traveling forward in the vehicle perhaps a couple car lengths is all it takes then the light goes out with no issues to the steering.

I'm not sure if at the root of the occurrence of the warning light during the charge-up procedure may have something to do with the VSS signal tied in with the steering and normally the vehicle is in motion at those rpm.

 

[Sheepdog 44]

Can i pay to use a gridcharger or just borrow one?

Ideally i'd like to just balance my battery once every three months or how ever long and whenever is most beneficial. I don't have the money or need to grid charge everyday. I just want to maintain or possibly restore some capacity to my battery which works fine at 130,000 miles but has certainly never been balanced before. I also drive 15-20 miles everyday up steep hills and mountains.

I live in Pittsfield, Western MA border of NY,CT,VT. I'd even be willing to drive to MIKE in eastern CT if he offered the service at a reasonable price.

I think the majority of people here just want the same service to balance their pack once in a while and have no further use beyond that to warrant a full investment.

 

[eq1]

...Does anyone have any advice on my other questions mentioned in an earlier post:

When I talked to Honda, they said that there is some sort of trigger at 4000 RPM which charges the battery, not simply that more revs equals higher amperage. What am I missing? Will 2000 RPM charge, but at a slower rate?

Perhaps there are differences from car to car depending on the year and ecm model. But if there are, I doubt there's much difference. Given that, I have an original ecm, mcm, bcm, 2000 canadian and this is what I've observed (I just got back from testing some things about this subject, so it's all fresh in my mind):

The rev charging seems to trigger at 3000 in my car. I've done this multiple times and 3000 does the trick. Rev it to 3000 and the amps start flowing. I think there's some variation in the amount of charge depending on factors other then engine speed, such as battery temperature, perhaps state of charge (in terms of the amount, not just whether there's a charge or not), and who knows what else.

Earlier I said 3000 was like 10 amps and 4000 was like 20 amps. But tonight I was revving to 4000 and saw 30 amps. This was after I had intentionally drawn my pack down till I got a negative recal. I'm not sure if it has always been closer to 30 amps at 4000 rpms or whether drawing my pack down so much enabled more amperage. I don't rev charge it that much, and I don't rev it to 4000 that much. But I was experimenting with the engine speed and rate of charge and was seeing 30 amps at 4000, around 10 amps at 3000, and somewhere in between between 3000 and 4000. I don't recall seeing higher amperage above 4000.

After triggering the rev charging at 3000 I can drop engine speed a little below 3000 and maintain a lower charge rate. I was seeing 3, 4 amps at about 2500 rpms. Typically I see around 7 or 8 just below 3000... BTW, I'm monitoring these things on the OBDIIC&C gauge, which is really indispensable for this sort of thing... I don't think I've seen a charge at engine speeds as low as 2000 rpms, that is, the rev charging. I get background charging at whatever rpms when the battery gets 'low'...

eq1 states that he can get rev-charging to occur at 3100 RPM with 10 amps. Is there a way to monitor this? ie will the green bars light up? I see that eq1 mentions that you can hear the motor rev freely when the car stops rev-charging and this is the indication. This seems to imply that the green regen bars don't light up. Also, why did the mechanic disconnect the power steering fuse?

The green bars do seem to light up, 4 bars, when you're closer to 4000 rpms. But they also disappear once in a while when you drop rpms - even though there's still charging going on. You couldn't use the bars as a reliable indicator as to whether or not you're charging, though you could probably use them to indicate that you've started charging - if you first take it up to 4000 rpms... I've taken it up to 4000, green bars come on, and I've dropped down to 3000 and the bars have remained lit. I'm pretty sure they'd go out when charging stopped - if you were able to hold the engine speed steady throughout the process...

On the power steering fuse, I'm with the last poster, the idea that it prevents triggering some trouble code. But I've never seen any codes not pulling the fuse...

When driving normally on the freeway and my SOC is at 60%, and there are no green regen bars, is there actually some battery charging going on behind the scenes? Could I simply drive at 3000 rpm and charge the battery at the beginning of a journey and avoiding braking while in gear to avoid the really big amperage spikes?

I doubt there's much to be gained trying to avoid 'big amperage spikes'. And unless you had an OBDIIC&C gauge, trying to do that based on the stock gauges would be a pain...

