>
> I bought 2 car emergency start battery packs from Amazon. One has about
> 15.5 volts on the open circuit battery cables. It also has one USB port
> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
> amps. That port puts out about 15.5 volts open circuit.
>
A USB port delivering 15.5V without anything requesting that or even
without anything connected to it? I would treat that whole unit as
suspicious. If it was mine, I'd return it.
> The other pack has 11.7 volts at the battery cable, then a USB port
> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
> another 12 volt port at 10 amps that puts out 11.7 volts.
>
>
> How does the USB port know what voltage to put out and more important
> how does it regulate that ?
>
By negotiating up, as requested from the connected device. Never down,
because if it starts high you might fry older and potentially still
expensive USB hardware.
Regulation occurs via switch mode conversion. On a portable car starter
with several Li-Ion batteries in series via buck.
> The second pack also charges off a 5 volt usb port. It must havve a
> boost inverter built in ?
>
If it's a decent enough car jump starter, yes. However, I have seen some
very sorry "designs" in that field.
--
Regards, Joerg
http://www.analogconsultants.com/
Reply by John Larkin●July 3, 20232023-07-03
On Mon, 3 Jul 2023 08:37:29 -0700, Don Y <blockedofcourse@foo.invalid>
wrote:
>On 7/2/2023 12:46 PM, Ralph Mowery wrote:
>>
>> I bought 2 car emergency start battery packs from Amazon. One has about
>> 15.5 volts on the open circuit battery cables. It also has one USB port
>> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
>> amps. That port puts out about 15.5 volts open circuit.
>
>Read CAREFULLY the intent of each of these ports lest you toast
>something that wasn't expecting a particular "power flavor".
>
>> The other pack has 11.7 volts at the battery cable, then a USB port
>> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
>> another 12 volt port at 10 amps that puts out 11.7 volts.
>
>The port is *power* limited.
>
>> How does the USB port know what voltage to put out and more important
>> how does it regulate that ?
>
>It can only "safely" deliver 5V@100mA to a load. At that point,
>the load must be functional enough to negotiate a higher voltage
>or current.
>
>The thinking being that a device that can't *handle* the higher
>voltage will never *request* it. A compliant host will, thus,
>never deliver it.
>
>PoE uses a similar scheme -- using hardware signaling to negotiate
>a "power class" and then in-band signaling to negotiate other
>characteristics ONCE THE PD IS OPERATIONAL.
>
>PoE, as originally envisioned, only handled the hardware
>negotiation at device insertion. So, you couldn't power
>down the device and have *it* request the reapplication
>of power -- unless it electrically disconnects and reconnects
>from the PSE.
>
>[This is shortsighted. E.g., I let my devices "sleep" drawing
>a tiny amount of power from the PSE -- just enough to run the
>power request protocol -- so they can pretend to disconnect/reconnect
>without actually breaking that contact *or* having to incur the
>cost of running an ethernet interface to communicate their wishes
>to the PSE]
>
>> The second pack also charges off a 5 volt usb port. It must havve a
>> boost inverter built in ?
>
> I knew the data rates and currents were always being upgraded but did
> not know the voltage was raised in some cases.
> I had thought they were always just 5 volts.
This to allow for more rapid charging of devices, among other things.
I have some "USB power sources" that are used to power small laptops,
etc.
> Did a little more research and found out there is a lot of electronics
> in those battery packs to do what I thought was a simple job of starting
> a car or providing voltage to charge a cell phone.
OTOH, it's a market that is ripe for chinese knockoffs... some of which
may not be very benevolent towards "other" applications.
Reply by Don Y●July 3, 20232023-07-03
On 7/2/2023 12:46 PM, Ralph Mowery wrote:
>
> I bought 2 car emergency start battery packs from Amazon. One has about
> 15.5 volts on the open circuit battery cables. It also has one USB port
> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
> amps. That port puts out about 15.5 volts open circuit.
Read CAREFULLY the intent of each of these ports lest you toast
something that wasn't expecting a particular "power flavor".
> The other pack has 11.7 volts at the battery cable, then a USB port
> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
> another 12 volt port at 10 amps that puts out 11.7 volts.
The port is *power* limited.
> How does the USB port know what voltage to put out and more important
> how does it regulate that ?
It can only "safely" deliver 5V@100mA to a load. At that point,
the load must be functional enough to negotiate a higher voltage
or current.
The thinking being that a device that can't *handle* the higher
voltage will never *request* it. A compliant host will, thus,
never deliver it.
