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Post by Deleted on Dec 8, 2020 22:05:21 GMT
Yes LFP looks pretty safe.
Being a cheap device this thing I had will have just had cheap and cheerful high C rate lipo batteries. Like remote control plane batteries and they are known to be quite dodgy.
I did know this and was why I removed the unit to the exterior of the vessel.
Thinking back this was quite risky as I put myself in a very small engine room area in order to remove it.
It's possible that hanging it off the side of the boat near the water it actually got wet and that could be what caused the venting with flame to occur.
Interesting they no longer do them with Anderson sb50 sockets.
That's asking for trouble really if the device relies on the original leads to prevent back-charging...
Sb50 is a standard high(ish) current plug system so fairly good chance of someone making their own leads up. Like I did.
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Post by thebfg on Dec 9, 2020 2:23:09 GMT
I'm no expert but the jump packs I have seen have some sort of diodes in, I believe they prevent a certain amount of power going back into the jump pack. That might be what the plastic module is in the original leads. However it is fitted with an Anderson sb50 chassis socket so there is always a chance of someone using the incorrect leads... This is the model But I don't think its available anymore. I wonder why that might be. Mind you if that rectangular red box is a diode pack to prevent charge-back occurring and I didn't use the original leads then... Maybe it is printed on the unit to always use the original leads. Going by that, I would say I was right. Wanted to double check and knew I seen something on YouTube.
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Post by Deleted on Dec 9, 2020 10:20:55 GMT
Being a cheap device this thing I had will have just had cheap and cheerful high C rate lipo batteries. Like remote control plane batteries and they are known to be quite dodgy. Do you have a preference for a similar device were you to replace it?
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Post by Deleted on Dec 9, 2020 10:24:50 GMT
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Post by Deleted on Dec 9, 2020 11:18:14 GMT
Quite useful if your engine was designed for it but the Japs haven't bothered for a while now. I guess you think all those lithium packs are as bad as each other?
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Post by Deleted on Dec 9, 2020 11:22:13 GMT
BMC engines. No I think the pack was safe but using an Anderson SB50 on it invites those of us who make things up on the spot to use the wrong leads. The fact is that the diode pack in the image posted by thebfg is what protects the unit from back-charging. Fundamental design flaw. I think if I did get another one I would go for one which had the protection circuit in the box rather than on the lead... Or one which had a non common plug so that you don't just make an Anderson plug setup. SB50 is a standard forklift truck and jumplead type connector so people WILL use the wrong leads and I DID. It's a standard product you can buy Like this. www.ebay.co.uk/itm/RDX-Defender-Jump-Lead-Conversion-Adaptor-with-175amp-Durite-Anderson-Plug-/362596708651IF YOU USE ONE OF THESE AND INADVERTENTLY LEAVE IT CONNECTED THE BATTERY WILL VENT WITH FLAME.
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Post by Deleted on Dec 9, 2020 11:35:33 GMT
Ok get it now. I was toying with the idea of something like that to have in the car just-in-case (and also for extended sailing trips to re-charge gadgets) but your pics looked scary.
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Post by Deleted on Dec 9, 2020 11:47:07 GMT
Ok get it now. I was toying with the idea of something like that to have in the car just-in-case (and also for extended sailing trips to re-charge gadgets) but your pics looked scary. I have used it before no problems it's just because I left it connected with non protected leads. Otherwise it's ok.
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Post by Deleted on Dec 9, 2020 13:47:19 GMT
Ok get it now. I was toying with the idea of something like that to have in the car just-in-case (and also for extended sailing trips to re-charge gadgets) but your pics looked scary. Another one which looks good is the capacitor based jump starter but they seem a little awkward to find.
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Post by Deleted on Dec 9, 2020 14:06:53 GMT
Ok get it now. I was toying with the idea of something like that to have in the car just-in-case (and also for extended sailing trips to re-charge gadgets) but your pics looked scary. Another one which looks good is the capacitor based jump starter but they seem a little awkward to find. You are obsessed with supercapacitors. Yes, they do seem a tad tricky to find (unless you search for 'Super Capacitor Jump Starter').
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Post by Deleted on Dec 10, 2020 18:43:55 GMT
Further thoughts on this and I have worked out exactly what happened.
It was definitely a 3s soft lipo pack which has a top voltage of 12.6v. if you put more than this in it will cause serious problems.
The soft enclosure will start to expand ,(well known issue).
So what happened here is that it expanded, split the plastic casing open which caused the device to fall onto the floor in the engine room.
Thats what alerted me to the problem, the battery enclosure (a pouch not a rigid box) then split and started to vent which was the beginning of the thermal runaway itself.
I don't know how serious it is if you overcharge LFP type batteries. They are meant to be a lot safer and are usually packaged in more durable enclosures.
although having said that I know that there are some LFP pouch cell based units around.
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