On background charging, again, perhaps there's variation depending on your pack age, condition. With my old pack I get quite a bit of background charging if I don't try to avoid it (but then, I don't really care if there's a little background charging going on; it's actually useful). Usually, when my dash SoC gauge drops down to 17 bars, which maybe happens at 65% SoC, I'll get some background charging, about 4-10 amps. Maybe the amount depends on engine speed as well. Before i got the OBDIIC&C gauge I didn't know what was going on. Like, I'd be on the freeway and use some assist for a bit, SoC gauge would drop down to 17 bars, but then it'd pop back up fairly quickly - even though I saw no green charge bars. It was background charging... Once I got the OBDIIC&C, I was surprised to see just how aggressive the IMA does its background charging... Since then I've also installed a clutch IMA kill switch, which also disables this kind of background charging. Overall, I sort of try to manage charging and assist, including background charging, so that my 'assist/charge cycles' are fewer and farther between... For example, I might disable the IMA to prevent background charging if I know I'll be able to get some coasting or braking regen soon. Or perhaps I've been using assist and regen aggressively; I might disable it for a while, let the battery rest a bit, and then turn it back on to just charge. Or perhaps I'll disable it and enable it just so I can get assist for a while... I'm still getting the hang of it. I just installed the switch a couple weeks ago...

Anyway, I'm not sure what the answer is. Some of the charging behavior I see is probably because my battery is old and tends to see quite a voltage drop under progressively heavier loads. For example, at no load the HV battery might be at 161 volts, but with a 20 amp load it will drop down to say 150 and soon 140 volts... I'm guessing the change in voltage over time factors into how the BCM treats the battery; how the IMA system behaves. Maybe it has to do with deteriorated cells and cell drop out, too. I'm not sure whether a new pack would experience background charging at 60% SoC; but mine does...

 

[eq1]

T...If can paraphrase my understanding, it seems that:
1) I have a new pack that should be balanced
2) Not driving for 2 weeks will result in the sticks or cells all depleting at a similar rate and shouldn't be out of balance
3) Grid charging is more for when sticks/cells are out of balance and is not really applicable to my situation.
4) As the battery ages, balancing will become more of a problem and discharging and then grid charging will be more applicable
5) Rev-charging is an effective strategy for a balanced but depleted battery
6) If I have had my car sitting for 2 weeks I could rev-charge at 3100 RPM until it charges to 19 bars and stop when an audible difference and possible RPM change is noticed in the engine....

1) 'Should' be balanced, but who really knows. If I bought a new pack from a dealer, I'd try to find someone with a grid charger and charge it full once early on...

2) I don't know what the quality control is like when it comes to our NiMH cells... In theory new cells should discharge at fairly similar rates, and slow rates - not so whacked that they'd be way out of balance after two weeks. I wouldn't worry about the occasional 2 week hiatus, but I wouldn't make a habit of it...

When I tested my aged sticks, my rough calculations for self-discharge were in the range of -0.9% to -4.6% per day, with an average of -2.7% per day. These are probably on the high side, and yes rough, as the sitting periods varied and were pretty short (about 50 to 200 hours). If these figures WERE true, MY pack would be pretty screwy after only 2 weeks... If all the sticks were at say 6500 mAh at the start, the one with the -4.6% self discharge rate would be at 3362mAh after 14 days, while the stick at -0.9% would be at 5727mAh...

3) Yes, but there's some useful maintenance that could be done on a new pack. If i had a new pack I'd make one of the cheap grid chargers or borrow one and grid charge the HV once early on and then at least once a year, but no more than 3 times a year... At least, that's my rough estimate, for starters. I'm more or less pulling this out of my ***...

4) True. Not sure how important discharging and charging, versus charging only, is. Ideally discharging and charging is what you want to do - I've read a fairly slow, deep discharge and a slow charge is best...

5) In general I'd say yes. If my battery was low, say below 50%, and i didn't have the time to do a strategic driving charge (i.e. using regen and disabling assist until the battery was up to 75%), bringing it up by rev charging would be a good thing to do - battery is cool, steady charge-only, seems like that's easier on the battery than taking off and driving, with charge and assist kicking in at-will...

6) True. But truthfully, there's a lot about this that doesn't make much sense to me. Your car, our cars, don't keep track of the self-discharge - the charge that's lost while the car is sitting. So unless your battery was less than full (i.e. less than 75%, 80%) when you left it, it seems like it should do no 'extra' charging when you get back to it in 2 weeks.

I'm not sure how the car knows how much to charge when you do the rev charging - or whatever charging when you get back to it... Maybe it doesn't. Voltage drops when the car sits. I can leave my car at 165 volts at night and come back the next day and it's at 160. Maybe voltage factors in there... I'm thinking there must be some known values for voltage and temperature, like a look up table, that the car uses in part to figure out how much to charge. I seem to recall reading something about that, maybe in the panasonic spec sheet, about charging and discharging regimes, where there's a correlation between change in voltage and change in temperature - like 'charge the battery until you get a 2 degree change in temperature per 1 volt change in voltage'... I don't know...

