Fix Laptop Lithium Batteries?

[CroMAGnet]

Hi all. I am starting to notice that my Rechargable Lithium Batteries on my Laptop only last about 1.5 hours. When I bought the laptop about 18-months ago they went for over 3 hours. I have a Dell Latitude D400.

Is there anything I can do to improve their performance, or do I need to just buy new ones? Thanks for the help /ubbthreads/images/graemlins/smile.gif

 

[BatteryCharger]

Pretty much just need to buy new ones.

 

[CroMAGnet]

Bummer. I read somewhere on CPF that guys took them apart to salvage something or another and saw that they were still good if they just did something... eheheh sorry to be so vague. Just thought it was something I could try. Save a $100 bucks.

 

[BatteryCharger]

You can take the pack apart and there are probably a few good cells in it, one bad cell can ruin the whole pack. You can't really replace the bad cells though, because once you've opened it up it's no longer useable in your laptop.

 

[rwolff]

A while back, I got a new battery for my laptop, and here's some stuff I gleaned from various sites (most were selling batteries, so take it with a grain of salt):

The charger circuitry inside the pack is "fine-tuned" to the cells used (laptop manufacturers buy large batches of cells, so they do a bit of tuning for each batch). As a result, it's not going to be a perfect match for any batteries you buy.

The case of the battery is sonic welded, so it can't be opened without damaging it. In other words, unless you need that particular model of laptop, and replacement packs are no longer available, it's not worth it.

One of the worst ways to abuse a LiIon battery is to keep it on trickle charge. Most laptop computers, when running on the A/C adapter, will keep their battery on trickle charge. In other words, don't toss your old pack - when you're using the computer on "shore power", slip in the old pack so you're abusing a pack that's already been trashed. Be sure to mark the batteries in some way so you know which is which.

FWIW, the battery for my computer is around 11 volts (3 cells series), is available in 3600 and 5400 mAH versions (old pack is 3600, new pack is 5400). Since the new pack weighs more, the balance is different, and its physical appearance suggests the presence of 9 cylindrical objects, my guess is that the 2 capacities represent either 2 or 3 strings of 3 cells, with the strings in parallel. My pack was around $100 CDN (could have got one for about $90 US, but I bought from a Canadian source to avoid customs fees) - if your source for LiIon cells is anywhere close to $10/cell for 1800 mAH, you're probably better off buying a new pack (especially if you use your machine plugged in, so you don't trash your new pack).

 

[mrme]

So would I be better off running my laptop with the battery removed after it is charged? I can make sure it is inserted for any application where data loss would cause any problems and I think Windows XP has some ways of preventing data loss when the power goes out.

Is there any reason I shouldn't? Self discharge rates on Li-ion batteries is low enough.

 

[CroMAGnet]

Thanks for all the info /ubbthreads/images/graemlins/smile.gif Guess I need to pony up for a new battery.

 

[greenLED]

mrme, when docked, I remove my laptop's battery. Periodic autosaves prevent major data loss. I only use the battery when on the run; it still holds close to 3 hours of charge, as it did when new.

 

[mrme]

That's good to know. My battery life has always been pretty poor and I can't imagine what abusing the battery would do to it.

 

[rwolff]

[ QUOTE ]

So would I be better off running my laptop with the battery removed after it is charged?


[/ QUOTE ]

Not a good idea. Some laptops rely on components inside the battery module, even when they're running on "shore power" (makes things tough if theirs is an out-of-production battery, and they get it fixed by sending it to a place that opens the shell and replaces the cells - they don't have the use of their computer until the battery comes back). It may be viable on a docking station (which is designed to run the laptop on "shore power" for an extended period) but not with the charger cord (which is designed to hook up "shore power" to charge the battery).

A friend of mine always runs his laptop on the battery. When it gets low, he plugs it in until it's full, then unplugs it. Alternately, if you've got a "dead" pack that you need to get a replacement for, use it as I mentioned earlier - think of it as a free UPS with a few minutes of run time.

 

[CroMAGnet]

Hey, thanks for the info rwolff. (as I put my battery back in)

Would this issue applie with the charger that JS (Jim Sexton) builds for the Tigerlight mods? He puts a switch on the Nihm charger that allows you to flip it to trickle charge after it is fully slow charged.

 

[KevinL]

Cromag, batteries degrade with age and use. That sounds like a little faster than normal degradation (poorer quality cells perhaps?)

Contrary to popular belief, lithium ion is NOT trickle charged as they do not tolerate trickle charging at all. It's only used with NiMH cells. Laptop chargers will apply a topping-off charge when you first boot them, then standby throughout the rest of the time unless the battery is actually used.

You may also want to try recalibrating the battery meter by running the battery down all the way and recharging it. This is *NOT* the same as 'conditioning' or 'discharging' the pack, it merely gives the electronics a better idea of how much is the max discharge. Sometimes the calibration gets out of whack.

Also, modern battery gauges 'predict' the amount of remaining time based on current draw, which can fluctuate dependent on exactly what the computer is doing at the moment. An extreme example: when running at full throttle, my projected battery life is much shorter than in Speedstep mode, where the processor is throttled to 600Mhz and run at much lower power. Ironically, the attempts to improve accuracy have added enough voodoo 'magic' to the circuitry that more ain't always better.

Sorry, but I've never really understood why people remove battery packs from laptops that are docked, unless you're using it almost exclusively as a desktop. I've put some of my Dells through very harsh usage, and I've never had to replace a pack even after years and years, and many more cycles than they are rated for. Currently on a D600.

I recently chopped up a Dell Latitude LM pack from 9 years ago. The pack was cycled around 1500 times in its working life and finally died after nearly 6 years. I left it to sit for a while, till I got my Maha C777Plus2 analyzer. Upon disassembly, I noticed the pack died of corrosion. I managed to save 3 of the 9 cells, which were cycled using the C777. The amazing thing? These 1300mAH Sanyo cells still yielded a useable discharge of roughly 800mAH after 9 years and so much abuse.