|16 forum posts|
Saw this advert on fleabay
One h*ll of a battery, 900 Ah if my maths is correct. Could start a Saturn V with one of these. Wouldn't want to accidentally want to short it out....
1571 forum posts
The Questions and Answers further down the page are interesting, including this:
-Question: Why does Power Bank have no print capacity(mAh)?
-Answer: If we printing capacity, the product can not be allowed to transport by the plane, we hope you can understand this.
... and the warranty is 3 months. Since it originates in China it'll probably take most of those 3 months to get to you.
|not done it yet||03/04/2020 16:26:53|
|4472 forum posts|
That shows just how much an Ah value is without the voltage supplied.
Was it Howell who started a nuclear reactor all by himself by pressing a button (and a milliammeter sprung into life🙂?
Rutland Water was inaugurated by someone pressing a button to power a relay to power a breaker that started a pump.
It’s that little bottle of champagne that pushes the boats off from the drydock, into the water, all by itself?
|Howard Lewis||03/04/2020 16:45:31|
|3123 forum posts|
Even longer now!
Richard, don't compete with me for "Cynic of the Week"!
|Neil Wyatt||03/04/2020 16:57:58|
17686 forum posts
I guess the output voltage is 0.005mV...
|Andrew Johnston||03/04/2020 17:26:42|
5388 forum posts
m = micro = marketing b*****ks
The spec, for what it's worth, states the voltage is 5V.
|Nigel Graham 2||04/04/2020 00:07:20|
|578 forum posts|
I once worked for a small electronics company that made a lot of equipment for Government labs, the Royal Navy etc. One year it gained a couple of contracts for making some special test-equipment for the old Central Electricity Generating Board's R&D lab, and our designer visited the customer to discuss what was needed.
he returned very impressed with two things he saw on a tour he was given. One was a flash-over test on a 132kV transmission-tower ("pylon" insulator. The other was a battery made to give a high direct voltage at very low current and even less noise to drive for some particular experiment. It consisted of a great stack of PP9 cells all linked in series!
|Michael Briggs||04/04/2020 00:16:12|
|183 forum posts|
It might have enough power to light the wick.
|John Olsen||04/04/2020 00:55:17|
|1028 forum posts|
If you wanted to charge it in the advertised 10 to 12 hours you would need to put in 90 Amps!
Buying stuff on the Internet is the modern equivalent of buying from those ads on the back of comic books.
|Martin W||04/04/2020 01:12:07|
|831 forum posts|
I note that they say before first use charge for 10-12hrs. If we assume that the unit is supplied in a fairly discharged state, the input charging voltage is 5v, see USB cable supplied, and the output voltage is 5V standard USB then the charge current would need to be something approaching 90 amps. Therefore I suspect that the charging cable they supply must be fabricated from a superconducting material. My problem is that I don't have to hand 100 amp 5V power supply to suit, that said I wonder if Tesla might be interested in the technology as a stack of these 'small' batteries would have the ability to power a car and not take up too much space.
Then it might be that my thoughts may be incorrect and, as Andrew says, the info is just a load of "b*****ks"
John you evidently type faster than me
Edited By Martin W on 04/04/2020 01:13:12
|Clive India||04/04/2020 08:28:15|
213 forum posts
Are we talking about such worthy contenders as Gamages or Headquarter and General supply?
No harm in it really - the spec is so obviously nonsense it's not worth working it all out.
Much of the Chinese stuff will fail if you drive it to the full spec.
Example - the variable mark/space ratio speed controllers that the uninformed call PWM. Cheap and cheerful, good value and they work, but don't try working them at their rated output for long.
|Michael Gilligan||04/04/2020 08:34:00|
15424 forum posts
Leaving aside the battery nonsense, Clive ... Please consider me amongst the ‘uninformed’ regarding PWM
I would be genuinely grateful if you could clarify.
|David Colwill||04/04/2020 09:26:34|
|622 forum posts|
No you are wrong. It's just that you have misunderstood "rated output".
In China this means maximum value attained before failure. This value only has to be maintained for 1µs.
|128 forum posts|
Long before we were inundated with Chinese imports I was once very tempted to buy what was advertised as a "2MW Laser Pointer"
|Neil Wyatt||04/04/2020 10:30:42|
17686 forum posts
It's amazing what a PP3 can put out. As a teenager we used them to light little bits of Brillo pad for "unspecified purposes".
A few days ago I removed a defective power switch from a multimeter using my hot air rework gun. I forgot to remove the battery first, the leads melted with the confusing result that after removing the hot air brown some literally billowed out of the PCB until Io realised what was happening.
My workshop had to be abandoned because of the nasty fumes and it stank well into the next morning.
|vintage engineer||04/04/2020 10:41:46|
246 forum posts
27 PP3 batteries will give you 243 volts dc!
|5597 forum posts|
Or could they be genuine, sort of?
Intense research into battery technology for at least 30 years, first for laptops and mobile telephones, now because of the increasingly urgent need to replace internal combustion engines in cars and to store erratic green electricity.
Considerable progress has been made! The batteries in USB rechargers are the same technology as those used to power electric model aircraft - high capacity and light weight rechargeables. Battery powered flight? Not in my young day!
900000mAh isn't equivalent to 900A for an hour; I doubt the batteries chemistry is up to that, or it's terminals! The capacity still seems unlikely to me, but is it unrealistic compared with the energy density of petrol, about 46MJ per kilo?
Anyone else up to checking the maths? What's 900000mAh at 5V from a 280g battery compared with 46MJ from 1kg of petrol?
As these things are only £10, I might take a punt and measure one! As their main purpose is recharging mobile phones, I guess the max amps output will be in the USB as power-supply range, no good for starting car engines! I suspect they won't last long either - the warranty is only 3 months.
Almost everything I learned about battery capacity at school is out-of-date. Super-capacitors were ruled impossible. NiFe cells, gone. Zinc Chloride, almost gone. Lead Acid - much improved. Since leaving school, Daniels, Weston and most other special types, gone. Mercury, gone. NiCAD almost gone. Today, Lithium rises; it's a battery Jim, but not as I know it...
|Andrew Johnston||04/04/2020 11:30:23|
5388 forum posts
A very simplistic calculation says the battery is better per unit mass. But in reality that's nonsense since I don't believe the battery is anywhere near 900Ah.
Battery chemistries have made big strides over the last few years, but the fundamental energy capacity hasn't kept pace. Lithium batteries compare well on Wh/kg since lithium is so light. A lot of the work on batteries has gone into reliability and charge/discharge cycles. It's no good having a sooper dooper electric vehicle if the battery dies after a few hundred cycles, or even several thousand.
|316 forum posts|
My only question is, what date was the ad posted. If 1 April then I guess the obvious answer is..........
|Michael Gilligan||04/04/2020 13:24:24|
15424 forum posts
I didn’t bother checking ... but there are many similarly rated alternatives listed.
Given that 9000mAh would be quite reasonable, I presume it’s just an innocent typo that has been repeated.
It has provided some amusement here; but I wonder how we would fare, drafting an advert in Chinese.
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.