# Can I charge my 12v deep cycle battery with any size solar panel?

I'm just wondering if the wattage of a solar panel only determines the amount of time needed to charge the battery? I'm in no rush to charge the batteries each day, and will only use the power minimally. Probably 100w for four hours each night. Will a 5w solar panel charge the battery for that use? Even if it takes all day?

Update:

I cant find the Ah

all i see is 550cca, 12v, 140 reserve capacity. it's a large marine battery, I assume at least 100Ah.

Update 2:

and what about a 12w, is that more feasible?

Update 3:

Even if I never get it to a full charge, could i get a few hours out of it per days worth of sunlight? would it damage the battery to never let it fully charge?

Relevance
• 9 years ago

Many factors. If this is a 12 volt lead acid battery, you need at least 15 volts from the panel to even start to charge the battery.

If the panel puts out 15 volts, at 5 watts, that is only 5/15 = 1/3 amp to charge the battery, under the best conditions. Actually, it will probably be a lot less.

If the battery is a large 100 amp-hour battery, 1/3 amp would take 300 hours to charge it. But probably a lot more, as leakage current inside the battery may use up a lot of that 1/3 amp. And if you get only 5 hours of sun a day, that is 60 days.

But why do you keep asking these questions without even mentioning the battery size? Please list all relevant data.

.

• 3 years ago

Deep Cycle Battery Solar

• Anonymous
5 years ago

RE:

Can I charge my 12v deep cycle battery with any size solar panel?

I&#39;m just wondering if the wattage of a solar panel only determines the amount of time needed to charge the battery? I&#39;m in no rush to charge the batteries each day, and will only use the power minimally. Probably 100w for four hours each night. Will a 5w solar panel charge the battery for...

Source(s): charge 12v deep cycle battery size solar panel: https://tr.im/iUDJC
• Anonymous
9 years ago

You are using 400 watt-hours at night. At best you may generate 50 watt-hours during the day and more likely half that amount. To be resonably secure, you will need about 100 watts of generating capacity at a voltage of 18 or greater. Panels marked nominal voltage of 12 volts will usually produce in excess of 20 volts. You will also need a charge controller. The 100 watt panel will generate 100 watts at noon when perpendicular to the sun. Derating by 50% should put you in the ballpark. So, 8 hours times 50% times 100 watts equals 400 watt-hours or about your nightly use.

By the way, a deep cycle battery means that it will recover from deep discharge. This is the proper type of battery to use with solar installations. A regular car battery is not deep cycle. They are designed for high starting currents, not deep discharge.

Source(s): My own solar powered off-grid cabin. 1200 watts of panels at 50 degrees latitude.
• mish
Lv 4
3 years ago

12v Deep Cycle Marine Battery

• 4 years ago

charge 12v deep cycle battery size solar panel

• 9 years ago

You used 400W per day but the solar panel only able to put back total 50W for ten hours full sun shine.

Therefore, battery shall be drained away in a few days.

"Deep cycle" is the wrong term to describe battery. "Deep Cycle" is an action to drain away all the power from storage cells with a resistance load for a few days until all the cells read ZERO VOLTAGE,so that the cells will not reverse its charge during next charge. "Deep cycle" is not doing all time because it shorten the life of cell. It is an action to restore the cell while it shows reverse polarity.

• 6 years ago

Yes I use a 50 watt panel to charge my boat batteries