Batteries in 2812 wind sensor

[kokketiel]

My wind sensor stopped working a couple of weeks ago and after taking it down and taking it apart last night, I found the problem.  The rechargeable alkaline AAA batteries in the sensor have leaked and they are not not charged anymore.  I temporarily replaced them with regular AAA to see if the sensor still works.  I went to BatteriesPlus today to get a new set of batteries, but was in too much of a hurry to check what I bought.  It turned out I got NiMH batteries, and not rechargeable alkaline.

Does anyone have any experience with changing out the batteries?  I am worried that the NiMH will not handle the cold as well as alkaline, but I am by no means a battery expert.  I am also wondering if the solar charging circuit will work for the NiMH.

For what it's worth, the old batteries were La Crosse branded.

[DanS]

The NiMh batteries should work o.k. with the cold. It's the reduced amount of time NiMh's can maintain enough power to operate the anny between charges that may give you outages. That is, the rechargeable Alkalines (RAM's) charge up to just over 1.5 volts each where the NiMh type will go up to just over 1.2 volts each. If you have several overcast days in a row with no direct sun then your anny may start dropping out sooner with NiMh's. I ran tests on mine using regular, purposely drained, AAA's to see where it would drop out. It continued to operate until battery voltage got down to around 2.3 volts (both batteries in series) and then started seeing intermittent communications from it. When I replaced the batteries with topped off RAM's the anny stayed up and ran for just over 3 days/nights with no sun. It also takes at least 1 full day of direct sunshine on the solar panel to fully charge depleted RAM batteries. The manual states using at least a 60 watt bulb to start off but this doesn't fully charge them, just brings them up enough to get started.
Hope this helps.

Dan

[kokketiel]

Thanks for the reply! 

The longer lasting charge was the main difference I saw while researching.  Unavailability of RAM's forced me to go with the NiMH.  I charged then up overnight in a wall charger, and put the sensor back together and up on the roof earlier today.  We'll see how well things work.  It is currently overcast and rainy, so I guess it's a good test of how long the batteries last and if they will get charged up again . 

It's not that bad to open the sensor and replace the batteries, so if these last a year, or don't work out, I can always source some alkalines from Amazon and replace them.

[DanS]

Thanks for the reply! 

The longer lasting charge was the main difference I saw while researching.  Unavailability of RAM's forced me to go with the NiMH.  I charged then up overnight in a wall charger, and put the sensor back together and up on the roof earlier today.  We'll see how well things work.  It is currently overcast and rainy, so I guess it's a good test of how long the batteries last and if they will get charged up again . 

It's not that bad to open the sensor and replace the batteries, so if these last a year, or don't work out, I can always source some alkalines from Amazon and replace them.

Sounds like a plan.   I guess you found out already that the wind vane has to come off before separating the two halves of main body or you can damage part of the optical reader inside. Did you add a small dab of sealant (RTV, silicone, etc.) around the solar cell and case rim for leak insurance? I have been lucky with mine but heard of others who have had leaks so I did mine anyway. I would be interested with your results using NiMH's over time to add to my notes.

[kokketiel]

I guess you found out already that the wind vane has to come off before separating the two halves of main body or you can damage part of the optical reader inside. Did you add a small dab of sealant (RTV, silicone, etc.) around the solar cell and case rim for leak insurance? I have been lucky with mine but heard of others who have had leaks so I did mine anyway. I would be interested with your results using NiMH's over time to add to my notes.

Mine showed no trace of weather getting inside.  I was careful to make sure the seal was seated properly.  I guess I did damage the optical reader, as I had la loose piece of L-shaped plastic that looked like it fit over a light and goes behind the slotted disc attached to the weather vane for direction readout.  I used a piece of blue tack to keep it in place when assembling the unit, and the wind vane direction seems to work fine.

For interest sake, how do you remove the weather vane before opening the case?  Does it just pull off?

[DanS]

Yes, it has a small weather cap you pry off that reveals a tiny phillips head screw. Once that is removed the vane separates straight up off a keyed shaft. It's snug but working upward all around it will free it.

[AbuMaia]

Kokketeil, how long did the original batteries last for you before they leaked and died?

[kokketiel]

Kokketeil, how long did the original batteries last for you before they leaked and died?

A year and a few months. 

I have actually replaced the NiMH batteries today with rechargeable alkaline batteries that I got of Amazon.  As I suspected, the NiMH batteries did not handle the cold well.  Whenever the temp dropped below around 40 or so at night, the wind meter would stop sending data.  I am hoping the replacement alkalines will fare better.  We'll soon see, I guess.

If I have to wager a guess as to the NiMH problem, it would be that they don't charge up to the same voltage as the alkalines, and the cold causes the voltage to drop below what the optical sensor needs to operate.

[kokketiel]

...check the local hardware (Lowes, Home Depot, Ace, etc.) stores for replacement "night-light" yard light LED batteries...sometimes labelled "solar" batteries...they're rechargable alkaline, not NiMh, as supplied with most of the night-light, solar-powered, yard lights.

Our closest Lowes sells NiMH and NiCd batteries in the yard light / solar batteries department.  That's different from the rechargeable alkaline batteries that shipped with the wind sensor.  I would think that NiCd batteries are the worst kind to use for this application, due to memory effect and cold.  We'll see how long my supposed rechargeable alkalines hold up.

[DanS]

Mine are the original alkalines put up in Dec. 2009 and still hanging on. We don't get the cold temperatures but 3 or 4 days in a row overcast during the rainy season happens a lot and the batteries have been holding up so far.