Hotest/coolest spots in automotive environments

Yeah, but you don't use the traction battery when you're not driving. :)

The traction pack does have a few thermistors scattered through it; some on the individual battery modules, and one in the cooling air flow. I

*think* the battery ECU has the ability to decide "the battery appears to be present and operating, but it's warmer than I really like, so I'm going to crank up the blower and take it easy on the charge/discharge rate for a few minutes to see if the situation improves." When this happens, you get a warning light, but that goes away on its own if the battery cools down - it doesn't *have* to be reset with a scan tool.

I don't think it does; you at least have to have the ignition key "on" (and you might have to have the car "ready") for the battery blower to work.

I don't think the battery blower is ever *not* turning if the car is "ready" - it just runs at a very low speed. It's hard to hear from the driver's seat if it's running on low. If you've been blowing and going down the Interstate in the summertime, take an exit and stop somewhere nearby, and turn off the radio and the HVAC blower, you can hear the battery blower cranked up. It throttles down after several minutes if you keep sitting there.

I know a few owners have modified the control circuitry for the battery blower to run at full speed, whenever *any* amount of blower is commanded by the battery ECU.

Matt Roberds

So, when you climb into that hot vehicle, the batteries magically return to operating/storage temperatures in the time it takes for you to turn the ignition? :>

E.g., in my original post, I wasn't driving the vehicle, just sitting in the driver's seat examining the controls. Yet, the camera-related features all managed to signal faults.

For as large/expensive a battery, I would assume more sophisticated monitoring and charging strategies. E.g., to detect failing cells, etc. before the entire pack "appears bad".

Hmmm... one of the neighbors has several hybrids: a Lexus RX (?), a full electric Rav4 and a plug-in Prius, IIRC. I'll have to ask them how the batteries fare in our heat (esp the Rav4).

No. But the battery ECU can command the blower to max, and at least get a few seconds of moving air in, before the battery is required. If the battery is really too hot, it has the authority to disallow its use. As I mentioned, this turns on a warning light. I have had this happen exactly one time in 14 years and >200k miles.

It *also* has a tap at every other module (every 14.4 V) to the battery ECU. These taps are not used for charging or discharging, but for monitoring the voltages of every pair of modules.

It *also* has a current transformer around the main output lead from the battery; the current transformer goes to the battery ECU.

It *also* has a conventional DC fuse located halfway through the battery stack.

I know the DC lines from the battery to the inverter, and the 3-phase AC lines from the inverter to the motor-generators, float with respect to the vehicle body. I am a little fuzzier on this, but I think the inverter deliberately injects an audio-level signal on the DC lines to the battery. If the battery ECU ever sees that audio coming back in on the +12 V line or from the vehicle body - which would imply that the DC insulation system is compromised in some way - it opens the main relay that lives in the battery box.

For short-term performance, warmer is actually better for a battery, but there are limits. There's a reason the EV1 (RIP) was mostly leased where it was flat and warm. Warmer is not as good for long life, though.

Matt Roberds

Do you have a hybrid or all-electric?

Regardless, isn't the battery *required* to power the vehicle even if a gas engine is present?

OK, trade-off *every* module for every *two* modules. Given that the cost of replacing one is the threshold that must be crossed, you can afford to discover which *one* (if only one) is actually at fault when you service the vehicle.

I would imagine that is just to monitor power consumption/load. I see most new cars (non-electric) also monitor current from the battery (a shunt in the negative lead)

Ah, that's clever!

Yes. Here, battery life is something we are keenly aware of. You

*plan* on replacing the battery in your (non-electric) vehicle pretty regularly.

While looking at cars, we have considered hybrids as well as all-electrics. But, the fear of battery failure is just too much of a deterent. Yeah, they may warrant the battery pack for ~100K miles... but, if it takes us 15-20 years to drive that much, the *effective* warranty will have expired at ~8 years!

[vehicle to be replaced just crossed 80K at ~13 years; at that rate, probably good for *another* 13 years -- given that we don't have things like "road salt" to contend with!]

I hate shopping! (for ANYTHING! Cars being among the worst!!)

Not necessarily. It depends on whether you have a series hybrid or a parallel hybrid.

