Quote:
Originally Posted by doog
old conversation here but I wanted to add the Lithium VS Lithium Po4 type chemistry which is not subject to fire danger as the case with the laptop and hoverboard explosions. Its much safer now as long as you stay LiPo4 chemistry. But you still need circuit breakers and BMS to protect from runaway charge or discharge damage.
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Let’s cut through the BS.
Firstly LFP technology is arguably safer then many LA installs. It’s very robust , capable of withstanding considerable abuse and poor
charging strategies.
There are three things that need attention in any LFP install
HVC , LVC and over
current protection.
LVC and HVC is easily implemented ( if not optimum) by a programmed voltage battery disconnect.
Over
current can be handled by simple and appropriate fusing ( most batteries are fused on modern boats anyway. )
That’s it as far as LFP is concerned. Clearly your charge source must be compatible with the simpler lithium
charging profile. ( with appropriate temperature interlocks )
Of course you can have much more complex systems but again what I have outlined is the minimum
safety solution
You do not need cell balancing , this is merely a “ nice to have “ but has no
safety ramifications or advantages. On fractional C charging and discharging systems , typical of boats , LFP cells actually converge not diverge and in fact once initially balanced tend to remain so.
So much of the
marine lithium industry seems to want to prevent lithium as complex and hence expensive, ABYC is abetting this by its proposed “ over the top” new advisory standard.
So in fact your average LFP install isn’t much more complex then a good LA install its just different.
Note that short circuits on big LA installs are quite spectacular too , I know !!!