So my 7.4V LiPo Asus Eee pc T101MT battery died, a new one costs about $65, which got me thinking (I'll probably buy it, but lets assume I go down this other road...)

The charger supplies 12V, so I thought I may have a 6 18650 3.7-4.2VV battery bank (3 series 2 parallel) watched over by a protection circuit and also a charge status/low charge warning circuit to let me know when to connect the mains charger again.

This would be set up in paralell with the mains charger and into the DC plug.

To be checked if it would fit in the battery compartment... I may need another type of battery - not relevant at this point.

Anyway, the idea is to keep the 11.1V bank (probably 12V+) charged, unplug the mains charger, and still get the 12V (ish) supply into the DC jack.

When the battery bank drains to the alarm level (maybe 10V or so?), this will trigger the warning (red led to be placed somewhere), when charging the protection circuit assures the battery bank is safe.

Total cost from fleabay around $20...

Makes sense?

 

How many pins does your charger have? Some laptops communicate with their chargers and do not work if an incorrect charger is plugged in. HP laptops are an example of these. I am not familiar with Asus laptops, so mention this only as a heads-up.

 

It's a simple dc jack charger, 12v and ground, I doubt the laptop "knows" where the current is coming from...

 

He wants to use the DC in jack and no battery. It should work fine but the operating system won’t know when the battery is getting low. When the power dies, it could trash the harddrive depending on what you’re doing at the time.

I have an HP notebook that I ran without a battery and if the connector came out, Windows would fix everything but I’d lose all of my internet passwords. It got a bit frustrating, so I found a used battery on EBay for $20. I was able to validate that it was a good one with a calibration program that HP supplied in a utility directory.

Check and see that the notebook wants to see pure DC or Rectified AC.

 

That's a good reason not to do it - the system is unaware of the battery status... nice one.

It would work, just to move the laptop around, but it's not a good solution, I'd need to find a way to hibernate the system as soon as a certain voltage was reached, this means hacking the power button or something like that...

Thanks for your valuable oipinion!

 

I'd invest a bit more time shopping for a battery. Sometimes you can find them much cheaper, and I've had good luck when I did that. Buyer beware, but when you're risking <$20 it's easier to stomach.

 

I'm all over the internet hunting for it... This model's battery seems to be pricier than other Eee pc's batteries, go figure...

And yes, one must be careful! Thanks.

 

Be careful and look at the specs. I noticed that some of the Chinese batteries had fewer cells in them. They’re probably saving cost by adding less batteries and using a charge pump to bump the voltage up.