In a series hybrid, only one device (usually the electric motor) can move the vehicle. In theory, you could run the combustion engine to power the generator, and have the generator power the electric motor, without the traction battery being there. (The classic version of this says Electro-Motive Diesel or General Electric on the name plate.) In practice, I think most series hybrid automobile control systems will give up trying to drive the electric motor if they can't see the traction battery.

Honda turned it around a little on the old Insight. The electric motor on it was directly mechanically coupled to the crankshaft of the combustion engine; the electric motor couldn't turn the wheels of the car unless the combustion engine was also free to turn. In theory, they could have cut off the fuel and spark to the combustion engine and let the electric motor drive the wheels and the "dead weight" of the crankshaft, flywheel, etc, but they didn't do that; the control system only allows the electric motor to "help" when the combustion engine is already running. If the "help" isn't there (because there is no traction battery), I'm pretty sure the control system still allows you to run the combustion engine and move the car.

In a parallel hybrid, either device (electric motor or combustion engine) can move the vehicle. This requires a fancy mechanical transmission, to let either device (or both) deliver power to the wheels. Priuses, from 1997 through to today, have this system. If the traction battery isn't there, I know the control system will still let you drive using the combustion engine.

With either type, the braking system is designed not to *depend* on the traction battery. If everything is working normally, it tries to capture some of the braking energy in the battery. If things are badly wrong with the electrical system, the plain old friction brakes are sized to stop a car of that weight with only a good stomp on the brake pedal.

Also, all the hybrids I know about have a small 12 volt battery to get everything booted. If that battery goes dead, it's just like the battery being dead in your '57 Chevy... you can jump-start it from another car and let the charging system fill it back up, or charge it on a 12 V charger, or replace it.

The 12 volt battery on most hybrids tends to last longer than a starting battery on non-hybrids, because it doesn't usually have to run the starter motor. It just boots all the computers, and maybe runs the radio for a while if you're sitting there parked with the key in "Acc".

Yes. The Toyota scan tool can give you the voltages it is reading from every "tap" in the traction battery. If you don't have that, you can (carefully) take the lid off of the traction battery, and walk your handy DMM down the stack to see who is unhappy.

Some people don't mind replacing individual modules if one or two go bad; other people like to replace the whole pack ("and cry once", as the saying goes). There are lots of factors: money, miles on the car, parts availability, DIY vs at the shop, etc.

In the early 70s, VWs had a 16 gauge wire from each end of the battery negative strap to a test connector. With that, and an inductive pickup for when #1 spark plug was firing, you could do a compression test with a voltmeter.

How often? Around here (Kansas City), I'd be annoyed if a starter battery in a recent car lasted less than about 5 years. 6 to 8 years is probably about average; more than that would be pretty good.

Spreadsheet time... get the cost of a new battery from the dealer (not a Texaco press release) and amortize that over the time from now until when you need it. Punch in the cost of fuel (and electricity if it charges from the wall) and see where the break-even is. (Shopping is fun, right?)

It's getting harder to buy a car that *won't* make it to 150K miles, given regular oil changes. Why are you replacing a car that's only half done? :)

Matt Roberds

Hi Matt,

[f> D>> Regardless, isn't the battery *required* to power the vehicle even if

This was my impression of how hybrids (vs. "all-electrics") worked. I.e., two cascaded control loops: driver dictates inner loop (via "accelerator") between battery and motor; "control system" handles outer loop -- deciding when/if/how aggressively to charge battery based on state of battery and current actions of inner loop.

I.e., if no battery, inner loop can't bootstrap.

So, the combustion engine must be sized large enough to do that. By contrast, in the first case, it need only be large enough to replenish the average power drained from the battery over some interval.

OK, worth knowing.

So, the mechanical brakes are "held back" during normal operation?

Understood. Fewer "deep discharge" cycles.

I think they claimed the battery was ~$5K -- no idea if that also included the overpriced labor charges... Or, if it is even possible to do any service on the battery without the dealer's involvement.

We *plan* on replacing a battery every 4 years. E.g., in other places that I've lived, if a battery went flat, you checked the charging system before replacing the battery (an alternator could have died, loose cable on battery, etc.). Here, when it gets sluggish, you look at the

*calendar*; if three or four years since last battery replacement, just replace the damn thing.

