Polarity of battery and OEM power adapter reversed on Gigabyte p25/p35

Hey all,

I came across my battery's voltage amps and polarity, and found it interesting that the manufacturer shipped power adapter (adapter A) output polarity is *positive*, and the laptop's input polarity is *negative*. The amps and voltage (and hence the wattage) are the same.

I've read that the input of the laptop should be the same as the output of the adapter. But, then why did Gigabyte send me one with reversed polarity?

If a battery has reversed polarity from its adapter, that normally means bad things for the battery and adapter. My CPU ambient temps creep into the 50s c with the original adapter in, but with one I found (adapter B) that has less amps, the same watts and the same polarity as the laptop the temps are generally around 35-38 c.

Should I use adapter A or adapter B, and was this possibly a big mistake on Gigabyte's part?

 

All laptop AC adapters should have a little diagram showing the polarity of its plug. It must match the polarity designed for the laptop (which can be found on the label of the original adapter it came with). So if you have a 2nd adapter with a plug with a polarity different than your original, it should not work on your laptop.

Another critical aspect is voltage. If your adapter B has less amps but the same watts as your adapter A (the stock adapter), then that means the DC output voltage of adapter B is higher than adapter A. This is not a good idea and could result in damage. You must use an AC adapter that provides the voltage required by your specific model.

I am not sure how your CPU temps can be affected by this.

Reply with the specs of both your adapters. Better yet, post a pic of both their labels.

 

Thank you kosti.

Both adaptors work, and I'm unsure why this is.

Adapter A is the one I've used since I purchased the lappy a year and a half ago. its stats are output 19.5 volts and 9.23 amps with a positive polarity diagram. (plus sign on the right)

Adapter B has an output of 19 volts and 6.23 amps with a negative polarity diagram (plus sign on the left).

The laptop battery compartment rates it at 19.5 volts and 9.23 amps (like adapter a), but with a negative polarity diagram (like adapter b with a plus sign on the left).

Could it be a mistake on the part of adapter a's manufacturer to make it positive instead of negative?

Thanks again!

 

@einigkeitundrecht you could attach photos of both diagrams.

 

Sounds strange, I don't have Gigabyte but my MSI, Dell, Sony and Acer that I do have, all have center post +plus, outside ring negative.
You wouldn't have voltmeter to actually check it? Just to make sure diagram is wrong.
If there is reverse polarity, one of 2 things could happen:
1. nothing if laptop's input is diode protected.
2. something will burn/blow if input is not short protected.
Often different amperage/ voltage connectors have different pin diameter, so wrong one may not make full contact, even if it fits.
As far as different cpu temp, maybe you have different power plans for AC/ battery and you run from battery only, even with charger connected (if polarity is reversed, or not full connection made, AC power won't do anything).
But without looking at it and testing it, it's just guessing.

 

When looking at the polarity diagram, pay attention to what the plus and minus signs point to, not whether they are on the left-hand or right-hand side of the diagram.

Look at the diagram below. Both are positive polarity, but the plus signs are on opposite sides on the diagram. They point to the same positions though (positive tip, negative ring).


I am assuming that adapter A is the stock OEM adapter (the one that ships with the laptop from the manufacturer). It has the same voltage and amperage rating as your battery compartment. The biggest difference between the two adapters is the power output. Adapter A should be 180W and adapter B should be ~120W. That 60W difference will be critical depending on your CPU and GPU power requirements (especially GPU). Adapter B is also lower voltage which probably won't do any damage, but you want to provide the laptop with the right voltage it needs. Maybe this plays a role in reduced CPU temps with adapter B because the board is getting a lower voltage than it should, but probably at the expense of CPU performance. This is just a guess though.

I bet that both adapters have the same polarity orientation (positive tip/negative ring like the majority of laptops), but the diagrams are a bit different which might lead to confusion.

Pics would help here. A voltmeter like Pete suggested on your AC adapter will tell you for sure.

 

Thank you guys again. Here's my laptop's battery diagram:


Here is adapter A:


Here is adapter B:


From what you say it looks like all the three the same, since they point to a positive tip and negative ring. That's odd the positive and negative diagrams would be on opposite sides, but it makes sense since both adapters seem to work perfectly. Lappy on adapter B is behaving normally, but I didn't play a game/graphic intensive application, which would probably cause the lappy to suck up more amps than adapter B could handle. Where on the adapters/laptop should I place the voltmeter, and what amounts should I be looking for? I'm assuming it'd be a 19.5/19 v reading, but what's the difference between the two polarities?

You were SPOT ON with your diagnosis Kosti, and if this were another website I'd give you gold.

Question: If I don't use the laptop for any intensive applications that could cause it to draw more amps (like as above, a game), might it actually be better to use the lower voltage charger? The difference is 0.5 volts and I would prefer lower temps so the CPU and GPU stay intact for a few more years. Not really interested in gaming anymore, sadly. Would a lower voltage actually harm the components? I ask this because I consistently see adapter A's tip becoming very hot, possibly from frequent use the past two years, and adapter B is hardly warm at all. A temp difference of maybe 20-30 c. Adapter B also seems to charge somewhat slower as well.