 

[Cobb]

With the newer Insight they recommend reving to 3 grand before storage of the vehicle to top off the ima battery. Normal driving results in like a 60% charge.

I will do a force recharge before exiting a driveway into heavy traffic or at a stop light. I find mines will do it as low as 2500 rpms.

Now I have a grid charger that puts out 350 ma. In 3-4 hours it will fully charge the battery. If left longer it starts the balance process. I believe charging can be done at hgher amps where as balancing needs to either be done at a low current unless you have taps to each cell.

 

[mn23]

Thanks eq1 That gives me some understanding of what's going on. Sounds like I need a new gauge. I tried the rev charging, and it started around 3100. This is good to know and also good to know approximately what magnitude. Maybe I'll look into a grid charger as soon as the sticker shock from my battery wears off. I reset the lifetime mileage, and it now reads 84 mpg. Don't think it will be like that for long, but new batteries are nice. Maybe a clutch switch is in my future too.

 

[eq1]

Yeah, the OBDIIC&C is pretty handy. It ended up costing a little more than I wanted to spend, yet I feel like it's been a good investment. One of Mike's grid chargers, assuming they'll actually be available some time soon, would be a good investment too, so long as you have a decent income, and especially if you got a new $2500 battery pack to maintain... The clutch switch is really useful. I mainly installed it because under some driving circumstances there's little I can do to stop constant assist from draining my pack, like on hills on the highway. Seems like a pretty indispensable tool...

I checked the rev charging output again, with my pack at about 75% SoC, and it was still about 30 amps at 4000, 7-10 amps at 3000. Kicked in at 3000 or just a little above...

If you do get an OBDIIC&C gauge, It'd be nice to see what your amps and volts numbers are looking like, with your new battery pack....

 

[diamondlarry]

6) If I have had my car sitting for 2 weeks I could rev-charge at 3100 RPM until it charges to 19 bars and stop when an audible difference and possible RPM change is noticed in the engine. - You could but if your planning on letting your car sit for 2 weeks at a time you will be money ahead to buy or build a grid charger. Rev-charging at the higher amperage 10 -20 amps as opposed to 350mA could cause battery venting due to over charging the good cells while trying to bring up the weaker cells.

One thing to keep in mind, if you were to have a really weak cell that had a high rate of self discharge, letting the car sit for two weeks could be a really bad thing; the very act of the car starting (using the IMA and not the 12V starter) could cause the weak cell to reverse which basically destroys it. If the pack was grid charged before starting the car after sitting for two weeks, you would probably be ok.

 

[eq1]

6) ....Rev-charging at the higher amperage 10 -20 amps as opposed to 350mA could cause battery venting due to over charging the good cells while trying to bring up the weaker cells.

Is it possible, or more than a remote possibility, to overcharge the pack/some cells using the car charging system alone? Don't the computers prevent over charging? I mean, I know they're supposed to, and they generally do. But I don't know exactly how they do that...

I've been playing with the SoC reset function on the OBDIIC&C, generally resetting the SoC lower, such as 60% when it's 'really' higher, like 75%. I can usually dump more charge into the pack, but also, it usually stops, does a positive recal rather than incrementing slowly all the way between 60% and 75%. I don't know how the BCM knows when to recal... I'm thinking it must be voltage related...

Point being, I don't think you can easily overcharge cells with the IMA...

We know there's 4 sticks with voltage taps [edit: there's 4 sticks with the main temp sensors; there's 10 2-stick pairs with voltage taps]: Is it that the BCM watches the voltage at these 4 taps and stops charging when at least one of the sticks reaches a certain voltage, or perhaps something similar to what I mentioned earlier, about change in voltage versus the change in temperature? Are there known, more or less fixed values for such things that factor into the IMA charging 'regime/s'?

[edit: After working with my pack again, stick-level, and some testing, not to mention that this is pretty well known, the BCM monitors the 10 voltage taps, yes. And it appears that there are predetermined voltage levels at predetermined current rates at tap-level that indicate when the pack is up to 75% or thereabouts. For my 'old' sticks it was about 8.8V at 10 amps per stick, might be a little different with my 'new' sticks. I found that this must be one of the most important factors that limits older packs: old, worn sticks cannot charge enough while keeping below the predetermined voltage threshold (internal resistance is too high). For example, my newer sticks could charge maybe 5000mAh at 10A while staying below 8.8V; my old sticks could barely hit 3000mAh. One question about this, though, is whether the threshold is at rest or under load, maybe both, I'm not sure. But it does appear to be at the voltage tap level, rather than pack level, as my total pack voltage is higher now at 'full' than it was before, that is, at least one voltage tap was hitting the threshold earlier with my old sticks while total pack voltage remained low; now total pack voltage reaches higher level because all the taps are more equalized and hitting that threshold closer to the same time/level...]

