12v setup review, Safe enough?

[SunnyD]

Hi All,

This is my first post on the forum I am selfishly looking for advice and guidance on my 12v setup for my shed. I am new to all this have limited electrical knowledge so if I sound like an idiot, sorry in advance!

I have recently setup a system in my shed but have since disconnected after the realisation that I am not sure how safe it is. I would like some guidance on if I have my fuses in the right places and if my cable ratings are ok. The system is only supporting 3 MR16 LED lights at present but I would like to add a 12v socket for a small radio at some point.

Here are my components with links where possible, My main question here is whether this is a safe setup or do I need something more. When finally installed all wiring will be concealed in conduit and blanking boxes where required.

Charge controller 30amp

https://www.amazon.co.uk/GSS-Navplus-Intelligent-Charge-Controller-Battery-Regulator/dp/B01CE9IACY/ref=sr_1_11?ie=UTF8&qid=1463485987&sr=8-11&keywords=30a+charge+controller

Battery 12v 7ah

https://www.amazon.co.uk/dp/B0013A7XOC/ref=sr_ph?ie=UTF8&qid=1463486065&sr=1&keywords=12+v+battery

25watt panel

https://www.amazon.co.uk/dp/B016D2VYTE/ref=sr_ph?ie=UTF8&qid=1463486090&sr=1&keywords=25+watt+ecoworthy

30amp cable between battery and controller 7.5 amp blade fuse as close as possible to battery + terminal
30 amp cable connecting solar panel to controller
8 amp cable for lighting circuit, 3 amp blade fuse between lights and load terminal on controller.

I am also using a 30 amp terminal block to wire the lights in parallel (is this a good idea / bad idea??)

I don't know how to draw circuit diagrams, in fact I am not sure I can even draw but I have attached a diagram to show my setup. Sorry it looks like it was drawn by my 5 year old daughter.
If I have missed the point / key detail please let me know.

Thanks
SunnyD

[ewarnerusa]

Your lighting circuit should be wired to the battery, not the charge controller. The link to the panel you have says it already has a charge controller, so no need for the additional 30A one you linked to. Kind of a funny mix of 3A and 30A rated stuff, but I don't suppose that hurts anything with your relatively small battery and panel. Your panel is rated at 1.4 amps max output in ideal conditions. You need a fuse located on the 30A-rated positive wire connection to the battery from the charge controller located as close to the battery as possible. That's where you could potentially supply enough current to worry about fire and where fuses to protect the wires are most important. The 3A fuse on your lighting circuit will bottleneck the current flow and when you put a 12V socket on that circuit to power a radio it may pop that fuse. Bump it up to a 10A fuse or something. The small battery won't power a radio for very long.

[Logan005]

Wiring looks ok, bt should also have a fuse or breaker on the neg post as well. All 3 links lead to junk sold on Amazon, Most of this stuff I would just throw away. SLA batteries only last about a year. cycled SLA batteries will last less than 300 cycles. a 7AH battery will at best provide a couple hours of minimal lighting. get a single grid tied panel and an MPPT controller and an appropriate sized FLA battery. The system you have listed will not be upgradeable and will be very inefficient if it's of any use at all.

[SunnyD]

Your lighting circuit should be wired to the battery, not the charge controller. The link to the panel you have says it already has a charge controller, so no need for the additional 30A one you linked to. Kind of a funny mix of 3A and 30A rated stuff, but I don't suppose that hurts anything with your relatively small battery and panel. Your panel is rated at 1.4 amps max output in ideal conditions. You need a fuse located on the 30A-rated positive wire connection to the battery from the charge controller located as close to the battery as possible. That's where you could potentially supply enough current to worry about fire and where fuses to protect the wires are most important. The 3A fuse on your lighting circuit will bottleneck the current flow and when you put a 12V socket on that circuit to power a radio it may pop that fuse. Bump it up to a 10A fuse or something. The small battery won't power a radio for very long.

Thanks for the helpful reply, why should the lighting be going directly to the battery and not the load connections on the controller? Not challenging it just want to understand.

[ewarnerusa]

Battery supplies power to your lights. Solar recharges the batteries. The load connections from the controller are meant to offer somewhere to divert unused solar input when the batteries don't need it. Common recipients of this diversion load are supplimental water heater elements where it isn't critical to have a continuous constant power supply.

[SunEagle]

Most of the cheap charge controllers have limited amp ratings for those "load" terminals. Although some of the higher quality charge controllers actually rate the load terminals at 15amps or better. So they can actually use the software to turn their loads on and off. Although using a relay wired to the "load" terminals and then connect the load to the relay contact might be a better system.

[SunnyD]

Wiring looks ok, bt should also have a fuse or breaker on the neg post as well. All 3 links lead to junk sold on Amazon, Most of this stuff I would just throw away. SLA batteries only last about a year. cycled SLA batteries will last less than 300 cycles. a 7AH battery will at best provide a couple hours of minimal lighting. get a single grid tied panel and an MPPT controller and an appropriate sized FLA battery. The system you have listed will not be upgradeable and will be very inefficient if it's of any use at all.

Thank you for your advce, i fullly appreciate this is cheap stuff the whole thing cost me £60. The alternative would have been to get an electrician in to connect house mains supply which would have cost £150 just in labour let alone the armoured cable and digging up the garden. If i get 2 hours lighting a day from it that will be more than enough. I dont spend much time in the shed. Maybe i will skip the radio the primary purpose was to power the 3 mr 16 bulbs which it seems to do ok adn the batery recharges to full through the day.

You mentioned in your post that i need a fuse on the negative post sorry for my lack of understanding here but do you mean on the negative connection to the battery? same as the positive as close to the battery as possible?

[Logan005]

I would go with the mains route, last time I visited my mother, I ran 120 volts AC to her garage, buried, was easy even in the conduit. minimal circuit for lighting and battery charger. Outside the US is mostly 220vac still seems mostly straight forward. even if you did get an electrician to do it, would save you money over the solar battery system you have selected .

[SunnyD]

Thanks both will take your advice and apply it.