What if the battery runs COMPLETELY flat?

[serendipity]

Does the battery need to be replaced if it is completely flat? Like even if the buffer is used up?

If so, how come your laptop or cell phone battery does not have the same issue?

 

[Don]

No - It's possible to drive the car until it will no longer move and then recharge it as normal . . . . no replacement needed. There was a video of someone doing exactly that in this tech article, but I see the YouTube link is no longer valid http://myimiev.com/forum/viewtopic.php?f=19&t=559 - At any rate, it was someone who turned on every accessory, drove the car at freeway speeds to see what the actual minimum range would be. She ended up back at their place of business and then drove the car many times around the block until it quit moving completely

As to what it does to the ultimate life of the battery pack . . . . that's a different (and presently unknown) matter. Safe to say it doesn't do it any good and repeatedly doing this will very likely shorten the life of the battery. The 8 year, 100,000 mile battery warranty specifically excludes any battery loss of capacity (that's 'normal' wear and tear) so if you eventually wind up with a car which has only a 25 or 30 mile range, the battery warranty isn't going to get you a new one. Better to plan ahead and never have to subject your battery to such abuse

Don

 

[MLucas]

I saw several videos of journalist and bloggers running their borrowed I MiEVs until they stopped moving to see how long it would take and what would happen. I also saw the one Don mentioned. I think its completely pointless, 'What happens when it runs out of juice?'. It stops running, just like anything else - there are no perpetual motion machines. 'How long does that take to happen?' Depends on how you drive it, just like anything else. Pointless. Unlike ICE vehicles that just give you a light when the fuel is low and then shut off when they are empty, our EVs give us the several warnings that we are low on energy and then have a creep mode to help the driver get off the road. Don't have that in ICEs, when its done - its done.

 

[leec]

Don't have that in ICEs, when its done - its done.

Thanks to the law of small numbers, I'm acutely aware of the stranded vehicles I see on the highways and byways with their fuel doors open. I have never seen an EV stranded in such a manner. Surely it's happened and happening upon a stranded EV would be a rarity anyway, but the "creep off the road" safety margin means you have to plan really poorly and have an extremely high tolerance for risk to have it happen.

The closest I came to this was drafting behind a semi to bridge the gap between Centralia and Ridgefield along I-5 before the Castle Rock charger was online. If I had spent another 40 minutes L2 charging at the Nissan dealership in Longview I'd have been fine, but I was trying to reach the Portland raceway for an electric motorbike race.

I drafted with the turtle light on for a while, chickened out and did some L1 charging at a Shell station but didn't quite make it to the top of the exit ramp before the Red Battery Light Of Doom blinked on. The Chevron station on the west side of the freeway had ungrounded electrical outlets on it's exterior and I didn't try to push it across the overpass given that a flatbed tow was much easier and safer.

Basically, ditto to what Don and MLucas have said: Don't do this.

I've made it down to Portland and back several times since the Castle Rock charger went in. When the Fife DCFC is in place, the trip won't require any L2 for an i-MiEV (modulo heater use, YVMV)

Pics & more reportage https://plus.google.com/108161928669055573248/posts/T4fFjCqdmgn

 

[MLucas]

drafted with the turtle light on for a while, chickened out and did some L1 charging at a Shell station but didn't quite make it to the top of the exit ramp before the Red Battery Light Of Doom blinked on. The Chevron station on the west side of the freeway had ungrounded electrical outlets on it's exterior and I didn't try to push it across the overpass given that a flatbed tow was much easier and safer.

:shock:

Never seen that before.

 

[TXCharlie]

Li-Ion batteries are damaged by running too low, but I'm sure the electronics in the MiEV won't let it get that low.

Some Li-Ion cells have a circuit built into them which prevents both over-charging and over-discharging. Usually they're called "Protected" batteries.

For example, the 18650 cells that are used by themselves in a lot of LED flashlights and in series inside laptop battery cartridges... The protected version for flashlights has a tiny round circuit board in the end of them below the + cap to prevent over-charging and discharging. You can also buy 18650 unprotected batteries, which are cheaper but shouldn't be used in flashlights because it's so easy to fully discharge them. Laptops have circuitry to prevent complete discharge, so they generally use unprotected 18650's, or something similar.

 

[psyflyjohn]

I think folks are unwise pushing their Miev lithium battery to the limit and beyond. Having used somewhat similar batteries in model airplane flying, I realized that they are vulnerable to overcharging (exploding) and running them dry (short life). Please come back here in a few years and report on how your lithium battery is performing. If it's not doing well, I don't want to hear any whining !

