Solar battery charging/LED setup

Post anything about batteries here. Lead acid, rechargeable, whatever.
dyeager535
Posts: 2
Joined: Fri Nov 09, 2012 12:15 pm

Solar battery charging/LED setup

Post by dyeager535 » Fri Nov 09, 2012 4:49 pm

So first, thanks for inviting me over! You really seem to stay on top of your posts, and your videos are fun to watch.

I haven't done a TON of research on it, but from what I did find, if not careful, slow charging NiCd and NiMh batteries can be harmful to them. The belowsetup has been running for two years on the same batteries thus far, so the "slow" charging so far (at best I'm guessing 300mAh into 5000mAh batteries) doesn't seem to have hurt them. I am fairly confident however that the storage batteries will be cooked in the summer, after I increase the charge current. I have yet to find a very cheap/small charge controller that will stop the batteries from overcharging. If I could get my hands on a small one of those, I'd be confident the batteries would last just as long as they have so far.

I haven't gotten my 410mA 2V panels yet, but if I ever got really good sunlight (not likely in winter in the NW) once my "array" is built, I'll have 1A going into 5000mA rated storage cells. If nothing else, I'll have quadrupled the available current, even if it's half of that based on sun exposure, it will be better than it is now.

What I did was take a couple of these http://www.harborfreight.com/solar-spot ... 95388.html and disassembled them. These lights are/were unique in my opinion because they do not use a photocell to control circuit operation...once the setup detects voltage from the solar cell, it shuts off the light, and starts charging. Also, the little solar panels are just screwed to the light housing...you can remove those and screw them directly to a board. There is an on/off switch that is easily bypassed/removed. The three LED's are attached to a very small circuit board that would be easy to mount/use somewhere else. I don't know how it could be correct, but I measured the output to the LED's at tenths of a volt...I expected to see somewhere around 3V. I verified multiple times...

I mounted two of those panels to a board, and stuck it on my roof. Using scrap telephone wire (just a long term experiment at this point) I extended the leads from the panels to a water-resistant battery box I made (repurposed a bad cordless drill battery housing) which houses two Harbor Freight NiMh 2500mAh D cell batteries. From the box come the leads FROM the batteries, which powers the three LED circuit board from the donor light. The circuit board that controls operation is contained in the battery housing.

At full brightness these LED's provide a very effective night light through the prismatic glass in the bathroom. Unfortunately with the two original panels, and our dim light during winter, the batteries get hardly any charge. I have some AA's that are 2700mAh that I will probably use in place of the D's, which will shrink the size of the battery holder by quite a bit, while increasing capacity.

The eventual intent is to mount the panels somewhere a bit higher with more exposure (like one of my large trees) and bury the cable/control box. Original intent was a solar powered driveway light, but I may stick with the LED night light. Really handy this time of year, being up before light, and going to bed well after dark.

techman
Site Admin
Posts: 1329
Joined: Thu Dec 22, 2011 11:49 am

Re: Solar battery charging/LED setup

Post by techman » Tue Dec 11, 2012 12:07 pm

Hi, first, sorry for being a bit late on the reply. Sort of embarrassing after your huge compliment. I have been out for the better part of the month. Went back to visit my parents and then spent over a week in the woods hunting and living off the land for some real Indian type of experience.

I hope your project is doing well. I only have one question tho, you said "slow charging" can be harmful. I think you meant the opposite?

I have read that with a slow charge, it is hard to ruin nicads, even if left on a bit longer. In my experience, these little batteries have a nice long life and are very forgiving as long as you totally drain them before recharge each time.

When you do make the final setup, use the thickest wires you can get which will reduce resistance in the wires, which causes power loss. This would actually help a lot in your test phase.

The LED driver in those little solar lamps uses a sort of step up booster to drive the LEDs. Normally they have a single 1.5 volt battery in them, but step up to 3.2 volts to drive the LED. The output is probably unfiltered AC voltage, which is why you measured such a low voltage to the LEDs.

