Rc Lipo Battery pack help needed

[Bryanc]

I am building a motorcycle for short sprints only. I plan to make an 18s 2p lipo battery pack out of 9 2s2p batteries.
The batteries are Turnigy Alpha 8000 mah with a claimed 140 continuous 280 burst capacity. I know that manufacturers' claims about c ratings are complete fabrications but they are what I have.
https://hobbyking.com/en_us/turnigy-alpha-8000mah-2s2p-140c-premium-hardcase-lipo-battery-pack-roar-approved.html?queryID=a112d5332672d3ceb31b1277babc208b&objectID=85616&indexName=hbk_live_products_analytics
I have used the same batteries successfully in RC car use.
My main question is that the batteries use a through-pack bullet connector. I have previously manufactured series connectors by soldering two connectors together. The maximum That I have done is 4 batteries in series. I am concerned that if the batteries puff ever so slightly in use that it will loosen the connection. All batteries are brand new and unused
Any suggestions about how to best connect them together is very welcome!
Thanks

 

[amberwolf]

Ratings:

Personally I trust the ratings on RC batteries of any kind about as far as I can throw a containerload of them without using my cane. If you find they actually have a low enough internal resistance (by testing this on your actual cells, not going by seller / manufacturer ratings) to supply this kind of current without heating up or sagging in voltage significantly, I'd be happy to be surprised.

What kind of current do you actually need from them to do the work your MC must do for you? If it's low enough, they may support it without damage to the cells. If it's high enough you may want to verify the cells don't heat up too much doing it, to ensure you never get a fire from them.

I recommend opening at least one of them up to see what kind of internal interconnects they use, to make sure the interconnects can handle the current as well. I recall problems posted with some old blue-shrink-wrapped packs where the interconnect PCB traces could not handle the amps the packs were spec'd for, so the manufacturers slathered solder over them, which could melt in the heat from sustained max usage and short packs out and start fires.

Interconnects:

You could simply stagger them (like bricks in a wall) and create a wiring harness with matching bullets, as short and thick a wire set as possible, to put them in the series/parallel configuration required. The harness would be made exactly as if they were non-cased versions, other than length of wires to reach all the packs. Try to keep all parallel connections'wires equal length for equal resistance/voltage drop across them.

Alternately you could replace the built-in casing interconnects that come out of the sides with ones that come out the ends, and plug them into busbars mounted to something else, with spacing enough between them to avoid any inter-pack movement caused by puffing. A strap could then be placed around each pack to secure it to the mounting surface of the busbars, to keep anything from moving or vibrating loose.

I am building a motorcycle for short sprints only. I plan to make an 18s 2p lipo battery pack out of 9 2s2p batteries.
The batteries are Turnigy Alpha 8000 mah with a claimed 140 continuous 280 burst capacity. I know that manufacturers' claims about c ratings are complete fabrications but they are what I have.
https://hobbyking.com/en_us/turnigy-alpha-8000mah-2s2p-140c-premium-hardcase-lipo-battery-pack-roar-approved.html?queryID=a112d5332672d3ceb31b1277babc208b&objectID=85616&indexName=hbk_live_products_analytics
I have used the same batteries successfully in RC car use.
My main question is that the batteries use a through-pack bullet connector. I have previously manufactured series connectors by soldering two connectors together. The maximum That I have done is 4 batteries in series. I am concerned that if the batteries puff ever so slightly in use that it will loosen the connection. All batteries are brand new and unused
Any suggestions about how to best connect them together is very welcome!
Thanks