Motorcycle Electrical Problem with New Battery - Page 1
Forum section: electronics / projects

author: paul_g_787
author_rank: Frequent Contributor
timestamp: May 03, 2023, 06:29:50 pm
content: I am having a problem with my motorbike's new battery and trying to prove if the fault is the battery or something else like the regulator/rectifier.We went away on a camping holiday at the weekend on the motorbike. I had problems the previous week starting the bike, so seeing as the battery was about 8 years old and was dropping to 7.5V when cranking and struggling to start, I decided to replace it.I bought a Yuasa brand battery and the battery had been activated with the acid packs only 3 weeks before I bought it.I gave it an initial charge with my Optimate 3 charger overnight and it was charged by the morning.I rode the bike to work for 4 days and charged the battery overnight again the night before I left. Rode over 350 miles on holiday with no problems.On the way home I rode about 120 miles then stopped for fuel. Got back on the bike and could not start it. It did not even turn over once and the voltage dropped so low the dashboard and digital display powered off.I left it a couple mins then tried again, same thing. I tried turning the engine over by pushing the bike forward in 4th gear but it was fine.I called the breakdown and luckily he was nearby. He jump-started the bike with his battery and it started instantly. He told me he sees this a lot and it is a faulty battery (which I was hesitant to believe).I left it idling for 10 mins while I re-assembled the seats then rode 70 miles home with no trouble, this was yesterday.I just got the bike out after work this evening to measure the battery with my meter connected to the battery in min/max record mode.It was initially at 12.8V. Then at 12.5 when the ignition was switched on and then dropped to a min of 10.3V while cranking.Once started the voltage is now 13.5VDC.I measured the AC voltage and there is 0.03V of ripple.As far as I can tell this looks normal.Any thoughts?Does this prove the regulator/rectifier is working alright?

author: Stray Electron
author_rank: Super Contributor
timestamp: May 03, 2023, 07:44:10 pm
content: Here in the US there have been massive numbers of bad brand new batteries in the past dozen or so years. Johnson Controls bought out several other battery manufacturers and the batteries made by them have been (still are?) absolute Shiit.Here in the US many of the auto parts stores will test your battery (also your alternator) for free. Do you have anything similar there?Who was the actual manufacturer of your battery? In the US there are only a couple of companies that actually manufacture batteries but they'll slap on a brand label for any company that you can think of. Actual Japanese made batteries have a very good reputation in the US but are rare and generally only found in vehicles that were actually made in and shipped from Japan with the battery installed there.

author: themadhippy
author_rank: Super Contributor
timestamp: May 03, 2023, 07:47:39 pm
content: Not a z200 is it? had one that coughed and spluttered a few miles into the journey ,flicked the indicator to pull off the road and it burst back in to life leading me down the faulty electrics rabbit hole when fact it was a knackered cam bearing, making the alternator work harder pulled everything tight and the bugger would run fine .

author: floobydust
author_rank: Super Contributor
timestamp: May 03, 2023, 07:48:32 pm
content: What kind of motorcycle is this - alternator, PM generator or what.Ten things can cause the problem you are having. It doesn't make sense that you can start and drive the bike yet the battery is flat dead hours later.I find first it's bad wiring- corrosion, broken wires that make for intermittent problems. Even one had issues at the ignition switch because they are out in the rain and wire flex too.The regulator/rectifier module usually is a steady failure, so you get high parasite drain or weak charging. Measuring 0.03V of ripple is wrong, you'll never see a value that low when an ignition system is involved.I would go through the basic wiring between battery and alternator, looking for bad connections. You could measure battery drain key off to confirm shorted rectifier diode is not the problem. But the battery had no reason to go that dead, as I find the bike's electrics will konk out so it must have been using the alternator/generator for powering things... so what was discharging the battery then?

author: Stray Electron
author_rank: Super Contributor
timestamp: May 03, 2023, 07:49:05 pm
content: PS batteries sold in the US usually have a manufactured date but the manufacturers must be fudging that. Two people that I know, recently purchased brand new batteries that had a manufactured date that waslaterthan the date that they bought the batteries on! So based on that, I wouldn't be absolutely certain that your battery was only activated only three weeks earlier!

