Sony Vaio VGN-AR21S not charging

[Cornfed]

I'm hoping someone can give me some advice on a laptop I'm working on.

I've got a customer's Sony Vaio VGN-AR21S laptop in for a hard drive replacement and memory upgrade. It's also running very hot so I'm about to take it apart to clean out dust, replace the thermal paste etc.

This laptop's battery is not detected in Windows or Linux, no charging light appears whether it's powered on or not, and appears to be dead. It runs fine from the AC adapter and the customer told me the battery has never worked since the day she bought it five years ago!? I'm not sure why she never took it back in the first place, but there you go...

I've tested the AC adapter, which is the original Sony one and it gives out the rated voltage. I also tested the six charging pins in the battery bay and they seem to be working (two read 0V, 3 read 3.3V, 1 reads 6V). My universal laptop adapter doesn't charge it either but the laptop will run from it the same as the Sony one.

The customer doesn't seem to mind if the battery issue gets fixed or not, but said if it was just a case of getting a new one she would go for it.

Do you think it has a problem with the charging circuit on the motherboard or would it be worth getting a new charger and/or battery to try with it? What do you guys normally try first with battery charging problems?

 

[NYJimbo]

Several important factors here:

1) Battery never charged since purchase
2) Battery is 5 years old or older
3) From a little poking around that laptop needs a 120w or larger AC adapter

As you know the laptop "charger" as most people call it is not a charger, but the converter which takes AC voltage and changes it to DC voltage and the "charger" is on the motherboard. Because of that its the motherboard that will decide if the battery should be charged or not.

If the laptop never charged from day one it could be that the battery was DOA out of the box, the charging circuitry is bad OR the AC adapter is not putting out enough amps for the charging circuit to allow a charge.

Some laptops will not charge when on IF the "charger" is not powerful enough but will charge if the laptop is off. Some will not charge for same reason if on or off.

A 5 year old battery, regardless of the AC adapter or charger is likely to be dying or dead. Its possible the battery did hold a charge at first but the customer probably can't remember. Never trust a customers memory, especially for that length of time.

So you have to take the items I mentioned in the beginning along with the other issues to determine where to go with this. If your/their AC adapter is 120watts or better then its LIKELY it can provide enough power to the charging circuit to charge the battery. However if it never charged it could be a DOA battery or DOA charging circuitry. Finding voltage on the battery pins on the laptop doesnt mean it can properly charge but power is going there for some reason. Checking the charging chip can be difficult and while you might get some voltage on some pins, if the whole circuit isnt working properly you will not get a proper charge. Replacing a charging chip can be difficult as they are not universal AND there are other circuits involved that could be damaged other than the charging controller. There are mosfets, resisters, caps, etc. to deal with as part of the charging controllers circuit.
Some charging controller packages have pins you can easily test, others are SMD with no exposed leads and are surface mounts so you cant test them easily incircuit.

Most times the customer themselves will buy a new battery FIRST before going to a shop for repair, I see that all the time myself. So if the customer is willing to eat the cost of the battery even if it doesnt work, then go for that. Tell them there is no other way to really test the charging circuit and the AC adapter to see if charging ever did work on this unit. This way if you get the battery and it works you are done. If it does not work then you at least know you have a new good battery and the issue is likely the motherboard. The customer can decide what to do next. A cheap battery for this is about $25 on ebay, if the customer will not eat $25 then its best to walk away from it.

 

[Cornfed]

Thanks for the indepth reply NYJimbo.

I'd forgotten to check the wattage on the Sony adapter, my universal one is only a 90W so it's not the best to test with I guess. I had a Dell Inspiron 1545 in a while ago with the same problem but that had both a faulty adapter and battery. The old adapter would run the laptop fine it just wouldn't charge the old or new battery.

I'll grab a 120W adapter to test with next week. Are there any schematics available online that would show the charging circuitry or how I might go about testing it?

 

[NYJimbo]

One of the biggest problems with most laptops is getting the schematics. Most of the time you can't even get a service manual for laptops from Sony, Gateway, Acer, Asus and others, forget about schematics.

Like I said, the battery is probably the quickest and cheapest way to go. The fact you got voltage on the battery bay pins tells me that at least some of the charging circuit is working. The fact you do not see a battery in windows tells me either the battery circuit board (in the battery) is dead OR the charging circuit cant talk to the battery. If I had to guess based on what I read from you and knowing you see voltage on the pins, the battery would be my next step. It doesnt require tearing down the laptop, it doesnt require a big investment and it elimnates the question of a DOA or dying battery.

 

[Martyn]

I had a 1545 recently where the battery was duff AND the charger was underrated. Replaced both all ok. Like NYJ says go for the battery and see afterwards. If they have an old battery you can justify the replacement which will help you in your diagnosis.

 

[Cornfed]

Yeah I didn't think there were any schematics floating around but I thought I would ask. Thanks both of you for the advice, I've ordered a new battery which should arrive sometime next week.

 

[NYJimbo]

Just keep in mind, even if you get the new battery and it still doesn't work, that should not put you off from approaching the next similiar battery issue the same way. The assumptions we are making here make sense based on what we can test on this particular machine and what we know about it and the customers memory.

