Reddit mentions of Battery Tender 12V, 270mA, 5W Solar Battery Charger

Thank you, didn’t see it.

So honestly, super easy project that anyone could do, I called it diy but it’s 99% just connecting wires. For speakers, I’d recommend scouring craigslist for a set of bookshelf speakers. You should be able to get a good set for under $30. The most important thing to look at is the sensitivity rating and the impedance of the speakers. Sensitivity is essentially how loud the speaker gets with less power running to it. Get the speakers with highest sensitivity (preferably 88+) and a low impedance (4 or 6 ohms if you can) if you want to be lazy, these are a damn good value. You could probably find better on craigslist but if you don’t trust your speaker buying go with that pair.

Next step is the amp. There are two pretty easy options that come immediately to mind. First, the “diy” amp you can go ahead and install this in one of the speakers. Parts express has videos showing you how this could be done. The second option and the one is probably recommend is this as far as I know it’s the same amplifier just this one comes housed, there may be small differences.

The final problem is how to power it, and once again you have options. The two basic options are either off some double a batteries or off of a large lithium ion battery pack. Between these options I’d say just go with the aa batteries for cost and just come down with a whole bunch (hit up Costco or bjs and buy like two packs of them). With the first amplifier you’ll have to buy a seperate battery pack to held them, with the second it actually has a place for the batteries already. Now, the coolest option but more expensive is what I’m hoping to do this year. Your car battery is actually 12V dc, exactly what you need. Therefore you can power the amps off of your car battery, just make the connections when you’re there and leave the wires running out of the hood with some quick disconnects (not necessarily this one but something similar) so that it’s easy to take down and set up every day. If you go with the second amp you will need the correct plug. Now, to ensure you don’t kill your car battery, you’ll need a solar panel, preferably with a with a trickle charger. I believe this is probably the best option. You can go cheaper but this is a well known brand so I trust it not to screw up my cars battery. This can sit on your roof all day if you have a tall car. Still do something to make it an inconvenience to steal. If you have a short car just leave it on while your there and use quick disconnects again to make packing up easy, or run the wires inside the car when your gone and have it charging through a window.

Hopefully this all makes sense, it seems like a hassle but for about $100 you’ll have a damn good sounding festival set up that you could take home and set up in a room and love the sound just as much at home as at the festival- I’m telling you, bookshelf speakers sound soooooo much better than your average Bluetooth speaker, just ask r/audiophile, and it’s a cool conversation piece while there. Anyone has any questions I’m happy to help!

I'm not an EE, but I know a bit about batteries. Low amp is fine, better for overall battery life. But, lead acid batteries get some kind of build up on the cells that needs to be zapped off with high-amperage from time to time. Solar charge controllers and automatic battery tending devices will go through a number of different cycle types throughout a month, for the health of the battery.

Your battery is probably damaged by now if it's been depleted several times. Best thing you could do besides buying a new battery is get some kind of trickle charge setup, so that it stays topped off. Whether it be a wall plug charger, or solar charger.

Secondly, open the battery and make sure that the lead cells are fully submerged. Add distilled water if the cells are exposed to atmosphere. Some car batteries are sealed and not able to be maintained in this way.

**Edit. Check this out, Battery Tender 021-1163 5W Solar Maintainer https://www.amazon.com/dp/B004Q83TGO/ref=cm_sw_r_cp_apa_ypxAyb2SXVHSN

These are easy to set up.

Battery Tender 021-1163 5W Solar Maintainer https://www.amazon.com/dp/B004Q83TGO/ref=cm_sw_r_cp_apa_n0.pzbQQMHT2C

I've been very happy with the Battery Tender brand. I have a friend who uses this on his boat (it's designed not to overchage).

http://www.amazon.com/Battery-Tender-021-1163-Solar-Maintainer/dp/B004Q83TGO/ref=sr_1_1?ie=UTF8&qid=1416250584&sr=8-1&keywords=battery+tender+solar

We use a traditional (plug in) tender on my wife's car. A fairly common setup is to permanently connect the terminals to the battery and then run the leads somewhere more convenient, like out the grill or fender. It makes connecting/disconnecting a lot more convenient.

http://www.amazon.com/Battery-Tender-081-0069-6-Terminal-Disconnect/dp/B000NCOKZQ/ref=pd_bxgy_auto_text_z

On a side note, for those at apartments without battery tenders I highly reccomend the solar battery tender. It's saved my ass...well...5 times now.

https://www.amazon.com/Battery-Tender-021-1163-Solar-Maintainer/dp/B004Q83TGO

Car like that? Try something like this: https://www.amazon.com/Battery-Tender-021-1163-Solar-Maintainer/dp/B004Q83TGO