Too much for me video...
Really simple though. Just get two of the holders from
ebay - best pick a UK seller as they arrive in a few days. You need two 18650 battery packs wired in series - i.e. each is 3.7 v x 2 (each battery pack is in series, you then wire the second pack together to create parallel (red red, black black) - i.e. more capacity, but same volts).
Then buy a Magicshine splitter cable. Just cut off one of the female ends. You will see one missing from my pics as this was used to repair one of my AA powered rear MJ818 magicshine packs.
Before soldering, place some shrink wrap insulation over the wires from the pack or electrical tape wrap after.
I usually just twist wires together really well, but in this case, due to using LIPO batteries (lots of amps), I hired in my son (12 years old) to solder both red wires from each pack to the red from the magicshine connector. Use a good cable stripper though. Then the
blacks were soldered. (PS I am crap at soldering - my son is quite good - takes after mum).
After this I cut electrical tape into a third width strip, and wound it round the soldered ends to insulate each wire. As the wire ends up quite thick, I just wound electrical tape round and round the joins from the magicshine wire and the 4 cables from the battery packs.
To relieve any stress on the connection of the wires to the packs, I led the cable down to the opposite end of the pack, then wound electrical tape round the whole pack to hold the wire in place - this stops any stress onto the wire/pack joints.
That's then the pack done. You now need to re-use a 'battery holder bag' from another magicshine battery to fit to the bike
The cheap T6 clone battery bags won't hold these packs as the fit it too tight, as you insert the battery from the end, the magicshine bags wrap round the battery - you insert from the side. One thing I would add is you still need to waterproof the home brew pack, so pop it in a freezer bag before going into the holder - this is to stop any short circuits, despite the batteries being 'protected', you don't want water causing the terminals to short.
As mentioned, you really need to buy
protected batteries - i.e they have an extra circuit in them to stop discharge, or overcharge - do not try and charge these via a Magicshine or clone charger - these need to be removed from the pack like a traditional AA.
The reason for this is you will end up with a pack that will last a long time, and you will be able to charge each cell separately, ensuring best run time, and life.
LIPO batteries need more care than traditional rechargeable batteries (AA, AAA etc) Reason is the Voltage and Ampage output of LIPOs. Cross circuit a few decent AA's and they start smelling and getting hot. Cross circuit a LIPO and they will set fire. Hence the reason to do a home brew pack if you want long run times, reliable batteries, and low risk of fires. I am still using the cheap batteries for my other Magicshine and clone, but the 3xT6 can eat a pack in 40 minutes or less at medium/full which isn't what the cheap pack it comes with were made to handle.
I am no expert, certainly not in electronics, and I've just read a few things and played it careful. There are some real experts on MTBR forums under MTB lights...
Lots of folk slate these cheap lights, but should the battery pack, in a couple of years, fail and not charge (happens with premium brands too), you can have a really safe and quality way of getting a good pack for about £30 - excluding charger.
Or buy the Torches, and quality batteries and chargers.
