a different kind of charging question.

[Bob S]

I've had problems with my Nicro Solar Vent and I think it has to do with battery life. I bought through a local Radio Shack a 2 pack of 1.2V 3500mAh rechargeable batteries. but the one I replaced didn't last very long. I read the backside of the package and it does say to "charge before using".

Can I use my Mastech variable DC power supply?

• Adjustable outputs: 0-30V and 0-3A
• Line regulation: CV <= 0.01% + 1 mV, CC <= 0.2% + 1 mA
• Load Regulation: CV <= 0.01% + 3mV, CC <= 0.2% + 3 mA
• LCD reading accuracy: +/-1% for voltage and +/-2% for current
• Protection: constant current and short-circuit protection

If so, Radio Shack told me @ 1.5V will charge at a rate of 20Ma/hr.
I have searched the internet and can't find a charge rate.

Any suggestions?

 

[dkbay]

We have one in each head and also have issues keeping them going. Not sure if the solar top is the weak link or if the solar batteries are the culprit. Thinking it's time to contact the mfg. for their suggestions.

 

[srhummer]

Have 2 fans mounted on my boat - charged them up by not turning them on for a few days while they were in the sun. One has died after 3 years but it is not the battery - I swapped batteries and both batteries powered the one that works, niether would power the other. I replaced with a new one and have old one at home to open up and see if a wire has come loose. I read that in an old post on this site. Good luck with it!

 

[Mike B1026]

Might want to Google those. They have had issues, especially the newer / cheaper models from China I believe. There are a few posts on how to fix them.

 

[Maine Sail]

Bob,

Your Mastech is much to big to charge those but Wal*Mart and many other stores sell C & D battery chargers.. In the winter those batteries perform horribly, plus the motor slows down due to the bushing grease getting more viscous and you have less solar gain. All in all running them in the winter is just bad Juju.... I replace my batteries each spring and use the Radio Shack cells. I buy the largest mAh version I can find.

The new Nicro solar vents are not nearly as reliable as they once were. :cussing::cussing: I would suggest turning them off in the winter if you want to get any sort of decent life out of them..

 

[Bob S]

I was curious and I started playing. I will check out Walmart for a charger, thanks.
I have a few C size 1.2V 3500mAh NiMh Radio Shack batteries.
I put onr on the Mastech this afternoon for about an hour. After reading Wikipedia I needed to get about 1.4 to 1.6V in order to charge. To get to 1.5v I had to pump around 1.6a (or .5C). I closely monitored it for heat as NiMh batteries are near impossible to know its state of charge. Am I correct in my understanding that 1.6a = 1600mAh? This should charge this battery in a few hours.

The admiral and I where up at Sugarloaf this past weekend. A bit icy but I hear they are getting around 2' in this storm. The recent snow has me back in ski mode

 

[JohnShannon]

The no-brainer way to charge NiMH is C/10 for 12 hrs.
C/10 is a low enough charge rate that even a fully charged NiMH can tolerate it.

in your case 350mA for 12hrs will do it.

12 times C/10 is 1.2C so for sure the battery is full.

Charging faster than C/10 requires more sophisticated termination.
If you poke around battery websites you can find lots of info

 

[Bob S]

John,

12 times C/10 is 1.2C so for sure the battery is full.

Are you saying this battery is fully charged? It's been sitting in my office for at least 1 year and who knows how long it sat at Radio Shack.
I am correct in 350mA = .35amps?
because I need to crank it up to 1.6 amps (1600mA) to get to 1.5V means it is fully charged?

Thanks
Bob

 

[JohnShannon]

No I am saying absent any sophisticated charger, the way to insure a NiMH battery is fully charged it to charge it at C/10 for 12 hrs.

In your case 0.35A.

Other charge terminations are based on things like temperature rise, rate of temperature rise, negative going voltage allow for faster charge rates (or require them)

The best way to determine the state of charge of a battery like that, is to discharge it, keeping careful track of the output AHr. Once the battery is discharged look at how many AHr you got out of it and compare it to the battery rating. That will give you a very good idea of how charged the battery WAS.

 

[Bob S]

John, battery technology is an interesting science. C/10 is what Battery University and Wikipedia listed as trickle charging. I'm still going to Walmart and buying a charger. Lot easier.

Thanks for the response! You're up early!

 

[Forrest15112]

I have had very good results with rechargeables of all types from these guys. They have packages of common sizes that include chargers. I use them in remote controls, clocks, flashlights, etc. They are typically higher capacity and much cheaper than what is available in stores like RS & Walmart.