friendly1uk said:
There are two main approaches. To bms or not to bms. If you research on RC (toy) forums, you will find the picture above. You can string them together on the bike, then take them off again and rearrange them to charge on an rc bench charger of some sort. Then re-arrange them again for the bike. The important thing to be aware of is that the wires from the packs won't simply fit, you have to use conversion boards. It does not seem hard perhaps, but it's this rearranging of the pack that causes nearly all the fires.
Let's put BS to rest. I've been using rc lipo for 3 years. I've never had to take a pack apart to balance charge it. Never. And I run a 10ah 24s2p pack. Takes about 10 seconds to take it off the bike. If I wanted to keep my charger in the garage, I wouldn't even have to remove the pack, but I take inside where I can keep an eye on it while charging. Never leave any battery pack charging where you can't get to it, or in a spot where a fire might cause damge. Both the batteries OR ANY charger may catch fire.
What 24s charger is this? how many wires are you in fact changing?
friendly1uk said:
Packs built for commercial purposes are different. They can be destined for ev's or backup or whatever, but they won't be done like toys. Instead they leave the batteries and the charger on the bike, and have one box at home. Still 3 boxes, but distributed differently.
No, the charger is not left on the bike in most cases. In fact, it's rare. And to think they are built better is just ridiculous. Most are wrapped with duct tape or shrink wrap.
How it's wrapped up has no relevance, either way people can hash it up. In rc terms, half the charger is left at home, and half on the bike. It's semantics. The bms approach is less boxes. Just one on the bike, and one at home. Just one 2 pin connects them. It's actually better than I said.
friendly1uk said:
It seems like the same thing, because it is. However to disconnect the batteries from the charger is a lot of dangerous work each time. Yet to disconnect the charger from the next box is a simple 2 pin cord.
I guess it all depends on your definition of dangerous. Yep, you could drop the pack on your toes if you're a klutz.
No no no lol, swapping about all them extra wires is why most fires happen. It's not anybody's definition, it is simple fact. Fires are reserved for RC users, and generally after getting the wires wrong. BMS users don't do this swapping about, and therefore non have reported a fire or blowing plugs apart, which is also a fire imo as an electrician.
friendly1uk said:
The bms approach means leaving a bit more on the bike. Mine weighs an ounce. It is not really a weight issue. While sat there is does a whole host of other protection duties. Some of which might save you from destroying your expensive batteries, or lighting up the wiring with a short circuit. Most people like the ease of charging their bike with as much fuss as charging their phone. There are many benefits from leaving a circuit board on the bike, and the cost? well it is actually cheaper, because it is the mass market way of doing things.
A 1 ounce BMS. Getting deep in here. And what about the disadvantages? Like the bms ruining your battery pack when left connected for longer periods of time. Or the output limits it will put on your battery pack.
A bms won't ruin your pack. That is one old chestnut. I see lots of posts from users needing packs because there rc system offers no lvc, but no posts about a bms killing a pack. I can leave my pack unused for 6 months and it will be back in balance within 15 mins on the charger. I calculate my tiny 5Ah pack will drop from a storage charge to empty just after they pass there shelf life. It just isn't a problem. Just like a bms puts no limit on how much power you can take by clipping on to the batteries. Yes, that does stop the over currant from working, and the lvc would require a contactor to keep functioning, but as an rc user your happy with lvc being a 99c buzzer anyway. Any sort of disconnection is just added luxury. You still get a cheaper neater package without the extras lost by clipping straight to the batteries.
friendly1uk said:
edit: Remember, Non of the fire threads are from bms users. What is and isn't safe is heavily stacked. That is why no commercial packs come without bms. You can do it differently if you like, but it puts you squarely in the 'at risk' group. All forums have lot of pics showing why you shouldn't stray to toy chargers but still lot of people do. We see many fires each year from this group. Sheds, garages, homes.
I can't state the facts much more clearly
The sky is falling. What a crock. There's been fires caused by BMS wiring reported and documented here. And afaik, there's only been one house fire that was caused by a charger a person was using to bulk charge a huge lipo pack left unattended in his garage. A strict no-no for charging any rc lipo pack, with or without a bms.
We have threads listing catastrophic events by the year. I see no bms users posting. Just lots of wire swappers. If there is indeed a bms related fire, I have not seen it, and it is so outnumbered there is no argument. I would like to see it though, If it does exist. Also, should we be just limiting our talk to 'house' fires, when other fires are important too? Two houses have gone, but the number of other buildings is higher, and just bikes higher still. Your picking house fires to limit results. Well, Limit them to 100% wire swappers.
If you want to hawk bms's, fine. But don't just show the advantages of them. There are just as many disadvantages. And a person needs both to make an informed decision.
If they were "Good For You!" If they weren't, I am glad you are learning!! 
