Aftermarket Charger

After a lot of research, time and effort there was found to be no EASY fix for the Makita 18v battery pack repair.  I am sure however it is possible to crack the on board chip design and reproduce it but the cost of which would require a full scale operation.   There are aftermarket batteries on the market and it would be nice to be able to source these aftermarket chips because I am sure that Makita did not release these to the companies!   So if any one knows how to get a hold of these chips please let me know!!!

Once again they have to be at the right price to make these repairs cost effective.

The Idea

So after trying to repair the batteries I ended up with all these BL 1830's hanging around and I knew there had to be something I could do with them.  So I decided to customise the batteries to and build my own custom charger using a spare Makita charging base I had laying around. 

The Batteries

Most of the time the batteries fail it is one cell or one cell pack.  By taking these dead cell packs out and replacing them with ones from a donor pack the balance charger was able to get the packs up and going. Some of the donated batteries were as low as 4 volts and got the batteries up and about!

As I do not afford a spot welder i had to solder then new batteries into the packs they are pretty tight to get in and out of the pack i used solder wick to stitch them all together which is narrow but should have the current carrying capacity for this project.

It was hard to get the heat into the batteries without getting them to hot.. so i apologise for the soldering job but it has stuck!  Just not pretty!  I think if you were going to build a pack from scratch again I would purchase the 18650 batteries that have the battery tabs spot welded on.  I used to use these batteries with the tabs when building the NiCd batteries for my old 12 volt stuff.  

The Charger

The charger that I decided on was the IMAX B6 balance charger.  There are many different chargers on the market and as I was trying to reduce my costs (because I was still unsure if it would work!).  Aftermarket balance chargers range from $40 to over $500! I am sure that if you are willing to spend that kind of money they would be great chargers with many having USB interface etc

The charger runs off a 5A 12v power supply (not connected in the picture above) similar to the power supply of a laptop.  The Red and Black banna plugs connect the battery while the smaller coloured cables are the balance leads connected to each of the individual cells inside the battery (connections shown later).

The charge time of the battery is going to be affected from the standard charger.  This charger has the capability of charging at 4.5 amp hours which theoretically should give a charge time of under and hour. The way in which the chargers automatic function works is that it slows the charge rate down after the battery is up to 80% gives a total charging time of around an hour.  With this many batteries it is hardly going to be a problem but for the tradey etc this could be a problem..

The Battery Modification

The primary function of the battery was to be connected to the tool so the modification of the actual battery connections was out of the question.  However as I wasn't going to be using the yellow control pins and I decided to use these pins on the charger and the battery to connect to the charger.

The chip itself was cut away and the individual cell voltages taken back to the yellow control pins.  The balance charger requires the connections as below.  As there are 7 pins on the control pin I separated the cell voltages by a pin for isolation and connected the + and - terminals inside the charger itself.

So this enabled the battery to be used in all the tools but due to the modification these batteries can NEVER be put back into the normal charger!  To avoid this ever happening i decided to paint the batteries to give a visual reminder each time you go to put a battery on a charger.  Below shows a picture of my pretty blue batteries!

The Custom Charger

So now it needed to be put together into the old charging base.  Due to my current living arrangement my workbench is my computer bench so I need to bend some aluminum plate etc to finish the job completely but you get the idea! 

Testing

So now it is time to test these batteries out.  I will report back in the next few months to see how these "repaired" batteries turn out and last.  I think this charger will keep these batteries optimized and running to their full capacity.  And if another cell was to die it would simply be replaced and the battery put back into service.

Feedback

So if anyone out there has any questions or some feedback on the design please let me know!  I am far from an expert in this field just trying things and measuring the results!  Happy drilling!

Ryan