6 V battery

[joeh]

hi all
is it alright to charge a single 6V battery only from my 30 W solar panel ? Up to now i have been using the panel to charge my two 12V batts. Tks

 

[William_H]

Yes just wack the solar panel on to the 6 volt battery. The panel is current self limiting so will not be damaged. Of course you will get the same current out of the panel so in fact only half the power because voltage is half.
Regards olewill (Waiting for the screams of dissapproval)

 

[ccscott49]

Well, the panel puts out 30 watts, at 6 volts thats 4 amps, so it shouldnt worry your battery too much, but why a 6 volt battery? anyway the voltage output from the panel will be about 14 volts, so the battery needs to be monitored, so it doesnt get overcharged. It's up to you, but i wouldnt leave it connected.

 

[joeh]

i have an idea of replacing 4 AA 1.5 V dry cell with a small 6V batt which is solar rechargeable. this is for my ancient depth instrument. saves continuous buying of AAs n more independance at sea.

on rereading my BP SX30U solar panel manual the junction box underneath can be switch between 12V or 6V but not possible for me due to inaccessibilty.

 

[bedouin]

How large is the 6V battery?

Unless it is high capacity with a 30W panel you should be considering some form of regulation even for charging a 12V battery.

I probably wouldn't connect the panel directly to the battery without a regulator.

 

[nedmin]

why not experiment with a 6v bulb in series if you use something with a small wattage you wont harm the small battery you are trying to charge.if the solar panel is giving 14v you may blow the bulb its just a case of experimenting.worth a try for the small cost of the bulb.if not you could get a kit from Maplins to give you a regulated supply from your 12v.

 

[William_H]

A 30 watt solar panel you will find is rated at 30 watts at max voltage normally around 18 volts. So the max current will be 30 divided by 18 equals about 1.6 amps. This ciurrent is the max you will get regarless of whether it is into 12 volt battery or 6 volt or even a short circuit. Yes if you leave the panel connected to the battery for a long period then you will need a regulator. If the battery is 6 volts at eg 6 Amp hour then it will be close to fully charged after 4 hours in the sun. If you left a SLA battery for a full day in summer sun without a regulator you could kill the battery.
If on the other hand you were charging a huge 220 AH battery then the 1.6 amps all day every day would not hurt the battery. The easy solution is to no0t use a regulator but discipline yourself to disconnect after putting aprox AH capacity. I suspect you will find it hard to find a 6 volt regulator.
If you want to leave it connected all day every day than a resistor of 1200 ohms would limit current to0 10 milliamps or 120 ohms limit it to 100 milliamps (.1 amp). The former should be ok for the smallest SLA battery.
As an alternative you might like to try connecting the 6 volt battery across your 12 volt battery system with about 1200 ohm resistor ( low wattage is OK) for continual charge at 10 ma aprox while the solar panel charges the `12 volt system. Just a few thoughts olewill