I got some questions by PM so I thought I would answer them here in case they are helpful for others:
I saw in the pictures 12,2 mph. Is that the average speed or you like to ride at low speeds?
I like to ride fast but at times I was on a bicycle path with families around and at other times I was grinding up a hill. Since the Boosted never seems to go above 21mph the average for the whole ride was low.
Now, did you connected all 3 of 18650 packs in parallel and then directly into the boosted wires (the positive and negative). If yes, why didn't use 10 AWG wire?
The blue packs came with 16 gauge wires on them. I would have preferred a slightly thicker gauge but the draw will be split between the stock pack and the three paralleled new packs so 16 AWG is more than ample thickness and 10 AWG would actually be overkill at this point.
Keep in mind that the Boosted discharge wires run in a small channel under the battery box. There isn't enough room for two thick wires. If I could do it over again I would not tap the wires in the middle of their length under the battery box - that was a mistake. Because the solder joint is a bit fat, the battery box doesn't sit perfectly flush anymore. Instead i would tap the wires at the point where they enter the battery box - the is a depression in the underside of the battery box at that point that the joint can sit in. Then I would tape the two wires together for their run under the box.
Is the BMS really necessary for the blue packs (18650)? I do not have any bms that small...where did you purchase the packs? Would they sell just the BMS...?
Many people operate without a BMS but for me I feel that it's important. It allows simple charging: just parallel them and plug them into just about any charger you have around - the BMS automatically disconnects the packs when they are full. You don't have the risk of over-discharging - the BMS protects you. I just want to ride - not worry about what my voltage is. I'm not interested in balance charging - just one plug and done.
I bought them from Grin Technologies (ebikes.ca) they referred to the packs as "prototypes" so I don't know how many they have to sell. I don't know if they can bring in the the bms separately to sell to you, but if not they may be able to tell you where to buy them if you want them. Be aware that they are spot welded to the cells with tabs so you would need a spot welder to build your own if you can get them.
I am concern that I will have to deal with big sparks every time I connect/disconnect. If I charge the BB with the stock charger and the external pack with my charger do I connect them together when the board is ON or OFF?
When the board is off the discharge wires are not energized therefore you will get a spark as the external pack's energy floods into the ESC. Also the board will refuse to turn on with the external pack already connected - this was scary for me as I was afraid the spark had damaged something!
You must connect the external pack with the board turned ON and you should first check with your multimeter that the difference between the two wires is less than one volt before you connect them - otherwise there will be an inrush current from one to the other in addition to possibly a spark.
I get no spark whatsoever as long as I have the board ON when I connect them.
You must also remember to unplug the pack when you turn off the board, otherwise the energized ESC will slowly draw down the external pack. I'm not sure how much of a draw the ESC is with the board off - probably not much. Sometime I will use my multimeter to figure out exactly.