Power Banks
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Clive Semmens (2335) 3125 posts |
What happens when you short circuit a lithium battery, with a sufficiently low resistance connector? I’ve seen a spanner explode when dropped across a car battery’s terminals; the battery didn’t explode (but was wrecked), but the spanner certainly did. That wasn’t an electric car battery – that was a lead acid battery in a diesel car. Of course a car battery doesn’t contain nearly as much energy as a tankful of petrol – but it can deliver what it does contain a damn sight more quickly. |
Rick Murray (539) 13396 posts |
Yeah, that’s a pretty big disclaimer given that petrol indeed does not self combust (unless you’re driving a Pinto 1), but batteries can and do.
Did you watch the video I posted? The guy shorted his charger once he clocked that there was a direct connection between the battery pack and the jump leads. In the name of science, of course. But… He opened the battery, and started to take out the plates inside to examine them. They subsequently caught fire. ;-) Having said all of that, the typical behaviour observed is massively swelling up and spewing a lot of toxic smoke. But this has been observed in various domestic batteries for various gadgets. I wonder what the behaviour would be for a car, which will have much more powerful batteries, and quite possibly a lack of space in which to swell. How would those then fail? 1 Ironically the infamous exploding Pinto is a fake. They wanted to test how the cabin behaves in a rear end crash. It’s well known that a Pinto and it’s fuel tank placement leaks fuel all over the place in a rear end crash. But they had to add something to ignite the petrol as it wasn’t going to self ignite. |
Clive Semmens (2335) 3125 posts |
Have to admit I didn’t. On laptop, poor wifi, videos don’t work well. 500A down a solid iron bar was quite a bar – or perhaps plated copper – if it didn’t explode. Well done the battery not breaching its container. The spanner my colleague (we were both garage mechanics at the time) dropped on the poor customer’s battery was pretty dramatic. Big ring spanner: one ring vanished completely, and a big bite out of the other end. Battery terminals both turned into big blobs. 1967, so no CCTV or anything sadly. Mate’s arm badly burnt, both of us temporarily deafened. Not sure whether that was when my tinnitus started, or perhaps just got worse. [Edit: ah – perhaps the bar was well connected to the beast in your video? The contact points were probably where all the heat was generated on my mate’s spanner.]
Of course it is. All these movies with exploding petrol tanks are. It’s not what happens. You’re very unlucky if there’s an explosion at all with petrol. A big, nasty fire, for sure, but an explosion will only happen if the petrol vapour doesn’t ignite for ages – not until it’s well mixed with air, Buncefield fashion. |
David R. Lane (77) 728 posts |
Clive/Rick take it to Aldershot. Now back to power banks. I have seen some Ansmann power banks on Farnell’s website, but the cheapest one that does 10,000mAh with 5V and up to 3amp output costs about GBP45! It has 3 output sockets and is about the size of a mobile phone. |
Rick Murray (539) 13396 posts |
Hmm, three days later you say that.
The quoted ratings are the rating of the battery, not the output. So that’s 10,000mAh at 3.7V. There’s a useful formula: (3.7 x rated mAh) / 5 Doing that, you’ll see that your 10,000mAh battery will theoretically manage 7,400mAh at 5V, which is a loss of 23%. However, providing the rating of the battery is not technically a lie, but it allows them to print a larger number and gloss over the efficiency of their power conversion hardware.