Solar98632
Posts: 246
Joined: Tue Jan 15, 2013 3:10 pm

Re: Solar battery charging/LED setup

Post by Solar98632 » Wed Jan 23, 2013 10:50 pm

hmm I amnot sure how "Chargers Work" I have Radio Shack charging system it can charge a lot of batteries in a about an hours time.
I am not sure if it has anything to do with "Charging" or not but I hear a definite tick, tick, tick as it charges various batteries the thing says it can charge up to a 3 volt battery that is a AA. It is the Enercell Charging unit .

At any rate, I I think that slow charging a battery is a myth.
Here are some facts I do Know.:

NiMH and NiCd batteries self discharge at a MUCH faster rate than alkaline batteries. In fact, at "room temperature" (about 70 degrees F) NiMH and NiCD batteries will self discharge a few percent PER DAY. Storing them at lower temperatures will slow their self discharge rate dramatically. NiMH batteries stored at freezing will retain over 90% of their charge for full month. So it might make sense to store them in a freezer. If you do, it's best to bring them back to room temperature before using them. Even if you don't freeze your NiMH batteries after charging them, you should store them in a cool place to minimize their self discharge.



Quick charging NiMH batteries will reduce their life.

For practical purposes with batteries that are designed to be quick charged, for example, Sanyo, GP, POWERhaus, that is not true.

It is important to use a battery charger that has been specifically designed to rapid charge NiMH cells.

Actually there is a much greater likely hood of reducing the life of a NiMH battery by using an "overnight" charger than by using a smart fast charger.

Overnight chargers rely on the fact that you will unplug them after a number of hours.

If you forget to unplug them they can continue to charge the batteries longer than they should.

Overcharging WILL reduce the life of batteries. From a strictly technical sense, a battery that is always slow charged will likely last a little longer than one that is always rapid charged. However, the difference is so small that it is not likely to be noticeable for most user

A battery with a capacity of 2,800 mAh can deliver a current of 2,800 mA for an hour

Assigning capacities to batteries can be very tricky, that's probably why you don't see capacity ratings marked on most alkaline batteries. When powering high drain electronic devices like digital cameras, computer peripherals, or portable music players, an alkaline battery will only deliver a small fraction of its rated capacity. A NiMH or NiCd battery is likely to deliver much closer to its rated capacity when it's powering high drain devices. This means that a NiMH battery with a rated capacity of 1800 mAh can take many more photos than an alkaline battery with a rated capacity of 2,800 mAh.

Info from:
http://www.greenbatteries.com/batterymyths.html

techman
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Joined: Thu Dec 22, 2011 11:49 am

Re: Solar battery charging/LED setup

Post by techman » Sun Jan 27, 2013 10:56 am

Good info. Battery chargers usually have a sort of computer control to measure the voltage while it charges and shut it off when its done.

grandads_shed
Posts: 12
Joined: Sun Jul 20, 2014 3:25 pm

Re: Solar battery charging/LED setup

Post by grandads_shed » Sun Aug 24, 2014 6:11 am

i would never put any batteries in a freezer ,, the formation of ice is water and will drain a battery

hi_tech_guy_18
Posts: 120
Joined: Tue May 07, 2013 6:46 pm

Re: Solar battery charging/LED setup

Post by hi_tech_guy_18 » Mon Aug 25, 2014 4:07 pm

You can get PCB/BMS/CMB/UPS board & DC-DC Regulated Converters
http://www.batteryspace.com/PCB/BMS/CMB/UPS.aspx" onclick="window.open(this.href);return false;

PCM or PCB ( protection circuit module or board ) is "heart" of Li-Ion battery pack. It will protect Li-Ion battery pack from overcharging, over-discharging and over-drain, therefore it is must have to avoid Li-Ion battery pack from exploding, firing and damage. For > 5 cells or 18.5V Li-Ion pack, you shall choose PCM with equilibrium function to keep each cell in better balance and good service life. For high voltage Li-Ion pack ( > 20 cell), you shall consider advanced BMS ( battery manage system) to monitor each cell's performance to ensure battery safer operation.


