Andrew Posted January 27 Share Posted January 27 I charged my original AGM battery on Thursday night/Friday morning. It's now Saturday. I charged it with my smart charger Ctek MXS5.0 smart charger. I had reason to removed my battery from the car so I took the opportunity to run a health check on it using a Topdon BT200 battery tester. The battery in question was made in week 50 of 2012 form my Jan 2013 build F10. It has a 90Ah capacity with 900 CCA, and yes it's over 11 years old. On connecting the tester the battery voltage is measured at a healthy 12.8 volts. So far so good. I then carry out a battery test after inputting the 900 figure for the cold cranking amps rating. and get a fail as a result of the test. The charge is still at 100%, I had disconnected the charger only 24 hours previously and had used the car earlier today. The % health of 67% almost ties in the the 737CCA score against the 900CCA rating. But what I want to know is why it has failed it. Is the internal resistance too high at 3 micro Ohms? Car starts fine, and more importantly the stop/start function works too. That to me means it's healthy enough? I'm not an electrical engineer so I'm a bit stumped. Any advice from anyone? Or is it game up for an 11 year old original AGM battery? https://www.tayna.co.uk/car-batteries/banner/59201/ Quote Link to comment Share on other sites More sharing options...
Steve84N Posted January 27 Share Posted January 27 I'm no expert on electronics either but have you tried running the reconditioning cycle on the CTEK? A quick Google shows that 'the main cause of low cranking amperage is stratification, where the sulfuric acid settles to the bottom of the battery due to low charge, underuse, or shallow discharges' . Quote Link to comment Share on other sites More sharing options...
duncan-uk Posted January 27 Share Posted January 27 I can't comment on the testing you've done but my experience these days is batteries either work or they dont - they go off pretty quick, you get a bit of a slow crank as a warning but then find them dead one morning but will jump ok. I'd be tempted to live with it a little longer and test again in a couple of weeks - see if it changes. Quote Link to comment Share on other sites More sharing options...
Andrew Posted January 28 Author Share Posted January 28 10 hours ago, Steve84N said: I'm no expert on electronics either but have you tried running the reconditioning cycle on the CTEK? I stand to be corrected but I’m sure I’ve read the recond cycle isn’t suitable for AGMs. Will need to check. It cranks and starts just fine. Quote Link to comment Share on other sites More sharing options...
Steve84N Posted January 28 Share Posted January 28 I found this: start attempt. Stratification also promotes corrosion on the upper half of the plates and sulphation problems at the bottom. Why does recond help? Recond causes a controlled gassing that remixes the acid and equalizes the acid balance and through that the battery capacity is reclaimed and battery efficiency is restored, partially or almost all of it, depending how severe the problem is. Just one more thing: Do not mix Stratification with Sulphation problems! Sulphation affects all kind of lead/acid batteries AND every CTEK charging program starts with a desulphation step, so you do not have to worry about that!! Hope this was helpful Best regards, CTEK SUPPORT TEAM So yes, it won't help unfortunately. 1 Quote Link to comment Share on other sites More sharing options...
Matthew Posted January 29 Share Posted January 29 On 28/01/2024 at 10:10, Andrew said: I stand to be corrected but I’m sure I’ve read the recond cycle isn’t suitable for AGMs. Will need to check. It cranks and starts just fine. Correct Andrew, the CTEK recon cycle is redundant for AGM batteries. Like has been said, I’d also continue with your current battery until it dies. The AGM battery in our F45 is 10 years old and the car only does short trips so I charge it with the CTEK every month or so and it continues to work fine, and like yours, the start stop is happy to work too. The start stop not working constantly will be my gauge as to how when the battery needs replacing. (You need an IBS for that though😆) Quote Link to comment Share on other sites More sharing options...
Andrew Posted January 30 Author Share Posted January 30 22 hours ago, Matthew said: The AGM battery in our F45 is 10 years old and the car only does short trips so I charge it with the CTEK every month or so and it continues to work fine, and like yours, the start stop is happy to work too. Thanks Matthew. Have you tested the battery in your F45? As in do you know it’s condition? Mine is obviously poor but I have no obvious signs of something amiss with it as it all works as it should. Well it did till I removed the IBS…. Quote Link to comment Share on other sites More sharing options...
BobA Posted January 31 Share Posted January 31 (edited) On 27/01/2024 at 21:57, Andrew said: But what I want to know is why it has failed it. Is the internal resistance too high at 3 micro Ohms? Not relevant to your issue @Andrew but I’d say that the resistance measurement is actually in milliohms and to put it in context the main battery feed is probably v-e-r-y roughly about 0.5 milliohms per metre (assuming 2 gauge but not checked what BMW actually specify). So the battery losses are in the same order as the cable losses and IMHO not an issue. back to sleep now ……. 🥱 Edited January 31 by BobA 1 Quote Link to comment Share on other sites More sharing options...
Andrew Posted January 31 Author Share Posted January 31 Thanks @BobA, of course yes milliohms, micro would be uOhms. Quote Link to comment Share on other sites More sharing options...
Andrew Posted March 10 Author Share Posted March 10 So a few weeks later, today I was testing the battery on my mums car. It was ok but I thought a check on mine would be in order. Checked on the under bonnet terminals this time. I did 50 miles in it on Friday, stop start was spot on, only did 6 miles in it yesterday and hasn’t been driven since. I had ordered some bolts from my local dealer last Thursday. I think I’ll collect a new battery when I’m collecting the bolts some time this week. Quote Link to comment Share on other sites More sharing options...
Matthew Posted March 12 Share Posted March 12 On 30/01/2024 at 20:45, Andrew said: Thanks Matthew. Have you tested the battery in your F45? As in do you know it’s condition? Mine is obviously poor but I have no obvious signs of something amiss with it as it all works as it should. Well it did till I removed the IBS…. Sorry, a late reply but no, I haven’t test the F45’s battery (don’t have a device) but the CTEK does a level of testing to make sure the battery is holding charge enough to continue the charge cycle and so long as the car works and start stop does its thing from time to time, I’m going to rinse every last Ohm from the battery before changing. Quote Link to comment Share on other sites More sharing options...
Andrew Posted March 12 Author Share Posted March 12 2 hours ago, Matthew said: I’m going to rinse every last Ohm from the battery before changing. Spoken like a true Yorkshireman or Scotsman.🤣 Despite mine looking grim, it started on the button this morning (not used since Sat am) and the stop start worked faultlessly. So clearly still serviceable. For now, anyway... 1 Quote Link to comment Share on other sites More sharing options...
Andrew Posted March 18 Author Share Posted March 18 After another week being used daily and faultlessly, well in the battery department anyway, I did a test on Sunday morning. Charge had dropped slightly since last week I then stuck it on to charge with my Ctek MXS5.0. It had fully charged by late Sunday afternoon, which was quite quick, normally it takes 12-14 hours, but it was about half that time to get to fully charged as indicated on the Ctek. Took it off charge about 30 mins ago (Monday) and did a test after less than 24 hours on charge. Everything is a bit better, but still needing replaced. Quote Link to comment Share on other sites More sharing options...
Andrew Posted April 22 Author Share Posted April 22 So At the weekend when I had a few moments, I found myself investigating the water leak in the boot. Didn't find that but I did do another battery test. Tester clipped directly to the battery terminals and its a better result than end of January. I then repeated the test with the tester clipped to the jump start posts under the bonnet. Quite noticeable differences but how clean are the jump starting terminals? Not worth testing unless direct on the battery terminals. Has the battery got 'healthier' then since I checked it at the end of January when again it was tested direct on the battery terminals? Quote Link to comment Share on other sites More sharing options...
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