Sometimes your guess will be right and sometimes wrong. In situations where further deep diagnostics is not possible you sometimes have to make the cheapest and fastest attempt at a solution. Its really up to how much time you or the customer wants to put in to it and how much the customer is willing to spend on the job.

Of course more knowledge and more tools makes for faster, easier and more accurate diagnostics, but that all comes in time as you get more experience.

 

[Larry Sabo]

These schematics are not for your exact model, but are possibly close enough to help test whether the charging circuit is functioning. For their low price ($12.50 USD) , they are a worthwhile buy for educational value alone, if you are familiar with reading schematics and electronics testing.

 

[PCX]

check the CMOS battery as well. I see dead or defective CMOS batteries do a lot of weird things like

no power on
no charge
no display
other functions directly related to the board not working.

 

[NYJimbo]

I had a 1545 recently where the battery was duff AND the charger was underrated.

That brings up another issue, Dell and HP for some reason decided to make the laptop talk to the charger in many cases to see if its "legit". The center pin on many Dell and HP laptops (can't remember if others do it at this moment) will look for a signal, if it's there it will charge the laptop, if its not it will NOT charge the laptop even if the voltage and amps are fine, the battery is fine and the charging circuitry is fine. This not only makes diagnostics more difficult but if the DC jack signal pin is messed up a new AC Adapter will not fix the problem either, but everything else about the jack will look fine and power levels on the laptop will be fine. Stupid design, but that's the norm for HP and Dell.

 

[PCX]

That brings up another issue, Dell and HP for some reason decided to make the laptop talk to the charger in many cases to see if its "legit". The center pin on many Dell and HP laptops (can't remember if others do it at this moment) will look for a signal, if it's there it will charge the laptop, if its not it will NOT charge the laptop even if the voltage and amps are fine, the battery is fine and the charging circuitry is fine. This not only makes diagnostics more difficult but if the DC jack signal pin is messed up a new AC Adapter will not fix the problem either, but everything else about the jack will look fine and power levels on the laptop will be fine. Stupid design, but that's the norm for HP and Dell.

I have also seen this with Dells when buying 3rd party batteries. Often times the original charger will not charge the new battery, but as soon as you give them a new 3rd party charger, it will charge just fine. Do you guys know of any battery brands (other than OEM) that does not do this with the original chargers?

 

[Cornfed]

@PCX
Thanks for the idea. I've just tested the CMOS battery, but it appears to be alright.

@Larry
Thanks for finding that one. There's a few sites like that around but they all look a bit dodgy to me. Have you bought anything from there before?

That problem with the Dell centre pin is a pain. I didn't know HPs had them as well.

 

[Martyn]

That brings up another issue, Dell and HP for some reason decided to make the laptop talk to the charger in many cases to see if its "legit". The center pin on many Dell and HP laptops (can't remember if others do it at this moment) will look for a signal, if it's there it will charge the laptop, if its not it will NOT charge the laptop even if the voltage and amps are fine, the battery is fine and the charging circuitry is fine. This not only makes diagnostics more difficult but if the DC jack signal pin is messed up a new AC Adapter will not fix the problem either, but everything else about the jack will look fine and power levels on the laptop will be fine. Stupid design, but that's the norm for HP and Dell.

Yes actually thinking back the battery was end of life and they had ordered a charger and it didn't charge at all. I replaced the non working charger with a spare 60W Dell charger I had and the laptop recognised it was a 60W charger and indicated I needed a 90W

 

[Larry Sabo]

@Larry
Thanks for finding that one. There's a few sites like that around but they all look a bit dodgy to me. Have you bought anything from there before?

Yes, a couple and they were fine, very helpful. One does get the "blind man describing an elephant by touch" feeling, as many pages contain a few circuits with links to circuits on other pages, so it's hard to get the big picture. But they were still very helpful. Being able to download the PDF immediately after payment was also appreciated, and I've never had any problem with my credit card after the purchases, which were over the past couple of years.

 

[Cornfed]

Here's an update on what happened if anyone was interested.

The new battery arrived the other day. I popped it in, plugged in the AC adapter and the charge light came on straight away. I left it charging for about a half hour until the light went out (it does this at 85%+ capacity I think) then I turned it on and logged into Windows. It recognised the battery and showed it at 88% and charging. I left it for a bit longer to check the charge level was going up, and all looked ok. At this point I unplugged the AC adapter so it was running just off the battery, and shut it down / started it up just on the battery. Everything looked ok, I called the customer and told her to come and collect.

I left the battery charging for about 4 hours, then 30 minutes before she was due to arrive I checked one last time to start from the battery. Nothing. Didn't power on at all. If I started with the AC adapter connected, the battery would be recognised in Windows and would show 99% charging. The moment I pull out the plug though the laptop died instantly.

I tried a few things I could think of eg. unplugging the battery and adapter and holding down the power button for 1 minute, starting up and shutting down without the battery connected then reconnecting it, but nothing worked.

Anyway, the customer didn't mind because that wasn't the problem it was brought in for and she's paid for the rest of the work. I've since sent the battery back for a refund. I guess it must have a fault on the motherboard somewhere?