SmartThings Community

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


(Bob) #14

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.


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.

(Ed) #18

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.

(Alex) #19

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.

Product Changes for 2017
(Tony) #20

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.


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?

(Steve Borsch) #22

Was stunned when I discovered this morning—on the SmartThings Facebook group, of all places—that the garbage RayOVac batteries supplied with my v2 hub tend to corrode after a short period of time.

Here are mine in this photo.

There are literally dozens of group users who have had this same problem. Why zero heads-up on this problem from our pals at SmartThings? You would think an email would be easy to do.

Now I have another calendar event to create so I can periodically check on the batteries. Sure thought this home automation adventure would see less maintenance vs. more. :wink:


Seems a lot of people with the Rayovac batteries and the ETH-200 hubs are having problems. At this stage, it would seem prudent to remove the batteries completely especially if you have either Rayovac batterys or an ETH-200 hub. A number of people with ETH-250 hubs have said their batteries (not Rayovac) have not had leaky batteries. Hmmm…


I have that combination and checked my batteries earlier - corroded. The hub was first set up on 10/21/16.

(Brett C) #25

I just happened to be starting the process of rebuilding my Zigbee and Z-wave networks for troubleshooting and noticed my stock batteries were corroded. Just got the hub in mid-October, so it’s only about 3 months old. We did have a 2 hour power outage last week; not sure if that’s connected or not.

If anyone has a recommended UPS I think we might want to look at those as well!

Seems simple, but how do I add a device that is far from the hub?

I just got the UPS that was recommended upthread. It’s fairly compact.


2 days ago I found that mine have leaked too. The battery cover was stuck from the dried stuff and very hard to open.

(Wayne) #28

This prompted me to check too and found them to have leaked and corroded too. :rage:
Cheap nasty batteries. Lucky to have seen this otherwise could have caused lasting damage. Seeing that there’s no v2 hub replacement tool, it could have been a painful process.

Replaced with energizer AA with their no leak guarantee.


My guess would be overheating.


It’s not the batteries, it’s the hub. Since the last update I’m chewing through batteries every two weeks. Someone on the FB group checked it with a shunt and the draw while the unit is plugged in is enough that the batteries are depleted approximately every 15 days. My hub is running is failing to run routines reliably anyway, so I didn’t bother to replace the batteries when I found them dead again last Sunday.

(Geko) #31

I think it’s safe to say at this point that the V2 hub has a serious design issue that causes either premature battery discharge or overheating, or both. I would not recommend leaving batteries in the hub under any circumstances.


Agree. Everyone with ETH-200 and/or Rayovac batteries should remove them until a resolution comes about

(Wayne) #33

I’ve got a UPS which pretty much negates the need for batteries except when I want to take the hub to another location to resync a device. If we remove the batteries then it pretty much negates the only remaining benefit from having a v2 over the v1. Seems pretty sad…