I'm going to try this. Hope it works.

http://www.eastmaze.com/Desktop-Battery-Charger-for-Nokia-BP-4L-Battery-p901.html

Two really dumb questions for you.

1. How much runtime difference is there between the 1500mah stock BP-4L battery, and the 1800mah Mugen battery?

2. How much bigger is it, and will it fit under the stock back panel?

Just thought I'd bump this thread since I never got a response to my question.

Sorry, busy......

The Mugen 1800 mAH battery adds about 3 hours depending on usage and is the same size as the original BP-4L

The Mugen 3600 mAH battery adds 12 hours depending on usage and comes with a replacement back panel for the N810.

Just to add my ebay charger/battery experience to the list...

Bought the charger with 2 batteries. I wasn't expecting much from the batteries but wanted them just to make sure the charger didn't burn them out. It didn't, it did charge them (after a lot of annoying dancing LED flashes -- why would an engineer have it do stupid things like that?) The batteries last somewhat less than half what the stock Nokia battery does. I don't really care as I wasn't expecting much from them anyway.

I did buy a "genuine" Nokia battery off a different ebay seller as well, paid a whopping $8, so, again, I wasn't expecting much. It has a Nokia logo and the N810 says it has the same life expectancy that the original had, but it suddenly dies about 2/3 of the way in. So, no, it's not the real deal. You do generally get what you pay for with these things.

But, the wall charger didn't blow up or smoke the batteries, and the batteries do work for a while - which is a nice backup to have while traveling. For $18CDN for the works, including shipping, I'm not complaining.

David...

My Mugen 1800 mAH didn't work in my N810 until I added a shim made from card stock to the end of the battery. I don't know if this an issue with the battery size or perhaps where the batterry contacts are positioned. Also my made in China, model DPL-1688, wall charger works well and also sports a USB connector for charging. It came from http://www.dealextreme.com/details.dx/sku.4071 and only costed $3.96.

Mine didn't work either. I notice that the contacts are recessed about 1/16" from the end of the battery. All the other batteries I've seen, the contacts go almost to the battery's end.

But I tried charging it in an external charger too - one with long contacts (and a built-in light show), and it wouldn't take a charge. And it fits snugly in the N810. So I don't think the shim would have helped me.

Customer service responded quickly, is sending a replacement and crediting me for return postage. I will report back on the replacement.

In the meantime, I am doing battery capacity tests on my batteries. I use battery-status to record the voltage levels to a file. Rather than type the whole command line every time, I've created an icon in Personal Launcher that runs the command. So I don't have to wait a week for the battery to run down, I turn on bluetooth, then run Flip Clock and turn on Insomniac Mode. For good measure, the browser is running in background, pointed to a web page that refreshes every five seconds. With all this going on, my spare battery ran down to the low battery warning in under 6 hours.

Oops, I guess I never posted my experiences with the wall charger either.

So I did get the charger after posting this. It works just fine, looks the same as the pictures. Though there are a few hundred chargers on eBay they're all basically the same model, some with very slight cosmetic changes. Without battery they're dirt cheap, not hard to get one for just $1. Basically it works about like you'd expect. You slip the battery into the changer and plug it in. There's an LED on the bottom which illuminates red while the battery is charging and changes to green after the battery is fully changed. So far I've been using it exclusively to change my (genuine) batteries for nearly 2 years and have suffered no ill effects.

Battery life and everything works fine, no problems with the N810, etc. There is also a USB connector on the bottom of the charger, I've never used it and I'm not sure what that is for. Despite this I do have two complaints. The first is that the plastic used is very cheap and thin. After 2 years of indoor babied use the plastic is starting to become extremely cracked (despite no initial event that caused cracking, i.e. dropping it), especially around the plug. For the time being this is just an annoyance but I have little doubt it will soon make that unit unusable.

My other complaint is that the unit uses a "flipping" plug which flips up into the unit to make it easier to store. Now at first that sounds great, the problem is that it is very cheaply made and after relatively few "flips" (maybe 60 or so) the flipper becomes essentially frictionless. The problem with that is when you plug it into a wall it will just fall out as the plug folds up. Basically this means you can only use it in a power strip facing down. Similarly the contacts for the plug become finicky and will only charge when it is plugged in "just so".

Over all though a decent buy for $1, considering there is no official alternative. Great if you have lots of backup batteries.

Fragos, can you confirm these charger works with BP-4L? According to the description, it is designed to charge N95 batteries (BP-5F or something like that). both are 3.7v and similar size, but do this charger fully compatible with BP-4L? If not, can someone points to a compatible charger from DealExtreme?

This link shows Nokia cell phones that use same battery, and therefore chargers, as the N810.

http://europe.nokia.com/find-product.../compatibility