Motorola E815 battery swelling

[ElectroM]

Last night I noticed that the battery cover on my E815 had a gap of about 1/8 inch on one corner. I removed it to see if it had warped somehow. When I saw that it wasn't, I checked the battery and saw that it was swelling. Has anyone ever heard about this happening before? Any ideas what could cause it?
Assuming I need a new battery since this is the original and is over 2 years old, where is the best place to buy one?
Any comments welcome.
Thanks

 

[pm]

Lithium polymer batteries swell due to outgassing from the electrolyte when they:
a. drop below about 2.7V per cell - there's supposed to be circuitry in the battery to prevent this though.
b. are charged above 4.3V per cell - there's supposed to be circuitry to watch for this too.
c. get really hot, particularly while on the charger, and yes, circuitry is supposed to be watching for this too
d. are short-circuited and drained very quickly - immersion in water can cause this. This too is checked by circuitry.

Manufacturers say that cells won't swell just from getting old, but this was a problem with early lithium polymer cells as well. Another problem is that cheap knock-off cells often have cheap circuitry - or none at all - and then none of these problems are being monitored. When a lithium polymer cell swells, it always results in reduced capacity - usually it loses 30-40% of capacity immediately. If the swelling continues, in rare situations the swelling of the cell can generate an exothermic reaction - it gets hot - which fuels the electrolyte conversion and the battery package can rupture and then catch fire.

You'll probably want to replace it. Ebay is an obvious choice, but a lot of the cell on Ebay are fake and can be safety issues, and often don't have the correct rated capacity. The alternative is to buy from the manufacturer, or a cell phone store, but this is expensive.

Good luck.

 

[Thump553]

I have two E815 phones (great phone BTW), both been in service since 09/05 with the original batteries. No swelling here.

When I've had to replace phone batteries for my other kids, buying them on Ebay has worked out fine. Just make sure you are buying a new phone from a dealer with a good rep. I've done this 3-4 times without any problem.

 

[ElectroM]

Thanks for the replies. The battery is a Motorola OEM that came with the phone. It hasn't gotten wet or been left in the sun or anything like that. The only thing I can think of is I leave it on the charger a lot, sometimes for a day or two. The manual said this would not be a problem. I ordered a battery from eBatt, cost about $26 shipped. I couldn't find a new Motorola battery anywhere online, even Motorola website didn't have it. My local Alltel store did have a new one in stock, but wanted $69.95 plus tax.

 

[pm]

The only problem with leaving it on the charger for a long time would be doing it in a car on a hot day. Otherwise you should be able to leave it charging forever.

I've bought all of my cell phone replacement batteries on Ebay and it's worked out well enough for me. A couple of times they would claim "extra long life battery 1200mAh!" or something like that, and I'd stick it on my R/C model airplane charger and cycle it and would see it holding more like 900mAh. But aside from things not exactly matching the advertising, I've never been burned on Ebay from batteries. (either figuratively or literally)

I bought a Dell laptop battery last week and it was $218 from Dell and $49.95 on Ebay... and the Ebay pack works fine. Stuff on Ebay is certainly cheaper.

 

[ElectroM]

I have never bought anything on Ebay. I have a couple of friends that got cheated there though, so I don't do business there.
You seem very knowledgeable about these lithium batteries, so I would like to ask about charging them. I have heard that they do not have "memory" like ni-cad batteries do. What I mean by memory is that the ni-cad batteries I have for my cordless tools need to be fully discharged regularly so that they will fully recharge. I have heard that the lithium batteries should not be run completely dead before charging. Is this true? What do you do?
Thanks

 

[pm]

No, there's no memory effect in lithium ion batteries, and the do not need to be fully discharged - or even partially discharged - before recharging. They don't really care whether they are fully discharged or not before charging. There is a limitation that if they drop below 2.7V per cell, they start to break down internally which causes permanent damage to the cell, but all manufacturers of lithium ion/polymer cells guard against this with internal circuitry so the end-user doesn't need to worry about this problem.

The biggest secret with lithium ion (and lithium polymer) batteries that I never see anyone talk about is that they just wear out whether you use them or not. They oxidize over time, so that, whether you charge them or not, or leave them on a shelf and never touch them, after about 2 years they will hold about half what they could hold when they were first manufactured. And they also suffer from an internal resistance issue that makes this problem even worse than just the capacity loss per year loss.

This is described very well in the first paragraph of the "Disadvantages" section of the wikipedia entry: http://en.wikipedia.org/wiki/Lithium_ion_battery

A unique drawback of the Li-ion battery is that its life span is dependent upon aging from time of manufacturing (shelf life) regardless of whether it was charged, and not just on the number of charge/discharge cycles. So an older battery will not last as long as a new battery due solely to its age, unlike other batteries. This drawback is not widely published.

They lose about 20% capacity per year, no matter what you do. So after about 2 years, most lithium ion and lithium polymer batteries need to be replaced. This also means that you want to try to get "fresh" lithium ion/polymer batteries when you buy them. So I would never recommend buying a used lithium-ion or polymer battery.

But aside from the fact that they just gradually die, there's really no penalty with lithium ion based batteries. You can discharge them completely and then recharge them, or keep them charged all the time with very little difference in terms of how long they will last. The wikipedia article mentions a problem with "deep discharge", but I haven't seen this problem myself.