Question about Amp/Voltage on UPS units for Router backup battery

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Hello,

I have a question about the meaning of the power requirements for two T-Mo internet gateways I am looking at to hopefully get the right UPS battery backup.

I have a Nokia 5G21 gateway that is rated at 12V2A and have been using a Shanqiu battery backup that can power that device correctly – has 12V2a connections.

That gateway has been having some connection and speed issues of late – unclear if it is TMo or the gateway, so TMo is sending me a different one to try, a 5G Gateway G4SE that is rated as 100 – 240V, 3A @ DC 15V, 50/60Hz. The Shanqiu backup won’t work as it is only 12V and this new gateway needs 15V.

I haven’t been able to find a battery backup that is both 15v and 3A. I did find one, a TalentCell Mini UPS Uninterrupted Power Supply at Amazon that is 15V, but only 1.5A.

My questions – might that work in a power outage for several hours even if it isn’t 3A? What is the drawback or possible warning for using a device that is rated at fewer amps than needed? Will it cause damage to the Gateway or will it just run more slowly? Or something else?

I am not even sure if the replacement Gateway will work any better than the one I have now – it may be a TMo issue and not the Gateway at all – overloaded towers, etc. I am just looking ahead to see if I can find the correct battery backup to keep that device running for several hours in a power outage.

Thanks for any help anyone might have!

 

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Voltage and amps don’t work like that.

A power supply’s output voltage must equal the devices voltage requirements (within ± 10%).

If it’s output voltage is too low, the device simply won’t power up!

If it’s output voltage is too high, the device will overheat and, if it’s high enough, it’ll immediately fry the electronics and may cause it to catch fire.

A power supply’s output amps must equal or exceed the devices amps requirements.

If it’s output amps are too low, the device simply won’t power up!

If it’s output amps are too high, the device will only draw the amps it needs and work just fine.

So, a power supply can damage a device if the voltage is too high, but it can not if the amps are too high; because the device will only draw the amount of amps it needs to work.

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LHiggins

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Thanks for the explanation. I really didn’t understand how it all works.

So – based on what you said – if my Gateway needs 3A and I used a 1.5A battery backup – the Gateway won’t turn on, correct?

The battery backup I am looking at is rated at 15W – which is what the Gateway needs, so that should be OK, but it is the lower amps on the backup that would be the issue.

The battery backup does have a 12V 3A output – but I guess that 12V isn’t enough?

So I guess the one I am looking at won’t work. I can’t seem to find one that has both 15V and 3A.

Thanks again for the help!

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LHiggins wrote:

The battery backup I am looking at is rated at 15W – which is what the Gateway needs, so that should be OK

No, that will NOT work.   The new router pulls 15 V @ 3 amp max.  That is 45 Watts (V x A = W) which is 3 times more power than the battery backup you are looking at can supply.   It will hook up OK at first, but the first time the Gateway draws over 1.0 Amp the battery backup will fry and heat up a lot too.

The simple solution is a battery backup for 110 V.  Plug the AC adapter for the Gateway into the 110 V battery backup.  One that costs less than the one you are looking at can give 250 W.

Amazon Basics UPS Battery Backup & Surge Protector 400VA/255W

HTH, Dana:))

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LHiggins

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LHiggins wrote:

if my Gateway needs 3A and I used a 1.5A battery backup – the Gateway won’t turn on, correct?

Correct!

FYI, you might want to take a look at these two battery backup units.

15V High Capacity Rechargeable Battery Pack (15V 4A)

16V Battery Pack Power Bank with 5V USB Port (16V 4A)

They’re intended for use with laptops but, if the connector is correct or you have the appropriate adapter, should work with your gateway.

BTW, a 16V output is within the ± 10% tolerance for a 15V device (it’s only +0.6%) so the device would still work just fine. It’ll just get slightly warmer than normal and experience a slightly shorter total life span due to the extra heat.

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LHiggins

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Drcard:)) wrote:

The simple solution is a battery backup for 110 V.  Plug the AC adapter for the Gateway into the 110 V battery backup.  One that costs less than the one you are looking at can give 250 W.

Thanks! But I am really looking for a battery backup that will provide power to the gateway for several hours in a power outage. And with the specs of the new gateway, that may not be easy to find.

n0ads wrote:

FYI, you might want to take a look at these two battery backup units. They’re intended for use with laptops but, if the connector is correct or you have the appropriate adapter, should work with your gateway.

Thanks! But those are really too expensive for my purposes.

Right now I have a different gateway that is rated at 12V 2 A, so that would be 24 W (12X2?). I have a Shanqiu battery backup unit that is rated at 74 W and it seems to work well. Haven’t tested how long it will last on battery power, but it is supposed to be around 4 hours with just my one device attached.

I may just give up on the idea of replacing that gateway with the newer one. TMo is sending it to me to try to see if it is better than the one I now have, but if it can’t stay running for a length of time in an outage, I might be better off sticking with the one I have, even if it may run a bit slower.

Thanks for all of the help! Much appreciated!

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LHiggins,

To help bring a bit of focus to the suggestions you’re getting from others, let’s make sure you understand there are two ways to tackle your problem. For discussion, here’s a diagram from the new G4SE gateway’s manual:

As you know, the power brick in the middle converts the AC current/voltage from the wall to the requisite DC current/voltage the gateway needs. But of course, that power brick doesn’t stay on if the AC power goes out — hence your quest.

