Lithium batteries, water tolerance - Page 1
Forum section: electronics / beginners

author: woodchips
author_rank: Frequent Contributor
timestamp: April 12, 2024, 08:38:45 pm
content: Just read an article in Practical Boat Owner where they are replacing the lead acid backup batteries with lithium LiFePO4 battery. No mention about the water, and salt water, tolerance of these batteries.Only just from interest sake but does anyone have real practical experience please?Could be underwater tolerance, or humidity, I assume that the cells have a breather, to they exhale in inhale? Temperature? External pressure?Thanks.

author: JustMeHere
author_rank: Frequent Contributor
timestamp: April 12, 2024, 09:15:22 pm
content: LiFePO4 is by far the most dominant battery in self-propelled kayaks.

author: Jwillis
author_rank: Super Contributor
timestamp: April 13, 2024, 03:09:58 am
content: Sealed or not the same precautions need to be taken for lithium batteries as lead acid batteries in marine application. Salt water is conductive and can short the terminals of any battery. Battery terminals can corrode. Even more so in salt water. Any battery should be kept in a dry enclosure.

author: BrokenYugo
author_rank: Super Contributor
timestamp: April 13, 2024, 05:13:46 am
content: To the best of my knowledge lithium chemistry batteries in general do not "breathe" unless something has gone horribly wrong, the cells themselves are sealed and I would imagine the lead acid style case you often see them packaged in (with BMS I assume) is sealed too.They bolt these things to the bottoms of cars now, a bilge is a nice place in comparison.

author: coppercone2
author_rank: Super Contributor
timestamp: April 13, 2024, 06:11:43 am
content: the point of aluminized mylar for pouch cells is no breathing

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 13, 2024, 06:14:31 am
content: cells are sealed, but metal contacts are not... if you know salt water, only assume stainless steel can survive, others... use conformal coating or enclosure. i live exactly above them. ymmv.

author: strawberry
author_rank: Super Contributor
timestamp: April 13, 2024, 07:38:37 am
content: fiberglass sealed(with watertight gasket) box with big stainless steel terminals 100mm apart

author: MarkT
author_rank: Frequent Contributor
timestamp: April 13, 2024, 08:28:07 am
content: Lithium reacts with oxygen in the air rapidly, all lithium battery chemistries therefore have to be hermetically sealed.Note many cells / packs come with a protection PCB built-in, this in general won't be salty-air tolerant unless its conformally coated or potted.

author: woodchips
author_rank: Frequent Contributor
timestamp: April 13, 2024, 09:06:56 am
content: Thanks.I had missed the fact that the lithium battery has to be totally sealed, so makes mounting it much easier. Also that any physical damage is much more serious than with other chemistry batteries. If the sealed box is pressurised then that will also stop any ingress of water.With water sealing of cabling, seems to make the lithium cells a better bet than lead acid. Only down side I can see is that they have no scrap value when replacement is due.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 13, 2024, 09:24:06 am
content: Quote from: woodchips on April 13, 2024, 09:06:56 amwhat scrap value? here scrapped sla is $2-5.. if its too important for you to get a free meal in a year or two, then stick with sla...

author: woodchips
author_rank: Frequent Contributor
timestamp: April 15, 2024, 09:40:19 am
content: Do not underestimate the real value of scrap value. How much is plastic worth, how much do you see in piles and blowing in the wind? A lead battery is about £0.70, $1.5, per kg so easily worth the cost of pulling them out and taking for scrap, not just dropping them in the ocean. Lithium still doesn't seem to have any scrap value, building recycling plants, but one for the whole of Europe doesn't sound very sensible, how many miles do they travel?

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 15, 2024, 10:32:53 am
content: Quote from: woodchips on April 15, 2024, 09:40:19 amwe are 3rd worlder are very aware of this, in each region we know some people do this for living as third party/middleman before sending to local collector before to state or district factory..you throw something worthy as scrap anywhere, someone will pick it up in few days... including on shoreline...