resistors as fuses

True, but note the four battery boxes have differing #'s of cells; a function of trying to cram lots of same into existing space and maintain a good CG.

[Further, we'll add more batteries later on, but want to get some systems locked in now.]

Since we'll pull peak loads of maybe 1000A under heavy acceleration, they better not be fused less than that.

Not sure what you mean by puncture tests? Jack Nickolson saying "Here's Johnny" maybe? The batteries are built into battery boxes.

And we have done that. But we here are discussing the individual sense wires and the sense processor modules they connect to.

There's nothing off the shelf in this. The motor controller, driver board, FET array, instrumentation CPU, battery controllers, AC line charger, etc. are all being designed and built by us. ARM based, mostly.

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

It is not difficult to put some type of active over current circuit that will work better and be safer.

A typical method is a crowbar which shorts the batteries on some condition(overvoltage, overcurrent, etc...) and causes a fuse to blow.

In some sense this is simply just making the fuse more effective and allows it to work in different modes that just overcurrent.

The problem with normal resistors is that they may have failure modes that do not resolve the problem. i.e., they are actually designed not to fail which is the opposite of what you are after. For example, if you use the power rating of a resistor as your basis for designing the blow point and it is wrong then what? What if the power handling rating was twice as much?

With some type of precision active current monitoring you can do many more things like trigger a relay and a buzzer. You can even warn when a fault condition is imminent.

Generally LI cells need current limiting protection. Many have this build in which is why they are expensive. The ones don't have been known to literally go up in flames(I'm sure you've heard the news).

That is very good information. And the entire article about CFLs,=20 incandescent lamps, LEDs, and other types, is enlightening as well. I am = a=20 long-time environmentalist, but I have never agreed with policies such = as a=20 ban on incandescent lamps, and I even disagree with the CAF=C9 standards =

mandated for vehicles. As the article points out, encouraging energy=20 efficiency and reducing unnecessary consumption of valuable and limited=20 resources such as electricity, oil, and energy in general, is better=20 accomplished by taxing inefficient products. Also, by pricing the energy =

appropriately (by means of taxation), people and companies will make the =

"right" choices. And the revenue from such taxes and surcharges can be = used=20 to finance research on renewable and clean energy, as well as reducing = the=20 carbon footprint by such actions as planting trees.

Thanks for the information.

Paul=20

YES - or wire in discrete units. This is THE solution IMHO.

"P E Schoen" "Phil Allison"

That is very good information. And the entire article about CFLs, incandescent lamps, LEDs, and other types, is enlightening as well. I am a long-time environmentalist, but I have never agreed with policies such as a ban on incandescent lamps, and I even disagree with the CAFÉ standards mandated for vehicles. As the article points out, encouraging energy efficiency and reducing unnecessary consumption of valuable and limited resources such as electricity, oil, and energy in general, is better accomplished by taxing inefficient products. Also, by pricing the energy appropriately (by means of taxation), people and companies will make the "right" choices. And the revenue from such taxes and surcharges can be used to finance research on renewable and clean energy, as well as reducing the carbon footprint by such actions as planting trees.

Thanks for the information.

** Nice of you to take the time to post your appreciation.

Rod and I took much time (and some debate) over the details presented on that page - with no chance of remuneration nor much thanks either.

A very happy and safe Christmas to you and yours.

.... Phil

Why? Fuses open without catching fire; so do resistors.

-- A host is a host from coast to snipped-for-privacy@nrk.com & no one will talk to a host that's close........[v].(301) 56-LINUX Unless the host (that isn't close).........................pob 1433 is busy, hung or dead....................................20915-1433

Hello, the last thing I wish to do is short a cell. You can likely turn a screwdriver orange by doing so.

I don't care. My range is "above the sense current (say one mA) but below where the {say} 24G wiring is on fire.." I think that will be doable.

So you want warning bells on 50 odd sense lines? Where will we put them all? I think that's unnecessary; the battery controller will report if one goes to zero volts...its JOB is to monitor the reported cell voltages.

These are the voltage SENSE lines; passing say 1mA. The power feed from the box is slightly bigger, say by a factor 1E6.

--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

Hmm electro-static pickup? Hey, you most likely only need a BW of a few Hertz above DC. Could you add some capacitance to ground after the resistor to get rid of all the high frequency 'crud'?

George H.

a a

ed

e

I totally agree. I read the congress has postponed the incandescent ban here in the US for a few more months. I think my wife and I have squirreled away close to 100 hunderd watt bulbs. But how do you determine a 'life time supply'? We use mostly CFL's but still......

George H.

Enjoy the mercury. The pricing of LED equivalents is starting to fall to rational values. So I'm considering judicious replacements, not because of any green (*) thoughts, but because of maintenance nuisance of bulbs in 16' ceilings... and outdoor lighting buried in the cactus ;-)

(*) Pansies, fairies and Democrats ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
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| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
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I love to cook with wine.     Sometimes I even put it in the food.

WHO "decides what to tax? And one thing leads to another. The path to hell is paved with (so-called) good intentions. The EU and the US have been conspicuously following the path to destruction for at least 10 years now; just look at the so-called value of the Euro and of the dollar - as well as the insane and patently stupid policies.

That is another kettle of fish entirely. There is really no need to fuse =

sense lines if you can locate resistors close enough to the battery that =

there is no possibility of a fault ahead of it. Any problem after the=20 resistors will be inherently limited by their relatively large value. = Then=20 you just need to physically isolate the rest of the circuitry from the = high=20 current conductors and terminals. Even worst case of 200V, a 50k = resistor=20 will only dissipate less than 1 watt, and you can use one of them on = each=20 terminal of the battery and use a differential amplifier to reference = the=20 voltage to a common ground. If you are really paranoid, use an = optoisolator=20 or an LED transmitter to sense the voltage and fiber optics to connect = to a=20 remote photoresistor receiver. Or even something like an rfPIC circuit = that=20 sends the information wirelessly.