We've taken to buying batteries at Costco. They fail often enough that we've only had to pay for the *first* -- the second, third, etc. all came within the "full replacement" period on the battery (i.e., no derating).

While folks may buy their batteries from a variety of sources, the concensus seems to be "4 years? it's dead!". Moral of story is not to invest in a "great" battery as it won't last appreciably longer (and, if it does, it just pushes you into the latter portions of the warranty period, causing you to spend *something* for it's "warranty replacement")

[My first battery, here, was ~$100. Living in places with winters had conditioned me to have lots of CCA's! Four years later -- just under 6,000 miles of driving -- it was being replaced.]

You probably consider trips to the DENTIST to be fun, too, eh? :>

Yes, we've been looking at all the "what-if's". The fact that we drive so little really skews lots of the calculus. E.g., one of the vehicles that we looked at is a frigging *boat*! Terrible gas mileage, etc. OTOH, even at $4 or $5/G, the "extra" fuel cost doesn't amount to more than a couple hundred dollars / year.

That's what *I* say! I've put about $1000 into maintenance for the car over the past decade (oil changes every *3000* miles -- despite the 6,000 recommended; brakes; *one* battery -- with warranty replacements thereafter; door checkers; starter; serpentine belt). Ah, no... that $1K is low as it doesn't include rubber! So, $1K not counting oil changes? :>

But, we're getting older so "falling" into the car seats is becoming more tedious; SWMBO also doesn't like driving in a sea of pickups and panel trucks (visibility); and, the number of folks without insurance, valid license, etc. So, bigger and higher are issues. Also wants to be able to haul around the plein air supplies without having to set them *into* a "trunk" (which requires "disassembling" everything and "reassembling" it when you arrive on-location).

As virtually all of them are "genuine" issues (though not for *me*! :< ), it would be wrong to ignore them.

Don,

Can you shoot me an e-mail? This address, snipped-for-privacy@att.net , is good. I suspect snipped-for-privacy@is.not.me.com doesn't work. :)

Thanks!

Matt Roberds

Done.

Well, it *may* work... but I haven't a clue as to *who* (or what!) would be on the receiving end! ;-)

--don

That's how a series hybrid has to work. With a parallel hybrid, if the driver demands a lot in the "inner loop", the combustion engine can send mechanical twist directly to the wheels, without involving the electrical system.

On the '01-'03 Prius, the combustion engine was about 75 hp, and the electric motor adds about 25-30 hp. I don't know what the balance is in newer hybrids. That same engine in non-hybrid Toyotas was rated about

100 hp; in the Prius it was tuned for least smog, not maximum performance.

Right. That's called a "charge-sustaining" hybrid. I have driven a (homebuilt) "charge-depleting" series hybrid, which essentially means that the combustion engine, generator, or batteries are "too small" for the load. If you drive it hard enough, eventually the batteries go dead, and you have to either seek shore power, or park it for a while so the combustion engine can run the generator and charge the batteries. For obvious reasons, commercial hybrids are not built this way.

Sort of. Usually what happens is that for light brake applications (either low force on the pedal, or the first few percent of the pedal travel), all of the braking comes from running the electric motor as a generator to recharge the battery. For the next little increment of force or pedal travel, the mechanical brakes and electric "brakes" are working together. At some point after that, it's all mechanical brakes.

Also, the electric "brakes" typically cut out at low speeds (below 3-5 mph or so), as it's difficult to brake all the way down to a stop with them. The mechanical brake is used instead.

You don't have to *think* about any of this stuff while driving; you just step on the big wide pedal to stop.

The mechanical brakes have ABS; I suspect if the ABS activates, the electric "brakes" are automatically cut out. The mechanical brakes also have a dual-circuit master cylinder, so you still have half of them if you get a hydraulic leak. If everything is going wrong, you also still have a parking brake/emergency brake, which usually applies via cable to the back wheels.

For most hybrids, that's probably list price for the battery and at least a few hours of dealer labor. You can do better if you can find a dealer that sells parts at a discount, and come up with your own labor.

I know it's possible on older hybrids. You probably need a "generic" OBD-II scan tool to reset the trouble codes the failing traction battery probably set, but you don't have to do anything special to "marry" the new battery to the car.

