Ya, making use of your existing battery sounds like a good idea...
The problem is this: where do you start if you have problems with your new gear and "old" battery?
I can also tell you from experience that electronic/electric part A can ruin electronic/electric part B can ruin electronic/electric part C can ruin electronic/electric part A (I've seen this vicious "chain of failures" rack up tremendous repair bills in both the automotive/motorcycle and computer repair fields). Often the only reliable answer to this "chain of failures" is to replace components A, B, and C at exactly same time.
And yes, some ebike conversion kit/manufacturers do utilize integrated components (which is also sometimes known as "proprietary" design and/or construction). This can be both a blessing and a curse...
Originally Posted by
scotiaredd
Think your right im looking into buying a kit of ebay and at least i will now it all matches lol...
Keep in mind that some, if not many, of the lower cost ebike conversion kits are supplied with less than adequate installation instruction guides. Some are down-right horrible (but you probably already know this). Anyway, we might be able to help you get through any "what the heck is the manufacturer talking about" and/or "what wire goes where" type of questions.
Anyway, good luck with your ebike project. Btw, feel free to ask any questions about which kits and types or brands of bikes are best suited for everyday conversions, etc, etc.