I tend to err on the side of paying too much for quality stuff, but $180 for a standard replacement battery for a Dell laptop makes the $80 knockoffs look pretty tempting. I wouldn't consider it (batteries really aren't something I want to take a chance on getting a refurb with) - but I was so surprised to learn how popular off-brand server rails are, that I thought I'd fling the question out there and see what stuck.
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I got my replacement battery from batteries plus for my laptop. It's worked as good as the original HP battery when it was new. In fact according to Linux it's still at 100% the batteries rated capacity and it's about 6 months old now.
It wasn't as cheap as the batteries on ebay but it all came down to if I wasn't happy with it I wanted the option to take it back and deal with a real person. I also didn't want to wait the couple of weeks it takes an ebay transaction to go through and get the shipment.
I bought a off-brand replacement battery for my old/spare Fujitsu laptop in Thailand. I happened to be over there so I stopped by their "IT Mall" in Bangkok.
I paid something like $50-$80 for it and its been working great for over a year now.
Basically your laptop battery is nothing but a certain number and type of cells put into a plastic case. There's really not a whole lot of difference between "Dell" and generic provided that the generic cells are reasonable quality. You're paying for a brand name.
If you're feeling really adventurous you can CAREFULLY take the plastic battery case apart and figure out which cell(s) are bad then simply order replacements (or all brand new ones) and solder them all back up.
I HIGHLY recommend buying the types of cells that already have the soldering tab attached to them as soldering directly onto the end of a battery can be a bit dangerous (ie. heat) if you don't know what you're doing.
But the short answer is... go for it... buy the generic battery. Most of the time they work just fine. Avoid the total "bargain basement/too good to be true" deals though.
Hope this helps.
When making your decision just remember that Dell don't make those batteries, they buy them in, so in some respects there is no such thing as a genuine Dell battery. $100 is quite a lot of money for a label.
I haven't tried non-"genuine" batteries in Dell laptops but I have tried tried them in several other brands. If it wasn't for the label I would never have been able to tell the difference.
I have used off-brand batteries for Acer laptop before - in fact they were purchased via ebay from some outfit in China, and they charged me half price because it was a prototype.
The comfort of using PayPal and being able to put the transaction into dispute if the goods are not up to spec.
I highly recommend intelligentbatteries.com.
Not only are they the cheapest online source I've found, they're also dependable and make good batteries (they buy the old casings and electronics and put new LiIon cells in them). I've already bought 4 replacement batteries from them.
The only place cheaper I've found yet appears to be very shady and has lots of negative reviews online.
I used to know a guy that refurbished his own laptop batteries. He would open the battery up, take one of the cells down to Radioshack, and buy however many were actually bad. He said most times it was just the first few that were dead. I only ever tried this myself once, and couldn't get replacement cells because the battery I opened was from a very small-name laptop manufacturer that has since gone bankrupt.
Don't forget to consider your warranty status when buying batteries. If you are out of warranty, then no problem - do what you want. But if you are covered by a warranty, then you might have to go with name-brand parts in order to keep coverage.
My laptop (property of my employer) is covered by a service agreement, so when I needed a new battery, IT didn't really have any options but to go back to Dell.
Not a problem in your case, but Sony laptops have a startup program that checks if the battery is genuine and force a shutdown/hibernation if it's not. It's not too hard to kill it, but it's another reason to avoid Vaios.
The company I work for uses a lot of laptops, and as such goes through a lot of batteries. I investigated both aftermarket and OEM batteries, and every single OEM battery had a higher rating than its aftermarket counterpart. If you need the most performance possible on a single charge, opt for the OEM. If you're fine with slightly lower performance and don't mind swapping out/charging sooner, then aftermarket will be fine. I purchase OEM batteries on our more current laptops, and aftermarket on our older ones.