Battery drain
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- dustin91
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Battery drain
Last Friday I picked up my 150 at the dealer for the 2,500 mile service. No problem riding it home from a cold start, but hadn't started it up until this morning, and it wouldn't turn over. Is it possible that the battery would drain that quickly, after 4 days without use?
Over the winter I use a trickle charger, and I do have a power line to a USB port on the handlebar – both installed by the same dealer. But nothing was plugged into the USB port, so there's no completed circuit and nothing to draw the power while it sat in the garage.
Just a bad battery?
Over the winter I use a trickle charger, and I do have a power line to a USB port on the handlebar – both installed by the same dealer. But nothing was plugged into the USB port, so there's no completed circuit and nothing to draw the power while it sat in the garage.
Just a bad battery?

- Mel46
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Re: Battery drain
Do you leave the key in the ignition when it is in the garage? Do you have anything else that was added that might have a direct battery connection? I have run mine down by forgetting to turn the key to completely off and leaving the key in the ignition. I have a power outlet attached also, but like you it shouldn't discharge unless something is attached to it. I do have additional external lights, and they can drain a battery rather quickly.
Currently own:
Red 2013 Honda PCX150
Givi tall windshield & tailbox - Lots of extra lights
Custom seat from Thailand - Bad Boy Airhorn
Takegawa Lowering Shocks - Michelin City Grip Tires
Headlight assy upgraded to LEDs w/HS5 main bulbs
NCY variator, drive face, and rollers
Red 2013 Honda PCX150
Givi tall windshield & tailbox - Lots of extra lights
Custom seat from Thailand - Bad Boy Airhorn
Takegawa Lowering Shocks - Michelin City Grip Tires
Headlight assy upgraded to LEDs w/HS5 main bulbs
NCY variator, drive face, and rollers
Re: Battery drain
Probably just needs a good run.
Four decades on two wheels has taught me nothing, all advice given is guaranteed to be wrong
- dustin91
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Re: Battery drain
Nope, no keys left in the ignition, ever (12 y/o son with a habit of leaving the garage door open), and nothing connected that would draw power while off. I was thinking maybe because it had just come out of service, that the battery wasn't fully charged, but I did an hour-long ride home, which I'd think should be enough to recharge it.
Maybe it's just one that needs to be trickled at all times during storage.
Maybe it's just one that needs to be trickled at all times during storage.

- Alibally
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Re: Battery drain
I presume the terminals are tight? If it's just been into the garage they might have been in there. It just could be a duff battery of course.

- dustin91
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Re: Battery drain
I'll check the terminals, thanks for the advice!
Otherwise, if they're good, I'll give the dealer a call.
Otherwise, if they're good, I'll give the dealer a call.

- Mel46
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Re: Battery drain
That does remind me of something that happened to mine. I had connected something directly to the battery and had screwed down the leads, but some how the lead vibrated and moved enough that the contacts on one side were loose by the time I got home and I had to retighten them. Make sure the trip home didn't jar the connections loose at the battery. It does happen..
Currently own:
Red 2013 Honda PCX150
Givi tall windshield & tailbox - Lots of extra lights
Custom seat from Thailand - Bad Boy Airhorn
Takegawa Lowering Shocks - Michelin City Grip Tires
Headlight assy upgraded to LEDs w/HS5 main bulbs
NCY variator, drive face, and rollers
Red 2013 Honda PCX150
Givi tall windshield & tailbox - Lots of extra lights
Custom seat from Thailand - Bad Boy Airhorn
Takegawa Lowering Shocks - Michelin City Grip Tires
Headlight assy upgraded to LEDs w/HS5 main bulbs
NCY variator, drive face, and rollers
- dustin91
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Re: Battery drain
Thanks Mel! I really don't have an issue with keeping it on the trickle charger whenever I'm not riding, as I hung the charger from the garage ceiling, and I pulled the charging cable through the battery door (with a little help from my Dremel), so it's easy enough to connect and keep the door in place. I just want to make sure I've got a good battery.

- kramnala58
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Re: Battery drain
After a 1 hour ride home, it should have been fully charged. How old is it? Maybe it needs to be replaced.
2010 Honda PCX 125 in Thailand (White) - "White Lightning" Sold in Sept 2017
2009 Yamaha Majesty YP400 in USA (Metalic Titanium) - "The Throne" Sold in June 2020

2009 Yamaha Majesty YP400 in USA (Metalic Titanium) - "The Throne" Sold in June 2020

- dustin91
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Re: Battery drain
Just under a year. And it wasn't dead, it just didn't have enough juice to turn over the engine. I went about a month earlier in the spring without riding or trickle-charging it, and it was dead then too.
Think I'm going to give the dealer a call...
Think I'm going to give the dealer a call...

