You should obsess over risks that do permanent damage and care little about risks that do temporary harm, but the opposite is more common.

Morgan Housel

Morgan is one of the best thinkers about financial risk around. Often his thoughts apply to offshore voyaging too.

This one applies best to the majority of cruisers who worry about lithium battery load dumps blowing the diodes in their alternators, a comparatively easy problem to fix, and completely miss the much greater risks from load dumps.

Turns out that the new ABYC E13 standard for lithium battery installations on boats in effect bans separate busses for loads and charging sources. (Thanks to member Rick for pointing this out.)

13.7.2.1A BMS shall respond to any conditions outside the SOE by activating the output disconnect device.

My guess, and hope, is that this is probably the result of poor drafting, rather than intended. The problem, of course, is the word output.

In my view, compelling the BMS to dump the loads just because of an overcharge does not increase safety, it decreases it, since load dumps are dangerous in and of themselves and overcharge is the most likely scenario to cause a disconnect.

Hopefully ABYC will fix what I believe to be a mistake soon. Banning something that most industry experts I have talked to consider much better design (separate charge and load busses) does their credibility no good at all.

The TE-13 technical note is now a standard: E-13. To me, a woefully inadequate one that relies far too much on the vendors to do the right thing, but it’s a start. Panbo has a good analysis, most of which I agree with.