Member Jonathan Kay Posted April 23 Member Share Posted April 23 3 minutes ago, aerobod - near CYYC said: With a brand new battery that has been charged to full capacity before use, the initial voltage before start on my Duratec drops to 8.5V for 80ms, before cranking at 10.5V before starting. The ECU logging captures this, but it is a bit quick to see on a voltmeter. What make is the starter? (I'm sure that you followed the investigation into transients with Brise starters.) Does the ECU drop out during this? Thanks Jonathan PS: We might be approaching another look at cheap oscilloscopes... Link to comment Share on other sites More sharing options...
aerobod - near CYYC Posted April 23 Share Posted April 23 7 minutes ago, Jonathan Kay said: What make is the starter? (I'm sure that you followed the investigation into transients with Brise starters.) Does the ECU drop out during this? Thanks Jonathan PS: We might be approaching another look at cheap oscilloscopes... Hi Jonathan, It isn't the Brise starter, it is the standard compact one from Caterham, but I can't remember the manufacturer and the sticker is difficult to see with it installed. The ECU has no problem, it shouldn't drop-out unless the voltage drops below 5V for 100ms or so. The sampling interval on the MBE ECU is 83ms, so it typically will capture transients down to about half the sampling interval, or about 40ms. The inrush voltage dropping in to the 7V range for tens of milliseconds is normal, though. Standard car starters can hit 500-1000A briefly. Effectively the battery is short-circuited and the current is only limited by the battery resistance until the motor is fully energised as the motor turns and the stator and rotor windings have opposing voltages established, it then draws of the order of 200A while cranking. A new battery will potentially show a lower voltage than a more "mature" battery that is still in perfect condition, as the internal resistance is lower, so the initial current spike is higher. My 8.5V drop captured with ECU logging is fairly consistent and normal from my review of recent Easimap logs, but if I put my Hantek USB oscilloscope on it, I would expect a bit more of a drop captured due to it's higher sampling rate. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 23 Member Share Posted April 23 Thankyou Jonathan 1 Link to comment Share on other sites More sharing options...
JP Posted April 23 Author Share Posted April 23 Thanks again all. I've just caught up. Been through the Best Battery thread again and (other than the sealed / unsealed point) I'm struggling to find a reason not to stick with the regular Banner at ~£80. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 23 Member Share Posted April 23 6 minutes ago, JP said: Thanks again all. I've just caught up. Been through the Best Battery thread again and (other than the sealed / unsealed point) I'm struggling to find a reason not to stick with the regular Banner at ~£80. What's the current (!) cost of the added lightness? Jonathan Link to comment Share on other sites More sharing options...
JP Posted April 23 Author Share Posted April 23 (edited) £27.18 / kg! (inc VAT) https://www.tayna.co.uk/car-batteries/banner/53034/ vs: https://www.tayna.co.uk/motorcycle-batteries/odyssey/pc535/ If I've selected the correct Odyssey....if I haven't, it could be a lot more! Edited April 23 by JP Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 23 Member Share Posted April 23 Thankyou Jonathan Link to comment Share on other sites More sharing options...
JP Posted April 23 Author Share Posted April 23 Or £40.66 / kg if I should be looking at this one: https://www.tayna.co.uk/motorcycle-batteries/odyssey/pc680/ Link to comment Share on other sites More sharing options...
BigCol Posted April 24 Share Posted April 24 (edited) I replaced my Banner with a PC680 before going LiFePO4… Edited April 24 by BigCol 1 Link to comment Share on other sites More sharing options...
JP Posted April 24 Author Share Posted April 24 @BigCol may I ask why? Was it only weight saving? The Banner seems to have greater capacity and cranking then the others. For me reliability is my primary concern as mine is mainly a road car with occasional track days. Link to comment Share on other sites More sharing options...
SM25T Posted April 24 Share Posted April 24 Odyssey PC680 here Link to comment Share on other sites More sharing options...
