Check your Hub V2 Batteries: might be leaking! Recommended hub batteries?

Many people including myself remove batteries in the hub and use a UPS instead. I have a large UPS that provides power to my hub, cable modem, router, network equipment and NAS. Power outages are rare for me but when they do they are often short lived and the UPS keep things going. Plus you have the added benefit of keeping your internet connection going that the ST hub relies on.


Do you have to pry off the cover to get to the batteries?

It slides off on the v2, dont pry anything.

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I use a few of these, They do drop to $21 every now and then


I already have my router on a UPS but I didnt think it would be a good idea to keep the hub next to the WLAN due to interference. If the batteries had worked as intended, there would not have been a service interruption.

Wifi only affects zigbee since they operate on the same frequency band. My hub is a few feet from my router and I haven’t had any issues. Maybe it is because I have a decent mesh of devices.

Well, I was thinking about turning off the wifi on that router and just adding a wifi access point at another location in the house anyway. I might try it.

If not, does anyone have any suggestions re. batteries in the hub?

Thanks, mine has RayoVac but I am plugged into a APC 1000 UPS, so I have nothing to worry ab out.

My fiber adapter outside, the Uverse Gateway (router handling DVR, rest is configured in passthrough), my router (so I can avoid using ATT’s junk), Hue and ST hubs, and all networking equipment is powered by a 1500VA UPS. This has worked pretty well maintaining my internet connection during outages and also reduced the time required to get things back up and running around the house. For example… when the Hue lights turn on when power comes back after an outage, I can turn them off sooner as I do not have to wait for all the equipment to go back online…

But I am wondering why do you all remove the batteries form the ST hub? Even though they may not be necessary if you have a UPS, is there a particular reason to do so?

Also, how did a simple power outage cause batteries to explode? Are you sure they had not “popped” before the outage?

I’m not sure if they were bad before, but I would assume the batteries are idle/basically in storage when the device is powered through the adapter. I don’t know for sure though

This post had a more accusatory tone than I intended, it could just be that kirkland batteries are garbage…I only put the batteries in a couple months ago.

Kirkland Alkaline batteries Are generally very high-quality, they’re almost always in the top 3 of anybody’s battery testing list, including consumer reports. You may have gotten a bad batch, I would talk to Costco. Assuming you were operating within the specified temperature ranges, of course. If it was the hub itself that overheated, that would be a different issue and would affect any battery brand.

It’s generally not a good idea to use rechargeable batteries in a device that switches itself from mains power to battery power unless it’s a battery specifically recommended by that manufacturer. So just in case those were rechargeables, that in itself could be the problem.

But if they were regular alkalines, something is wrong, either with the battery batch or with the hub overheating. :scream:

I have seen quotes and pictures on various threads where the batteries start to corrode in the hub.
Not sure why this should be so.
As a precaution people, including me, have removed the batteries.
Also as I don’t have UPS, my ST hub is back working before my router.
Luckily I lose my power or Internet very rarely.

Ah, so it is the hub then?

Im glad you told me this, I was about to return them haha. Sounds like it is the hub that is to blame based on other peoples input.

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I also (fortunately) had my batteries drained fully during a power outage. I purchased the UPS that @tommyincville posted. This UPS is sufficient for my modem, router and ST hub. It’s useful only for my internet access and quick HA recovery once power is restored.

I have v2 of the hub and noticed stock batteries started to corrode. I’ve only had them in there ~6 months. I agree that this is not an isolated incident as other users have experienced similar behavior.

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Top result in Google for “why do batteries leak” says the following:



All batteries will slowly gradually self-discharge over time. This will occur whether they are setting on the shelf (a much slower process) or installed in a device (which often occurs much quicker) – and dead batteries will eventually leak.

Very high temperatures can also cause batteries to rupture and leak (e.g. in hot car during the summer).

The “alkaline” of the battery is potassium hydroxide […], and this will leak out, forming a white “fluff” of potassium carbonate, typically on the negative end of the battery cell[…].

Why do batteries leak?

A reason for battery leaks (e.g. alkaline batteries, AA, etc…) is that as batteries discharge — the chemistry of the battery changes and some hydrogen gas is generated. This out-gassing process increases pressure in the battery. Eventually, the excess pressure either ruptures the insulating seals at the end of the battery, or the outer metal canister, or both.

Why do batteries corrode only if left installed?

While consumer alkaline batteries can leak and corrode while on the shelf (although less likely), batteries that are left installed in devices will gradually self-discharge or discharge because of small trickle current drains put on the battery (sometimes called ‘parasitic drain’). This leads to a dead battery (or batteries) which will out-gas and corrode.

Many devices have a parasitic drain which slowly discharge batteries. When the device is left unattended for long periods of time (with the batteries installed) the drain will slowly kill the batteries (which will then leak). […] Many modern devices have active circuitry which is always ‘on’ to some extent and slowly draining the batteries while you may not even realize it.

How to prevent battery corrosion

By simply removing the batteries from devices that will not be used for some time, will prevent a slow discharge of the batteries, and therefore prevent leakage because you are preventing ‘dead batteries’. Dead batteries are more likely to leak.


My take on this is that the ST Hub may be draining a tiny amount of current at all times that over time will kill the batteries even though you did not have a power outage. Once the batteries are dead, they will eventually leak. The technical solution would be for ST to eliminate the parasitic drain (if there indeed is one), and for the user to replace the batteries regardless of outages every so often… or you simply do not install any :wink: if you have a UPS. I might just remove my batteries too the first time I see a sign of leakage.


Yikes. Really was not expecting to find anything but I just checked on the SmartThings supplied batteries in my 10 month old hub. Three of the four Rayovac alkalines were corroded. The remaining battery which looked to be in good shape was completely dead. They looked OK when I last checked them (some months ago when this phenomenon first surfaced). Never had a device with battery backup that couldn’t go a year between scheduled replacements without risking damage; I’ll leave that compartment empty.

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it begs the question…what is the point of putting in this battery backup? It seems like it should be totally isolated with a mosfet or something and enough capacitance to keep the hub on while it switches to the backup?