How Accurate are Battery Testers? part1 Topdon BT600 (Battery testing only)

[@Mickytdi]

Battery manufacturers clearly state you can’t test a brand new battery with any conductance tester. The results will be unreliable. They need to be conditioned with use.

[@azerotha4531]

I know, hence, I tested some used batteries as well. You can test new batteries perfectly fine with the conductance testers but the batteries won't be at perfect health untill after several start cycles but they should still pass a test, if they fail then its pointless fitting it to the car as it will soon come back with a battery fault. This is also one reason hybrid and EV cars go through 12v batteries faster than standard internal combustion engines the current draw when turning them on isn't helping the plates stay in good condition, or condition them in the first place.

[@Mickytdi]

@ i found the cheaper Topdon arti 100 a very reliable indicator of my AGM battery failing over time. It was rated at 680 A EN. I watched it gradually drop to 350 A over the years. I could predict it failing with that tool. It started struggling to start at 350 when cold. The new battery i fitted was 760 A en but only read 560 A when new. After a couple months of use it read 790 A

[@azerotha4531]

@Mickytdi I've never actually seen a new battery test 200 Amps bellow the rating obviously not impossible lol most of the new batteries I test tend to be the rated number, higher or around 10% bellow the rated number, but your experience shows how much they can improve over time 👍

[@Mickytdi]

@ i have noticed temperature can give different results with these testers. I did come across one 5 year old battery that fooled my tester. A friend had a bad battery. My tester read 40 A over it’s rated A and passed it but was still causing intermittent low cranking issues. Do you see much of a Amperage loss before cranking issues? When someone comes to you with battery issues what’s the average SOH % are they reading? I replaced my last battery at 30% SOH. It still was starting but low cranking in frost.

[@azerotha4531]

@Mickytdi batteries are a mine field lol I've seen batteries show 800 amps out of 850 but when Cranking the voltage will drop to 2v the fault in the battery can sometimes trick the tester, these Testers are not perfect but they have a good track record, I did a range rover last week because the electronic boot would not lift open but when running it worked fine, the battery passed a test but was only just a pass, new battery on it and the boot was back to normal operation, modern cars have smart charge and stop start and most car manufacturers will have a 60 to 75% SOH replacement figures again this varies between manufacturers, older cars let's say pre 2000 can get away with 45 to 50% SOH before replacement is recommended. If I come across a car that fails a test but only just and once running the battery is accepting 50% or more of the AH then its a good chance a good charge will recover it but if the battery is say accepting less than 30% of its AH it will usually not recover you might get the odd one but most won't tricke chargers can do wonders to recover batteriesbut you will only know once you try to charge it. Temp plays a big part as the temp drops the engine reqs more amps to turn over but the batteries ability to deliver tge Amps drop, so if you have a car that needs say 300 amps to start the car at 20 degrees and the battery has 330 amps it will start fine once you hit say 0 degrees the engine will need say 320 amps but the battery can now only deliver 310 amps it might just catch and start or just not quite make it this is one reason batteries produce more power than needed to allow wear overtime and still be reliable and to deal with the very cold temps some places get, those numbers are just examples lol and not scientifically tested 🤣