Whether you have a factory bus conversion as we do, or a bus you or someone else converted, you no doubt have heard a lot about the benefits of using lithium-based batteries for your house batteries. Unfortunately, you likely have also been exposed to a lot of information of dubious value and some downright dangerous information from reading internet posts or by watching You-Tube videos.
In this article, I will try to give you the right information you need to make an informed decision for yourself and along the way will try to dispel the many myths and half-truths that are floating around about this subject.
The first thing is to recognize that there are six, entirely different battery chemistries offered that are all called, “Lithium”. Only one of those, Lithium Iron Phosphate, is appropriate and safe for use as house batteries in our buses.
The other five chemistries also called lithium all have significant issues that make them far less than ideal for use in a bus conversion. The following chart summarizes all six of these chemistries.
This chart shows the capacity (in watt-hours per kilogram of weight) for nine common battery chemistries. The red bar on the left shows the common lead-acid auto/RV battery. Whether it is called a wet cell, gel cell, AGM, or SLA, all of these have a capacity of about 40 watts per kilogram (2.2 pounds) of weight.
The green bars show the familiar Nickel Cadmium (NiCd) and Nickel Metal Hydride (NiMH) type batteries that offer up to twice the energy density of lead-acid and have proven themselves in decades of use in portable power tools, portable audio devices, and other portable applications, but which also have known issues in terms of things like limited life, rapid self-discharge, limited amperage output, and memory issues that make them less than ideal for use as house battery banks for bus conversions.
The orange bars show six different types of lithium batteries. The letters at the bottom of each bar are shorthand for what all is alloyed with lithium for each of these six different battery chemistries.
The three bars at the right employ cobalt, a rare earth mineral that is environmentally difficult to mine, to ship, to handle, and to dispose of. It also makes active battery management, especially active heating and cooling, mandatory to avoid unintended thermal events like the Samsung engineers encountered with such batteries in their phones a few years ago.
These cobalt alloyed battery chemistries result in very high energy densities, up to six times the energy density of lead-acid batteries, but unless you really, really know what you are doing, I recommend you stay away from them as house batteries in your bus. They simply can be too dangerous if improperly deployed.
I really caution you not to get caught up in the idea of cracking open electric vehicle batteries to harvest these cells for use in your bus. The internal voltages can be very high, high enough to be deadly for some. And, safely managing harvest-ed cells is not something for a neophyte!
Editors Note: This is the beginning of a multi-part article on why you should now be considering Lithium Batteries for your bus conversion.
You can reach Jerry Work by email at: firstname.lastname@example.org