 

[Cobb]

I was of the assumption you can over charge the pack as it also does a counting of amps in, amps out in addition to the voltage taps and the diff between the counting, voltage and taps is what causes the sudden negative or positive recal as it thought the SOC was in one spot, then it discovers its in another.

I guess the better question is, since it doesnt use 100% of the battery capacity, how hard would it be?

In my experience with my Enginer kit I can see the pack voltage on the IMA system and the dash SOC display as well as the behavior of the car seems 30 seconds delayed. I think 30 amps for 30 seconds could at least generate a lot of heat.


Sent from my Autoguide iPod touch app

 

[eq1]

....I can see the pack voltage on the IMA system and the dash SOC display as well as the behavior of the car seems 30 seconds delayed. I think 30 amps for 30 seconds could at least generate a lot of heat.

I've been keeping an eye on battery temp with the OBDIIC&C. I haven't seen big jumps in temperature with 'just' a 30 amp charge or discharge. Temp starts to creep up, though, when I'm doing lots of high-amp charges and discharges back to back... It doesn't seem to get very hot, the temp doesn't seem to rise very fast, with long periods of charging-only... Most of this 'testing' is happening at pretty moderate ambient temps - like 50s and 60s F. I've seen 112F on hotter days, like in the 80s... I think high internal resistance, such as in an old pack, contributes to heating. I think a decent pack shouldn't experience too much heating with moderate, normal assist/charge usage...

I've been kind of using some findings from stick-level refurb to gauge what's going on with the in-car charging. For example, when I took the sticks out fully charged from the car (i.e as much charge as they would take, though they weren't fully charged by far), they were at about 8.1-8.2 volts each, or 162-164 volts for the pack. When I charged each stick fully the cutoff voltage was about 9.1-9.2 each, at I think 7 amp charge. That's 182-184 volts. I typically see about 160-164 volts at around 75% SoC. And the highest I've seen when charging is something like 181, and that's at higher charge amps than what I was using at the stick-level.

So, even when I'm trying to dump amps into the pack in the car, I'm not seeing that 182-184 volts - which is probably good, since the car isn't supposed to charge the pack above say 80%... But then, I'm not really sure how solid, how static, voltage is for our cells/packs - like does a particular voltage indicate "full". I think there's a lot more to it, like the amps-in and -out counting. It just seems like counting amps wouldn't be very reliable, as it's not like all the amps being sent to the pack are actually finding a home there, i.e. all the current doesn't get stored cuz the battery isn't perfect, or in my case, the battery is old... And i guess that goes with discharge, too: internal resistance will cause some current to be lost as heat...

[edit: Amps counting seems to be the main, moment-to-moment method for keeping track of state of charge, perhaps among other longer-term goals. Yet one of the main maintenance functions the car performs, to keep track of, to recalibrate, state of charge, is the '72% hang': for some if not most or all these cars, the nominal state of charge will hang at 72% while the BCM continues to allowing charging of the pack until the voltage tap voltage threshold/s are reached that indicate the 'full' state (75% or thereabouts). As your pack ages, the percentage-point jump from 72% to 75% will progressively take more than 65 X 3 mAh. It also takes more when the car's been sitting. If the pack is charged fine it will take just about 65 X 3; if it's overcharged, such as after a grid charge, it will take less...]

 

[Cobb]

The cooling system for the newer insight has a variable speed blower. Before I removed the plastic pieces in the rear it would sound like a jet taking off over head from a local air port when doing a charge by reving the engine.

Now with the covers off it sounds like a cross between a leaf blower and turbo charger spinning up. It seems to vary in speed around 20 mph on up and the pack temp and or electronics. I think that was a clever way to hide the noise to vary it with vehicle speed, however the CRZ they will allow it at idle running full til.

Well, long story short if I ride the brakes off the interstate I can hear the blower wind up like its going to take flight. Secondly when I idle through a parking lot I can hear it increase in speed.

The air coming out feels rather warm and I think removing the plastic pieces to allow more air flow has further my mpg.

To tell you the truth I think it likes running warm. On hot days in the 80s+ it seems to run fairly constantly at its full speed and it seems at that I see the assist/regen needle swing from one extreme to another and just keeps on getting it. When its cold or the blower isnt spinning at full til I see so-so assist and regen.


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