Pass through power bank

[Gordon Levi]

I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

 

[David Taylor]

On 24/01/2015 14:07, Gordon Levi wrote:

I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You haven't been reading the group messages, have you?

Someone recommended this to me:

http://uk.rs-online.com/web/p/product/7757508

and there is a 10 Ah one as well. Also a smaller 2Ah unit.
--
Cheers,
David
Web: http://www.satsignal.eu

 

[Don McKenzie]

On 25/01/2015 6:40 AM, David Taylor wrote:

On 24/01/2015 14:07, Gordon Levi wrote:
I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You haven't been reading the group messages, have you?

Someone recommended this to me:

http://uk.rs-online.com/web/p/product/7757508

and there is a 10 Ah one as well. Also a smaller 2Ah unit.

I just got a similar unit from dx.com

What I found was if there is power being put into the unit, then no power comes out, so it won't work as a UPS type of
supply, which basically is what you want, correct?

Mine is a 20000mAh. Sure it has 2.1A and 1A outputs, but nothing comes out unless you either pull out the input plug, or
switch off the source of input power.
http://www.dx.com/p/bp-l2k-1-0-lcd-20000mah-dual-usb-mobile-power-source-w-led-for-iphone-samsung-silver-white-328011#.VMQQGy6WXKA

May pay to check the unit before you purchase.
BTW
I got mine for phone backup, not as a micro UPS.

Cheers Don...






--
Don McKenzie

http://www.dontronics-shop.com

All Olimex products now 60% to 95% off normal Olimex Prices.
http://www.dontronics-shop.com/olimex-ltd.html
Many other items discounted up to 95% off.
Also discounts on FTDI modules, Sparkfun, CCS, SimmStick, etc.

 

[Chris Jones]

On 25/01/2015 01:07, Gordon Levi wrote:

I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You might find something you like on here, (though availability looks
like a problem and I would prefer a fully open-source option).

http://juice4halt.com/

 

[Gordon Levi]

David Taylor <david-taylor@blueyonder.co.uk.invalid> wrote:

On 24/01/2015 14:07, Gordon Levi wrote:
I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You haven't been reading the group messages, have you?

Someone recommended this to me:

http://uk.rs-online.com/web/p/product/7757508

and there is a 10 Ah one as well. Also a smaller 2Ah unit.

Honest Mister, I have been paying attention. In fact that is how I
learned that not all power banks have pass through charging. I should
have acknowledged those posts and explained I am in Australia. The
10Ah RS product costs three times as much as an eBay sourced one
<http://www.ebay.com.au/itm/XIAOMI-10400mAh-Portable-Power-Bank-Li-ion-Battery-Charger-5V-2-1A-iPad-iPhone-/261478644375#ret>.
I was hoping that someone had bought something similar and could
assure me it had pass through charging or had a general method for
determining if a unit has pass through charging.

 

[Gordon Levi]

Don McKenzie <5V@2.5A> wrote:

On 25/01/2015 6:40 AM, David Taylor wrote:
On 24/01/2015 14:07, Gordon Levi wrote:
I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You haven't been reading the group messages, have you?

Someone recommended this to me:

http://uk.rs-online.com/web/p/product/7757508

and there is a 10 Ah one as well. Also a smaller 2Ah unit.

I just got a similar unit from dx.com

What I found was if there is power being put into the unit, then no power comes out, so it won't work as a UPS type of
supply, which basically is what you want, correct?

Mine is a 20000mAh. Sure it has 2.1A and 1A outputs, but nothing comes out unless you either pull out the input plug, or
switch off the source of input power.
http://www.dx.com/p/bp-l2k-1-0-lcd-20000mah-dual-usb-mobile-power-source-w-led-for-iphone-samsung-silver-white-328011#.VMQQGy6WXKA

May pay to check the unit before you purchase.

My post was intended to check the unit before I purchased! Thanks for
eliminating the DX one.

BTW
I got mine for phone backup, not as a micro UPS.

Cheers Don...

 

[David Taylor]

On 24/01/2015 21:36, Don McKenzie wrote:
[]

I just got a similar unit from dx.com

What I found was if there is power being put into the unit, then no
power comes out, so it won't work as a UPS type of supply, which
basically is what you want, correct?

Mine is a 20000mAh. Sure it has 2.1A and 1A outputs, but nothing comes
out unless you either pull out the input plug, or switch off the source
of input power.
http://www.dx.com/p/bp-l2k-1-0-lcd-20000mah-dual-usb-mobile-power-source-w-led-for-iphone-samsung-silver-white-328011#.VMQQGy6WXKA


May pay to check the unit before you purchase.
BTW
I got mine for phone backup, not as a micro UPS.

Cheers Don...

