[EE] 5V UPS

Discussion:

[EE] 5V UPS

David Duffy (AVD)

2018-10-18 04:08:18 UTC

I have a need for a "5V UPS" for want of a better term.

Input from the mains power source is 5V and limited to around 150mA .
Output to the system is 5V, 90mA at idle with short bursts of up to
500mA required.

Battery capacity required is somewhere in the 1AH - 2AH range. Battery
can not be Lithium based. Options are Ni-Mh or SLA or ???

Mains will normally be available 24/7, but if it fails I need to keep
running from battery until it reaches its safe low voltage point.

Any pointers on the best battery chemistry to go with and what type of
charging will keep it healthy long term?
David...
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___________________________________________
David Duffy Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717 Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au
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AB Pearce - UKRI STFC

2018-10-18 08:45:14 UTC

Permalink

There are "UPS" devices around for use with raspberry Pi. The one I recall seeing is done as a HAT board. Maybe something like this could be adapted to your usage.

-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of David Duffy (AVD)
Sent: 18 October 2018 05:08
To: PicList <***@mit.edu>
Subject: [EE] 5V UPS

I have a need for a "5V UPS" for want of a better term.

Input from the mains power source is 5V and limited to around 150mA . Output to the system is 5V, 90mA at idle with short bursts of up to 500mA required.

Battery capacity required is somewhere in the 1AH - 2AH range. Battery can not be Lithium based. Options are Ni-Mh or SLA or ???

Mains will normally be available 24/7, but if it fails I need to keep running from battery until it reaches its safe low voltage point.

Any pointers on the best battery chemistry to go with and what type of charging will keep it healthy long term?
David...

--
___________________________________________
David Duffy Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717 Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au ___________________________________________

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David Duffy (AVD)

2018-10-18 09:23:52 UTC

Permalink

Yeah, I've seen a few but so far they are all lithium cell based.
David...

Post by AB Pearce - UKRI STFC
There are "UPS" devices around for use with raspberry Pi. The one I recall seeing is done as a HAT board. Maybe something like this could be adapted to your usage.
-----Original Message-----
Sent: 18 October 2018 05:08
Subject: [EE] 5V UPS
I have a need for a "5V UPS" for want of a better term.
Input from the mains power source is 5V and limited to around 150mA . Output to the system is 5V, 90mA at idle with short bursts of up to 500mA required.
Battery capacity required is somewhere in the 1AH - 2AH range. Battery can not be Lithium based. Options are Ni-Mh or SLA or ???
Mains will normally be available 24/7, but if it fails I need to keep running from battery until it reaches its safe low voltage point.
Any pointers on the best battery chemistry to go with and what type of charging will keep it healthy long term?
David...

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AB Pearce - UKRI STFC

2018-10-18 09:39:33 UTC

Permalink

Why don't you want Li cells?

-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of David Duffy (AVD)
Sent: 18 October 2018 10:24
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] 5V UPS

Yeah, I've seen a few but so far they are all lithium cell based.
David...

--
___________________________________________
David Duffy Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717 Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au ___________________________________________

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David Duffy (AVD)

2018-10-18 10:04:56 UTC

Permalink

Customer specification. Not my call.
David...

Post by AB Pearce - UKRI STFC
Why don't you want Li cells?
-----Original Message-----
Sent: 18 October 2018 10:24
Subject: Re: [EE] 5V UPS
Yeah, I've seen a few but so far they are all lithium cell based.
David...

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Neil

2018-10-18 11:32:36 UTC

Permalink

Diode (or MOSFET) and supercap?

Customer specification. Not my call.
David...

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mike brown

2018-10-18 12:28:35 UTC

Permalink

How much time do you need after main supply fails? Based on battery
capacity you mentioned, it sounds like 10-20 hours. OTOH, a later
statement implies that you might only need a couple of minutes.

Post by Neil
Diode (or MOSFET) and supercap?

Customer specification. Not my call.
David...

