I have a Toshiba Satellite laptop. My charger has stopped working.
I have access to a Lenovo charger. Can I use this charger on my laptop?
It depends. If the charger is compatible then the answer is "yes", if it's not then the answer is "no".
Chargers must match in a number of ways:
The size and shape of the connector must be the same.
If they are the same size & shape then the polarity of the tip must match. This will be on the spec plate on the PSU/chargers themselves. Don't use if polarity is reversed.
The output voltage must be the same. Half a volt difference is probably well within tolerance, but anything greater, find another PSU.
If the voltages match, then you must also ensure the Amperage it can supply is the same, or greater.
Amps are 'pulled' by the device, not 'pushed' by the charger, so if it can supply more amps than the device needs, there is absolutely no issue.
If it can only supply less than the device needs, then you may suffer anything from very slow charging, to actually discharging even while the charger is connected, to in extremis, the device crashing or freezing because it just cannot get sufficient power.
With recent developments in uniform chargers for phones and tablets, it's likely that laptop chargers have become more uniform in recent years too.
Take a look at what voltage they supply, the voltage shall be the same.
And then check polarity on the connector, i.e. positive pole in the middle.
And lastly is it big enough, how many ampere do they delivere?
All this is usally printed on the power supply or on the computer it self, and if the above seems ok then you can try at your own risk.
This only partially answers the question and I place it here just in case it happens to someone else and can help them. I just tried to use an adapter (19.5v) for a new laptop in an older laptop (19v). What I did not realize was that the old laptop used a slightly larger connector. I ended up bending the pin inside the power adapter.
I tried a couple of different things to bend it back but it was too difficult. I then found a bobby pin and used the sharper end to try straightening the bent pin. Using a sweeping (circular) motion inside the adapter fixed the problem and unbent the pin. Moral of the story: No it is not always safe to use another charger. Also, yay for bobby pins!
A word of warning. I inadvertently used a power adapter with a lower amperage but the right voltage on a machine without a battery. It seemed to work find but I later found that data that was written was corrupted.