Drayton Wiser central heating

[shagster]

Having had this system for a couple of years now it's OK, but the alkaline batteries for the rad valve units are indicated as in need of replacing when only about half the capacity is gone. So it generates large amounts of half-used batteries and I don't have enough other devices (e.g. torches) to put them in. Switching to rechargeables is cheaper but means they need to be replaced more often. It's a bit of a headache.

I wondered if anyone has experimented with the new lion AA batteries that are appearing:

https://www.amazon.co.uk/Henreepow-Rechargeable-Batteries-Capacity-Charging/dp/B0C8J4LDG1

Would they maintain the voltage for longer? They are quite expensive, so don't want to experiment.

Thanks!

 

[Mister Banks]

Not tried them but I can’t see how they can be cost effective at £4 each when I am paying just 55p for a non rechargeable battery which lasts 12-18 months in my Wiser TRV’s. It would take roughly 6-9 years to break even.

 

[pcaouolte]

The lion rechargeable AA batteries will work in a Wiser TRV but they will fail without warning as there voltage does not drop gradually like an Alkaline battery but will suddenly drop from 1.5v to close to 0v. When this happens the TRV will lose connection to the hub.

If the TRV was calling for heat when it loses connection to the hub the call for heat (and your boiler) will remain permanently on until you change the battery. If this happens at the start of a holiday you could use a lot of gas while you are away.

 

[polesapart]

How are you testing for "half the capacity gone"?

The symbol on the controller is not a literal representation of remaining capacity, rather flags up detection of a reduced voltage from the battery which occurs towards the end of battery life.

 

[pcaouolte]

The Wiser app does flag up a low battery quite early. It displays a warning message when the batteries get to 20% capacity, this is based on Wiser's voltage readings. The TRV will continue to run happily for more than a month whilst still showing 20% charge. It might be significantly more than a month, it will depend on external factors like room temperature, signal strength between the TRV and the hub, and the strength of the spring in the valve body.

 

[screamer]

There was a post about batteries for TVRs on the Drayton FB page not long ago, some were saying Energizer ultimate lithium batteries & Amazon AA batteries.
They were saying most change them out every year

 

[shagster]

The Wiser app does flag up a low battery quite early. It displays a warning message when the batteries get to 20% capacity, this is based on Wiser's voltage readings. The TRV will continue to run happily for more than a month whilst still showing 20% charge. It might be significantly more than a month, it will depend on external factors like room temperature, signal strength between the TRV and the hub, and the strength of the spring in the valve body.

Hi, I'm not saying you're wrong, but would be interested to know which batteries, which discharge curve you're using to estimate this, which voltage was measured, what battery make and so on because I didn't get a figure of 20% when I last calculated it, much closer to 50. Thanks.

 

[pcaouolte]

I have three TRV's using Energiser MAX alkaline batteries that are reporting low battery in the Wiser app at the moment. All three currently measure 2.6 volts for the pair of batteries (1.3v per battery).
I understand that Wiser TRV's report the following battery levels in the hub diagnostics which are available to Wiser support (these voltages are for the pair of batteries):
3.0v or more: 100%
2.9v: 80%
2.8v: 60%
2.7v: 40%
2.6v: 20% at this point the app generates a warning that battery level is low. You will need to replace them soon.
2.5v: 10%
2.4v: 5%
2.3v: 0%
I have not yet run any TRV batteries below 2.6v to see what happens at lower voltages but I will record the results when available.
I am not doing my own percentage calculations or using any discharge curves, I am following the percentages that Wiser use for their TRVs. I know that they use a different voltage to percentage calculation for room stats.