solar powered battery question

[solarguy333]

Hey all,

I recently made a solar-powered cooler stereo (a Coleman cooler housing an old car stereo) for outdoor use. I also added a 12v outlet for RV accessories. The idea is to have a rechargeable portable solar setup that I can take camping. After a few days of testing and light use, the system seemed to be running great, but now I'm running into a strange problem: all my voltmeter readings, whether I take them directly from the battery terminals or from anywhere else in the circuit, have started to look very strange. Yesterday I got 11.6V, despite the fact that the battery was still able to run a stereo just fine. This evening I'm getting 18.6V, so I've turned the stereo off to prevent possible damage.

I used the following 10W panel:

http://www.amazon.com/dp/B004FWW1M4/ref=pe_385040_127541860_TE_dp_1

I then hooked that up to this solar controller:

http://www.amazon.com/dp/B00JKDZVRU/ref=pe_385040_30332200_TE_item

This is all to power/maintain the following battery:

http://www.ebay.com/itm/Chrome-12V-35Ah-U1-Deep-Cycle-AGM-Solar-Battery-Also-Replaces-33Ah-34Ah-36Ah-/291080513696

Have I done something wrong? Or is it more likely that I have a faulty component in the circuit? Does anyone have a guess as to whether the battery or the controller is the guilty party?

Thanks in advance for any help.

[solarguy333]

BTW - I have never charged the battery except with the 10W solar panel (via the controller). It has never been connected to a wall socket or another battery. So the extremely high voltage reading is strange to say the least.

I never tested the battery when it first arrived, only today after having run the system (without issues) for a few days.

[Wy_White_Wolf]

I feel you have 2 problems.

1. Solar panel to small for the load. Most likely the stereo pulls around 50 to 100 watts. You only have a 10watt panel. That's only enough to power it for about 10 minutes a day this time of year.

2. Either the charge controller is bad or you're taking the voltage reading on the panel side of the charge controller instead of the battery side.

WWW

[thastinger]

So far, you've just been draining the battery. A 10W solar panel is not going to recharge a 35Ah battery.
The 11.6V reading you took is the battery voltage
The 17V reading you're getting is what you should see at the input of the CC. Read the specs on the CC and see if it has a low voltage cutoff, your battery may be in too low a state of charge for the CC to work.
I'd recharge that battery with a plug in charger asap, you don't want it to sit in a discharged state for very long.
If you draw that battery down to 50% in a days use, then go buy yourself an 85W panel if you want to be able to fully recharge it in a single day.

[solarguy333]

I took the battery to an Autozone to get it checked. Turns out I was using a faulty voltmeter.

The actual voltage on the battery was 14v. Which is high but not crazy high, right?

Like I said, I've never plugged the battery into a wall charger. And I've run the stereo + pair of 6.5 speakers for over 30 hours at moderate volume since I rigged this up (over a period of a few weeks - not daily use).

So it looks like the solar panel is working fine to recharge the battery between uses? That's all I intend for it to do. I don't need it to recharge in a day, more like in a week or two.