Small shed system, fuses / breakers / wire

[raymate]

Hi,

New here.

Just started to build a new project for my shed, nothing fancy or big, I'm using a BP Solar 40w panel, MorningStar ProStar 15 and a small 9-18amp sealed lead acid battery (not got the battery yet)

I'm starting from scratch and want some advise on wire and fuses / breakers.

My system is basically going to run LED lights in the shed, 5v USB charger and a small 12v dc pond pump. I'm going to run direct from the ProStar load output, I don't see myself with an inverter at this stage (battery maybe too small for one anyway) but it's possible I may use one latter (if I change out the battery)

I'm location in Toronto (after moving from the UK) for some reason finding anywhere local that has solar stuff is not easy.
Can anyone recommend a good reliable online source for solar stuff. Locally everything is so costly.

My question are I was going to get some 10awg wire and use that for the whole system, to connect everything.

I want to run fuses on all the positive lines and maybe use breakers for the battery feed and panel feed so they can double up as disconnects.

Does this sound like a good idea?

As it's not a large system I was thinking of using 3-5 amp midnite solar breakers, but the fuses I'm getting conflicting info online, I was going to use car ratted blade fuses but that seems like a bad idea, so I was thinking glass quick blow fuses again at 3-5 amps

Any advise would be great

Thanks

[Mike90250]

The weak spot for most fuses, is the holder. If the contacts loose their spring tension, resistance goes up, the contact heats up and it just goes badly. So for little stuff, 3, 5, 10 amps, glass or automotive blade fuses are OK. After 10A, I like breakers.

[SunEagle]

I agree with Mike. Those 12v automotive type fuses work well as long as you keep them on the lower amp rating end. Going above 10amp can be an issue unless you have a very good fuse block.

My concern is your desire to run your loads from the Morningstar CC Load output. That should be ok for the LED lights but maybe not for your 12v pump.

Depending on what that pump is rated in wattage or amps will help make the decision. It will also help determine if your battery is big enough to provide power for your loads. 18Ah is only going to provide you about 50 watt hours a day.

First determine what each load is in watts and how long you will run it in a day. Add that up and you should get close to the total daily watt hours.

For longevity of the battery life you should only discharge it to 80% SOC so you would multiply that watt hour number by 5 to size your battery.

From that you can determine if you have enough panel wattage and charging amps to put back what you take out of that battery daily.

[raymate]

I agree with Mike. Those 12v automotive type fuses work well as long as you keep them on the lower amp rating end. Going above 10amp can be an issue unless you have a very good fuse block.

My concern is your desire to run your loads from the Morningstar CC Load output. That should be ok for the LED lights but maybe not for your 12v pump.

Depending on what that pump is rated in wattage or amps will help make the decision. It will also help determine if your battery is big enough to provide power for your loads. 18Ah is only going to provide you about 50 watt hours a day.

First determine what each load is in watts and how long you will run it in a day. Add that up and you should get close to the total daily watt hours.

For longevity of the battery life you should only discharge it to 80% SOC so you would multiply that watt hour number by 5 to size your battery.

From that you can determine if you have enough panel wattage and charging amps to put back what you take out of that battery daily.

Thanks for the reply, What can I use on the load from the morningstar, I mean how much amps can I use from the output?

The pump is tiny it's a solar 12v micro pump, rated I think at around 300-350mAh (it's inside the fountain right now running from a tiny solar panel it shipped with)

Guess it will run for maybe 4-6 hours at the weekend so maybe 1-2amps a day.

What I also want to hook up to the morningstar load out put was a 12v accessory socket for things like phone chargers, so you say thats a bad idea?

I actually just ordered from the states some midnite solar breakers, I was going to use a 7amp one on the load output from the morning start, a 10amp on the battery and a 5amp from the panel. Then other stuff like the LED lights and pump using 3amp blade fuse then a 10amp on 12v accessory socket fuses. All wired with 10 awg wire.

Wanted to use the load output so it would show me the amps I was taking from the battery.

I could get a 22amp battery but I really wanted to keep costs down a bit.

[SunEagle]

Thanks for the reply, What can I use on the load from the morningstar, I mean how much amps can I use from the output?

The pump is tiny it's a solar 12v micro pump, rated I think at around 300-350mAh (it's inside the fountain right now running from a tiny solar panel it shipped with)

Guess it will run for maybe 4-6 hours at the weekend so maybe 1-2amps a day.

