Sharp Posted February 21, 2023 Share Posted February 21, 2023 I want to: 1 - feed my radio from my leisure battery 2 - have a second switch in the rear of the vehicle to switch it on. My radio has a permenant live feed and an ignition live feed. My plan is to have one live feed from the leisure battery to where the old permenant live went, and another running through a relay activated by (1) the ignition live that was previously feeding the radio, and (2) a switch in the back. I basically just want to be able to turn the radio off from the back and not run my starter battery down by listening to music. Will this work? Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 21, 2023 Share Posted February 21, 2023 Yep, all good. Quote Link to comment Share on other sites More sharing options...
hurbie Posted February 21, 2023 Share Posted February 21, 2023 only thing is , you have to get to the back off the car to turn the radio on ... Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 21, 2023 Share Posted February 21, 2023 1 hour ago, hurbie said: only thing is , you have to get to the back off the car to turn the radio on ... He has two triggers for the relay that isolates the stereo from the leisure battery - one is the ign switch and the other the toggle switch in the rear. As long as one of those is on, the relay will close. Quote Link to comment Share on other sites More sharing options...
hurbie Posted February 21, 2023 Share Posted February 21, 2023 29 minutes ago, Snagger said: He has two triggers for the relay that isolates the stereo from the leisure battery - one is the ign switch and the other the toggle switch in the rear. As long as one of those is on, the relay will close. yep , need to look beter before commenting 🙂 isn't it wise to put a diode in the feed from the leisure battery to the switch , to stop a huge current flowing when the leisure battery is empty and you turn the ignition to "on" (and you forgot to turn the back switch off) ? 2 Quote Link to comment Share on other sites More sharing options...
Sharp Posted February 21, 2023 Author Share Posted February 21, 2023 Something like this? https://www.ebay.co.uk/itm/400517898772?hash=item5d40ba2214:g:KcIAAOSwHkReqyZV&amdata=enc%3AAQAHAAAA4DxhwTM%2F7%2FwblP2%2FR07t96jDRX0qa4nHPkvKY9sN0NZnfi7orINmzmv5MNIL4ScWfC1Bs7XIqsbZyVZcyTtU83bEnbx%2F9LdgwLMxY57enOZcZL3moiuYKzIcuMT2nAFn6Bpxp%2BFE2%2BsCJaxsSMM7TglM3Fn7A04SW9fOnpWEWJQISwY%2F7LWyKjnH9IAL21c6L9OpRTDBhXuPEvJwUlZeVT3YHtGhic5pewgMmySRrzJJv60GikuPHdwR%2BXuHAb%2BksjqpuM2cpjEEU7KJNWC12qxKwETd7fMEIWBEMAwTAHxR|tkp%3ABk9SR5D5h9nOYQ 1 Quote Link to comment Share on other sites More sharing options...
Sharp Posted February 21, 2023 Author Share Posted February 21, 2023 Thanks for the comments everyone, still finding my feet with the electrical stuff! Quote Link to comment Share on other sites More sharing options...
hurbie Posted February 21, 2023 Share Posted February 21, 2023 4 minutes ago, Sharp said: Something like this? yes , i think that will do Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 21, 2023 Share Posted February 21, 2023 I could be mistaken but when you switch the 2nd switch, you will be back-feeding your whole ignition live feed from the leisure battery. You either need a diode in there or a slightly different scheme. 2 Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 22, 2023 Share Posted February 22, 2023 Yes, diodes would be needed in both switch lines for the reasons given. Quote Link to comment Share on other sites More sharing options...
Sharp Posted February 22, 2023 Author Share Posted February 22, 2023 Thank you for this. Is this the correct placement? What do people normally use for this purpose? I can't seem to find many options for purchasing diodes with spade connectors. Is it acceptable to use something like the below and solder it onto a couple of connectors or to use an led? https://www.ebay.co.uk/itm/264588472065?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=YRTmJau9QrW&sssrc=2047675&ssuid=Dk2aGYJqTmq&widget_ver=artemis&media=COPY Quote Link to comment Share on other sites More sharing options...
hurbie Posted February 22, 2023 Share Posted February 22, 2023 just solder them between the wire's , and use some heatshrink . Quote Link to comment Share on other sites More sharing options...
Escape Posted February 22, 2023 Share Posted February 22, 2023 As above, you need the 2 diodes to prevent back feeding. I've used similar to your link for switches, seems to work fine. In (older) wiring looms you often find diodes with spade connectors, like this and I see they're even available to fit in a fuse holder like this. Quote Link to comment Share on other sites More sharing options...
Sharp Posted February 22, 2023 Author Share Posted February 22, 2023 Thanks for your help! Quote Link to comment Share on other sites More sharing options...
Snagger Posted February 22, 2023 Share Posted February 22, 2023 That revised plan is perfect. Think of diodes as a non-return valve. That configuration will prevent the main battery from draining into the auxiliary battery via the ignition spur to the relay when the ignition is on or the auxiliary battery from keeping the ignition live when the ignition switch is off (which would have prevented engine shut-off). Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 22, 2023 Share Posted February 22, 2023 3 hours ago, Sharp said: What do people normally use for this purpose? I can't seem to find many options for purchasing diodes with spade connectors. Is it acceptable to use something like the below and solder it onto a couple of connectors or to use an led? You've picked Zener diodes there which are not what you want - to activate a relay you can get away with bog standard 1N4001 ( or 2,3,4) PM me your address I'll post you a handfull. Likewise an LED would not work as they are NOT designed to pass current. Quote Link to comment Share on other sites More sharing options...
Sharp Posted February 22, 2023 Author Share Posted February 22, 2023 Thanks for that FridgeFreezer. I ended up ordering "ExcLent 100Pcs 1N4001 1A 50V Diode" off amazon, more by luck than good management but it looks like they might have been the right ones? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted February 22, 2023 Share Posted February 22, 2023 From Amazon they could be any old thing chiselled out of a pile of e-waste in Shenzhen but for what you need it's not critical Quote Link to comment Share on other sites More sharing options...
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