I think this application needs to be conceptualized better and determine = the=20 nature of any sort of fault and the probability of occurrence. You can't =

protect against every possibility, but for vehicular batteries the big = issue=20 is crashworthiness. There has been some hype recently about the Chevy = Volt=20 catching fire in a crash test:

and a more reasonable analysis from a design engineer's POV:

"If that was a gasoline car that was not properly constructed, and the=20 gasoline burst into flames, it would have been a far worse accident, = because=20 of the big difference in energy," Cairns says. "Yet, we accept the tank = of=20 gas, and the energy that it represents, and the type of fire that it=20 represents, every day."

The negativity is likely promoted by the Big Energy companies who stand = to=20 lose if and when most people switch to electric vehicles.

Paul=20

ally

n

m a

as a

s y e

used

the

n

A democratically elected government.Proportional representation gets you better legislators than first past the post (single member plurality) systems.USA and the UK are demonstrating this with some enthusiasm at the moment.

The Tea Party Movement seems to be rather more explicitly hell- directed than most - what kind of a faction requires its members to abjure scientifically established facts if they want to enjoy the factions' whole-hearted (if half-witted) support.

James Arthur would agree with you, as well as any number of other right-wing nitwits. They'll also tell you that global warming isn't happening.

In fact the US is in economic decline because it isn't investing enough in keeping the system going - bridges and other infra-structure are the more obvious victims, but short-changing social security, health care and education is doing more damage in the long term.

The EU isn't in any kind of economic decline. Parts of it are suffering because they adopted the euro without getting their economies into a state where they didn't need to devalue their cirrency from time to time, but that's getting sorted out.

Their policies may look insane and patently stupid to the average right-wing nitwit, but the average right-wing nitwit believes that the free market is perfect and can't be improved by any kind of regulation or control, which has about as much to do with reality as the proposition that the earth is flat (as opposed to close to spherical).

-- Bill Sloman, Nijmegen

Not all resistors. Some resistors are designed to act as fuses if over- loaded,

but not every resistor can be relied on to be so well-behaved.

-- Bill Sloman, Nijmegen

Doesn't matter. The end-to-end voltage is what is being interrupted in a series string fuse, and is what determines the prospects of maintained arcing.

Agree, my the question remains unanswered.

There are codified tests for behaviour of Li-XX cells when punctured. For small cylindrical cells (e.g. 18650) this can be crudely described as forcing a nail through the cell. The larger the Ah rating the more important the behaviour.

We are discussing *only* the fusing/protection of the sense wires? That wasn't clear (to me at least) from your O/P.

I understand that, but that doesn't mean you need to reinvent the wheel when it comes to protection and charge/discharge control. As the designer of a commercially produced Li-XX charger, I have BTDT with industrial Li-Ion packs and I was thankful for the availability of commercial pack protection modules..

On Tue, 20 Dec 2011 18:11:24 +0000 (UTC), David Lesher wrote: (snip)

Picofuses would serve this role adequately.

which (second link above) should be recommended reading for anyone tooling around with Li-XX electric vehicles. The following from p2 of that second link is particularly relevant here:

"Automakers don't just slap blocks of cells in hollowed-out car trunks. They invest heavily in designing and building cooling systems."

It seems there are certain things that are packaged together with most=20 political factions that make it difficult for me to support any one=20 wholeheartedly. I consider myself a conservative democrat with strong = views=20 toward protecting the environment and limiting unreasonable consumption = of=20 resources, yet I am opposed to the "cradle-to-grave" welfare system and=20 softness in dealing with (violent) criminals.

The only valid argument is whether or not the actual global warming has = been=20 caused by humans or by natural cyclical effects. But it is still = necessary=20 to reduce our insane consumption of energy in the form of coal and oil.

Yes, we are increasingly paying the price for neglect of such important=20 things. The US is spending way too much on foreign aid, undeclared wars, = and=20 the so-called "war on drugs" and other failed and fundamentally flawed=20 policies. What departments did that memory-challenged Republican = candidate=20 want to eliminate? Education, energy, and commerce, IIRC. Yeah, where do =

they dig up these losers:

The economies of most of the world are on the brink of collapse, because =

much money has been made on speculation and the assumption that the = economy=20 will continue to grow. But that is absolutely not sustainable over the = next=20

10, 20, and surely 50 years, because growth and wealth is ultimately=20 determined by scarce and valuable natural resources. We are now seeing = the=20 effects of peak oil, which was predicted by Hyman Rickover in 1957:

But, ultimately, it will come down to resources we absolutely cannot = live=20 without, which are food and water. With dangerous methods such as = fracking=20 and deep water oil drilling and nuclear disasters, we are surely=20 contaminating our environment in our insane efforts to grow our economy, =

which is based largely on energy, and its accelerating usage. We must = accept=20 and deal with a flat, and even receding, economy and be satisfied to be = able=20 to live our lives in reasonable comfort. We have become so convinced of=20 materialistic measures of wealth that we neglect our basic needs.

Rich people are not inherently happier than poor people, as long as = their=20 basic needs of water, food, shelter, and health are taken care of. But = the=20 corporate sector and the GOP are doing their damnedest to destroy all of =

these for the majority, just so their little conglomeration of fat cats = can=20 continue their extravagant lifestyles for the few more years most of = them=20 will live.

Paul=20

..which is STUPID of the Big Energy companies, because they will profit from the _extra_ power drain due to the added waste / inefficiency.