Is a charge controller necessary with VW solar panels?

[(unknown)]

I have a 3.2 watt VW panel that I am planning on using to charge up a 12 volt, 7AH lead acid battery, which is going to lead to an AC inverter to occasionally charge up my cell phone and other small electronics.  I took the cigarette plug from the panel apart and attached alligator clips to the wires.  I put what looks like a blocking diode(which was inside the plug) onto the positive wire.  My question is, does this diode just prevent backwards leakage at night, or will it protect my battery from overcharging as well?  Do I need to buy a charge controller?  Thanks alot.

[wooferhound]

you don't need an inverter if you plan on charging your cell phone. just use a car charger comming off of your 7ah battery. if your just going to charge other batteries from this system then you probably don't need an inverter at all.

you are right about the diode preventing the battery from feeding the panel when the panal is dark. The diode will not keep your battery from overcharging, but I don't think your panal is capable of overcharging that battery. you may think about adding more of those solar panals if the price is right.

[ghurd]

The charge controller was all that stuff inside the original plug.

It would have stopped overcharging and reverse current at night.

The panel is very capable of overcharging a 7AH battery.

I think under ideal conditions the panel can make about 275ma.

I had a VW PV with a bad controller connected to a full 7AH battery (12.67V), while experimenting with an intermittent 75ma load in less than ideal sun. In about 3 or 4 hours the battery was at 15.6V. Ouch.

If the original controller is no longer an option, maybe try a PB137ACV chip. It is just 3 wires to connect, and costs about $1 at a real electronics shop but they will probably have to order it.

Watch out for those cheap cell phone car chargers. They will kill your phone batteries.

G-

[bruce]

     I bought 4 of those VW panels, wired them in parallel into one larger frame, and used it to charge a car battery. After days the voltage was 15ish volts, alittle high, so I hooked up another battery to make the capacity bigger, and it will keep both of them charged up pretty high.

     There is no charge controller in that plug, only a diode.

                                            Good Luck, Bruce

[ghurd]

There must be a couple different kinds then.

Maybe thats why one of mine does not regulate.

This is how 7 out of 8 I have look inside. Maybe I just got lucky.

G-

[ghurd]

Not a great photo.

But that's 9 resistors, 3 transistors, 3 caps, 1 diode, and an 8 legged SMD chip!

G-

[(unknown)]

Yeah you must have gotten lucky!  Mine just had the diode inside a peice of red insulation, no circuit board.  Do you think Radio Shack would be able to order the PB137ACV chip?  I've been looking online but it seems that sellers are targeting mostly towards businesses ordering alot of them.

[ghurd]

Check your email

G-

[bruce]

     Wow, mine had nothing in there except a diode. I learned something again!

                            Later, Bruce

[Bruce S]

G-

  Not on subject , but thanks for the chip info. This one will work perfect for my NiCd charging problem. And at about a buck each, I can afford 'em..

Bruce S

[ghurd]

I'm using one for 9 AAA-ish cordless phone NiCd's and a droping diode to run a pair of 12V computor speakers for a MP3 player.

It works!

Not only does it work, the "stereo" was actually the 70ma load I mentioned first, when the 7AH battery overcharged!  I wonder if anyone would have the slightest interest in some of these strange little projects I do?

I never had any problems with a solar/battery setup just using the chip. No caps.

I do overly heat sink them, just in case.

Mouser now lists them as a stock item, but I doubt it.

I usually have to get them through 'unusual channels'.

Do you have an email address you wouldn't mind posting?

Yes. All the neighbors think I'm crazy.

G-

[ghurd]

Let us know how it goes!

G-

[Marck]

I just got two of those from an eBay auction... I immediatly opened them up... Both of mine have all the circuitry inside.

[ghurd]

The PB137ACV would be a lot easier!