Posts tagged ‘li-ion’

Makita 9500d Cordless Angle Grinder on Steroids

I wanted one for a long time, but getting one wasn’t easy. I don’t think that they were good sellers at all, most of them most likely went to trash several years ago. Anyway, I was able to find one on ebay kleinanzeigen in Germany. Seller told that it is in good working condition, battery was missing, and the shield was missing as well. I didn’t care for the battery, as I wanted to do a Li-Ion conversion. For the shield, I’ve found a solution on Aliexpress, the Chinese sell shields that you can attach to your drill, and then do ridiculous things with it… It was quite easy to adapt one to the Makita.

When I got it, I tested it out with

my existing Makita NiMH battery, the performance was a lot worse than expected, and the motor was pretty worn, or at least it sounded like that. I looked in my parts that I’ve salvaged from cordless drills, and found a matching motor out of a green bosch drill (don’t remember the model, but it was a 12v NiCD model that I got for free because of the dead battery). This one felt quite beefy (strong magnets, compared to the original), and felt like new. I’ve removed the pinions and pushed the Makita pinion to the Bosch motor using my vice.

I’ve built a battery out of 3 18650 cells (Warning: you need to know what you’re doing, you cannot use normal 18650 cells, it needs to be high discharge cells – like the ones used in cordless tools). There’s no over discharge protection, I’m able to handle this by myself, worst case I would have to replace the battery, if  I run it too low.

Makita 9500D Complete

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Stabmixer – Electric Outboard Project

Ever since I was a kid, i wanted an electric outboard motor to use with a light rubber boat (without a hard floor). I actually even started experimenting when i was 12, but that didn’t work out at all.

Now, many years later, I wanted to give it a try again, my goal was a lightweight electric outboard, driving a chain inside a tube down to the propeller. Unfortunately, it all went wrong after I’ve made a prototype that was running the chain directly through the water. It worked so well, that I’ve decided to keep the chain outside. What I built is good for more than 1kw, but my intex excursion has it’s limits at around 6kph, which requires roughly 400watts.

The part’s I’ve used are:

Battery: 12s4p 18650 High drain (powertool) cells.
Motor: Chinese no-name Hub, good for about 1000w continues
Gear Ratio: 22×14
Propeller: JXF 15×13 / 381 x 330mm
Other Parts: Aluminium Rods, Steel Plates, Road frame parts, Buttom Bracket, Bolts, Nuts, Washers, Stem, Handlebar.

Be sure to check out the videos:

 

Yet another Lux-RC / Easy2Led bike light

Training off-road during the colder days often also means that it’s getting quite dark. There are lots of bike lights on the market, most of them are either too expensive or not 100% satisfying. There’s however a simple solution using components from Lux-Rc and Easy2Led.

Lux-Rc light engine:

A small board, 3 leds and a boost regulator is already integrated, different configurations are available

Easy2Led light housing:

A good fit for the L33X light engine from Lux-Rc, in addition you’ll need a handlebar mount (Lupine or the Chinese equivalent that can be ordered at Lux-Rc), cables, battery, a momentary switch.

Battery:

Input voltage depends on the light engine, mine is optimized for 2s Li-Ion batteries, I’m not going into detail about building a Li-Ion battery pack. This is dangerous, and you should know what you do, or better leave it. My battery pack has some additional heat-shrink tubing over each individual cell, heat shrink tube over the whole pack, and then a layer of plastidip liquid rubber on top of the heat-shrink tubing. Additionally, I’ve added some foamed rubber on the side that touches the frame when the Pack is mounted to my bike.

Oh yeah, and please use a little less thermal glue, maybe 1/3rd of what I’ve used should be enough.

Balancing the Magicshine MJ-836 Bike Light Battery

There are many reports about unbalanced Li-Ion cells in Magicshine Bike lights. This can lead into overcharged cells, which is dangerous, or at least will damage the cells. The charger which comes with the light does not have any balancing capabilities, the battery itself only has some very limited under/over voltage protection.

To solve this problem, you’ll need to modify the battery (add a balancing connector), and use a different charger, or external balancer. I’ll use my hobby charger, which has an integrated balancer.

This is no complete guide, it needs common sense, and some knowledge about electronics. You should also know, that working with Li-XX cells is dangerous.

If you don’t know how Li-XX balancing works, please read:
http://scriptasylum.com/rc_speed/lipo.html
http://www.rcgroups.com/forums/showthread.php?t=599316
before starting to modify your battery pack.

Adding the balancing connector:

Open up the pack:

The interesting part is the four 18650 cells, remove the top of the pack (shown on the left):

Add a new wire which will end as your balancing connector, this is connected to the “middle” of the pack, the pack is 2S2P.

Your Magicshine Pack should now look like that:

The next Step is to put back the isolation, and bring the balancer wire out of the case. this can be done through the original cable exit:

I’ve added a 2mm banana connector, some heat shrink tube, and a cable tie:

Finished Pack, charging:

test

As you can see, the connections were made as follows:

– from the battery goes to – of the charger, and pin1 of the balancer.
newly made balancing wire goes to pin2 of the charger
+ goes to + of the charger, and pin3 of the balancer.