how many volts is too many ?

Most laptops are 19v. Are you shore the laptop is only 12v

Not sure what you mean by new unit? The 13.7 volts is common, the voltage is stepped down by internal rectifiers and regulators etc. Laptop motherboards fail every now and then just like a normal PC mainboard. What brand laptop is it? My recommendations when buying laptops is stick to brand names, stay clear of no-name stuff due to quality and inability to buy parts. So no is the answer.

Hi Wicket

Supplying a voltage higher than the system is rated to receive can definitely do damage. Depending on how the laptop is set up internally it could have cooked a battery or blown the internal power circuitry, both of which I have seen before. Seems strange to do the motherboard as I thought the other things would get in the way first, however have no specific knowledge of your product and some of the tech experts on site might have a better idea.

It is also worth checking that the charger is actually limited to 13.7 as if that's only averaged you may be seeing peaks much higher than that.

I would assume that the original unit output is pretty well controlled and matched to the laptop.

regards

A

I am sure i have read that even to little voltage will damage a computer.
If it is meant to take 19 and you supply say 14 volts it can do damage.
Someone else may be able to confirm or denie this.

Honky

Hi Wicket,

If you measured the new charger without the computer connected (no load) then I would expect that its output could be 13.7 volts, or even more. This would drop to around 12 volts when loaded. So there may be no voltage problem with the new charger.

There could be other than voltage problems with it however. It may have a high 'ripple' in the DC output or it may be producing spikes. This is especially so if it is a cheaply-priced unit.

Whoever told you that the "main board" is fried should be capable of testing the car charger and advising if it is suitable or not.

I rang my local laptop repairer and he felt that new car charger at 13.7v would be ok and probably did not cause the damage , the fact that it happened the first time I used it was more than likely just a coincidence. The repairer though thought it would probably be cheaper to buy a new one rather than attempt a repair ( he doesn't sell them though just repairs them )
He did test the ac adapter and it was 12.25 whereas I tested the new car charger and it was 13.7, as mentioned above there was no load on either so the new (cheap) charger may well come down to around 12v when on load.
I have always used a pure inverter with the ac adapter in the past with no issues I just bought the car charger for convenience more than any thing else.

Anyway it's a moot point now as I've bought a new one, a much lighter Acer netbook from OW for $308. ( love the way they do business ! )
I will not be using a car charger in the future though ( coincidence or not ) but will continue to use the inverter.

thanks to all those who replied.