Lithium Phosphate batteries? DIY - Just how bad an idea

BruceK

BruceK

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Having spent nearly a decade in the RC fraternity I am well aware of the inherent dangers of Lithium based batteries but even so I am tempted to change the house batteries from gel to Lithium Phosphate for all the obvious reasons of discharge, capacity etc to run an inverter rather than having a generator as well. The price of these batteries though is horrendous and for a decent setup will cost the same as a genny. Then I came across this fellow's channel and it got me thinking along the DIY path. The vid is long but there is a ton of tips in it so well worth watching the whole thing if you're interested. So, what pitfalls?

 
Genny's are so unsociable. Underwater exhasts may make them nearly silent for thos onboard but I can feel my neighbours chugging away through my hull. I'm a big convert to solar power, so much of it though is wasted because I cannot fully utilize my battery bank due to it's restrictions on discharge and capacity.
 
Have also been thinking of the next boat running on batteries rather than geny at anchor. If charge running low then the engines need to ideally switch on automatically to charge them (obviously disengaged from the props). If I have a seakeeper again then this might not be an option and would still have to be a geny - but am hoping it can be an option
 
the way I've read through this (and a few other) threads is that LifePO4 is fine and safe as a source, CHARGING them and BALANCING them has to be dealt V.CAREFULLY and I'd add at great expense, on the danger that failing that you buggered the batteries fullstop.
My Trojans probably have a couple of years more in them (due to me letting them dry on the first year but that's another story) so v.keen on a better solution, not sure now is the time though, I'd hope prices will drop in the following year or so. Overnight (600W solar) I need approx 80-100Ah, could easily go up to 150Ah, sun through my panels can sort of break even in July and August (not Sept though!) so looking for 200+Ah LifePO4 and then ways to sort out my victron multiplus inv.charger, victron mppt solar and sterling advance regulator for engine alternator... not easy or straight forward!

V.
 
Luckily my mppt can handle LifePO4 and being into RC I already have all the balancers and gubbins needed and still have spare.



Restoration man said:
Could you not just use these save buying the cells and making them up ?? Not sure how it would be balanced though ?

100Ah 12V LITHIUM LiFePO4 Battery for Leisure, Solar, Wind and Off-grid 12 volt | eBay
Click to expand...

I suppose you could but running multiples of them in parralel or series is where the balance issues come into play and 100 A/hr doesn't cut it solo. Buying the big capacity batteries gets expensive. Look at the following and ramp it up to 500 A/hr (parallel @12V)

NDS 250Ah Lithium Battery
 
I have 8 270ah cells on there way from China to build a DIY pack ? I'm sick of being like apollo 13 having to conserve every amp if we moor up for a few days. I also want to be able to run the immersion heater off them so we can have warm showers every morning without running the engine
 
For those who are interested. This chap recently gave a very good overview of his new lithium battery installation, giving his (and his wife’s aims for the project) and a before and after walk through. He also talks about mission creep , project costs and their subsequent experience of living with the new system. I have subscribed to this guy for a while, he looks after his vessel and systems to very high standards and produces cracking videos.

This project is a lot bigger than than that needed for the average yacht but gives an indication of the scale of things (big hands small map?).

You Tube LINKY
 
I would not boat in the Med without a geny .Opens up many possibilities planning trips .
Even on a small boat the sound insulation theses days seems to work , you add more .

You never worry about power .
 
In an anchorage it’s often impossible to identify who has their genny on, so not really antisocial
 
Simple solution Bruce, get her indoors an exercise bike and fit to the boat, connect an alternator to the back wheel and tell her its the latest trend in keeping fit.
 
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