Yes, that's the problem. I guess you could always ask before purchase.
Anyway, I can confirm that RS 10 Ah unit /does/ work as a UPS. I have
one of my Raspberry Pi PCs working on it right now. Unplugged the main,
and the RPi carried on working. Replugged the mains and the device
continues to supply power to the RPi.

--
Cheers,
David
Web: http://www.satsignal.eu

 

[David Taylor]

On 25/01/2015 14:42, Gordon Levi wrote:
[]

Honest Mister, I have been paying attention. In fact that is how I
learned that not all power banks have pass through charging. I should
have acknowledged those posts and explained I am in Australia. The
10Ah RS product costs three times as much as an eBay sourced one
http://www.ebay.com.au/itm/XIAOMI-10400mAh-Portable-Power-Bank-Li-ion-Battery-Charger-5V-2-1A-iPad-iPhone-/261478644375#ret>.
I was hoping that someone had bought something similar and could
assure me it had pass through charging or had a general method for
determining if a unit has pass through charging.

Good point, Gordon, you /had/ indeed been paying attention. As I said
to Don, you could always ask before purchase. I also saw the cheap
units and was very tempted.
--
Cheers,
David
Web: http://www.satsignal.eu

 

[Martin Gregorie]

On Sun, 25 Jan 2015 16:21:08 -0500, rickman wrote:

On 1/24/2015 2:40 PM, David Taylor wrote:
On 24/01/2015 14:07, Gordon Levi wrote:
I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You haven't been reading the group messages, have you?

Someone recommended this to me:

http://uk.rs-online.com/web/p/product/7757508

and there is a 10 Ah one as well. Also a smaller 2Ah unit.

The spec says, "Input power source rating: 500mA @ +5V"

I'm not sure if that limits the input current to 500 mA or if it is
saying 500 mA is required from the power source. If the unit won't draw
more than 500 mA it won't power the rPi at max current draw without
draining the battery, no?

Does that mean that this:
https://www.modmypi.com/pi-modules-upis-advanced-stacking

is currently the best bet at GBP 48.99? This charges at 350 mA, but then
again it is a UPS and can run off mains, batteries or solar cells and
seems to accept supply voltages from 5v - 18v.

This looks a bit more reasonable when you know that Amazon flogs 2500 mAh
'phone chargers, i.e. a pocketable 2500 mAh hard-cased Li-poly battery
for anywhere between GBP 9 - GBP 25 and only the more expensive ones have
chargers and a micro-USB output connector.



--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

 

[Don McKenzie]

On 26/01/2015 2:22 AM, David Taylor wrote:

On 25/01/2015 14:42, Gordon Levi wrote:
[]
Honest Mister, I have been paying attention. In fact that is how I
learned that not all power banks have pass through charging. I should
have acknowledged those posts and explained I am in Australia. The
10Ah RS product costs three times as much as an eBay sourced one
http://www.ebay.com.au/itm/XIAOMI-10400mAh-Portable-Power-Bank-Li-ion-Battery-Charger-5V-2-1A-iPad-iPhone-/261478644375#ret>.

I was hoping that someone had bought something similar and could
assure me it had pass through charging or had a general method for
determining if a unit has pass through charging.

Good point, Gordon, you /had/ indeed been paying attention. As I said to Don, you could always ask before purchase. I
also saw the cheap units and was very tempted.

"pass through charging"

One of the sad points about attempting to buy from dx.com and similar, is you will never get an answer out of them to
any technical question. Almost like trying to get an answer out of Paypal on anything, unless things have changed since
I last tried asking them.

And ebay sellers, you may be lucky to get a sensible answer out of most of them too David. I am in Australia also, so I
understand your problem.

Keep asking for suitable types.

Perhaps the EEVblog forum, whirlpool, or similar Aussie forums may help.

Cheers Don...



--
Don McKenzie

http://www.dontronics-shop.com

All Olimex products now 60% to 95% off normal Olimex Prices.
http://www.dontronics-shop.com/olimex-ltd.html
Many other items discounted up to 95% off.
Also discounts on FTDI modules, Sparkfun, CCS, SimmStick, etc.

 

[Don McKenzie]

And ebay sellers, you may be lucky to get a sensible answer out of most of them too David. I am in Australia also, so I
understand your problem.

Ohhppps, sorry David, I meant Gordon of course.

Cheers Don...



--
Don McKenzie

http://www.dontronics-shop.com

All Olimex products now 60% to 95% off normal Olimex Prices.
http://www.dontronics-shop.com/olimex-ltd.html
Many other items discounted up to 95% off.
Also discounts on FTDI modules, Sparkfun, CCS, SimmStick, etc.

