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Cheap batteries. 19c per battery for pick up. 29c per battery for one 50 pack delivered.
Eveready AA 50 Heavy Duty Batteries $9.56 Pick up or + $5.06 Delivery @ The Good Guys eBay
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Offering single use batteries to the Eneloop crowd.
How quaint.
I'd love someone to post a cost analysis of the eneloop (particularly using solar power to charge them..).
It'd also be very useful for ozbargain to post something about everdeady vs duracell vs aldi vs eneloop as a bit of a 'rule of thumb' in terms of the economics of which is a better short vs long term deal.
I picked up a 30 pack of AA from Aldi yesterday for $5. Really just to use for the hall sensor light that has no power point near it which chews 4xAA every couple of months because it gets triggered a fair bit every night by cats walking up the stairs..
'… (particularly using solar power to charge them..).'
This got me wondering, does anyone have a smart charger for 'standard size' (AA, AAA, C, D, 9V) batteries that can run on solar power? I suppose it would not be wise to have the actual charging unit/batteries sitting in the sun while they're charging, so a solar panel (sat in the sun) would be attached to the unit (sat in the shade) via a cord? Or maybe there is no demand for such a thing, because the same end-point could be achieved by using a smart charger that is powered via an AC adapter w/cord (rather than a built-in 120-240V plug), with a solar panel hooked up to the charger instead of the AC mains adapter?
For example, I have an OPUS BT-C3100 which I love (I would actually mary it if it was legally possible… maybe one day here in Australia we will have marriage equality), and it requires 12 V 3.0 A to power it. Does anyone out there (camper/hikers maybe?) have experience with powering a smart charger such as this via a 'third-party' solar panel, rather than mains power?
Does anyone out there (camper/hikers maybe?) have experience with powering a smart charger such as this via a 'third-party' solar panel, rather than mains power?
The easiest way is to use the solar panel to charge a 12V lead-acid or gel battery, through a solar regulator, and run the charger from the 12V battery.
The more difficult way is to start with a 24V solar panel, and use a switchmode supply to regulate it down to 12V. But that can be more expensive than the 12V battery way, because you have to allow for the possibility of clouds during the charge cycle. Moderately heavy cloud drops the output power of solar panels to about 20% of their full output power, so to guarantee a supply of 36W (12V @ 3.0A), you will need a 200W panel or thereabouts.
With the 12V battery method, you can use a 10W-20W panel to charge the 12V battery (over about two days of sunshine) and then keep it topped up. A pre-used car battery will probably do nicely, as long as it hasn't actually shorted internally, and hasn't been left flat for more than a couple of days. It may not be able to start a car (requiring a peak current of about 900 Amps), but it will easily power your 3A charger for at least ten hours. And it means you can use your smart charger at night!
Check first to see if your charger can handle more than 12V. A car battery at full charge is 13.8V nominal. If your charger comes with a cigarette-lighter adaptor, use that and you'll be fine.
Awesome response, thank you so much for taking the time to compile it. MUCH appreciated!
For safety, I recommend keeping the car battery in a "battery box" like this:
https://www.whitworths.com.au/battery-box-smallAnd also put a 10A fuse in the power output line from the battery.
It's frightening how quickly a car battery can release power. If you accidentally short something between the battery terminals, it will usually melt. Instantly. Take extra care when tightening the battery terminal clamps, spanners and screwdrivers conduct electricity VERY well.
Oops, I just looked again at my calculations, and it will take longer to charge the car battery than I said.
On a sunny day, a non-tracking solar panel will achieve the equivalent of 4-5 hours of full power. So a 20W panel will put out 80-100 Watt-hours in a day.
A typical small-car battery contains about 550 Watt-hours of energy, and charging isn't a 100% efficient process, so it will take about a week of sunny days to charge the car battery from flat (if you ever let it get flat).
Russ - I know you did sums on a 20W panel but I was looking at using a 200W panel to do something similar.
Do all your points still work ? e.g
200W panel - use a solar regulator to charge a 12V battery, then use something to run off the battery (at 12V) or an inverter to go from 12V to whatever voltage you need (48V, 240V..)
