Evohome Battery replacement

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  • Tractorboy
    Automated Home Jr Member
    • Nov 2015
    • 22

    Evohome Battery replacement

    Hi,
    Do the battery operated devices (radiator valves, room thermostats and hot water thermostats) need to be 'reset' in any way after battery replacement, or do I simply remove old batteries and replace with new? Also, with the radiator thermostats (HR80), should I remove the complete unit or just the top part when replacing the batteries?
    Thanks
  • Mavis
    Automated Home Ninja
    • Oct 2014
    • 322

    #2
    I have HR92s and a DT92 and both were straightforward swap the batteries over without having to reset anything.

    Comment

    • G4RHL
      Automated Home Legend
      • Jan 2015
      • 1580

      #3
      Just prise off the end cap, you don't need to take the whole unit off to change batteries although I think it easier doing so. Just remember to turn the black wheel in the bit attached to the radiator fully anti-clockwise before putting the control head back on.

      Comment

      • HenGus
        Automated Home Legend
        • May 2014
        • 1001

        #4
        The instructions aren't that clear. I assume that the reference to the notch is to ensure that the little black wheel isn't damaged. Presumably, best advice would be to replace the cap from the front to the back. I confess that I removed the TRV head from the radiator before removing the cap.

        Comment

        • G4RHL
          Automated Home Legend
          • Jan 2015
          • 1580

          #5
          Not sure anything is wrong taking the TRV off to replace the batteries. I have to do that with one of mine.

          Comment

          • Evo
            Automated Home Lurker
            • Nov 2015
            • 8

            #6
            Hi you can replace the batteries on or off the rad. I have done mine off the rad. Make sure you don't knock the lock switch back on with it off the rad, as it will prematurely start the cycle process. When I have done this, I have just pulled the batteries and started again.

            Comment

            • paulockenden
              Automated Home Legend
              • Apr 2015
              • 1719

              #7
              Has anyone tried using Eneloop (or equivalent low self-discharge) NiMh batteries rather than Alkalines? You can get 2450mAh versions these days, which is equivalent to an 'average' Alkaline battery.

              Not cheap though...

              Comment

              • HenGus
                Automated Home Legend
                • May 2014
                • 1001

                #8
                Originally posted by paulockenden View Post
                Has anyone tried using Eneloop (or equivalent low self-discharge) NiMh batteries rather than Alkalines? You can get 2450mAh versions these days, which is equivalent to an 'average' Alkaline battery.

                Not cheap though...
                I have a box full of these which I use with such things as Apple keyboards etc. I find that they are great for high usage over a short time but not do good when left used; for example, in a torch. Bulk batteries are pretty cheap: £10 for 40.

                Comment

                • IvanOpinion
                  Automated Home Jr Member
                  • Dec 2015
                  • 48

                  #9
                  The low self-discharge rechargeables are designed to hold their charge better. I use some in my bicycle lights and I can't remember when I last had to change them. I'd say a couple of years ago.

                  Like Paul, I was wondering if they would work for Evohome devices. The problem might be that alkalines start with a voltage of 1.5V, whereas I understand rechargeables are 1.2V, so some devices require a higher voltage than the rechargeables can deliver. (Voltage on alkalines drops quite rapidly, however, so some devices think an alkaline is empty when in fact it has plenty charge, but its voltage has dropped too low. Rechargeables show a much more gradual decline in voltage.)

                  I see you can set the Evohome devices for different battery types, so perhaps this means that if you set them to rechargeable setting they can cope with the lower initial voltage. I'll probably give this a try when the original alkalines peg out.

                  Comment

                  • paulockenden
                    Automated Home Legend
                    • Apr 2015
                    • 1719

                    #10
                    NiMh is one of the setting options.

                    P.

                    Comment

                    • HenGus
                      Automated Home Legend
                      • May 2014
                      • 1001

                      #11
                      I am still not sure how the sums work out. My original batteries are now over 18 months old. I am still showing 2 bars of charge on some HR92s. Enloops cost about £1.50 plus for each battery. I have 40 Duracell Industrial batteries sitting on my shelf which cost about £10; i.e., 25p a battery. The crossover point in terms of cost is about 10 to 12 years - assuming Honeywell is right when they say a bog standard AA battery will last 2 years. I have a number of Enloops that I use for various things so I may well take a look at how long a fully charged battery lasts in a HR92 environment. I doubt that they last as long as a standard AA.

                      Comment

                      • IvanOpinion
                        Automated Home Jr Member
                        • Dec 2015
                        • 48

                        #12
                        Good point. The payback period might be quite long. I've saved £100's on batteries for things like digital radios and Wii remotes, because they would go through alkalines quite quickly. But if they last 2 years...

                        There's also the hassle factor. If the rechargeables need to be replaced more often in Evohome, that's another mark against them.

                        Comment

                        • IvanOpinion
                          Automated Home Jr Member
                          • Dec 2015
                          • 48

                          #13
                          Does anyone know what is the minimum alkaline voltage that Evohome devices require? This could affect which batteries will last longest and cost less per year.

                          I tried looking for tests with very low drain, but the best I can find is Which? magazine and this website, which shows the life depending on the voltage you consider to be "dead": www.batteryshowdown.com/results-lo.html They both assume constant low drain, so they are still exhausting the battery over a day or a few days. So I don't know if they tell you much about how long they would last with the tiny demands of Evohome.

                          Looks like the key factor is buying at the cheapest price per battery. The Ikea ones are currently 15p each.

                          Comment

                          • IvanOpinion
                            Automated Home Jr Member
                            • Dec 2015
                            • 48

                            #14
                            Actually, having looked into this a bit more, I'm thinking alkalines should be avoided altogether, because they tend to leak. (Source: http://michaelbluejay.com/batteries/disposable.html) That would ruin a device that cost £50-100. So I'm going to go for lithium or NiMH rechargeables.

                            Comment

                            • rotor
                              Automated Home Guru
                              • Aug 2015
                              • 124

                              #15
                              Hmmm... From the linked article: potentially lose a finger with an exploding Lithium battery vs. the equally minuscule chance of ruining a £50 device. Let me think...

                              I know Alkalines do leak, but in my experience only after many years, so as long as you insert them fully 2 years before their "best by" date, you should be completely fine.

                              @HenGus analysis above is spot on, rechargeables do not make sense in low-drain scenarios like the HR92. And replacing rechargeables more often will lead to a higher chance of you breaking the HR92 (removing that top requires scary amounts of force).

                              Edit: wow, Lithium batteries are really expensive!

                              Comment

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