author: Stray Electron
author_rank: Super Contributor
timestamp: May 03, 2023, 07:52:27 pm
content: The other thing that you need to do is to check the parasitic drain on the battery if you haven't already. Disconnect the ground lead at the battery and connect an amp meter across the gap and see what kind of current is flowing in the circuit under various conditions.

author: mikerj
author_rank: Super Contributor
timestamp: May 03, 2023, 07:58:50 pm
content: Check all the high current starter connections and crimp terminations, especially on the solenoid itself (where the unswitched supply for the rest of the electrics typically comes from) and the grounding cable for the battery. It takes very little resistance to emulate the effects of a dying battery.

author: CaptDon
author_rank: Super Contributor
timestamp: May 03, 2023, 10:13:21 pm
content: I had a brand new car battery act that way years ago. The internal cell to cell strap was cracked. The battery showed full voltage and tested good on a tester but when I turned the key it would go stone cold dead. They argued that I had a shorted starter. I said "Put my old piece of crap battery back in and give me my money back. They put the old battery back in and it cranked slow but started so they gave me a new battery and everything was fine after that.

author: paul_g_787
author_rank: Frequent Contributor
timestamp: May 15, 2023, 06:43:25 pm
content: I checked the main starter motor lead and the main earth lead and they are good and have good connections as far as I can tell.Haven't had chance to look further yet.It is a Suzuki SV650S, the original model made in 2000.

author: WI_Hedgehog
author_rank: Newbie
timestamp: May 19, 2023, 08:08:53 pm
content: Check for bad connections / loose battery wires, pull on them--loose wires at the terminals is the most common problem I find on Harleys due to vibrations. They need to be tight.Otherwise, watch your voltage. If you start the bike and it goes to 13.2V or more it's likely the battery. I have a carbon pile tester because as others said, the U.S. gets bad imports (due to lead regulations).https://www.amazon.com/gp/product/B014T7HL3I/Check the fluid levels if it's wet, AGM of course is sealed, lithium is a different monster (I have all three, use depends on the bike).I also run a home-made SAE cable up to the headlight for a battery maintainer, and by adding a short extension whip can Velcro this on top the brake fluid reservoir:No longer on Amazon, here's the description: Eriding Motorcycle SAE to USB Plug with Voltmeter Dual USB Charger Blue LED Quick Disconnect Plug Waterproof Smart PhoneNOTE: None of my links are affiliate links, I get no compensation other than hopefully helping a mate out.

author: bson
author_rank: Unknown
timestamp: May 21, 2023, 07:25:04 pm
content: Quote from: floobydust on May 03, 2023, 07:48:32 pmIf the alternator or rectifier fails the ignition, lights, and electronics will run off the battery, draining it. Then when you stop for fuel and try to start a few hours later the battery won't have enough voltage to turn the starter.Another thing to consider is if there's an external alternator it likely has a belt which might be in need of replacement or tensioning. If the belt slips the alternator won't turn. On other bikes the stator is inside the main engine case and there's no alternator per se.Sometimes glued stator magnets will come loose and flip over.

author: mikerj
author_rank: Super Contributor
timestamp: May 21, 2023, 08:46:49 pm
content: Quote from: paul_g_787 on May 15, 2023, 06:43:25 pmI missed this, my father has a 2002 SV650 and some years back it suffered from corrosion in the wiring loom causing non-start problems. It was in the main wiring loom section towards the rear of the tank IIRC and I had to unwrap the loom covering to find it.

author: paul_g_787
author_rank: Frequent Contributor
timestamp: June 08, 2023, 08:48:33 pm
content: Hey all. Just wanted to update you as I found the issue and my bike is now working again!I took off the rear cowling and probed the generator which was outputting >90V between all the 3 coils which was good.I then measured the battery again terminals and was only getting 13.5V which seems low.So I disconnected the regulator rectifier and tested it and I found one of the 6 diodes was shorted!I noticed the regulator rectifier was not the original. So the previous owner obviously has a problem too. (I am the second owner).The after market one has proved reliable though as I have had the bike over 11 years now.Unfortunately it is potted in a hard JB-Weld / epoxy looking compound that I cannot dig out, so I have purchased a new one.Just another Chinese no name one from eBay for £21. I have installed it on the bike and I now have 14.4V across the battery when running!Been using the bike all week and everything seems fine now.Thanks for the advice and information, it really helped me understand what is going on.