phil Dean Posted October 28, 2023 Report Share Posted October 28, 2023 Now I have finished converting from Dynamo to Alternator and completed the thin belt conversion. I have also fitted a 60 amp ammeter. I just wondered before I put the rest of the dash back is there a way of checking the accuracy of a ammeter. I have no doubts mine is ok but just wondered. Phil. Quote Link to post Share on other sites
RogerH Posted October 28, 2023 Report Share Posted October 28, 2023 Hi Phil, they are not accurate.They give a good idea of what is going on. 10(ish) amps may register a 10 on the dial but it is apprx. Roger Quote Link to post Share on other sites
RobH Posted October 28, 2023 Report Share Posted October 28, 2023 A rough check - Assuming you have 60 watt main beam headlamps - 2 x 60 = 120 watts which at 12 volts is 10 amps. With nothing else powered and the ignition off, switch on main beam. The ammeter should read 10A discharge. Quote Link to post Share on other sites
phil Dean Posted October 28, 2023 Author Report Share Posted October 28, 2023 Ok Thanks Rob I Have tried that it looks more like 15 amps discharge but I honestly don’t know the watts in the headlight bulbs Quote Link to post Share on other sites
RobH Posted October 28, 2023 Report Share Posted October 28, 2023 (edited) Ah - perhaps the sidelights were on as well. That is another 20 watts which is just under 2 amps so it would be nearer 12 than 10 I suppose. As Roger says they are not precision instruments but just intended to give a reasonable indication. Edited October 28, 2023 by RobH Quote Link to post Share on other sites
Andy Moltu Posted October 28, 2023 Report Share Posted October 28, 2023 In many ways the accuracy isn’t important. What is important it reads 0 when no current is flowing and discharge when the current being drawn exceeds the output from the alternator. Quote Link to post Share on other sites
RobH Posted October 28, 2023 Report Share Posted October 28, 2023 55 minutes ago, Andy Moltu said: What is important it reads 0 when no current is flowing and discharge when the current being drawn exceeds the output from the alternator. You've hit the nail on the head Andy. Exactly that. Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 29, 2023 Report Share Posted October 29, 2023 I treat the ammeter like a balance Yes the numbers are interesting but simple plus or minus serves me well. Quote Link to post Share on other sites
phil Dean Posted October 29, 2023 Author Report Share Posted October 29, 2023 (edited) As usual thanks for everybody's help as people have said above I am getting positive and negative readings and it is only an indication. A lot more pleasing than watching the ammeter dive to the negative side when you switched the rad fan on in a traffic queue when I was running a Dynamo. On with the auxiliary wiring now I have already mounted a auxiliary fuse box near the regulator now junction box i will take my feed from there, just pondering on how to wire in the cut off switch to the earth side of the battery, thought I had it sorted last night but realised I need one complete lead from the battery to the switch unlike the lead that goes to earth eventually on the engine block which I can join on the bulkhead. Phil. Edited October 29, 2023 by phil Dean Quote Link to post Share on other sites
Lebro Posted October 29, 2023 Report Share Posted October 29, 2023 (edited) Click on to enlarge How I did it on my TR3. The isolation switch also cuts the ignition circuit when in the off position. Bob Edited October 29, 2023 by Lebro Quote Link to post Share on other sites
phil Dean Posted October 29, 2023 Author Report Share Posted October 29, 2023 Hi Bob it looks like you have gone to the live side of the battery I just want to go to the earth side this time and have it incorporated in the dash panel. However yours is a good example very neat. Phil. Quote Link to post Share on other sites
RobH Posted October 29, 2023 Report Share Posted October 29, 2023 (edited) This is mine in a similar position switching the earthy side. (The cable at the bottom is an extra engine earth connection. ) This switch doesn't have the extra low-current contacts like the one Bob used . Edited October 29, 2023 by RobH Quote Link to post Share on other sites
Lebro Posted October 29, 2023 Report Share Posted October 29, 2023 I switched the live side so I could take a feed(unswitched) to my tracker. Bob Quote Link to post Share on other sites
phil Dean Posted October 30, 2023 Author Report Share Posted October 30, 2023 Again Rob a neat job. I hope I can make as neat a job. Mine also has a earth to the engine block. Phil Quote Link to post Share on other sites
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