I'm new to this, so can you explain why my Vamo V3x kit came with two 350's and the extension tube to hold both? The Vmax that I am selling did the same. Can you educate this newbie on why we should not stack in an APV that seems designed to do so?
Because there is variability from battery to battery, even within batteries produced by the same manufacturer. Even though they are manufactured using high levels of quality control, there is still some difference between the capacity of one cell and the capacity of what looks like its twin. One with a nominal capacity of 800mAh may have an actual capacity of 790, while its apparent twin might be as high as 830.
When the higher capacity "twin" sees that its lower capacity brother is getting low on his charge, it could try to share his charge and the result is usually very bad. Edited to add: One battery going into thermal runaway inevitably heats the other and causes it to do the same thing. So, now you've got two unstable batteries venting flames and hot gasses. BOOM.
There are also minute differences in the exact amounts of chemical goo inside the battery, as well as potential differences in the battery's own internal resistance.
We're using these cells in a high drain system that is capable of putting enormous demand on them. There are many variables involved, and all it takes is one of the cells to exhibit one bad value in any of the variables to cause problems. And, the lower the quality of the battery, the higher the probability that one of the cells does so.
Those two 18350's may work just fine for a while, but as they age (measured in charge cycles, not time), the less stable they can become and the more likely they are to misbehave when placed under the demands that your Vamo is capable of putting on them. The lower the quality of the battery, the more likely they are to misbehave. Pairing batteries of different chemistry and different manufacture only increase the probability of failure.
Unprotected ICR cells can explode, and the ones that come with the Vamo are just that. Unprotected IMR cells vent gases and enough heat to cause a fire. Unprotected hybrid chemistry batteries just die gracefully.
Go get one (or two) of those AW IMR batteries from RTD. They're not that expensive and they're the safest available.
All that said, you
can stack batteries in the Vamo. It is indeed designed to do so. But the batteries that ship with it are just about the worst possible ones to do it with. If you must stack, do it with IMR's.
More in the next post...