Quote of the Day

[mdlbear]

Discussing phone chargers, in the context of today's high wind warning, I mentioned to my housemates that we have a 65-million milliamp-hour battery parked in front of the house. (About half-charged at the moment.)

ETA: as it turns out I hadn't divided by voltage, which for a phone charger is typically 5V. So that should be 13M, not 65M. Thanks to madfilkentist for the correction.

Comments

[azurelunatic]

That sort of battery on hand does seem useful.

[acelightning73]

It's hard to get that out of the battery and into the household in any reasonably simple or safe manner. But lately the news has been full of reports of homes that have caught fire because of a battery for a scooter or bike has decided to overheat and explode. And a lot of the auto industry backlash about electric cars has been about the risk of fire and explosion while you're driving down the road. (Of course, a normal car engine is just a box full of fire and explosions that can dance in synchrony.)

[mdlbear]

I do my charging sitting in the car where it's warm, or charge up a pocket-sized battery to bring inside.

People have figured out the necessary wiring, but it's not something I'd trust myself to do. I kind of draw the line at 120V.

[acelightning73]

In one case, it was an e-bike used by the delivery person for a Chinese take-out place. He had the charger plugged in at work, and left the bike inside until he needed it. It caught fire, burned down the building the restaurant was in, and set the building next to it on fire, someplace in Brooklyn. The city officials keep reminding people never to charge scooter or bike batteries INDOORS.

I can handle more electricity than line voltage, but it's easier if it's medium-band RF.

[freyjaw]

Yikes!

[acelightning73]

Well, we managed to replace it before the car caught fire.

I had a boyfriend who owned an old 1957 Chevy BelAire. One day we were driving somewhere when I noticed that the headlights kept changing in brightness. Then I saw flames under the hood. The battery was held in place with a big metal bar over the top that was firmly bolted to the frame of the car. Somehow the battery had gotten to where it could slide around under the bar. It had slid until the bar shorted across the terminals. It got red-hot, and there was some old grease and stuff on top of the battery, which ignited. There was some road sand left over from winter in the gutter of the road, which I scooped up with my hands and threw on the fire. Then someone showed up with a fire extinguisher. My boyfriend had to get a new battery and a new hold-down.

[freyjaw]

Yikes!

That reminds me of how our Ford Escort (now what I call the Ford Defect) died: self-immolation. The car died a few blocks from the house, but hubby got it started again. We saw some smoke from under the hood, but nothing else until we stopped at the top of the driveway. We saw flames when he raised the hood, so a neighbor got an extinguisher whilst hubby called 911 on his cell. Busy signal. (WTH?!?) I called from the landline without any problem. It took the fire department 20 minutes to put it out. That was one dead car. After a bit, we got the 2007 Ford Taurus SE in 2009, and we still have it.

[mdlbear]

Presumably that doesn't apply to mobility scooters etc. with lead-acid batteries.

[acelightning73]

The chargers for lead-acid batteries (we have a trickle charger for car batteries, we once owned a car with a dying voltage regulator. To replace it, we had to put the car up on a frame jack so the wheels hung down as far as the shock absorbers would go, then I had to reach up inside the left front wheel well to remove the regulator, which was bolted to the inside of the engine compartment. I bought a new one and replace the defective one... when I was three months pregnant with my son.

Anyway, battery charges have large transformers and rectifiers that can overheat.

But the lithium batteries overhead themselves. Have you ever noticed how warm your mobile phone gets when you've been talking for a long time?

[madfilkentist]

I'm feeling dumb, as everyone else seems to get the joke. 65,000 amp hours (at 12 volts) is a lot more than a normal electric car's battery, isn't it?

[mdlbear]

Good catch -- I somehow confused watt-hours and amp-hours. Let's see if I can get this right.

The battery is 65kWh. I suspect phone charging batteries are rated at 5V rather than 12 -- that's what charging voltage used to be before fast-charging and USB-C power delivery. So 65kWh/5v = 13kAh = 13,000Ah = 13M mAh. So I was off by a factor of 5.

Which is pretty bad, but maybe okay for a spur-of-the-moment quip.