 

The lower voltage and wattage charger won't fully charge the battery. (I don't see how the higher voltage charger can either... A battery needs to be connected to a higher voltage source to be fully charged).

The lower wattage charger may also power throttle the system too (even if not used for gaming).

If the adaptors are not worn out and the higher wattage model is 20 to 30 C higher (the 'tip'? or the notebook?), then that is an indication to me that the lower wattage model may possibly self destruct in the near future if it is used continuously.

The notebook is what places demands of the power supply - the lower wattage power supply is not capable of meeting that demand (even if the voltage was 0.5V higher to match the other PS). I would be not be using it even if it was cooler.

 

Using lower voltage (and lower amperage) than designed could prevent components in your system from working properly, depending on how your system is configured and its power draw. The best advice for non-native power supplies is to go higher voltage than spec to ensure everything has enough power to function properly. Many (perhaps even most) modern power supplies are designed for efficient operation, so you won't be wasting power by using the higher voltage power supply.

The hotter tip of adapter A could be normal for your power supply (they're all a bit different), or it could be the result of increased resistence in the computer's charging port or a problem with the power supply. The cooler tip of adapter B makes sense because it's trying to transfer less current, which also would mske the system charge slower. But despite the cooler tip temperature, adapter B is not a good choice to use for the reasons stated above.

 

How would an electronic component develop increased resistence in its charging port? Heating to extreme temps (80-90c) then cooling repeatedly? Because I've definitely done that. When I looked at batterymon, the newer adapter b was charging at maybe 100 less mW. It wasn't much of a discernable difference (normally 42,000 something), but the system was idleing.

If I don't use the newer adapter B for emergency charge when the lappy's on, would it theoretically be bad to use when it's shutdown and just charging the battery?

If it still is I definitely won't, I'm just afraid adapter a may be kaput if adapter b doesnt get very warm. I've noticed that it becomes hot even after charging when the lappy's shutdown, so there's either a problem with the adapter's wire or the physical part of my laptop that charges. Or do adapters after use for a year and a half consistently just eventually get old?

Thank you tiller and djembe!

 

You might want to clean the contacts (both the battery and battery connectors and the DC plug and the connector on the notebook) with something like DeoxIT Gold contact cleaner.

Even with the notebook off, the battery won't be fully charged with the 120W adaptor.

Was the 180W adaptor always that warm, or is it just recently? It would (of course) be warmer even with the notebook off because it is actually charging the battery per spec's.

AC/DC adaptors do get old. If it's been used heavily, you might want to get a replacement (19.5V highly recommended (max 20V) and anything higher than 9.23A but (both) not less). The actual output voltage and meeting or exceeding the amperage is what you're aiming for (and the notebook will draw what it needs, as stated before).

With the system idling, both adaptors would deliver similar charge levels, with the system working hard (any 'heavy' workload), the lower wattage PS could self destruct and possibly take your notebook down with it (not to mention house and properly too).

Good luck.

 

Just use adapter A. Sometimes they run a bit warm and sometimes they run hot. It depends on how much power they draw. Some power will be lost in the form of heat.

If you do opt for a replacement, you should look for one with the same voltage and at least the same amperage of your stock rating.

You never mentioned your laptop's specs. I'll assume that the 180W of adapter A will be more than enough power though since that's the one Gigabyte shipped with the laptop. Delta is a good dependable brand used by many laptops.

 

The label on the computer (posted earlier) indicates 180W PSU. Often these labels reflect the most power-hungry hardware configuration and the only way to find out what the computer really needs is to use a mains socket power meter (but remember the worst case power demand is both the hardware fully loaded and the battery being charged).

It is possible that PSU B ran cooler because the computer recognised an under-rated PSU and throttled the system hardware. A program such as HWiNFO will show CPUand GPU speed and CPU power consumption. If the PSUs have the same efficiency then the conversion losses (represented by the heat from the PSU) will be lower. It is also possible that PSU B is more efficient. Newer designs of PSUs tend to be more efficient than old ones but I suspect there could be some cost premium.

John

 

Thanks man, and just recently. How do I make sure I have the correct polarity on a charger? I've only seen chargers for this laptop sold on ebay or the manufacturers website, and if they do provide amps and voltage they rarely provide polarity.

HWiNFO is a friggen great program.

Under sensor status and the list under "performance limit reasons" the same four items (IA: Electrical design point, IA: Max turbo limit, IA: Turbo attenuation and RING: Max VR voltage) pop up as "yes" no matter which charger I use. Without a charger plugged in they are "no". The CPU clockspeed also speeds up to the same amount (3.7 ghz) the second I plug in either power adapter. The CPU power limit doesn't adjust itself no matter whether I have either adapter plugged in or not.