When in my motorhome, the deep discharge lead-acid batteries, which are resilient, are never discharged more than 50% in order to preserve their life.

 

[Don]

Li-Ion batteries are damaged by running too low, but I'm sure the electronics in the MiEV won't let it get that low.

Some Li-Ion cells have a circuit built into them which prevents both over-charging and over-discharging. Usually they're called "Protected" batteries.

I'm sure there is associated circuitry which prevents owners who know nothing about the technology from destroying the battery pack . . . . otherwise, they couldn't offer a warranty at all. On the other hand, I'm also relatively sure that prudent owners who do understand their limitations and pamper their battery pack can make them last lots longer than they're going to last everyone else - Just like some owners can drive their gas engine cars for 250,000 miles with few problems while other owners are lucky to get 100,000 out of their vehicles

You can run your DeWalt or Makita lithium cells completely flat (I'd bet most owners do) and recharge them a few hundred times before they lose much of their capacity - I wouldn't be happy if my car's battery only lasts for 1,500 or 2,000 recharges . . . . I certainly hope to do better than that, but if you abuse them, that could be all you'll get

Who knows? I suspect once we get a few owners who have 50,000 miles or so on the car, we'll have a better idea what to expect. I'll bet some will do better and some will do worse. With the cost of replacing the pack, I'm going to try to be the one who gets the most life out of mine of anyone . . . .

Don

 

[MLucas]

Please come back here in a few years and report on how your lithium battery is performing. If it's not doing well, I don't want to hear any whining !

With the cost of replacing the pack, I'm going to try to be the one who gets the most life out of mine of anyone . . . .

Sounds kind of righteous and snarky to me.

An electric vehicle should be able to drive the average number of miles each year just as a gas vehicle does. It must be nice to be retired or have the resources to own multiple vehicles. However, as I can tell from the many postings I have read on this site, most of us are not in that position. Instead of continuing to pollute our air and hand our money over to the petrol companies, we have decided to be the early adopters and take on this challenge. Will my batteries last as long as yours do, maybe - maybe not. Who knows and who cares. Its my battery pack and I'll do with it what I like.

Besides, cars are meant to be driven not to be kept in the garage. That's like someone laying on the couch saying if I don't go outside nothing bad will happen to me, while their heart is getting clogged up from lack of exercise.

 

[Don]

I think you misunderstood what I meant - I hope all of us get miles from our cars with without any battery problems. It may take me a little longer than it takes you. My comments were intended to point out that if you're careful with your machinery and treat it right, it will probably last you longer than someone who doesn't

As for the other cars, I've mentioned here more than once that we've put gas in each of them only once since we bought the iMiEV in May. We've probably put less than 500 miles on the both of them combined, while the EV is now getting close to 7,000 miles

Don

 

[psyflyjohn]

Snarky - No Cautious - yes

Seems to me that pushing these new tech batteries to their limits unnecessarily is just asking for trouble.

Let's talk to Boeing about that.....

 

[aarond12]

A little off-topic, but it appears not only the batteries but the charging circuitry is to blame for the Boeing issues. Elon Musk noted they have no spacing between the batteries to avoid thermal overload spreading from cell to cell.

Since our batteries don't have to work at the temperature and pressure extremes that the Boeing and SpaceX batteries do, I think our batteries will be much safer.

 

[peterdambier]

Our batteries are Lithium Iron Phosphate - mostly undestructable. Theirs have been Lithium Cobalt - an intense stare at them may start a thermal runaway that cannot be stopped until there remain only the ashes.

A battery management system staring intensely at them might decide bleeding a cell to get the others top balanced. Getting a little bit hotter than expected it might fail to stop bleeding resulting in a short circuit resulting in a thermal runaway of the cell resulting in other desaster ...

http://www.nextgov.com/emerging-tech/2013/01/lithium-ion-battery-short-circuited-first-787-dreamliner-fire/60869/

An airplane being the first of its kind, being borne and grown up by a computer who knows everything of each and every part and origin being outsmarted by some people who want to save some money may be the other desaster.

http://www.nextgov.com/emerging-tech/2013/01/2006-battery-fire-destroyed-boeing-787-suppliers-facility/60809/?oref=nextgov_today_nl

I am glad our car is no rocket science but I am afraid airplanes are.