A battery management system (BMS) is any electronic system that manages a rechargeable battery (cell or battery pack), such as by monitoring its state, calculating secondary data, reporting that data, protecting the battery, controlling its environment, and / or balancing it. A BMS may monitor the state of the battery as represented by various items, such as:

Voltage: total voltage, or voltages of individual cells
Temperature: average temperature, or temperatures of individual cells
State of charge (SOC) or depth of discharge (DOD): to indicate the charge level of the battery
State of health (SOH), a variously-defined measurement of the overall condition of the battery
Current: current in or out of the battery

techman
Site Admin
Posts: 1329
Joined: Thu Dec 22, 2011 11:49 am

Re: Solar battery charging/LED setup

Post by techman » Tue Aug 26, 2014 9:11 am

You seem to the the man for tech gadgets. Here is something I have never seen and want to build.

I want to set up a solar battery charger for standard AA, AAA, C and D cell batteries. But I want to have an auto sensing and automatic control circuit build in. I have never seen such a thing.

I would greatly appreciate it if you could help me find a low cost one for DIY people so I can finish this project finally.

thanks in advance.

hi_tech_guy_18
Posts: 120
Joined: Tue May 07, 2013 6:46 pm

Re: Solar battery charging/LED setup

Post by hi_tech_guy_18 » Fri Aug 29, 2014 5:56 am

I use to have a Smart Battery Changer (it walked, someone who was helping me with a clear out throw it away by mistake)

it was micro controller controlled Ni-MH Ni-Cd + Dry Cell Refresh AA AAA Battery Changer (cant get it any more)
nice thing about it it was a Rare one that could "Refresh" Dry cells - Single Use Battery's allowing you to recharge them
- use to save a fortune in dry battery due it allowed me to re use Dry cells 10x more times (Energizer)
- even detected if a battery was bad.

it used a AC Mins Adapter plug instead of built in
- if you know about DC DC Converters Regulators then this is easily replaced

Example of the setup your looking for
Maha MH-C800S Precision Charger Dock for 1-8 Cell AA/AAA Battery

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http://www.amazon.co.uk/Maha-MH-C800S-Precision-Charger-Battery/dp/B001JK7SVE/ 
- LED Screen a Must
- Separate Power supply

You could hack Mod a

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http://www.amazon.co.uk/Energizer-Universal-Battery-Charger-Charging/dp/B0013DEJUK/
You just replace the AC Adaptor (Internal AC power converter) with a
DC DC Regulator that can control Both the Voltage + the Amps and tune it to the specs of the AC Adapters output
UK

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 http://www.amazon.com/DROK-Converter-Constant-1-25-25V-Regulator/dp/B00GZBHTG6/ 
USA

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http://www.amazon.com/DROK-Converter-Constant-1-25-25V-Regulator/dp/B00GZBHTG6/
- nice thing about Step down regulators it they Auto Shut off if the input voltage is too low and auto wake up if voltage get up again
- Also useful to know you can also use them to charge Between two Battery backs where the specs of one bank and the other bank are different
(you can finally have a Emergency lights only 2nd battery bank)

You can get Cell Size adapters
2x AA to D cell

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http://www.amazon.co.uk/Battery-Converter-Adaptor-Adapter-Holder/dp/B00HHN6QQA/ 
1X AA To C Size Cell

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http://www.amazon.co.uk/Battery-Holder-Converter-Adapter-Xbattery-2-case/dp/B00JWM6WJU/ 

hi_tech_guy_18
Posts: 120
Joined: Tue May 07, 2013 6:46 pm

Re: Solar battery charging/LED setup

Post by hi_tech_guy_18 » Sun Aug 31, 2014 7:22 am

Speaking on the subject DC DC Regulators

DadHav videos has recently covered them
https://www.youtube.com/watch?v=9YeFHQse-8o" onclick="window.open(this.href);return false;

This one a 3A

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http://www.banggood.com/DC-LED-Digital-Controlled-Step-Down-Driver-Power-Module-p-910096.html

techman
Site Admin
Posts: 1329
Joined: Thu Dec 22, 2011 11:49 am

Re: Solar battery charging/LED setup

Post by techman » Wed Oct 08, 2014 5:53 pm

I was browsing ebay last night for dc to dc step down inverters. They are between 1 and 3 dollars for low current modules. Perfect for small projects

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