- use a battery box for the battery
- use a fuse (20A?)
Do all your points still work ?
They do. I have a stand-alone solar system with ~500W of panels feeding into two 38Ah gel cells, wired in series so I get 28V. It powers some of the lights in my house, and I also have a 600W sine-wave inverter to power my fridge during blackouts.
28V is better for long wire runs, and for high power, as you can use thinner-gauge wire. If you run lights on the end of 25m of cable, you'll lose maybe 6V in the cable, that's half your voltage gone if you're running a 12V system! For the same wattage at 24V, the current is half, the cable voltage loss is halved (3V), and losing 3V from 24V is tolerable.
Don't go above 28V, fuses and switches that handle more than 30V DC are rare and expensive.
Get a good solar regulator. I used this one, but bought elsewhere at a lower price:
https://www.jaycar.com.au/12v-24v-30a-mppt-solar-charge-cont…My solar panels have an open-circuit voltage of 47V, 36V under load. That way the panels are always at a higher voltage than the battery pack, so can always charge. Don't use 12V panels to charge 12V batteries, your charging current will be horrible.
If you're going to have an inverter, locate it as close as possible to the batteries. Shorter cables = less loss, and you can afford to use thick cables for short runs.
The fuse is mostly to protect against accidental short-circuits. As long as it blows quickly for a short circuit, you can use whatever fuse you like. But fuse holders for fuses larger than 10A are harder to obtain, and fuses get quite hot when the current through them is close to their rating, so your fuse holder may need to dissipate quite a lot of heat.
My stand-alone system has been running since 2013, and I haven't had to do any maintenance on it. Of the lights on the house, one is in the hallway, and I used to switch it off during the daytime. I don't do that anymore, I realized that the light wasn't discharging the batteries whenever the sun is up, and I have an excess of power to charge the batteries, so now that light stays on 24/7/365.
Thanks for taking the time to share - appreciate the comprehensive replies!
I'm a little surprised that above 30V is expensive - coming from a telco background I've seen a lot of 48V and assumed it was common to find gear to support that (as well as 24V, 12V and 6V). I've learnt something today..
I've assumed that even though thicker gauge wire is more expensive you may as well pay the extra (1 time) cost in the interests of reducing loss..
I'm just about to pickup 8 x 200W panels for around $450 - mainly for me and my neighbour to experiment with running standalone power in various sheds etc.. and may have a source of 12V lead acid batteries - so hoping to learn a few things by building stuff..
If you're wiring up a shed for low-voltage DC, and want very low voltage drop in the distribution wiring, consider using copper pipe instead of copper wire. 1/2-inch copper pipe has about 30mm^2 cross-sectional area, for about $5 per metre. That's cheaper than wire that can easily be bought, although admittedly it's more difficult to install. You'll need a gas torch to join the pipes together, and sleeving.
3m lengths for $14.90 at Bunnings, might be cheaper from a plumbing supplier:
https://www.bunnings.com.au/kinetic-1-2in-3m-copper-straight…For insulation, maybe use 3/4-inch irrigation pipe, and use electrician's tape at the corners. Hold the pipe in place with 3/4-inch pipe stirrups.
We need more Eneloop deals,i find these above listed batteries good for kids toys and so do not have to worry where are all my Eneloop at.
Yeah exactly! When those crappy toys get left in the rain or taken to the Salvos, don't need to make sure my $2 Eneloop was left in it!
Please don't buy carbon-zinc batteries.
Varta alkalines from Bunnings are cheap and good.
How can you tell which ones are carbon-zinc ? I've noticed many manufacturers talk about being mercury free but other than nicad or lion or lipo.. i hadn't seen carbon zinc mentioned on packaging?
Usually "heavy duty" or "super heavy duty".
Alkaline batteries will always (?) say so.
Only $12 at reject shop without discount not looked elsewhere,what are these like?
I normally get the Varta AA Alkaline Batteries - 30 Pack from bunnings which im sure where voted good batteries a while back.
A 30 pack only costs $4.94 so you could get possibly 60 batteries for almost same price.
Im sure i used to pay 9.99 for these before.