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Replacement batteries?

Posted: Sat 10 Oct 2020 4:56 pm
by clarets7
Hi, I've got Watson 1080 (? well maybe) that was bought for my 60th birthday just under 6 years ago. The batteries are no longer holding any charge, so I was wondering what people have replaced them with? Mine has the solar pod, and the batteries say they are 1.5V Alkaline rechargeable. Would ordinary NiMh rechargeables be ok or is the voltage too low?

Re: Replacement batteries?

Posted: Sat 10 Oct 2020 5:50 pm
by Mapantz
They would probably work fine, but it's overkill to use NiMH's in a weather station as they're more suited to use in high power devices.

Re: Replacement batteries?

Posted: Sat 10 Oct 2020 10:09 pm
by Super-T
NiMh voltage is too low.

I am trialing 1 x Lithium 3.6Volts AA with a dummy battery as well but then again I don't have a solar pod doing the recharging. Anyone know if the lithiums will stand being charged by the solar pod voltage?

Using a spare transmitter and base station for the trial.

Lots of power available and hasn't blown up the transmitter with the 3.6 volts, yet.

Re: Replacement batteries?

Posted: Sun 11 Oct 2020 7:09 am
by clarets7
I was toying with the idea of using an old phone battery, but not sure again if the recharging circuit in the pod would deal with that very well, but anyway they are too big. I've got a couple of NiMh batteries in at the moment, only been in 12 hours, in the dark, voltage is 2.72V. It is working but the receiver is only in the same room! Are replacement batteries not available anymore, same type as the original?

Re: Replacement batteries?

Posted: Sun 11 Oct 2020 12:34 pm
by AllyCat
Hi,

It might depend if it's just a "charging" Solar Pod (WH-208x ? ) with I believe no "electronics" or a "Solar Data" Pod (WH-308x) which has a voltage regulator.

IIRC the "charging" voltage from the WH-308x Solar Pod is around 3.0 volts (a 3.3 volt low quiescent current regulator feeding through a Schottky diode to prevent reverse leakage), which is marginal even for the original "Rechargeable" Alkalines. The battery manufacturers' recommendation is that these should never be allowed to fall below 3 volts. But there's almost no difference between "ordinary" and "rechargeable" Alkalines (a misnomer if ever there was one), so you could just replace them with reasonable quality normal (primary) Alkalines.

If you do want to use rechargeables, then a pair of AA NiMH is probably the best choice. The final charging voltage for NiMH tops out at around 1.5v per cell and that little PV panel is not going to give enough current to damage them. The only issue is that the "Low (Transmitter) Battery" Icon might come on, (if that irritates you) and the wireless range might be a little reduced. Other possibilities are a pair of NiZn AAs (nominally 1.6v each) or a singe LiFePO4 (Lithium Iron Phosphate) with a dummy (short-circuit) both in AA profile, which also gives nominally 3.2 volts. But I certainly wouldn't expect a 3.7 volt lithium cell (whose charging should top out at 4.2 volts) to be satisfactory in long term.

Cheers, Alan.