[SOLVED] Using lower than specified current plug-in adapter

Using a power adapter with a lower than specified current

Hello,

Recently I found an old wireless router and it's original AC plug-in adapter was rated at 5V 2.5A.
The old adapter does not work anymore so I modified an old cell phone charger with 5V 0.7A, to use it instead.
This improvised setup has been working without any noticeable problems for over a week now and still is.
My question is what problems can I expect with this setup, if any?

Thanks
Jure

I found an old wireless router and it's original AC plug-in adapter was rated at 5V 2.5A.
It does not work anymore so I soldered the original plug that goes into the router to an old cell phone charger with 5V 0.7A.

Click to expand...

Sorry to say & please forgive me......... This part of the question is not clear for me. Can you please clarify it?

Thanks in advance

None… It’s a perfect match. This AC plug-in adapter and the old cell phone charger have the same power supply voltage (that’s important) and not to exceed the maximum current available (here it’s about 2.5 Amps) , so the phone charger will draw the necessary current (up to a maximum of 0.7Amps) from this new adapter.

Yes,
after reading his reply, for me the question is clarified. Now as Mister_rf said, it will workperfectly, since the circuit will only draw the current that it is required. In this case, it is 0.7 Amps............ so there is no need to worry by using a 2.5 Amps adapter.....

Wait a minute, then why not that cell phone adaper is having a higher current rating.......... In my view there is two things.
1). The most important thing is, as the rating increases, the cost will also increase......... Very important.
2). Second thing is security,

How.?

Consider, the equipment is short circuited. then a large amount of current will flow......... if it where .7A adapter, if the current exceeded that, the transformer (inside the adapter )may be destroyed thus it may prevent equipment damage or damage to the person who handles it. Since you are using 2.5A rating, the currnt can flow upto 2.5A.. this may result in a disaster. to avoid this we need to use a fuse of 700mA (.7A)

So it is ok to use a higher current rating adapter, provided you are taken precautions for worst case incidents........

Hope this post is infromative....

I'm kind of confused too.
Your title Using lower than specified current plug-in adapter implies that you have connected the low current phone charger transformer to the router that had originally a 2.5A psu.
And then so I soldered the original plug that goes into the router to an old cell phone charger with 5V 0.7A so I think you have plugged the charger psu to the router, is this correct?

I don't know what kind of router you have but 2.5A seems rather high so maybe it was overrated or you are using the router in very simple configuration which doesn't need all that current so it works fine even though the psu can only provide 0.7A.

Alex

You need to ignore the topic title…

original AC plug-in adapter was rated at 5V 2.5A… I soldered the original plug that goes into the router to an old cell phone charger with 5V 0.7A.

Click to expand...

All seems to be connected OK, no problems at all.

OK so my assumption is:

You are using a 0.7A cell phone charger to power your router.
The router was originally powered by a 2.5A supply.

Your question is; what problems might this cause?

The answer:

If you have been using the router for a while now and have no problems then so long as you don't change the configuration you have now it will probably be ok.

However the router could draw more current if for instance you changed the connection type to wireless n from wireless g/b or if you connected an Ethernet cable, if you are running close to the current limit of your charger then you may find the router starts resetting or the internet connection drops out.

Also if you are already on the limit of the charger don't be surprised if the router resets on a hot day, this is because the chargers output maybe reduced in a warmer environment.

But otherwise I expect you will be fine, personally I would just feel the temperature of the charger and if it felt red hot I would be discouraged from using it. Most chargers will be fine but if its a "no name" Chinese cheapo, I think I would find a higher rated adaptor.

Regards
Chris

C'mon, no router involved here, only an old AC adaptor 5V/2.5A and a cell phone charger 5V/0.7A...

mister_rf said:

You need to ignore the topic title…
C'mon, no router involved here, only an old AC adaptor 5V/2.5A and a cell phone charger 5V/0.7A...

Click to expand...

But it is not only the title, as you can see he describes the router psu as an AC plug-in adapter but then he mentions that he has soldered the original plug that goes into the router to the cell phone charger and the only reason I see to keep the router plug is to use another adapter and be able to plug it in the router.
Actually we will only verify the real case if the OP provides an explanation so I guess we'll have to wait.

Alex

Recently I found an old wireless router and ....It does not work anymore so...

Click to expand...

He's trying to recycle an old AC to DC adapter, and not too many mistakes done trying to.

Assuming he really wants to bring his old router back to life and his grammer isn't too good, a couple of small tweaks to his post and...

"Recently I found an old wireless router. It's original AC plug-in adapter was rated at 5V 2.5A,
it does not work anymore so I soldered the original plug that goes into the router to an old cell phone charger with 5V 0.7A."

Now it all makes sense

Thank you all for your answers and sorry for my the bad description of the problem.

mister_rf put it briefly:

He's trying to recycle an old AC to DC adapter, and not too many mistakes done trying to.

Click to expand...

Let's try this again...
1) the original power supply is rated at 5V 2.5A
2) the replacement power supply is rated at 5V 0.7A
What are the possible effects of a lower than nominal current on an electronic device, in this case a wireless router.

I should have skipped "the original plug that goes into the router" part.
Here I was actually referring to switching the two adapter power cables, because the DC connector that is used for the cell phone is not compatible (can't be plugged into) with the wireless router.

Recently I found an old wireless router and it's original AC plug-in adapter was rated at 5V 2.5A.

Click to expand...

His question is based on a ROUTER reference.
As the router is working perfect, forget all. But if you are concerned, try to look at the Specs Label of the router, what current it specifies for it.

@jure8479
Now, as you have changed the initial statements, all my assumptions about this experiment were wrong. Difficult to predict how this situation change, leave it for the moment, but keep an eye on the power adapter.
By the way, many power AC to DC adapters were destroyed by cause of faulty small electrolytic capacitor. Replacement of the electrolytic capacitors it is a fairly simple task to do. Open the adapter case is the most difficult part of the whole procedure.

@Raza
The specs on the router read 5V 2.5A

@mister_rf
While examining the inside of the broken power adapter I have noticed that two electrolytic capacitors have a bulge on top of them, but their safety valves have not been ruptured.
I would have already replaced these capacitors just to test if they are the cause for the adapter failure. The problem is that none of the local electronics shops have a 680uF 10V electrolytic capacitor. However el. capacitors with the same capacity but with different voltage rating are available. The two closest to the original are 680uF 6.5V and 680uF 35V.

I will now remove the two suspicious electrolytic capacitors and test them. Should I replace them with the 680uF 35V, if I find out that they are broken?

You may change faulty capacitors with other caps at least same voltage (higher voltage better) and the same or higher capacity. In this case 680uF/35V. Important to have space for it. :-D
Look and replace also a small capacitor in the primary section of the adapter, (a value of 10-100uF/35-50V).

Thanks for your quick reply mister_rf. I thought this might be the case. The replacement has to have at least the same voltage (in this case 10V) or more.
I will buy the electrolytic capacitors tomorrow, replace them and post the results.

Since my multimeter is not able to test capacitors above 100uF, I had to replace all caps that we over 100uF. The two 680uF/35V that I got from the store were to wide to fit on the circuit board, so I connected them with wires just to test. Then I put back the two old ones (680uF/10V), to check if they were ok. My old adapter works fine now.

Thank you all for your help.