Re: Switch to LiFePO4


Oliver Henrichsen, SV Vela Nautica
 

Hi,

In the long run it is even more advisable to abandon the traditional car batterie style and take one 24 volt 400, 500 or 600Ah lithium batterie instead building it up from 12 or 24 volt sections. 

I would prefer a central based BMS controller supervising the hole batterie at once, not packages without com port where one cell does not know what the other does. 

And you should look at the guaranteed capacity. Means this battleborn has only 90% capacity, according to their discharge graph. In my eyes thats a hint for low quality? 
A good quality batterie, with good chemistry inside, will guarantee 100 to 108% capacity.

There is no "drop in batterie" that is misleading because in the end you need to setup all the electronics, chargers, BMS aso. to lithium. That is the real change. Not in what plastic case the cells are packed.

Oliver from Vela Nautica 
A54#39 
Martinique 





On Thu, Aug 13, 2020, 07:21 Arno Luijten <arno.luijten@...> wrote:

Battle  Born was not very explicit about it in the Zoom meeting last week but in the long run it is very much advisable to use the 24 volt units instead of the 12 volt units. 

Using 24 volt units makes sure you will balance cells across 24 volts instead of 2 x 12 volt leaving a potential unbalance between the two 12 volt banks.
For capacity the answer is simple, as much as you wallet can last. You will always find ways to spend the available capacity in the end, so more is better. 

For your chargers you will need to investigate if you can set them to the exact same charging parameters. That may be difficult.
Also think about your charging regime. Again Battle Born was not very explicit about this but if you boat is connected to shore power for extended periods, you should lower your float voltage to reduce the state of charge to 70-80%. This can be difficult to achieve if you have several charge sources as this means adjusting it very precisely, up to tenths of volts accurate.
I did not like the way Battle Born played down this issue but Lithium batteries do not like to be kept at 100% charge level for extended periods. Even Tesla has extended logic in their battery management to handle this issue. So when Battle Born claims it has superior cells that do not suffer from this problem, I’m skeptical.

Just my 2 cents....

Regards,
Arno Luijten
SV Luna,
A54-121

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