Faults with new lead-acid batteries - Page 1
Forum section: electronics / projects

author: AndyC_772
author_rank: Super Contributor
timestamp: May 31, 2018, 11:15:55 am
content: Hi all,A couple of months ago I bought a new lead acid AGM motorcycle battery.Even after fully charging it from the mains, it wouldn't start the bike more than a few times. Today I've tested it by fully charging, then discharging at a constant 3.0A into an electronic load. It lasted just over 1 hr before the terminal voltage fell below 10.0V, meaning a useful capacity of ~3Ah instead of the rated 12Ah.I'm inclined to simply send it back, but I'm curious as to what the fault might be, and whether it can be easily fixed. Does anyone know anything about manufacturing faults with this type of battery?Also, does anyone know what a garage "battery test" actually consists of, and whether it's likely to show up a problem?

author: PChi
author_rank: Frequent Contributor
timestamp: May 31, 2018, 11:45:42 am
content: I was under the impression that a garage battery test was usually measuring the terminal voltage during a high current discharge test to simulate starter motor operation.It was able to start the motorcycle a few times so would be considered fit for purpose.Also the Ahr rating is usually for something like a 10 or 20 hour discharge instead of 1 hour which I would expect would give a slightly higher capacity measurement.I would treat the Ahr rating of vehicle batteries as a name not a capacity unless it's a reputable brand like Yuasa. There used to be (and probably still is) crap out there.

author: C
author_rank: Super Contributor
timestamp: June 01, 2018, 03:29:17 pm
content: First problem is that the ah rating is not what starts a car or a motorcycle.The specification for this is the "cranking current rating in amps"This is a max safe current possible.If greater then what is needed to start then you are good.If less then needed you may or may not start and are harming the battery.A battery will often go bad with a high resistance cell.Works ok at low current draws but at high current draws the voltage at the terminals drops fast.When testing a battery that is used to start something, a high current draw test is one of the tests.Nothing you can fix as far as the battery.Battery specifications is a bunch of conflicting want's.C

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2018, 05:17:39 pm
content: It was probably defective right from the start. It's also possible that it was stale stock that had been on the shelf long enough to go bad. I would try to exchange it, certainly nothing you can fix.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 01, 2018, 05:58:59 pm
content: When buying batteries from a physical store, I suggest taking a multimeter in order to make sure you don't buy a battery that has been on the shelf for too long.

author: IanB
author_rank: Super Contributor
timestamp: June 01, 2018, 06:11:03 pm
content: In the old days when you bought a battery it was shipped dry and was filled with acid at the point of sale. This avoided shelf life degradation and made sure the battery was "fresh" when you first received it.This days if a battery is shipped wet there is less control over its condition on delivery.As for the OP, did you test the battery voltage on receipt, and did you test the voltage periodically while installed in the motorcycle to make sure it was being charged properly? If the charging system was not working properly (i.e. not charging the battery) then the battery could be damaged through over discharge after just a few attempts to start the motorcycle.

author: C
author_rank: Super Contributor
timestamp: June 01, 2018, 07:32:24 pm
content: Note that the high current used during attempts to start the motorcycle will heat the battery.Even a good battery can be damaged by repeated attempts to start.IanB's note to check charging system is a good one as some are not very good.Check that battery is being charged and not over charged.C

author: AndyC_772
author_rank: Super Contributor
timestamp: June 01, 2018, 08:00:13 pm
content: It was delivered dry, with a sealed acid container. I've no reason to suspect a fault with the bike, but time will tell whether it damages the old (but otherwise OK) battery that's now fitted. Perhaps it's worth logging voltage over time while it's being ridden; I have a Fluke 289 that's perfect for the job.In the meantime, the supplier has asked for a garage test before accepting the return, which personally I regard as a total waste of time, but if it smooths the process...

author: tautech
author_rank: Super Contributor
timestamp: June 01, 2018, 08:40:15 pm
content: Quote from: AndyC_772 on June 01, 2018, 08:00:13 pmGood battery dealers do test batteries before sale these days with tiny little smart testers that indicate CC (Cold cranking) capability and AHr capacity. In the old days tests were done with Carbon pile testers, they had 2 analog gauges displaying V & A as you wound (compressed) the pile of conductive carbon piles together.They were tough on batteries if not used with care and would indicate a substandard battery immediately to an experienced operator. If a battery was tiring you could be fairly sure it would finish it off.So find a battery dealer with a modern smart tester and get it checked that way rather than with a carbon pile tester. To me it sounds like a dud battery.Good luck.

author: james_s
author_rank: Super Contributor
timestamp: June 01, 2018, 11:32:31 pm
content: The surprising thing is just how good some batteries can be. I sold an old car a while back that I had resurrected. When someone gave it to my dad the battery was several years old. It sat for a few years before I got around to replacing the head gasket and went *completely* flat. I assumed it was a goner but thought I'd try charging it just for fun and what do you know, it came back to life. I used it to start the car which at that point required a good deal of cranking and it worked fine. Well now we couldn't find the bill of sale to get the title transferred so again it sat. Fast forward another 4-5 years and my dad finally got the paperwork squared away, car had sat all that time and the battery was again completely flat. I guessed it was really done for this time but I put it on the charger and it again charged up and was able to do at least a couple minutes of intermittent cranking before I gave up. A few months later I started working on the car again, replaced the fuel pump relay which had gotten water in it, charged up the battery yet again and after a minute or so of cranking it fired up. Now drivable I was able to keep the battery from slowly draining but at this point it was almost 15 years old and had been drained down to 0V twice, sat that way for years at a time and then it was deeply discharged a couple more times and it still performed well. Amazing.On the other hand I've had batteries that barely lasted 2 years.

author: floobydust
author_rank: Super Contributor
timestamp: June 02, 2018, 05:12:06 am
content: Get a replacement battery.New flooded lead acid batteries, I've seen not work:Wrong acid mix used (too dilute)Plates oxidized from dry storage for a long timeBroken interconnects between plates (factory defect)A bad cell will gas a lot and use more water. Or you got a "new" battery sitting around for a long time that is sulfated.