PoE uses a similar scheme -- using hardware signaling to negotiate
a "power class" and then in-band signaling to negotiate other
characteristics ONCE THE PD IS OPERATIONAL.
PoE, as originally envisioned, only handled the hardware
negotiation at device insertion. So, you couldn't power
down the device and have *it* request the reapplication
of power -- unless it electrically disconnects and reconnects
from the PSE.
[This is shortsighted. E.g., I let my devices "sleep" drawing
a tiny amount of power from the PSE -- just enough to run the
power request protocol -- so they can pretend to disconnect/reconnect
without actually breaking that contact *or* having to incur the
cost of running an ethernet interface to communicate their wishes
to the PSE]
> The second pack also charges off a 5 volt usb port. It must havve a
> boost inverter built in ?
Reply by John Larkin●July 3, 20232023-07-03
On Mon, 3 Jul 2023 06:29:14 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
>On Sunday, July 2, 2023 at 8:20:56?PM UTC-4, John Larkin wrote:
>> On Sun, 2 Jul 2023 14:52:18 -0700 (PDT), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>> >On Sunday, July 2, 2023 at 3:46:53?PM UTC-4, Ralph Mowery wrote:
>> >> I bought 2 car emergency start battery packs from Amazon. One has about
>> >> 15.5 volts on the open circuit battery cables. It also has one USB port
>> >> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
>> >> amps. That port puts out about 15.5 volts open circuit.
>> >>
>> >> The other pack has 11.7 volts at the battery cable, then a USB port
>> >> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
>> >> another 12 volt port at 10 amps that puts out 11.7 volts.
>> >>
>> >>
>> >> How does the USB port know what voltage to put out and more important
>> >> how does it regulate that ?
>> >>
>> >> The second pack also charges off a 5 volt usb port. It must havve a
>> >> boost inverter built in ?
>> >
>> >You should consult the manual for the characteristics of those ports. USB is 5V. There are many accessories that use the connector for power only and there is no data exchange.
>> Classic USB was 5 volts. Newer versions can negitiate for 20 or 48, up
>> to 240 watts.
>
>A can't believe that crummy little connector will support even 2 Amp without getting hot eventually.
The c connector is the first USB connector that makes sense. It uses
several pins for power.
I assume that someone sells the negotiation chips to let us design a
box that gets lots of power from USB. There are chips and baby boards
for PoE, a similar situation.
PoE has the advantage that lots of power is available from even the
wimpiest compliant hubs.
Reply by John Walliker●July 3, 20232023-07-03
On Monday, 3 July 2023 at 14:29:19 UTC+1, Fred Bloggs wrote:
> On Sunday, July 2, 2023 at 8:20:56 PM UTC-4, John Larkin wrote:
> > On Sun, 2 Jul 2023 14:52:18 -0700 (PDT), Fred Bloggs
> > <bloggs.fred...@gmail.com> wrote:
> > >On Sunday, July 2, 2023 at 3:46:53?PM UTC-4, Ralph Mowery wrote:
> > >> I bought 2 car emergency start battery packs from Amazon. One has about
> > >> 15.5 volts on the open circuit battery cables. It also has one USB port
> > >> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
> > >> amps. That port puts out about 15.5 volts open circuit.
> > >>
> > >> The other pack has 11.7 volts at the battery cable, then a USB port
> > >> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
> > >> another 12 volt port at 10 amps that puts out 11.7 volts.
> > >>
> > >>
> > >> How does the USB port know what voltage to put out and more important
> > >> how does it regulate that ?
> > >>
> > >> The second pack also charges off a 5 volt usb port. It must havve a
> > >> boost inverter built in ?
> > >
> > >You should consult the manual for the characteristics of those ports. USB is 5V. There are many accessories that use the connector for power only and there is no data exchange.
> > Classic USB was 5 volts. Newer versions can negitiate for 20 or 48, up
> > to 240 watts.
> A can't believe that crummy little connector will support even 2 Amp without getting hot eventually.
Some USB-C connectors are rated at 5A!
John
Reply by Carlos E.R.●July 3, 20232023-07-03
On 2023-07-03 15:29, Fred Bloggs wrote:
> On Sunday, July 2, 2023 at 8:20:56 PM UTC-4, John Larkin wrote:
>> On Sun, 2 Jul 2023 14:52:18 -0700 (PDT), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>>> On Sunday, July 2, 2023 at 3:46:53?PM UTC-4, Ralph Mowery wrote:
>>>> I bought 2 car emergency start battery packs from Amazon. One has about
>>>> 15.5 volts on the open circuit battery cables. It also has one USB port
>>>> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
>>>> amps. That port puts out about 15.5 volts open circuit.
