solar panel conversion 24v to 12v

[jason p]

ive got a 175 watt panel that i want to charge the boat batteries and run various other things with it but the only problem is that its a 24v panel. just wondering if any one knows how to change it to 12v. thanks for any help.

jp

[beardedone]

G'day Jason easiest way is use a DC-DC convertor from Jaycar.
you would need one that does about 20A 24v-12v like this
CAT. NO. MP3063
24 - 12V DC-DC Converter 20A
DC to DC converters are useful for running 12V devices from a 24V supply in a truck or bus. These have switchmode technology for light weight and compact design, and come in a range of current ratings up to 40 amps.
Specifications:
• MP-3063 24 - 12V DC-DC Converter 20A
• Input voltage: 20 - 30VDC
• Output voltage: 13.8VDC
• Max, output current: 20A
• Continuous output current: 15A
If you want to get fancy you can get a 24v-12v battery charger from Victron
If you are going to leave it on battieris 24 7 then you will have to get a properly regulated charger or risk overcharging.

[ScottB]

Yep, easily done with something like this

http://www.bepmarine.com/home-mainme...-converter-20a

or this

http://www.gme.net.au/products/acces...-dc-volt/VC10S

We've used heaps of them at work (different brand on the front but they are all identical) and very rarely get any problems from them. We have 24V battery backup on all of our equipment but use these when there is something that needs to run on 12V.

Regards

Scott

[cormorant]

A lot of products are designed for 24v trucks so 12v accessories can be used and aren't that tollerant of the v change and aren't that effecient and 12v won't charge a battery very well you really need 13.8 ( like GME) for standard lead acid and more for other types. Check the true voltage from your panel as well throughout the day. If it isn't set up as battery charger then you can boil batteries and wreck good expensive batteries quite fast.

Some are really ineffecient and use heatsinks and fans to regulate output and other are effecient but still use a fan. Not a fan of salt air through electrics or heatsinke in enclosed areas.

Check they work with a resistor in the circuit or solar controller if you have one?

Have a chat to a couple of Aussie suppliers who also make stuff and check how they will go in a salt water environment.

May be simpler to swap to a 12v panel as a lot more specialised product avaliable?

http://redarc.com.au/products-and-se...to-12v-charger

[Grand_Marlin]

Jason, check what your regulator does.
We had one yesterday that has 2 x 175w panels.
Voltage in is 35.7 volts.
Voltage out through the regulator was 13.5 volts.
Also, you need a regulator if the panel output capacity is more than 2% of the amp hour rating of the battery to avaid battery damage.
A panel like yours would typically output 5 amps.
A typical battery will be around 90 ~ 100 amp hours.
Therefore the output capacity is 5% of the battery amp hours.

Cheers

Pete

[oldboot]

Not real keen on the 24 to 12 volt converters used to run 12 volt appliances in trucks, as they will not give you any battery supervision...and half the energy generated by the solar panel will be wasted as heat in the voltage step down.

lots of the boxes sold as DC to DC converters are not technocaly that....they are often simply step down regulators.

Anything that is a simple regulator or voltage reducer will waste at least 50% of your power.

if you can get a true DC to DC converter ( a switcmode device) you will get close to 100% of the output of the pannel deliveerd to the battery.

You may find that you can get a maximum power point tracking regulator that will cope with the voltage difference......this will be the best choice if you can get one.

I am sure there are planety of situations were 12 volt batteries are required to be charged from 24 volt systems

cheers

[TheRealAndy]

Some panels can be (or could be once up on a time) reconfigured in the termination box on the back. Check that first.

[jason p]

THANKS ALL some very usefull info cheers.
andy that was the path i was looking at or hoping to achieve. may have to dig alittle further.

jp