|
|
Post by mick on Jul 2, 2024 6:31:10 GMT
A mate has just ordered one of these
Apparently, it charges (itself) with a USB plug and cable. I would have expected that it needed much more power than a USB can give.
Can anyone explain please.
Mick
|
|
|
|
Post by peterob on Jul 2, 2024 7:19:45 GMT
A mate has just ordered one of these
Apparently, it charges (itself) with a USB plug and cable. I would have expected that it needed much more power than a USB can give.
Can anyone explain please.
Mick
It's a bit early in the morning but I'd guess it just needs to acquire charge. It'll probably take a fair while to do with a USB feed although these days a USB-C feed can deliver 40 W at 5 V which is 8 coulombs/s. I don't know how many coulombs a jump starter needs, a full car battery can do lots. I think the stop-start batteries are rated for something like 50 starts. Best thing is to not let the car battery go flat in the first place. Our old car doesn't do many miles, the usual journey is allotment and back so less than 10 mins running per start. It also has a current draw somewhere which drains the battery. I put the battery on charge once every three weeks or so - a trickle charge takes 5-7 hours. I've noticed the battery stratifies if the car isn't used for months so it is best maintenance charged after a journey, the bumpier the road the better, to shake the electrolyte up. |
|
|
|
Post by geoffr on Jul 2, 2024 7:39:10 GMT
It is really quite simple, if you imagine the device as a bucket and the usb cable as a hose, the hose can fill the bucket but it takes some time. When the device is used it is like upending the bucket. USB C can deliver over 100W which is considerably more than the original USB rating of 5v at 500mA. Starting a car requires something like 100A for a couple of seconds, assuming an engine in good condition. Some people suggests that a four stroke engine needs 1/4 turn to start, realistically though you need the induction and compression strokes on any cylinder, once that cylinder fires the others should follow.
|
|
|
|
Post by andy on Jul 2, 2024 7:59:12 GMT
Could be the most readily available and cost effective charging circuitry.
|
|
|
|
Post by zx9 on Jul 2, 2024 9:54:17 GMT
I have had a Noco GB-40 which I have been using on and off to start a couple of little used cars. It tops up the charge after starting a sub two litre car with a poorly charged battery quite quickly. On the occasions that I have started a larger engined car with a completely flat battery that required the forced connection it has taken several hours to re charge the pack on a USB charger.
They (GB-40) are good but it struggles with a large modern diesel, I guess it has both high compression and a high electrical load from all the distributed computing to cope with. In retrospect I should have bought a more powerful pack to cope better with my 3L BMW, the 1.4L Toyota it has never had a problem with.
|
|
|
|
Post by JohnY on Jul 2, 2024 10:11:08 GMT
The original power capability for usb was a maximum of 5 volts at 500mA . i.e. 2.5 watts .The communication between source and sink was simple. The device you mention would need many hours to charge at this level.
Next came a series of specifications for Power Delivery (PD) All specifications are backwards compatible. These specifications include communication protocols in which the charging device offers what is available and the receiving device defines what power it can receive. The maximum current for the present standards is 5 amps. The maximum voltage is 48 and therefore the maximum power is 240 watts.
USB C specifies the connector not the PD. Many USB C cables are not capable of carrying 5 amps.
Examples
The Motorola Turbo Power charger that came with my old phone can deliver up to 3 amps at either 5 or 9 volts. My present Google phone can control its charging rate from this charger. It is also capable of charging a Nikon EN-EL15c battery installed in my Z 8 camera.
The Nikon EH-7P charger delivers 3 amps at 5 volts
The Nikon EH-8P charger delivers 3 amps at 5 or 9 volts, or 2.25amps at 20 volts
My old laptop computer provides 2.4 amps at 5 volts.
I realise that this is more information than you asked for but thought it useful to summarise the present state of play.
|
|
|
|
Post by zx9 on Jul 2, 2024 11:43:52 GMT
The original power capability for usb was a maximum of 5 volts at 500mA . i.e. 2.5 watts .The communication between source and sink was simple. The device you mention would need many hours to charge at this level. Next came a series of specifications for Power Delivery (PD) All specifications are backwards compatible. These specifications include communication protocols in which the charging device offers what is available and the receiving device defines what power it can receive. The maximum current for the present standards is 5 amps. The maximum voltage is 48 and therefore the maximum power is 240 watts. USB C specifies the connector not the PD. Many USB C cables are not capable of carrying 5 amps. Examples The Motorola Turbo Power charger that came with my old phone can deliver up to 3 amps at either 5 or 9 volts. My present Google phone can control its charging rate from this charger. It is also capable of charging a Nikon EN-EL15c battery installed in my Z 8 camera. The Nikon EH-7P charger delivers 3 amps at 5 volts The Nikon EH-8P charger delivers 3 amps at 5 or 9 volts, or 2.25amps at 20 volts My old laptop computer provides 2.4 amps at 5 volts. I realise that this is more information than you asked for but thought it useful to summarise the present state of play. The one I have has a micro (?) USB which limits the current to previous USB standards. |
|
|
|
Post by zou on Jul 2, 2024 12:50:53 GMT
The original power capability for usb was a maximum of 5 volts at 500mA . i.e. 2.5 watts .The communication between source and sink was simple. The device you mention would need many hours to charge at this level. Next came a series of specifications for Power Delivery (PD) All specifications are backwards compatible. These specifications include communication protocols in which the charging device offers what is available and the receiving device defines what power it can receive. The maximum current for the present standards is 5 amps. The maximum voltage is 48 and therefore the maximum power is 240 watts. USB C specifies the connector not the PD. Many USB C cables are not capable of carrying 5 amps. Examples The Motorola Turbo Power charger that came with my old phone can deliver up to 3 amps at either 5 or 9 volts. My present Google phone can control its charging rate from this charger. It is also capable of charging a Nikon EN-EL15c battery installed in my Z 8 camera. The Nikon EH-7P charger delivers 3 amps at 5 volts The Nikon EH-8P charger delivers 3 amps at 5 or 9 volts, or 2.25amps at 20 volts My old laptop computer provides 2.4 amps at 5 volts. I realise that this is more information than you asked for but thought it useful to summarise the present state of play. The one I have has a micro (?) USB which limits the current to previous USB standards. I've got one at work which is the same, takes forever to charge but holds enough juice to start a recently flat battery maybe 2 or 3 times. Best I've seen was about 10x the amps and revived a 2.2 diesel which hadn't run for about 3+ years!  |
|
|
|
Post by mick on Jul 2, 2024 15:21:32 GMT
Thanks chaps. Useful and interesting replies.
I had no idea that USB could handle as much power as it does and so didn't really feel that the "trickle in/ surge out" explanation could be right. It clearly is.
The gadget arrived half charged and he's got in on charge now to top it up. I'll let you know if it works.
Mick
|
|
|
|
Post by andy on Jul 2, 2024 15:36:07 GMT
Thanks chaps. Useful and interesting replies. I had no idea that USB could handle as much power as it does and so didn't really feel that the "trickle in/ surge out" explanation could be right. It clearly is. The gadget arrived half charged and he's got in on charge now to top it up. I'll let you know if it works. Mick FWIW half charged could well be a low stress state for the battery chemistry as storing them empty or full can degrade performance. |
|
|
|
Post by Ivor E Tower on Jul 2, 2024 21:01:04 GMT
^
More to do with transport legislation that dictates that lithium-ion rechgargeable batteries cannot be shipped fully charged. IIRC they have to be at around 30 to 60 percent charged when shipped - however many companies choose to ignore this, possibly because they are unaware of the regulations
|
|
