Panasonic Eneloop AA 1900 mAh NiMH or Pro 2500mAh rechargeable batteries

I've just taken delivery of 20 Ikea LADDA 1900 rechargeable AA batteries in preparation for the forthcoming winter season. I've seen a few comments here and YouTube comparisons which suggest they may be Eneloop 1900s in disguise, with equivalent performance and dimensions, but at significantly lower cost - £5 per pack of four.

They're on the charger now, so far too early to comment on performance in the long term, but I tried two pairs in one of my Tado SRTs and the fit was easy peasy. Also, no problem to operate the SRT with the "ready to use" charge they came with.

My understanding regarding other brands and capacities is that there is a question mark over physical fit. That would include the 2500 LADDAs, just like the larger Eneloops.

By the way, although only one of my SRTs was grumbling about battery life, as I set about re-fitting them all (dismounted over summer months) I had another three start moaning about the batteries as they tried to calibrate. So don't get caught out when the time comes to fire up the heating this year.

Has anyone else had this problem?

nope. Had issues with one a Tado trv that used a lot of battery, nothing else.

kr, H

I get over a year in the SRTs from non-rechargeable Energiser batteries. Only using the one-set of rechargeables so far but if I expand them out it will become once or twice a week. Replacing and recharging so often will drive me crazy over the winter.

can you only use rechargeable batteries on the newer radiator thermostats?

My recently acquired knobs all have a healthy mix of serial numbers starting with VA0, 1, 2 and 3, so I doubt you can tell directly from the leading digits of the serial numbers. When you use the unofficial python stuff to query the webAPI, one of the items returned is 'deviceType': 'VA02', for all of them in my case. Probably it also has this info on the device itself, but I'm not going to take one off to check, that is left as an exercise for tge reader..

A small update on my IKEA LADDA experience. I've now had four SRTs whine about battery condition in under for months.

The first set to go, I simply recharged without thought. I've no idea of the actual charge state when Tado complained.

The next couple of sets reported low battery within 30 minutes of each other. Both sets only took a small recharge - about 15% of capacity to refill. i.e. They were still at 85% when Tado complained.

The fourth set gave the warning a few days ago. Based on the experience of others on the forum I ignored the message.

So, I think that the LADDA 1900 batteries are completely fine to use, but Tado might have some work to do on the battery alerts. There's a bit of "cry wolf" going on.

While trying to find more information on this, I came across the following accepted suggestion, where Tado has explained why Panasonic.

So far my experience:

1. I've used IKEA LADDA 2450 mAH on one of my TRVs. It works fine.
2. Today I changed batteries of another. It did its "cry wolf" thing. But after removing and re-inserting batteries one more time, it worked fine. Also, one of the batteries got stuck in the battery compartment, but I was able to pull it out with a finger.

I think this is why Tado doesn't recommend other types of batteries. By observing their "very diligent" documentation style I can imagine that they don't want to recommend inserting fingers or tweezers into the battery compartment in case things go wrong.

Also, thinking this hypothesis out loud - What if VERY cheap non-standard battery types tend to heat up (event) at mechanically idle current and thus cause reading error? (I don't think anybody will do that though :) )

In conclusion, I will continue using the pool of IKEA LADDA 2450 mAH batteries which I have already stockpiled.

Im testing the Pro variety now as the standards showed poorer performance,

Will report back when they need replacing

@PaulEd Sorry for the late reply. I'm happy to report that the Pro 2500 batteries are performing well. I have only had to swap out 3 sets over the last 3 months and they are radiators that are at the limits of good reception. This is a very good thing as I work away a lot and my wife does not like changing the batteries. I would have no problem recommending them.

I started to get alerts from the radiator thermostats furthest from my bridge (thick brick walls between them) after only a few weeks. I panicked and bought the 'approved' eneloop 1900 batteries to avoid falling foul of any warranty. Tado support simply kept repeating that battery as the only one to use when I asked about the Pro (or Lithium) ones, without explanation.

I have come to the conclusion that the alerts are false. I've since ignored their notifications to change more (and not started to use my stock of re-chargables) and everything seems to be continuing fine... Thinking about the alerts, I assume that it's based on the at-rest voltage and it's not always accurate. Somehow they have to detect the difference between NiMh and Alkaline (1,2V vs 1.5V) and, maybe, that's the defining property for rechargeable type and capacity? Lithiums would be 1.5V but their voltage is likely to remain stable until near the very end, meaning that a drop-off would not be measured until it's too late to report low state of charge. On the other hand the battery state may be a function of the signal strength received by the bridge(?)

I could cope with a once-a-season replacement regime but my hasty choice of eneloop was to overcome the need to buy fresh batteries so frequently. I'd suggest that simply keeping an eye on those valves that are flagged as 'failing' might see you through a season without changing them after all.