It sounds like the solution you think you need is to replace the power brick with some type of UPS device that will match the AC requirements on one end and the DC requirements on the other end.

But a different solution is to keep the power brick and add a UPS between it and the wall outlet. That’s the solution Dana suggested upthread. That way, the UPS does not need to match the DC volts/amps required by the gateway, it merely needs to provide uninterruptable AC power to the gateway’s power brick and let the power brick do the converting. Those can be much more cost effective than the first option.

 

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LHiggins, satrow

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dg1261 wrote:

But a different solution is to keep the power brick and add a UPS between it and the wall outlet. That’s the solution Dana suggested upthread. That way, the UPS does not need to match the DC volts/amps required by the gateway, it merely needs to provide uninterruptable AC power to the gateway’s power brick and let the power brick do the converting. Those can be much more cost effective than the first option.

Thanks for the reply and information. I had considered such a set up – but I don’t think any regular UPS units that I would plug into would provide the power for any extended period to keep my gateway and internet running in a power outage. I am looking for something that will provide battery power for 3-4 hours to keep my internet connected, and it seems that the regular UPS units just supply the power for a short time to allow proper shut down of equipment – not extended working time.

And since I haven’t found one that matches the configuration of that gateway, I have decided to keep the old I have, that does work with the Shanqiu backup and that is supposed to run for an extended period.

Thanks again for all of the help and suggestions. Much appreciated!

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Any UPS can supply power for 4 or 5 hours, or more, if you choose the right unit.

First you need to look at your load, in your case the gateway. The new unit consumes, at most, 45w.
Next you need to work out how long you want the unit to run. Let’s call it 4 hours.
UPS batteries are 12 volt and at 45 watts that will be 45/12 = 3.75 amps.
You need a UPS that has batteries rated at 3.75 x 4 = 15Ah (amp hours). These are quite big batteries.

The easiest way to work this out is to find the runtime charts from the manufacturer. To get 4 hours you may need to add an external battery.

If the UPS quotes capacity in VAh (Volt Amp hours) you need to multiply the watt figure by 1.8. 18 x 45 x 4 = 324VAh

cheers, Paul

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LHiggins

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Paul T wrote:

Any UPS can supply power for 4 or 5 hours, or more, if you choose the right unit.

Thanks Paul! I guess that is the key – finding the right one!

Thanks for the explanation of how to math out the possible runtime. I think in this case, a very large UPS might not really be what I need – but I will certainly keep this information in mind as I continue my search!

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@LHiggins, why not ask T-Mobile if they have a battery backup unit for that gateway? Especially if the gateway’s signal is used by any sort of medical device(s) that use the signal to report in to a medical provider of some sort.

After reading through this thread and your experiences in trying to find an aftermarket battery backup for it, it sounds to me as if you might be “stuck” with a proprietary power feed for that gateway. If so, you might have no other recourse than to use whatever battery backup is made available from T-Mobile or the gateway’s manufacturer.

 

 

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LHiggins

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LHiggins wrote:

I am looking for something that will provide battery power for 3-4 hours to keep my internet connected, and it seems that the regular UPS units just supply the power for a short time to allow proper shut down of equipment – not extended working time.

To get longer time out UPS units I used the old piggy back trick.  Two cheaper UPS devices that the combined up time is longer than a more expensive longer up time UPS.  Plug the first UPS into the wall outlet.  Plug the second UPS into an outlet on the first UPS.  Plug my devices into the second UPS.  When electricity goes out the first UPS goes on battery and the second UPS is still on electricity from the first UPS.  When the battery goes out on the first UPS, the second UPS will go on battery.   Result is longer up time.

HTH, Dana:))

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LHiggins, TechTango

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Daisy chaining UPS units is not recommended. See the two links below for more info.

https://www.apc.com/us/en/faqs/FA157424/

https://www.eaton.com/us/en-us/support/eaton-answers/daisy-chain-ups.html

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LHiggins

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Drcard:)) wrote:

To get longer time out UPS units I used the old piggy back trick.  Two cheaper UPS devices that the combined up time is longer than a more expensive longer up time UPS.

Wow – thanks so much for that idea! I never thought of it that way, but that sounds like something to look into! Great idea – much appreciated! Sounds like I have some thinking and figuring out to do!

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Mothy wrote:

Daisy chaining UPS units is not recommended. See the two links below for more info.

OK – but is it OK to plug a UPS unit into a power strip to have more outlets available – not directly into the wall outlet?

 

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Yep, that’s OK because it’s a direct connection to the power, although you probably want the UPS direct into the wall and the power strip off the UPS.

cheers, Paul

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LHiggins

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Mothy wrote:

Daisy chaining UPS units is not recommended. See the two links below for more info.

Maybe the UPS units are different now, but I have done it in the past on several occasions and it works.  Sure a line spike will go thru both units and fry both, but I used a spike arrester between the wall outlet and the first unit.  That bit about one unit going on battery causing the second to go on battery states “sine” waves, which bad spiking electricity.  In those days my UPS battery could keep you up and running for about 20 – 30 minutes.  When I piggy backed the UPS devices as I posted, it would stay up for 40 – 45 minutes, which is longer than either alone.

The UPS units may be different now and I noticed that the sites that say you should not piggy back UPS units also sell the extra battery packs and more expensive longer running systems that you should get instead.  BTW: Isn’t the second UPS the same as a battery pack?

HTH, Dana:))

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LHiggins

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