Try your supermarket? I got a 15000mAh battery with two USB outputs, 2A output, and a proper percentage battery level for €10 in the winter sales. I think normal price would have probably been about twice that. Runs my tablet for ages. |
Rick Murray (539) 13396 posts |
Is it this? Must be Brexit pricing… :-p |
Steve Pampling (1551) 7928 posts |
The routine pricing for imported (USA) texts always used to be1 based on tippexing out the $ and putting in a £. 1 1970’s and seemingly onward. |
Colin Ferris (399) 1748 posts |
I was going to say – something about paying for our free Vaccine :-) |
John WILLIAMS (8368) 485 posts |
But as this is NOT Aldershot, you thought better of it! |
David R. Lane (77) 728 posts |
@Rick
Yes, that’s the one. That website mentions only a 5V output, but on the Farnell’s website it says 5V, 9V and 12V outputs. The Ansmann model number is given as 1700-0115, the same as on the RS-online website where the price is about GBP34. |
Rick Murray (539) 13396 posts |
I was wondering if that was the USB C port, but no, it’s all ports.
https://www.ansmann.de/en/consumer/powerbanks/powerbank-10-ah-type-c-18-w-pd#productSpecifications |
David R. Lane (77) 728 posts |
So, I have ordered the Ansmann model number 1700-0115 power bank from RS-online, aka Radio Shack online, coming tomorrow! I found the RS-online website difficult with the most capable RISC OS browser, you know the one that can see more websites than others. It even gets me into another kind of bank’s website now, Co-op bank website, hooray! But, first time, it stumbled through the ordering only to fail on the very last “place order now” button. It worked second time round. |
Steve Fryatt (216) 2045 posts |
It is? |
Clive Semmens (2335) 3125 posts |
RadioSpares. No relation, afaik. |
Steve Pampling (1551) 7928 posts |
No connection at all, and I think they went from RadioSpares to RS Components back in the 70s1 Opened a big distribution centre at Bermuda (south edge of Nuneaton) location of the old Griff1 Clara mine. Two pubs nearby, one on the A444 junction and the other2 tucked away. 1 Just looked it up. Memory not totally shot – 1971 2 The less obvious pub in the area is the Griffin Inn @ Griff, at one time apparently just the Griff Inn @ Griff. Local speculation is how long it will take to add another “In” to that name :) Down the road from the obvious big road pub on the island. |
Alan Adams (2486) 1125 posts |
and at that time they were trade-only, so my shop of choice was Electrovalue. That name seemed to disappear some time later (about when Maplin appeared). However last week I ordered some bits from an Ebay seller with a completely different name (Bright Components I think), and the packaging had a printed label saying “Electrovalue”. Nice to think the business survived. |
David R. Lane (77) 728 posts |
Apologies for mixing up Radio Spares with Radio Shack, both started as radio shops, one in London the other in the USA, and within 16 years of each other in early 20th century, but that’s as close as it gets. (sources: rs-online website and Wikipedia) I didn’t know Bermuda was in England, you learn something new everyday, let alone that such a popular holiday resort was on the edge of Nuneaton. So now Brits can holiday in Bermuda without breaking the coronavirus rules. Continued in Aldershot …. |
Chris Evans (457) 1614 posts |
Someone is using the name Electrovalue but it doesn’t sound like it has any relationship to the old compant. Goggle found “It was wound up….” “The owner/founder/director David Longland wanted to retire and sell his business, but nobody was interested.” |
David R. Lane (77) 728 posts |
Got the Ansmann POWERBANK 10.0 today and it powers the Vonets WiFi-Ethernet adaptor just fine. I am typing this on my ARMBook running RISC OS with the Vonets Wi-Fi-ing the home router. The sequence was: power up the Vonets with the power bank; after the Vonets establishes communication with the home router hotspot, connect the Vonets to the ARMbook via the ethernet-USB adaptor; and only then power up the ARMbook. |
Rick Murray (539) 13396 posts |
The way I do it here, as things are set to restart themselves after a power cut, is that the Pi has a static IP address, and in the router, that same address is marked as “reserved” to the machine’s MAC address. That means that DHCP will only ever give out that IP address to the matching MAC, which won’t happen as that device (the Pi) uses static IP. This arrangement was necessary as the Pi boots in about 10 seconds. About 20 for the Vonets. And somewhere between three and four minutes for the Livebox. |
Colin Ferris (399) 1748 posts |
Has anyone tried Linux RO on the Armbook – so you can use the inbuilt WiFi? |
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