The electrical work is designed such that somebody with reasonable skills can get it done without getting shocked. It's more involved than swapping a 12 V battery, but somebody that's familiar with domestic or light commerical wiring (120/240 V AC) would be able to do it just fine.

For newer cars, I don't know. I have read that on newer GM vehicles (of all types), replacement engine computers, body computers, etc come

*without any firmware*. Somebody (either you or the dealer) has to have a (proprietary?) scan tool, and a *subscription* to a GM web site, to download the firmware from the Web site and load it into the computer. I don't know if the aftermarket has figured out a way around this yet.

That doesn't seem like very long, but then again, it doesn't get to

110 or 120 degrees in the summer very much here.

However, *you* are only one of the inputs into the equation. I get it; my mom prefers one of the two cars available to her because the door sill is lower and easier to step into.

A few years ago, my car insurance dropped by about a third when I moved one state away. When I asked my agent, he said there were lots of uninsured drivers in my previous state, which drove up the premiums there.

*google* I don't get it... you can stick a good DSLR in a shoulder bag!

Matt Roberds

Drag is proportional to the square of speed and the power needed to maintain constant velocity is proportional to the cube of speed. Thus the combustion engine power determines what long term speed can be maintained.

If the battery is going to be depleted, drop the driving speed below that limiting speed and the batteries will be charged. Of course, the charging rate will be slower if you continue driving slowly than when parked, but at least you can continue your journey.

The Toyota hybrid drive is a compound of series and parallel: There is one electric motor/generator directly on the combustion engine shaft and another separate. The systems are connected with a planetary drive which sums the outputs and provides the continuously variable transmission from the combustion engine to the drive wheels. The variable transmission rates are made by circulating the electrical energy between the electric motor- generators, using the battery pack as buffer storage.

In my Lexus 300h the combustion engine is 181 DIN hp (133 kW) and the electric motors 143 DIN hp (105 kW), but the total is calculated as 230 hp.

The braking power is first fed to the battery, and on long descents, the traditional engine braking comes afterward, if the brake pads are not being burned (I tried it in a Prius on Tenerife when descending two km (nearly 7000 ft).

The engine uses the Atkinson work cycle instead of the traditional Otto cycle. It gives somewhat less power for the engine size, but the economy is clearly better than on a traditional engine.

--

-TV

Hi Matt,

[break between movies :> ]

Understood. I will have to ask the neighbor with the electric (Tesla-built?) RAV4 what sort of performance he gets from that vs. his old plug-in (or his Mom's Lexus hybrid).

So, commercial hybrids are "gasoline limited" vehicles? I.e., the liquid energy in the tank determines driving capacity (+ some constant)

Is the "brake pedal" just an "input" to an electric control system? Or, does it have linkages to mechanisms in addition to electrical sensors, etc.? (i.e., how much of a kludge is it and how much of that kludge has to do with reliability -- brakes have to work even if controls crap out)

Understood.

OK. The folks at the dealer were real "squishy" about specifics. As if they didn't like the fact that someone was asking questions about a *known* failure mechanism.

One of the reasons I am not fond of newer vehicles! Too much crap that is BFM (for all intents and purposes).

It's just a fact of life. We don't have to swap winter/summer tires...

Exactly. Silly to have a vehicle that doesn't address *your* needs.

A buddy down the street has three vehicles for the two of them:

- he drives a big 7L pickup (w/ an extra 60G tank)

- wife drives a "minivan" He can't ride in her minivan because of back problems (too many helicopter crashes :> ). She can't ride in his truck because it "shakes her t*ts off" (her term!). So, they also have a Caddy when they need to go places together!

We're an hour from the (MX) border. So, you have folks who probably don't have licenses (fear of being "on the books") and/or insurance. And, you know they aren't likely to "hang around" in the event that they are involved in a fender bender with you!

So, we have to carry UNinsured and UNDERinsured coverages (in addition to ourselves as "insured")

Painting. She carries a cart similar to (watch wrap):

(the "chair" is normally folded up to form the back of the cart).

