You're getting all worked up about nothing.
With respect, I'm not 'getting worked up' about anything, this is a new field for me, we are talking a lot of money and it's not just me on a bicycle on the road (when talking about the on-topic use of LiPo's here) but potentially my family, in a small wooden boat, some distance from the land (in time if not actual distance etc). So, part of my questioning here is playing devils advocate and testing for the 'worst case'. Once I know that I can then work back to a more 'real world' usage but whilst accepting there are (extra, over say lead acid) risks. ;-)
You need to be aware of the risks and you need to handle lipos properly, but you don't need to worry about them exploding spontaneously.
Understood.
The main real dangers are:
Charging them incorrectly, especially after over-discharging.
Dropping a non-hard-pack
Shorting of any of the wires
Connecting them incorrectly
Piercing them
Understood.
If you're going to put them in an ammo box, you might as well use a lead battery.
Depending on the size of the box of course. ;-) Whilst I get your point, I'm pretty sure 4 x 4s 16000mA LiPo packs, even in a small ammo box aren't going to be anywhere near the weight and size of my existing battery! ;-)
Avoid complicated parallel looms. that's why I recommend the balance board connection system. There's no wires other than what's already on the packs from the manufacturers, so nothing to short out.
Understood. That said, I am an electronics / field support tech (BT, Kodak, Datacomms Co) and have been soldering since I was about 7 and pride myself in both the care and neatness of my work. However, I have no issues re using a balance board either.
If you pack them in a light-weight plastic box, they will be protected from dropping and piercing.
I'm assuming that if I went with 4 x 4S, 16A LiPos ... and was drawing a continuous 15A for 3 hours, the batteries wouldn't suffer from lack of ventilation (cooling)?
In all the videos I've seen, where they were deliberately or accidentally set alight, the combustion started slowly. They start with fizzing and smoking. You'd have plenty of time to sling the box overboard.
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That's the sort of practical / real-world advice that I like. ;-)
Personally, the last thing I'd ever do is chuck them in salt water. It's highly conductive. Probably, only one pack or cell would be burning. When you chuck the whole lot in salt-water, they'll all start burning at once. My mobile phone got totally burnt all around the battery connections when it went in salt water.
I guess that is like the 'what would I grab first when running away from your burning house'. Ignoring the idea that any reaction could make matters worse, I think once I saw smoke coming from my battery box I wouldn't be worrying about potentially throwing good packs away!
I used lipos for a couple of years on my electric bikes. they got a lot of abuse - bumped about in my panniers, dropped on the floor, etc, but they never caught fire. I had several big flashes and burns when I connected them up incorrectly. see this burn on my forefinger:
<burnt hand picture> Ouch. ;-( Trust me, with 48V (8 x 6V X 200Ah LA monoblocks) and a potentially massive short circuit current available in the EV I've had for over 30 years now, I treat all these things with a high level of caution and respect. ;-)
I'm perfectly relaxed using lipos with my trolling motor on my inflatable dinghy. It's nothing to worry about provided that you know how to handle them.
Quite, as I'm sure I will be, once I have some usage under my belt. Until then, I'll be proceeding with caution! ;-)
Thanks very much for your help and advice. It's all filed away and fully considered I promise. ;-)
Cheers, T i m