Xenon Li Battery Test & Observations

Hardware
1

I’d just like to post my observations so far, testing the Xenon Li Battery connection with an 18650 cell. There doesn’t seem to be any low voltage protection. The Xenon will drain your battery cell until it reaches the cutout voltage of the board (below 2v). The 18650 Cell was pulled from an old laptop battery, tested at 2.2Ah before being connected to the Xenon. Runtime was over 120 hours (looping every 10 seconds and publishing the battery voltage) before it gave up. I couldn’t find this info anywhere else, so thought it may prove helpful to someone searching the forums. Without a BMS or Low Voltage shut off, I wouldn’t recommend running your Xenon on a raw 18650, as the cell integrity may be compromised and unsafe if the voltage drops below 3v.

2

When using 0.8.0-rc-27, the mesh devices won’t boot below 2.8 volts, though I think it keeps running so it would continue to drain the battery, but should do so somewhat harmlessly. That’s done in case you have something like a solar panel, because otherwise it would never resume operation when the battery was recharged.

3

Just to clarify, you mean “harmlessly” to the Xenon? From what I gather on other battery forums, discharging Li-on or LiPO past their lower discharge spec is detrimental to the life of the cell, and may even cause venting/fire/explosion of the cell. Sounds pretty low risk, given the charge/discharge rate of the Xenon, but still good to be cautious I guess.

4

Not harmful to the Xenon. Might decrease the battery life. The Particle battery includes under-current protection so it should not be catastrophically bad, but it’s generally best to avoid completely discharging the battery if you can help it.

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5

That's a very good recommendation...... not just for the Xenon.

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6

So by having my xenon only hooked up to lipo battery for 14 days could potentially start a fire if the cell is depleted?

7

When a cell is depleted it’s then out of energy that could be used to heat up and start a fire so a fire from a discharged battery is very unlikely but it will lower the lifespan of the battery.

You can get batteries with PCB on them that will turn off the connection to the cell if the battery voltage get’s too low although it’s usually at a voltage that is lower than you would like to cut it off.

Overcharging, short circuit, and actual physical damage conditions are where you normally see a LiPo cell catch fire.

Just buy PCB’s with Protection circuits built in because it will save you from most of the potential issues.

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8

Thanks bro.

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9

Looks to me like the Panasonic NCR18650B has a protection circuit built in. You can see it in thisvideo. There is an excellent article about these batteries here. I hadn’t realized that the NCR18650 is what Tesla is using in the Model S.

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