Originally Posted by Pizzazz
Forget about slow charging solar
, forget about current expensive lithium batteries.
Just some thoughts as an amateur DIYer.
I bought 15kWh of LiFePO4
for $3,250 a couple months back. Or $217/kWh. I've seen $174/kWh, and some better deals here. It'll get cheaper. You can probably take another 20% off overnight in a year if the Trump Tariffs go away. So I expect prices will steadily decline to a point, but not hit the $100/kWh mark for NMC/NCA cells the EV OEMs are aiming for.
See the graph on this page: https://www.motortrend.com/news/tesl...harger-tested/
The Tesla Model 3 charges at about 4C for 5 minutes at a low SoC. By 25% SoC it drops to a 2C rate and at 55% SoC it starts dropping linearly hitting 1C around 75%.
That's not particularly remarkable with this chemistry, but if you do that type of charging routinely you'll quickly be looking at dramatically reduced cycle life that will result in a much more expensive 10-year TCO. NCA cells are also not safe. Sure they don't pop-off as frequently as a fuel
line might leak on a gasoline engine, but when they do you're losing the entire boat
If that happens anywhere offshore
you can only imagine the consequences. It's a very very bad idea. Given you can pick up 70kWh of LiFePO4
for about $12K these days, you're risking your boat
and your life for pennies on the dollar.
I've only recently gotten back into looking at cell options, but things have come a long way in the past few years in the LiFePO4 market. Lighter, smaller aluminum
cased cells substantially cheaper than they've ever been. If you're looking to build a house or propulsion
bank, it's a great time to be shopping
IMO (though Summer 2021 is probably better!). Keep the automotive chemistries on the dingy where weight and charge rate is more important, and safety
, cycle life and other concerns less so.