The battery has a lower voltage than the chargers (16-17 volts depending when it's measured), so that may explain why the battery does appear to fully charge. Does the voltage from the battery change? Or is it different from that required by the computer on the label underneath the battery? I was under the impression only amps differed, not voltage. Perhaps 19.5 is just a "safe zone". That being said...

I'll make sure to take Kosti's advice and buy a new one with the same voltage and possibly more amps. The laptop is a gigabyte p25w v2 with i7-4810MQ, 8gb ddr3 @ 800 mhz, an intel integrated gfx card for desktop and an 870M for games. Has a DVD drive and I used to occasionally plug in a 360 controller.

I've replaced the thermal compound on the CPU but little in the way of temp differences. I'm a little bit obsessed with temps because my last lappy met its end in 1.5 years (a sager) because of high temps.

and once again, THANK YOU GUYS

 

What are your actual load temps? I'm obsessed with temps too . Try a couple of different programs because sometimes specific programs report wrong temps. Open Hardware Monitor and Realtemp are very good.

Some of these newer and thinner performance and gaming laptop simply run hot though, especially the CPU from what I've seen, so there may not be that much you can do. A good cooler or stand can help a bit.

 

haha nice, I use realtemp and coretemp. My load temps are pretty consistently 75-80 C, even with the fan full blast in the middle of winter. That's why I tried not to game with the power adapter in, but sometimes it was unavoidable. Idle temps range from 35-45 C, with an average of 40 C. Youtube generally gives me about 50-55 C. This is with only the intel gfx card, btw.

Do you have any recommendations on what cooler or stand I should buy?

 

I wouldn't lose sleep over the plug polarity. I don't recall coming across a notebook PSU which has the +ve on the barrel. It makes sense to keep the +ve on the inside where it is protected from accidental shorting (not that manufacturers can always be relied on to do the sensible thing).

Plus or minus half a volt from what the label on the computer says is very unlikely to cause problems. It looks like Gigabyte's requirement of 180W isn't an over-estimate: The CPU is rated at 47W under full load and the GPU probably wants over 100W. I think you will find that something doesn't run at full speed if you try gaming on a 120W PSU.

John

 

Those load temps aren't that bad. If it creeps into the 90s is when I'd worry. Again, lots of the thinner models run hot.

http://www.notebookcheck.net/Gigabyte-P35X-v3-Notebook-Review.129889.0.html

Can't say for sure what cooler to get for your specific model, but I have a Coolermaster U3 that I modded with two 12V 120mm fans. It pushes out a lot more air than the stock fans. Search the cooler thread or look in the Gigabyte subforums to see what others are using:

http://forum.notebookreview.com/thr...-a-buyers-guide.304671/page-192#post-10205388

http://forum.notebookreview.com/forums/gigabyte.1111/

A stock cooler powered by USB will not drop temps dramatically, if at all. If it pushes enough air though it will keep the bottom of the laptop relatively cool, and most importantly it will give the laptop a nice flat surface to sit on.

 

As kosti said, your load temps are within the expected range for a powerful system. And CPU temerature has very little influence on connection temperature, so there's no need to take the power adapter out when gaming. On the contrary, gaming on battery power can put more stress on your battery as a result of the high power drain and cause it to wear out faster.

 

19 vs 19.5V really isn't a big deal, since your battery lis likely 11-12V, but certainly less than 19V, and there's voltage variance in adapters anyhow, so it should still charge just fine, although I wouldn't go less than 19V or more than 20V if stock PSU is 19.5V. Total Wattage is only important depending on what your system will draw at load. If it only draws 100-120W then a 150W at 19.5V will be fine. Anything less the system won't get the power it needs.

And about them "getting old", PSU's usually just stop working, I've never heard of them dropping voltage. Usually the capacitors are rated higher than the output voltage and is regulated to the output voltage. Caps usually just corrode or pop and stop working.

You do not want to game on battery regularly. For one your system is probably throttling CPU and GPU and other component speeds like RAM as well to work with what power the battery can push. If you say the "tip" gets hot, what is the "tip" or did you mean the "top" of the power supply. Power supplies can get hot when taxed.

Read this interesting post on batteries and voltage and charging, etc: http://electronics.stackexchange.com/questions/31618/why-do-many-laptops-run-on-19-volts/31621#31621

 

HTWingNut, 0.5V less is a big deal when the battery is 19.5V (see pics previous page).

Total wattage is important because it gives an idea of how robust a PS is (or should be). If the platform was shipped with an 180W PS, I would be looking for 200W or higher replacement. Why? Because everything is taxed more with passing time.

If the original 180W PS wasn't heating up, and is now, that is the best sign that the notebook shipped with an under rated PS (or at least one whose quality is in question after only 18 months).

You're right, a PS won't drop voltage, per se, but the internal resistance can increase to effectively show that effect under load.