 

[rickman]

On 1/24/2015 2:40 PM, David Taylor wrote:

On 24/01/2015 14:07, Gordon Levi wrote:
I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

You haven't been reading the group messages, have you?

Someone recommended this to me:

http://uk.rs-online.com/web/p/product/7757508

and there is a 10 Ah one as well. Also a smaller 2Ah unit.

The spec says, "Input power source rating: 500mA @ +5V"

I'm not sure if that limits the input current to 500 mA or if it is
saying 500 mA is required from the power source. If the unit won't draw
more than 500 mA it won't power the rPi at max current draw without
draining the battery, no?

--

Rick

 

[Andrew Gabriel]

In article <20150126125503.66027f7e@ntlworld.com>,
Rob Morley <nospam@ntlworld.com> writes:

On Mon, 26 Jan 2015 11:01:57 +0000
David Taylor <david-taylor@blueyonder.co.uk.invalid> wrote:

The instructions are along the lines of: if the input source can
supply 1A or more the unit will draw 1A otherwise it draws 0.5A. Not
sure how it determines that. Mine has been running an RPi B with
Wi-Fi and a GPS attached for 20 hours now, and as soon as I started
it the "charge greater than 80% LED" was flashing, and it still is.
When running, that RPi takes 0.4A. My USB ammeter is only USB-A
connectors, so I can't easily measure the current into the unit, or
know how it determines whether to draw 0.5A or 1A.

USB devices negotiate current draw with the host when connected.
Default is 100/150mA (USB2/3) maximum 500/900mA. If the data pins are
shorted the device knows it's a dumb charger and can draw 500-1500mA.

There are (at least) 3 different schemes for the data lines to indicate
it's a dedicated charging port. Shorting (usually done with a 200 ohm
resistor) is one way. Another is 2.0V on one and 2.7V on the other data
line to indicate 10W output (2.1A), or 5W output if the voltages on the
two data lines are are swapped. Another is 1.2V on the DP line.
There are USB PSU chips which detect which method the USB device is
trying to use, and adapt the effective resistance and voltages on the
data lines to match it (such as Texas Instruments TPS2511).

However, the mess with USB charging standards (the Chinese standard, EU
standard, Apple, and USB Consortium standard) mean many devices nowadays
work out the current available by steadily increasing the draw whilst
monitoring the voltage drop, and back off a bit when the voltage drops
below some device specific threshold (such as 4.75V), or if the supply
cuts out. This can mean that a low spec charging cable can severely limit
the ability to draw max current from a supply even when both the device
and the supply are capable of high current use.

ISTR there's a recent extension (USB3.1?) to this that provides 2A at 5V
but I don't recall the details, and of course Apple chargers/devices
have their own method.

10W (2.1A) can be available from USB chargers to Chinese and EU standards.

The USB consortium standards allow for up to 1.5A on USB2 dedicated
charging port I think, but they also have standards for up to 90W or 100W
for laptops but using different connectors and higher voltages. I've never
seen these in use anywhere, possibly because you have to pay a license
fee to implement their standards, which I don't think is the case if you
use the Chinese or EU dedicated charging port standards.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

 

[David Taylor]

On 25/01/2015 21:21, rickman wrote:
[]

The spec says, "Input power source rating: 500mA @ +5V"

I'm not sure if that limits the input current to 500 mA or if it is
saying 500 mA is required from the power source. If the unit won't draw
more than 500 mA it won't power the rPi at max current draw without
draining the battery, no?

The instructions are along the lines of: if the input source can supply
1A or more the unit will draw 1A otherwise it draws 0.5A. Not sure how
it determines that. Mine has been running an RPi B with Wi-Fi and a GPS
attached for 20 hours now, and as soon as I started it the "charge
greater than 80% LED" was flashing, and it still is. When running, that
RPi takes 0.4A. My USB ammeter is only USB-A connectors, so I can't
easily measure the current into the unit, or know how it determines
whether to draw 0.5A or 1A.

--
Cheers,
David
Web: http://www.satsignal.eu

 

[David Taylor]

On 26/01/2015 01:50, Martin Gregorie wrote:
[]

Does that mean that this:
https://www.modmypi.com/pi-modules-upis-advanced-stacking

is currently the best bet at GBP 48.99? This charges at 350 mA, but then
again it is a UPS and can run off mains, batteries or solar cells and
seems to accept supply voltages from 5v - 18v.

This looks a bit more reasonable when you know that Amazon flogs 2500 mAh
'phone chargers, i.e. a pocketable 2500 mAh hard-cased Li-poly battery
for anywhere between GBP 9 - GBP 25 and only the more expensive ones have
chargers and a micro-USB output connector.

It's only a quarter of the capacity, though. In any case, as I am only
experimenting, I preferred the more versatile in-the-power-line unit,
although it's not a true UPS.

