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Hi from England
#1
I'm just beginning to look at replacing a 12V lead acid system (nominally 460Ah) on a narrowboat (canal boat for those who aren't familiar).
I naively thought this would be simple...

So far I have discovered that lithium technologies a) are unstable, b) don't charge below 0°C c) are much less understood than lead acid and d) can be expensive.

I thought maybe I'd found an answer to the stability and charging temperature difficulties in LTO and started looking a little harder.

I then realised I don't know very much about how modern intelligent chargers work and even less about how to regulate the current from an alternator spinning at not much more than tickover.

I also started wondering why the boat builders fitted a 12V 3kVA inverter - 300A requires some hefty copper...


ufabet
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#2
looks like the entire boat would be conditioned space so LiFePo4 and LTO would be your options. A heating pad, or a light to keep the battery compartment above 0c. Is the boat of primary residence? How often is it below 0c and for how long?

A picture of the boat and your battery compartment would help.

Later floyd
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#3
(10-27-2020, 12:05 PM)Bbb837 Wrote: I'm just beginning to look at replacing a 12V lead acid system (nominally 460Ah) on a narrowboat (canal boat for those who aren't familiar).
I naively thought this would be simple...

So far I have discovered that lithium technologies a) are unstable, b) don't charge below 0°C c) are much less understood than lead acid and d) can be expensive.

I thought maybe I'd found an answer to the stability and charging temperature difficulties in LTO and started looking a little harder.

I then realised I don't know very much about how modern intelligent chargers work and even less about how to regulate the current from an alternator spinning at not much more than tickover.

I also started wondering why the boat builders fitted a 12V 3kVA inverter - 300A requires some hefty copper...
Look at LiFePo4, they are quite stable when used with the correct chargers & a decent BMS.
LiFePo4 cell voltages also match well with L.A. voltages.
Lithium tech is very well understood, you just have to find the right sources!
Hopefully you've found the advantages too eg
- larger DoD range
- much longer life
- no water to top up
- no acid corrosion issues
- no hydrogen gas issues
- lighter (maybe not so important on a large boat)
- not harmed if left at say 20% SoC (state of charge)

Most people go for 48V systems for higher powers but 24V might be good for your boat too.
Maybe find separate prismatic cells vs 12V blocks.
Running off solar, DIY & electronics fan :-)
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