What I also want to hook up to the morningstar load out put was a 12v accessory socket for things like phone chargers, so you say thats a bad idea?

I actually just ordered from the states some midnite solar breakers, I was going to use a 7amp one on the load output from the morning start, a 10amp on the battery and a 5amp from the panel. Then other stuff like the LED lights and pump using 3amp blade fuse then a 10amp on 12v accessory socket fuses. All wired with 10 awg wire.

Wanted to use the load output so it would show me the amps I was taking from the battery.

I could get a 22amp battery but I really wanted to keep costs down a bit.

It looks like that Prostar 15 can power a 15amp load so you may be ok. Some micro dc pumps are bigger and can draw more then what the load terminals are rated for. Your pump is only 350mA and running 6 hours a day will not drain that 18Ah battery much. So you should be good to go.

I would be careful with connecting a 12volt accessory socket to the load terminals until you know what loads they will draw. A phone charger is probably ok along with that pump but I would caution you to keep an eye on the amount you use in a day and if that battery is being overworked.

Based on the information you provided your small solar battery system should work for your loads using 10 awg wire. But that 18Ah battery will only provide you a maximum of 4Ah in a day and depending on the amount of sun you get that 40 watt panel may not provide enough charging all year long.

[raymate]

It looks like that Prostar 15 can power a 15amp load so you may be ok. Some micro dc pumps are bigger and can draw more then what the load terminals are rated for. Your pump is only 350mA and running 6 hours a day will not drain that 18Ah battery much. So you should be good to go.

I would be careful with connecting a 12volt accessory socket to the load terminals until you know what loads they will draw. A phone charger is probably ok along with that pump but I would caution you to keep an eye on the amount you use in a day and if that battery is being overworked.

Based on the information you provided your small solar battery system should work for your loads using 10 awg wire. But that 18Ah battery will only provide you a maximum of 4Ah in a day and depending on the amount of sun you get that 40 watt panel may not provide enough charging all year long.

Some great info, thanks very much. I was wondering how much I should extract from the battery to keep it in good shape so around 4amp I have some reference to work with, looking forward to getting it all wired up, just waiting now on parts. During the winter the pump will not be used and the shed lights are not going to used much either so it should work well.

I shall report back once built

[SunEagle]

Some great info, thanks very much. I was wondering how much I should extract from the battery to keep it in good shape so around 4amp I have some reference to work with, looking forward to getting it all wired up, just waiting now on parts. During the winter the pump will not be used and the shed lights are not going to used much either so it should work well.

I shall report back once built

That 4 amp is a guideline for your battery but not necessarily the correct amount for all batteries.

Since most loads are rated in watts you can figure how many "watt hours" it will use in a day. A battery can also be rated in "watt hours" where wh = battery voltage x battery Ah rating or (wh = v x Ah).

So an 18Ah 12volt battery has a 100% full rating of 12 x 18 = 216 wh. 25% of that is 54 wh or 54wh / 12volt = 4.5Ah

Basic plan to follow for most battery chemistries is 20 to 25% maximum daily discharge. That usually fits into the manufacturers highest "cycle" count and life. Going to 40% daily can cut the life in half.

You also need to make sure you can put back what you take out which is why having a battery sized 5 times what you need in a day can still allow you to go a couple days without sunshine "once in a while" and not drain the battery completely.

Hope that helps you understand it a little better.

[raymate]

That 4 amp is a guideline for your battery but not necessarily the correct amount for all batteries.

Since most loads are rated in watts you can figure how many "watt hours" it will use in a day. A battery can also be rated in "watt hours" where wh = battery voltage x battery Ah rating or (wh = v x Ah).

So an 18Ah 12volt battery has a 100% full rating of 12 x 18 = 216 wh. 25% of that is 54 wh or 54wh / 12volt = 4.5Ah

Basic plan to follow for most battery chemistries is 20 to 25% maximum daily discharge. That usually fits into the manufacturers highest "cycle" count and life. Going to 40% daily can cut the life in half.

You also need to make sure you can put back what you take out which is why having a battery sized 5 times what you need in a day can still allow you to go a couple days without sunshine "once in a while" and not drain the battery completely.

Hope that helps you understand it a little better.

Yes that was helpful, thanks, this forum is great for info. Learning so much