BigCol Posted April 24 Share Posted April 24 7 hours ago, JP said: @BigCol may I ask why? Was it only weight saving? Banner —> Odyssey was (sort of) like-for-like but latter had a better reputation for longevity and being AGM, could be mounted on its side and I think was a tad lighter. Odyssey —> LiFePO4, yes - weight-saving though neither of the previous batteries had lasted a particularly long time (four and five years respectively from memory) so wasn’t motivated to go back to either. 1 Link to comment Share on other sites More sharing options...
JP Posted April 25 Author Share Posted April 25 (edited) Right! I've lost patience and ordered a new Banner and a new IACV! One of those must fix the problem! Having thought about this more, I do recall the cutting out happening once before, before I took the car off the road in about 2008/2009. It ran fine again afterwards, but perhaps that is a sign of a failing IACV... I'll look at lighter batteries next time once everything else is sorted. Thanks for all the help and guidance! Edited April 25 by JP Link to comment Share on other sites More sharing options...
John Vine Posted April 25 Share Posted April 25 2 hours ago, JP said: Right! I've lost patience and ordered a new Banner and a new IACV! One of those must fix the problem! To be sure you diagnose the problem, can I suggest you try these one at a time? JV Link to comment Share on other sites More sharing options...
JP Posted April 25 Author Share Posted April 25 (edited) Will do! Battery first and I'll keep the IACV in the boot just in case... Edited April 25 by JP 2 Link to comment Share on other sites More sharing options...
JP Posted April 26 Author Share Posted April 26 Battery and IACV arrived today. Battery fitted, but not test driven yet. However, I thought I would test the voltages on a fresh battery straight out of the box from Tayna. Here are the numbers for comparison: Voltages: Everything off, FIA off: 12.54V Everything off, FIA on: 12.54V Lights on for 10s, then switch off: 12.40V Cranking: No initial momentary large drop visible on my multimeter. Cranked steadily at 10.35V. Engine started (on the button, no throttle needed), idling at 13.95V. No 3000rpm voltage tested this time. Current IACV could be felt "stepping" briefly after switch off. I'll drive the car over the weekend. If it fails at idle again, I'll change the IACV. If I get to Sunday and it hasn't failed, I might change the IACV anyway, because the new one is shiny and new... 1 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 26 Member Share Posted April 26 Thanks for sharing the numbers. I'm surprised at that 10.35 V while cranking, and would be interested in what that is after charging. Jonathan Link to comment Share on other sites More sharing options...
JP Posted April 26 Author Share Posted April 26 I'll recheck it after driving, but I don't think I should have to put a new battery on a charger... Link to comment Share on other sites More sharing options...
SM25T Posted April 26 Share Posted April 26 Why not. It may have been sitting on a shelf for months. Link to comment Share on other sites More sharing options...
JP Posted April 27 Author Share Posted April 27 Out for a short spin today ~30 mins. No idle problems at all. Here are some further voltage readings for comparison after this morning's drive: Everything off, FIA off: 12.84V Everything off, FIA on: 12.84V Lights on for 10s, then switch off: 12.72V Cranking: No initial momentary large drop visible on my multimeter. Initial cranking at 10.90V, which dropped smoothly while cranking to a steady 10.71V. And looking at the revs drop as per @revilla posting above, I think I see a momentary pause during the fall: Videopro 20240427 110103-1.mp4 So, I now have a new IACV sitting in a box. I guess I might as well fit it... 1 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 27 Member Share Posted April 27 That sounds good. Thanks for adding the voltage measurements. That load test is now giving over 10.5 V, which is the diagnostic threshold that I've been suggesting. And I suspect that the charging did make a difference. Jonathan Link to comment Share on other sites More sharing options...
JP Posted April 27 Author Share Posted April 27 I'm sure it did JK, but, for clarification, it was only charged in the course of driving. I haven't had it on a charger. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted April 27 Member Share Posted April 27 18 minutes ago, JP said: I'm sure it did JK, but, for clarification, it was only charged in the course of driving. I haven't had it on a charger. Sure. And from the 3,000 rpm test we already know that the car's built-in charging system is up to scratch. That's why it's a good idea to include it asap. Jonathan 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now