--
Cheers,
David
Web: http://www.satsignal.eu

 

[Rob Morley]

On Mon, 26 Jan 2015 11:01:57 +0000
David Taylor <david-taylor@blueyonder.co.uk.invalid> wrote:

The instructions are along the lines of: if the input source can
supply 1A or more the unit will draw 1A otherwise it draws 0.5A. Not
sure how it determines that. Mine has been running an RPi B with
Wi-Fi and a GPS attached for 20 hours now, and as soon as I started
it the "charge greater than 80% LED" was flashing, and it still is.
When running, that RPi takes 0.4A. My USB ammeter is only USB-A
connectors, so I can't easily measure the current into the unit, or
know how it determines whether to draw 0.5A or 1A.

USB devices negotiate current draw with the host when connected.
Default is 100/150mA (USB2/3) maximum 500/900mA. If the data pins are
shorted the device knows it's a dumb charger and can draw 500-1500mA.
ISTR there's a recent extension (USB3.1?) to this that provides 2A at 5V
but I don't recall the details, and of course Apple chargers/devices
have their own method.

 

[Gordon Henderson]

In article <ksl6catkkg0n06kuer62pkkj80asl7gdod@4ax.com>,
Gordon Levi <gordon@address.invalid> wrote:

I want to use a power bank as battery back up for a Raspberry Pi. The
power bank has to have pass through charging so that I can leave the
power bank connected to the mains while the Pi is powered from the
output. I gather not all power banks can be used that way.

Does anybody have any general or specific advice about how to choose
the power bank?

FWIW: I have an Anker 15,000 mAh unit (bought from amazon) and I powered
a Pi from it last week - noticed the following morning it was down to 1
dot, so plugged it in to charge - and it started charging. However it's
taken 3 days to charge fully - while powering in the Pi.

That, I suspect is the biggest issue with these units - the ability to
take 2x the output capacity to enable charging in a sensible time span...

I suspect it would go off an stay off when it ran out of juice though.

Gordon

 

[Martin Gregorie]

On Tue, 03 Feb 2015 17:10:12 +0000, Gordon Henderson wrote:

FWIW: I have an Anker 15,000 mAh unit (bought from amazon) and I powered
a Pi from it last week - noticed the following morning it was down to 1
dot, so plugged it in to charge - and it started charging. However it's
taken 3 days to charge fully - while powering in the Pi.

That, I suspect is the biggest issue with these units - the ability to
take 2x the output capacity to enable charging in a sensible time
span...

Might this have something to do with limitations in the mains PSU you
were using to charge it? I assume that's a USB charger, so what's its
maximum current capability?

I suspect it would go off an stay off when it ran out of juice though.

Might be worth testing that.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

 

[Martin Gregorie]

On Tue, 03 Feb 2015 18:32:26 +0000, Gordon Henderson wrote:

In article <mar191$7hp$2@dont-email.me>,
Martin Gregorie <martin@address-in-sig.invalid> wrote:
On Tue, 03 Feb 2015 17:10:12 +0000, Gordon Henderson wrote:

FWIW: I have an Anker 15,000 mAh unit (bought from amazon) and I
powered a Pi from it last week - noticed the following morning it was
down to 1 dot, so plugged it in to charge - and it started charging.
However it's taken 3 days to charge fully - while powering in the Pi.

That, I suspect is the biggest issue with these units - the ability to
take 2x the output capacity to enable charging in a sensible time
span...

Might this have something to do with limitations in the mains PSU you
were using to charge it? I assume that's a USB charger, so what's its
maximum current capability?

2 amps.

As a 72 hour charge for that battery should (in theory) need just 208mA,
a 2 amp PSU should have plenty of capacity for running both.

Charging a LiPO or Li-ion battery is fairly complex: a good charger
provides constant current at a 1C rate (a 1000mA cell is charged at 1
amp) until the full pack voltage is reached and then constant voltage
until the current falls to an arbitrary small value, when the charger
reports fully charged and turns off.

My guess is that the built-in charger was designed on the assumption that
there is no load on the pack when its being charged, so the running RPi
is simply eating some of the 1C current, meaning that the battery is
being changed at a rather lower rate than expected. That shouldn't hurt
the battery as the charging circuit will just dimly sit and wait until
the battery gets to the end of the constant current phase. After a power
outage I imagine that the charger restarts in constant current mode.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

 

[David Taylor]

On 04/02/2015 02:46, news13 wrote:
[]

My 2c is to choose the appropriate sla/wet/agm/lipoly/???? to provide for
what ever duration blackout/relocation period you want and then mate it
to the appropriately battery charger and USB power supply.

Which is just what the pre-made units I've been mentioning do.

--
Cheers,
David
Web: http://www.satsignal.eu