>>>>
>>>> The other pack has 11.7 volts at the battery cable, then a USB port
>>>> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
>>>> another 12 volt port at 10 amps that puts out 11.7 volts.
>>>>
>>>>
>>>> How does the USB port know what voltage to put out and more important
>>>> how does it regulate that ?
>>>>
>>>> The second pack also charges off a 5 volt usb port. It must havve a
>>>> boost inverter built in ?
>>>
>>> You should consult the manual for the characteristics of those ports. USB is 5V. There are many accessories that use the connector for power only and there is no data exchange.
>> Classic USB was 5 volts. Newer versions can negitiate for 20 or 48, up
>> to 240 watts.
>
> A can't believe that crummy little connector will support even 2 Amp without getting hot eventually.
On Sunday, July 2, 2023 at 8:20:56 PM UTC-4, John Larkin wrote:
> On Sun, 2 Jul 2023 14:52:18 -0700 (PDT), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
> >On Sunday, July 2, 2023 at 3:46:53?PM UTC-4, Ralph Mowery wrote:
> >> I bought 2 car emergency start battery packs from Amazon. One has about
> >> 15.5 volts on the open circuit battery cables. It also has one USB port
> >> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
> >> amps. That port puts out about 15.5 volts open circuit.
> >>
> >> The other pack has 11.7 volts at the battery cable, then a USB port
> >> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
> >> another 12 volt port at 10 amps that puts out 11.7 volts.
> >>
> >>
> >> How does the USB port know what voltage to put out and more important
> >> how does it regulate that ?
> >>
> >> The second pack also charges off a 5 volt usb port. It must havve a
> >> boost inverter built in ?
> >
> >You should consult the manual for the characteristics of those ports. USB is 5V. There are many accessories that use the connector for power only and there is no data exchange.
> Classic USB was 5 volts. Newer versions can negitiate for 20 or 48, up
> to 240 watts.
A can't believe that crummy little connector will support even 2 Amp without getting hot eventually.
Reply by John Larkin●July 2, 20232023-07-02
On Sun, 2 Jul 2023 14:52:18 -0700 (PDT), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:
>On Sunday, July 2, 2023 at 3:46:53?PM UTC-4, Ralph Mowery wrote:
>> I bought 2 car emergency start battery packs from Amazon. One has about
>> 15.5 volts on the open circuit battery cables. It also has one USB port
>> that is labled for 5 volts and 9 volts. Another port labled 12 Volta 10
>> amps. That port puts out about 15.5 volts open circuit.
>>
>> The other pack has 11.7 volts at the battery cable, then a USB port
>> labled 5 v, 9v, 12 V with lower amps for the higher voltage. There ia
>> another 12 volt port at 10 amps that puts out 11.7 volts.
>>
>>
>> How does the USB port know what voltage to put out and more important
>> how does it regulate that ?
>>
>> The second pack also charges off a 5 volt usb port. It must havve a
>> boost inverter built in ?
>
>You should consult the manual for the characteristics of those ports. USB is 5V. There are many accessories that use the connector for power only and there is no data exchange.
Classic USB was 5 volts. Newer versions can negitiate for 20 or 48, up
to 240 watts.
Reply by Joe Gwinn●July 2, 20232023-07-02
On Sun, 2 Jul 2023 19:37:22 -0400, Ralph Mowery
<rmowery42@charter.net> wrote:
>In article <nl19njxt2a.ln2@Telcontar.valinor>, robin_listas@es.invalid
>says...
>>
>> > How does the USB port know what voltage to put out and more important
>> > how does it regulate that ?
>> >
>> > The second pack also charges off a 5 volt usb port. It must havve a
>> > boost inverter built in ?
>>
>> The USB ports have to be connected to corresponding USB ports on
>> chargers or batteries, and they negotiate what voltage to put there and
>> how much current to draw. It is not just dumb electronics.
>>
>> https://en.wikipedia.org/wiki/USB
>>
>> https://en.wikipedia.org/wiki/USB_hardware#USB_Power_Delivery
>>
>>
>>
>
>I knew the data rates and currents were always being upgraded but did
>not know the voltage was raised in some cases.
>I had thought they were always just 5 volts.
>
>Did a little more research and found out there is a lot of electronics
>in those battery packs to do what I thought was a simple job of starting
>a car or providing voltage to charge a cell phone.
Project Farm did a study of these units.
Joe Gwinn