Voltage Regulator Necessary?

[WeekCamper]

My camper has two deep-cycle 6-volt batteries connected in series for 12 volts. I ordered an 80-watt solar panel to help recover the charge used during the night for my heater blower. The solar panel is rated 21.6 VOC and 17.3 VPM.

Is that matched close enough to get by without a voltage regulator? I could get a cheap voltage regulator but that would limit the efficiency of the solar panel for charging during the short daylight hours. Can I simply check periodically with a volt meter to make sure the batteries are not being overcharged?

Thanks!

[Mike90250]

At first glance, without knowing the battery capacity, you would be close to the border.
What style of batteries, Gel, AGM, flooded ? What is each capacity - 200AH ?

Will the fan run daily/nightly/occasionally? Weekends? 2x a month?

What's the power draw of the fan ? How many hours?

You would not use a voltage regualtor, you would use a charge controller. A MPPT style charge controller would help deliver your 80W, PWM style, you coudl see 50W

we need more data

[WeekCamper]

Going without a Charge Controller

Mike,

I

[Mike90250]

In your case, for the week you are camping, you would be safe with just a panel.
Your heavy nighttime loads will never be made up by the solar.

I'd suggest the following scheme: Fire up the gennie in the AM, make your coffee, whatever you need power for. This will also quickly bulk the batteries. The solar 80W is barely more than a trickle charge, and will slowly top off the batteries in the day.

You don't want to let your batteries get too low, for too long.
Deep discharges ruin by flaking plate material off, duration causes sulphate crystals to form and reduce capacity. 24 h at 25% discharged (75% remaining) starts sulphation.

[Vern2]

Weekcamper'

Found this for you at http://store.solar-electric.com/chco.html

Depending on the type and brand, solar panels put out 16 to 50+ DC volts, so if there is no regulation the batteries may be damaged from overcharging. Generally, there is no need for a charge controller with the small 1 to 5 watt trickle charge panels. A rough rule is that if the panel puts out 1/60th or less per day of the rated battery amp-hour capacity, you don't need one.

Mike, are the hotdogs done yet?

Vern2

[Mike90250]

Mike, are the hotdogs done yet?

Done, and gone !


For the weekend, I don't think he needs a controller at all, but after the weekend, don't leave the panel connected, or you will begin overcharge, which from a 80W panel, into 200A of batteries, won't be much. (6A is only 3% charge, and a panel flat on a roof, won't give your full 80W)

Now a blocking diode may be needed, and you don't want to drive off with the panels on the roof !

PV panels are "current (amp) devices", so if you connect a 30V panel to a 12V battery, the voltage instantly (and harmlessly) falls to the battery voltage, and you are just pumping amps into the battery. Since 12v is way below the peak power curve of a 30V panel, you will not get full power, but more like the short circuit amps listed on the nameplate.
With an 80W panel, 200AH battery, heavy nighttime loads, and 1 week camping connected only, no controller needed.