Post by AB Pearce - UKRI STFC
Why don't you want Li cells?
-----Original Message-----

David Duffy (AVD)

Post by AB Pearce - UKRI STFC
Sent: 18 October 2018 10:24
Subject: Re: [EE] 5V UPS
Yeah, I've seen a few but so far they are all lithium cell based.
David...

Post by AB Pearce - UKRI STFC
There are "UPS" devices around for use with raspberry Pi. The one I

recall seeing is done as a HAT board. Maybe something like this could be
adapted to your usage.

Post by AB Pearce - UKRI STFC

Post by AB Pearce - UKRI STFC
-----Original Message-----
David Duffy (AVD)
Sent: 18 October 2018 05:08
Subject: [EE] 5V UPS
I have a need for a "5V UPS" for want of a better term.
Input from the mains power source is 5V and limited to around 150mA .

Output to the system is 5V, 90mA at idle with short bursts of up to 500mA
required.

Post by AB Pearce - UKRI STFC

Post by AB Pearce - UKRI STFC
Battery capacity required is somewhere in the 1AH - 2AH range. Battery

can not be Lithium based. Options are Ni-Mh or SLA or ???

Post by AB Pearce - UKRI STFC

Post by AB Pearce - UKRI STFC
Mains will normally be available 24/7, but if it fails I need to keep

running from battery until it reaches its safe low voltage point.

Post by AB Pearce - UKRI STFC

Post by AB Pearce - UKRI STFC
Any pointers on the best battery chemistry to go with and what type of

charging will keep it healthy long term?

Post by AB Pearce - UKRI STFC

Post by AB Pearce - UKRI STFC
David...

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David Duffy (AVD)

2018-10-19 00:44:22 UTC

Permalink

10 - 20 hours would be correct assuming that the unit stays idle (90mA)
for most of the time. The 500mA figure is for an RF transmitter but
this would only operate briefly a few times during that period.
David...

Post by mike brown
How much time do you need after main supply fails? Based on battery
capacity you mentioned, it sounds like 10-20 hours. OTOH, a later
statement implies that you might only need a couple of minutes.

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AB Pearce - UKRI STFC

2018-10-18 13:33:34 UTC

Permalink

OK then, look at the Linear technology LTC4015 chip from Analog Devices.

https://www.analog.com/en/search.html?q=ltc4015

This is a multi-chemistry buck battery charger and controller chip that manages the transition from outside power to backup battery. It is capable of doing lead Acid as well as all the Li variations.

Has I2C interface so the battery state can be monitored.

Regards

Alan

-----Original Message-----
From: piclist-***@mit.edu <piclist-***@mit.edu> On Behalf Of David Duffy (AVD)
Sent: 18 October 2018 11:05
To: Microcontroller discussion list - Public. <***@mit.edu>
Subject: Re: [EE] 5V UPS

Customer specification. Not my call.
David...

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David Duffy (AVD)

2018-10-19 00:47:30 UTC

Permalink

Thanks for that Alan. I'm checking it out now. I may be able to limit
the charge current to 150mA and also disable the RF transmitter (500mA)
if the battery voltage is too low.
David...

Post by AB Pearce - UKRI STFC
OK then, look at the Linear technology LTC4015 chip from Analog Devices.
https://www.analog.com/en/search.html?q=ltc4015
This is a multi-chemistry buck battery charger and controller chip that manages the transition from outside power to backup battery. It is capable of doing lead Acid as well as all the Li variations.
Has I2C interface so the battery state can be monitored.
Regards
Alan
-----Original Message-----
Sent: 18 October 2018 11:05
Subject: Re: [EE] 5V UPS
Customer specification. Not my call.
David...

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AB Pearce - UKRI STFC

2018-10-19 06:46:48 UTC

Permalink

Thanks for that Alan. I'm checking it out now. I may be able to limit the charge current to
150mA and also disable the RF transmitter (500mA) if the battery voltage is too low.
David...

Yeah, that is one chip I have been looking at for a project, they have some other similar ones, some are specifically for Li family batteries (presumably for phones and tablets) but others were other chemistries with lower power requirements where this one is potentially quite beefy.

It is worth probing around the LT family of devices, they tend to be my first hit when looking for devices for power functions.

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