DIY Laptop Battery Rebuild

by Kevin O'Brien

A day will come when your notebook's rechargeable battery will no longer charge and instead serve better as a paper weight. As you use your battery more often, the battery loses more and more capacity until it finally won’t accept a charge and goes flat. Replacing a battery is easy, but the new battery price could be so steep that it costs more than the notebook is worth. Buying a refurbished battery can drive the price down even lower, but what if you are super cheap? Well, we are going to cover this last option, which means tearing apart your old battery and fixing it yourself.

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Dell E1705 Battery Specs:

• Voltage: 11.1v
• Capacity: 53WHR
• Original Cells: Sony SF US18650BR
• Replacement Cell Specs: LG 1650 mAh li-ion Battery w/ tabs

Teardown Process

Breaking the battery apart was probably the single most painful moment of this entire article. I had no documentation to work with, the plastic halves of the battery were glued together, and all I had was a mini snipper. I first started by peeling off the top sticker exposing the open framework with cells in view. After this I took my little snippers to the plastic, and cut away piece by incredibly small piece till the entire top was removed. I had black plastic bits flying everywhere; I think even into someone’s can of soda. The end result was a brutalized battery case that looks 100 percent safe for future use.

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Once all of the excess plastic was removed, I could get to the cells I would be replacing. All of these were glued in place, so prying them out with a screwdriver was the only option. As I slowly lifted each group form the plastic case without shorting any circuits, I took my clippers to the metal bridges to fully disconnect the batteries. During this time I also made special note of the wire leads off the charging circuit and where they connected for future use.

Finding the Correct Replacement Cells

Who would have thought finding something as simple as US18650BR batteries would be so hard? It actually took two of us about 30 minutes to find a site that sold equivalent batteries. We narrowed in on MegaBatteries.com, as we found it mentioned on some odd website as a place to find batteries. Now the standard name for the battery size we were looking for was 1650, and we picked one at random since they had quite a few options to choose ... and I was too lazy to run the math on the correct cell capacity. With the cell selection locked in I ordered the batteries, and sat patiently until they would arrive.

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Build Day

Once the new batteries arrived at the office, I got to work on prepping the batteries for installation. I verified battery orientation from the pictures of the old assembly, and started to solder together pairs of cells. I used some old wire to bridge together each group on the positive and negative side, and hooked the first battery group to the red power lead. Next step was soldering together the second group, attaching it back of the first group, and soldering both charging leads in place. Last was the third group soldered to the back of the second, and attaching the black lead to the rear of the battery group. The final result doesn’t instill much confidence of a non-firey demise, but it was finished. To add a layer of safety I placed some packing tape over the exposed battery groups, and mashed the "rebuilt" battery into the bottom of the notebook. To the surprise of all those around me, the battery did not ignite into a ball of flames, and actually started charging.

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Performance

The Dell E1705 laptop was not the pinnacle of mobile performance from the start, but with the old battery it was difficult to get more than 25 minutes of life before the notebook shutoff. Anything above that value with the rebuilt battery would be a mild success, so I crossed my fingers and hoped that an hour of smoke inhalation (soldering) wasn’t wasted. The results of the rebuilt battery ended up being roughly 47 minutes of battery life, and a Dell battery warning saying the battery had reached the end of its useful life. While the cells were fresh, the batteries charging circuit hard already reached the point of no return. No matter what we could do, it would never reach the charge levels of its prior brand new state.

Conclusion

With the labor involved in rebuilding the battery, and the $53 spent on parts, the DIY rebuilt Dell battery never got anywhere near the performance of a new battery. Although it was a fun process the money could have been better spent on a professionally refurbished battery or a brand new OEM battery from Dell.com. Even if the rebuilt battery did achieve results similar to those of a brand new module, I don’t think anyone in our office would have trusted that notebook to charge unwatched for any significant period of time. With brand new batteries exploding left and right, do you really trust something you rebuilt yourself?

Pros

• Tons of soldering smoke that freaked out coworkers
• People don’t mess with you after they see this in your hand

Cons

• Bringing this through airport security creates a stressful and unhappy situation

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What a shame that it didn't end up giving you much more battery life. Do you happen to have a multimeter on hand? A fully charged Lithium battery should reach 4.2v's from my experience. But since the battery is 11v's it has to have some sort of regulated circuit. I assume this is also preventing the batteries from fully charging properly. If the batteries are at 4.2v's than you can be sure that they are fully charged and that the batteries are just... crappy batteries with a low mah capacity. If the voltage is lower than this, then it might not be fully charged.

Also, I just noticed the 18650 in the model # on the batteries. 18650 Lithium battery cells are actual a very popular and easy to find size. I have a CREE LED flashlight and a Xeon light that runs off of them or two CR123A Lithium Cells. DealExtreme has them for $4.70 shipped per cell. Or $4.06 shipped if you order in bulk (5 ore more). So 6 x $4.07 = ~$24.

I also have a charger for charging lithium CR123A's and 18650's. When fully charged they are in the 4.17-4.21 range. If they are not, then they are not fully charged. The cells are rated at 3.6 or 3.7v. The reason for this is they quickly decline in voltage from ~4.2 to 3.6 then stay around this range. They can be used till about 2v but this will limit the life of the cells.

Also, I think you put in lower capacity LG cells than the original Sony ones. The LG ones say 1650mah. So 6x1650 = 9.9 ah. 9.9x3.7v = ~36Whr's. The original capacity of the 6 sony cells combined was 53Whr's. So using basic math, this would tell us that the capacity of each sony cell was about 2400mah. 2400mah is just about the highest 18650 cells get too. So that’s encouraging to see that dell is using the highest capacity cell's available.

What was the original battery life like with the Sony Cells?

 

Cool Pros and Cons .

 

"A" for Effort?

 

Nice work, man!
Although, I am hoping that no one from FAA is reading this post otherwise there might be some new rules come out to make sure no one is carrying some explosive self-made "batteries" onto the airplane.

 

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  LOL
  
  Thanks for the interesting read. I see you can't help disassembling things. Can I make a wish list for the next things you should take apart?

 

LOL at the cons become a a terrorist suspect

 

Wow, maybe Jason should offer a counter review to show he knows what he's doing better than Kevin when it comes to rebuilding batteries

Nice attempt Kevin, it's probably safe to avoid doing this unless you really know what's up.

 

While the difference in battery capacity is true, in a prior review we got close to 2 hours and 41 minuted on the 6 cell battery. On the rebuilt battery we barely broke 47 minutes. The batteries we bought were not 30% of the original capacity

 

Christ, you're not joking about that last pro...