BushDoctoR Posted December 30, 2023 Share Posted December 30, 2023 Hey all, Just finished building a 12v battery back up so thought I'd share the build. The purpose of the back up is so that my ventilation - and most importantly my carbon filter - remains active in the event of a power cut or if the power needs to be shut off for whatever reason. I've managed to do this pretty cheap as I was able to utilise bits I had lying around and 'borrow' some bits from work. If I had to buy everything it may or may not be cheaper than just buying a UPS. You'll have to work that one out for yourself. The main components are as follows: • Large 12v battery. I've used a CSB1251W as I got it for free. But any large 12v battery should do, 12v motorbike batteries can be picked up pretty cheap. • 11 pin 10a/240v relay. I've used a RCP11003 from TLC direct and it cost about a tenner with the base iirc, you'll be able to get similar relays from any electrical wholesalers but the terminal numbers may be different so you'd have to adjust accordingly. I'd avoid cheap nasty chinese components from amazon etc. • car battery charger. Cost about £12 • 12v-240v car power inverter. Needs to have a high enough wattage for your fan(s). Around £20 • plug socket and back box • A box to contain the relay in, plus glands, terminals, cable etc. 5 Link to comment Share on other sites More sharing options...
Banarchylamp Posted December 30, 2023 Share Posted December 30, 2023 Been looking into this for a while, well done on getting something DIY done. Sticky this 1 Link to comment Share on other sites More sharing options...
BushDoctoR Posted December 30, 2023 Author Share Posted December 30, 2023 I started by drilling the holes for the 4 glands I needed, I then mounted all the components onto the board. I'm lucky enough get metal bent up at work for free so I had a bracket made up for the battery. I had a load of din rail terminals knocking about so mounted a few of those on the rail with the relay. If you don't have any then some terminal strip or wagos will do the job fine 5 Link to comment Share on other sites More sharing options...
BushDoctoR Posted December 30, 2023 Author Share Posted December 30, 2023 The relay was wired up as per this sketch. It's important not to connect the battery until the rest is complete as it will liven up parts of the circuit with 240 even before its connected to the mains!! If you're using a different relay you may need to adjust the terminal numbers. If you need to do that its important that the inverter/battery side of the switches are closed when it's in its depowered state. 5 Link to comment Share on other sites More sharing options...
BushDoctoR Posted December 30, 2023 Author Share Posted December 30, 2023 Once it's all connected its time to hook up the battery, pop in the relay, and power it up and test it I connected to the battery with 6mm spade crimps and covered the terminals with some heatshrink to protect them 5 Link to comment Share on other sites More sharing options...
BushDoctoR Posted December 30, 2023 Author Share Posted December 30, 2023 Finished and mounted on the wall. Only thing missing in the 240v sticker for the relay enclosure as I'm out. All seems to be working perfectly. Switches my phresh hyperfan and G.A.S EC1 controller seamlessly from mains to battery without even a flicker on the screen. Jobs a good'un! 12 Link to comment Share on other sites More sharing options...
Banarchylamp Posted December 31, 2023 Share Posted December 31, 2023 2 Link to comment Share on other sites More sharing options...
Military Grade Posted December 31, 2023 Share Posted December 31, 2023 Nice work, far too tekkers for my to understand tho 3 Link to comment Share on other sites More sharing options...
Openairbud Posted December 31, 2023 Share Posted December 31, 2023 Nice one! This needs saving somewhere 2 Link to comment Share on other sites More sharing options...
BushDoctoR Posted December 31, 2023 Author Share Posted December 31, 2023 4 hours ago, Military Grade said: Nice work, far too tekkers for my to understand tho Thanks man. I was going to do it more of a detailed step by step but it was taking far too long and I figured it wouldn't make sense if people don't have the exact same relay and terminals etc. This is more of a inspo tutorial for people with a bit of electrical knowledge that are comfortable changing it up a bit 2 Link to comment Share on other sites More sharing options...
latigid aikon Posted December 31, 2023 Share Posted December 31, 2023 Good job Have you got any idea of its run time? And what size fan is that with? I tried googling the battery you used to get an idea of it's capacity but the only hit is this page! 1 Link to comment Share on other sites More sharing options...
BushDoctoR Posted December 31, 2023 Author Share Posted December 31, 2023 4 minutes ago, latigid aikon said: Good job Have you got any idea of its run time? And what size fan is that with? I tried googling the battery you used to get an idea of it's capacity but the only hit is this page! Apparently the battery is 12ah, and the max wattage of the fan (150mm hyperfan stealth) is 42w. Based on those numbers an online calculator suggests it should give me 144 mins which is just under 2.5 hours. This is of course just a ball park figure, there are so many variables like the fan running a varying speeds and the age of the battery etc so I'm going to test it at some point and see how long I actually get from it 2 Link to comment Share on other sites More sharing options...
latigid aikon Posted December 31, 2023 Share Posted December 31, 2023 Just now, BushDoctoR said: 144 mins Sounds good. Let us know when you have some real world numbers please. 1 Link to comment Share on other sites More sharing options...
Slippy One Posted December 31, 2023 Share Posted December 31, 2023 I haven't had a power cut for years, and I agree, this is too complex for the majority of us. Probably less headache to just buy a decent UPS 1 Link to comment Share on other sites More sharing options...
catweazle1 Posted December 31, 2023 Share Posted December 31, 2023 (edited) If anyone is interested in knocking up their own battery units, I noticed my 18650 vaping battery supplier Fogstar does a range of components for doing this. If you want to gen up on lithium ion cells, Battery University is straightforward. This has got me fired up to have one. Edited December 31, 2023 by catweazle1 1 Link to comment Share on other sites More sharing options...
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