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LiFePO4 vs LMO-NMC

jdege

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Dec 16, 2020
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I've been thinking about electric propulsion, and have been weighing different options.

EPropulsion uses LiFePO4, which seems to be the standard in marine systems.

https://www.epropulsion.com/e-series-batteries/

But Torqueedo uses LMO-NMC, which I know nothing about.

https://www.torqeedo.com/us/en-us/pr...0/2104-00.html

Compared to LiFePO4, most Li-Ion technologies are considered unsafe and have fewer charge cycles.

Anyone know anything about Torqueedo''s LMO-NMC batteries in these respects. Are they safe?
 
My major concern is flooding. If I've got seawater deep enough to short the batteries, I'll have problems enough without dealing with thermal runaway.
 
My major concern is flooding. If I've got seawater deep enough to short the batteries, I'll have problems enough without dealing with thermal runaway.
Not a worry for me at all. If the batteries flood, any battery is going to short out and be a hazard. And then you also have a lot of cooling. Really, your priority should be to keep water out of the boat. If there is enough water in my cabin to flood my batteries terminals (about thigh-high on my boat), I am inflating my life raft regardless of what the batteries are doing.
With that in mind, LFP do not go into thermal runaway when submerged in seawater. Notwithstanding a few companies like Torquedo that opt for something else, LFP is *the* battery to use on a boat.
 
Notwithstanding a few companies like Torquedo that opt for something else, LFP is *the* battery to use on a boat.
Torqueedo''s batteries are waterproof, rated IP67 - safe to immerse to 1 meter for 30 minutes.

And the BMS is programmed to shutdown when submerged.

The combination might be safe...
 
Torqueedo''s batteries are waterproof, rated IP67 - safe to immerse to 1 meter for 30 minutes.

And the BMS is programmed to shutdown when submerged.

The combination might be safe...
Yes, it probably is safe. Never said it wasn't.
 
Yes, it probably is safe. Never said it wasn't.
I raised the question as to whether it is safe in my original post.

If choosing between EPropulsion and Torqueedo, should I eliminate Torqueedo from consideration, solely because of the chemistry.

At this point, I'm thinking no. It will remain in the list of possibles.
 
Not because it isn't safe. The question is "is this the right battery for my boat?" The torquedo battery has a higher energy density and higher power handling ability. For a boat that is a high speed planing boat those are important traits, and one might pay a higher price and accept a shorter battery life (fewer charge cycles) for that extra needed power. For a displacement boat, weight isn't as important, nor is raw horsepower. So, one might instead choose to have a higher capacity battery for the same cost, that will last for more charge cycles.
The only boat that I have seen (personally) that uses Torquedo batteries (not that I have any great knowledge of who all uses them) is a high-speed hydro-foiling electric boat. It is a fine choice for that boat, or other high-speed/high output electric craft.
For $5200 you can have a 5000Wh battery from Torquedo, or more than 7000Wh LFP from other high-quality suppliers, or over 10,000Wh LFP if you shop around and do your homework.

Anyway, I have no idea what kind of boat you have, so it might be a good choice.
 
For $5200 you can have a 5000Wh battery from Torquedo, or more than 7000Wh LFP from other high-quality suppliers, or over 10,000Wh LFP if you shop around and do your homework.
EPropulsion's 8960Wh battery is $4400.
 
NMC degrades at a faster rate than LFP when cycled in a similar fashion at the same temperature.

Similar was a strong word without qualification. When talking 2000 cycle life, NMC is pretty close, but LFP seems to be stretching that way out.

I have > 600 Panasonic NMC cells from short range plug in hybrids meaning their batteries were typically cycled daily. 5-9 years old with most having 1000-3000 cycles on them. The worst of the bunch are at 80%. The best of the bunch are at 95%.

So, 1000-3000 cycles of near 100% DoD of this flavor of LMO/NMC cells in cars using passenger compartment air cooling is "similar" to the 2000 80% DoD cycle life of LFP cells, which may be outdated based on some recent cycle life claims.
 
It isn't just a matter of chemistry or individual battery cost at this level - system integration is.

If you read the ePropulsion faqs, you'll also need a proprietary charger. This prevents noobs from trying to charge it with the Schumacher Speed-Charger in the garage from the 1970's.

Other concerns may be that the ePropulsion system seems designed to communicate between the battery and the ePropulsion motors. Will YOUR motor work or take advantage of this? How does the Torquedo compare - will it fit your needs?

This may sway your decision for this motive-power application beyond just a quick glance at chemistry.
 
Both Torqueedo and EPropulsion provide integrated systems. I'm sure that both can be used with generic batteries, but there'd be some configuration that's need to be figured out.

As integrated systems both have advantages and disadvantages.
 
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