In it:

- umbrella (sun)

- paint brushes

- paints

- palette (about the size of a 17" laptop)

- 3qt water (1 to drink, 1 for "clean water", 1 for "dirtying")

- wide brimmed hat

- windbreaker (for winter... in case it's only 70F)

- paper (taped to a masonite board)

- easel

- tripod

- digital camera (to record scenes)

- snacks

In a conventional car, this needs to lay down in the trunk. So, remove all the "wets" from the bag and stash them in a milk crate in the trunk. Remove the "bag" from the cart and set it in the trunk (lying flat). Set the cart in the trunk on top of the canvas "bag".

Arrive at painting location. Reverse process to reassemble everything.

Wheel cart off to whichever spot from which you've decided to paint. Unpack everything, setup easel, umbrella, water containers, etc.

Then, reverse the whole procedure a few hours later to head home.

Do this 3-5 days each week...

Much easier if you could just *set* the assembled cart, upright, in the back of a vehicle (possibly strapping it in place so it doesn't roll around or tip over).

Or, decide to COLLECT STAMPS, instead! ;-)

On to next flic...

As far as I know, Toyota builds all their own hybrids. Telsa builds all their own full-electric cars. I'm pretty sure Honda builds all their own hybrids. Other makes I am not as sure of. Earlier in the game (early 2000s), some manufacturers were licensing hybrid drives from Toyota and Honda; they may have started rolling their own, now.

Yep. Just like your father's Oldsmobile.

On mine, the brake pedal is connected to a lever, which pushes on a rod, which goes into the vacuum booster biscuit. The other side of the vacuum booster pushes on the master cylinder, which then pumps hydraulic fluid through solid tubing to the ABS valve block. From the other side of the ABS valve block, solid and flexible tubing runs to the calipers and wheel cylinders.

I know the control system looks at the brake light switch (brakes off vs. brakes on) and I think it might look at the brake line pressure, which it can get from the ABS valve block.

Going is optional, stopping is mandatory.

They always are. If you do just a little research before you go, it's not hard to know more than they do about the cars they are selling.

When I was a kid, my dad used to do that, but tires (and possibly cars) have improved to the point that it isn't an absolute requirement around here, anymore... on a "normal" sedan, you can run all-season tires all year. If you drive a big truck or have to drive out in the country a lot on unpaved roads, winter tires are still a good idea.

Safety wire? Loctite? :D

Aw, true love.

Yeah, I figured it out.

Extra bonus points: get one of those small electric cranes that people use to winch powered wheelchairs up into the back of a minivan, or sometimes to unload heavy stuff from a pickup truck.

Matt Roberds

From what he's told me (I wasn't paying close attention to the details, at the time), the all electric RAV4 was a joint venture with Tesla. His is obviously not "new" (though, perhaps, "NOS"?) and no idea how much he paid, etc.

[He claims to have wanted it as he saw no need for the gas engine in a vehicle that he's only driving 30-40 miles, daily]

There is (supposedly) a new RAV4 hybrid in the works which is probably "all Toyota".

So, it's more like "regenerative-braking-assisted"...

We've encountered one salesperson who was really on top of his game. Most of the others try to ply you with platitudes.

In Colorado, I made a point of driving with studded winter tires. Then, come Easter, swap them out for "all weather" tires.

[Easter being the practical "last time it will snow"]

I won't *touch* that one!

Olde Farte mobile. I think it was recently replaced with a Buick

I'm looking for *less* to do, not *more*! :-(

Den torsdag den 25. juni 2015 kl. 01.33.31 UTC+2 skrev Don Y:

I believe a mechanical system is required for brakes and steering, no steer or brake by wire

you'll need mechanical brakes anyway, they can handle the several hundred megawatt you need for hard braking, I doubt we'll see batteries that can handle charging at that rate soon

-Lasse

[snip]

I've seen steer-by-wire, actually electrically power-assisted, but fail to mechanical linkage only.

Yup. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Den torsdag den 25. juni 2015 kl. 01.49.37 UTC+2 skrev Jim Thompson:

the electric power assist is just a "helper", steer-by-wire would be sensor on the steering wheel and a wire to a motor controlling the wheels

I of course meant hundreds of kilowatt

-Lasse

I have seen such as well, but not in a production car. I would be very leery of such a control system... which is why I avoid Airbus

...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Den torsdag den 25. juni 2015 kl. 02.03.21 UTC+2 skrev Jim Thompson:

because Boeing uses exactly the same system but with slightly different software ?

-Lasse