- dustin91
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Re: Battery drain
Got word back from my dealer on the battery issue:
"The battery control test take 3 days. We need to measure the battery voltage and then let it sit and then measure the voltage again to see what it drops down to. Also we need to check for a draw cold then hot and the same thing for the charging system."
I'm right on the edge of one year since purchase, but I did get the extended warranty. Hopefully this will get covered if I wait until the end of the month to let them test it while I'm on vacation.
"The battery control test take 3 days. We need to measure the battery voltage and then let it sit and then measure the voltage again to see what it drops down to. Also we need to check for a draw cold then hot and the same thing for the charging system."
I'm right on the edge of one year since purchase, but I did get the extended warranty. Hopefully this will get covered if I wait until the end of the month to let them test it while I'm on vacation.

- you you
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Re: Battery drain
dustin91 wrote:Just under a year. And it wasn't dead, it just didn't have enough juice to turn over the engine. I went about a month earlier in the spring without riding or trickle-charging it, and it was dead then too.
Think I'm going to give the dealer a call...
The old rule used to be that a lead acid accumulator needs a round 70% of capacity to start an engine and it it loses around 1% per day. So after one month.....
- dustin91
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Re: Battery drain
Thanks you, but it was the 4 days without use after an hour-long ride and a mostly-dead battery that concerns me. Shouldn't an hour have been enough on a battery that had no issue turning over the engine for said ride?
If it was so drained that an hour's ride didn't charge it enough, then I shouldn't have been able to turn on the engine in the first place... I'd guess, but I'm no expert.
If it was so drained that an hour's ride didn't charge it enough, then I shouldn't have been able to turn on the engine in the first place... I'd guess, but I'm no expert.

- Alibally
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Re: Battery drain
My bike lay in my shed for nearly 3 months last winter and started on the button. 4 days shouldn't be a problem. The battery is bad or there is a drain on it.

- dustin91
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Re: Battery drain
Starting to think exactly that, maybe they did something when they installed the USB power port. Thanks Ali!

Re: Battery drain
Assuming it's possible for you to get access to the battery, it would be a quick test with a digital multimeter (DMM), frequently available at Harbor Freight for $2.99 and even free sometimes, if you don't already have one.
Disconnect the negative battery lead, then set the meter to current measurement mode, and put one test lead on the negative battery terminal and the other on the disconnected battery cable. Read the current displayed on the meter, and it should be pretty much zero mA, (no more than 5mA anyway), assuming no aftermarket accessories like alarms have been added. Any significant parasitic current draws and it'll have to be tracked down, maybe pulling fuses if it has a fuse panel.
If that's okay, reconnect the battery, and if you can get it started, when it's running, put the DMM in voltage measurement mode and see what voltage it reads across the battery terminals as you raise the rpm's up slightly (wheel off the ground, as I guess there's no neutral on scooters- scooter noob here ). I'd expect the voltage should read between 13.0V and 14.5V. If not, the charging system's suspect.
Disconnect the negative battery lead, then set the meter to current measurement mode, and put one test lead on the negative battery terminal and the other on the disconnected battery cable. Read the current displayed on the meter, and it should be pretty much zero mA, (no more than 5mA anyway), assuming no aftermarket accessories like alarms have been added. Any significant parasitic current draws and it'll have to be tracked down, maybe pulling fuses if it has a fuse panel.
If that's okay, reconnect the battery, and if you can get it started, when it's running, put the DMM in voltage measurement mode and see what voltage it reads across the battery terminals as you raise the rpm's up slightly (wheel off the ground, as I guess there's no neutral on scooters- scooter noob here ). I'd expect the voltage should read between 13.0V and 14.5V. If not, the charging system's suspect.
- Alibally
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Re: Battery drain
That's only going to tell you if it's charging. To check drain you need a 10amp or above ammeter or multimeter. The meter wires have to be put in series with the negative terminal of the battery so what your doing is wiring it between the negative battery terminal and the earth wire. If there is a drain on the battery it will show on the meter. This is not something you should do if uncertain of what your doing as wired wrongly or drawing too much current through the meter ,eg by operating the starter for example will damage the meter.
If it's under warranty then leave it to your dealer is probably the best advice.
If it's under warranty then leave it to your dealer is probably the best advice.
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- dustin91
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Re: Battery drain
Thanks for the advice guys, but this stuff's above my pay grade, and as Ali said, if I'm unsure of what I'm doing, let the dealer do it.
I am *very* unsure of what I'm doing!
I am *very* unsure of what I'm doing!
