Light Circuit Dropped Voltage
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,586
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From: Honah Lee
Your battery test seems strange to me. A 15 amps drops it to 11.7. is way too much. At 12.3 will barely crank. Load test should have been way more then 15 amp.
Try with on **** after a fully charged 24 hours on a maintenance charger, check it on bike. It should not drop below 9.7 or so cranking. That is how I load test it. Most car battery testers are lost of these little batteries.
If it truely was load tested at 15 amps and it dropped like that, your battery has about as much reserve cranking amps as a flashlight battery.
Try with on **** after a fully charged 24 hours on a maintenance charger, check it on bike. It should not drop below 9.7 or so cranking. That is how I load test it. Most car battery testers are lost of these little batteries.
If it truely was load tested at 15 amps and it dropped like that, your battery has about as much reserve cranking amps as a flashlight battery.
Last edited by Jackie Paper; Mar 18, 2021 at 04:13 PM.
HDF Community Team
Joined: Dec 2005
Posts: 5,419
Likes: 2,621
From: NC USA
Your battery test seems strange to me. A 15 amps drops it to 11.7. is way too much. At 12.3 will barely crank. Load test should have been way more then 15 amp.
Try with on **** after a fully charged 24 hours on a maintenance charger, check it on bike. It should not drop below 9.7 or so cranking. That is how I load test it. Most car battery testers are lost of these little batteries.
If it truely was load tested at 15 amps and it dropped like that, your battery has about as much reserve cranking amps as a flashlight battery.
Try with on **** after a fully charged 24 hours on a maintenance charger, check it on bike. It should not drop below 9.7 or so cranking. That is how I load test it. Most car battery testers are lost of these little batteries.
If it truely was load tested at 15 amps and it dropped like that, your battery has about as much reserve cranking amps as a flashlight battery.
Even a 32 amp system takes 20 minutes or more of riding to build back full charge after a cold electric start on a good battery. If you just kick one off on a low battery and putt around a little while with lights on it takes a good while, even on a healthy battery. A deficient battery will almost never build back without 30 - 40 miles at speed and a bad one that might E start cold may never build back.
I've seen (and done) too many parts swaps all because of a bad battery that never got fully tested and ruled out... just sayin'
Thread Starter
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Cruiser
Joined: Jun 2015
Posts: 104
Likes: 2
From: Olympia, WA
Im just going by the spec sheet of the tester used at advance auto, the Spectre HP. They also put it in an analog load tester and it was also 12.5 down to 11.5 or so.
i did also take it to autozone but the practice squad there barely knew how to hook their tester up and didnt give me much confidence they knew what the hell they were doing anyway. But, they said it tested good also.
from the tester user manual:
The SABRE HP hand held battery testers utilize the SPX Micro Load technology to determine the dynamic Impedance.
The first load is 1.5 Amps and is applied for 5 seconds, this load
Conditions the battery
Establishes an accurate state of charge that is used for test corrections
The second load is 15 Amps and is applied for two seconds
This load is used to measure the internal impedance of the battery and calculate the actual capacity of the battery. It does this by precisely measuring the voltage drop over the time that the 15 amp load is applied
The battery is then allowed to recover for 5 seconds The tester plots the recovery curve of the battery once the load is removed. Characteristics of problem batteries can be identified by how the battery recovers.
i did also take it to autozone but the practice squad there barely knew how to hook their tester up and didnt give me much confidence they knew what the hell they were doing anyway. But, they said it tested good also.
from the tester user manual:
The SABRE HP hand held battery testers utilize the SPX Micro Load technology to determine the dynamic Impedance.
The first load is 1.5 Amps and is applied for 5 seconds, this load
Conditions the battery
Establishes an accurate state of charge that is used for test corrections
The second load is 15 Amps and is applied for two seconds
This load is used to measure the internal impedance of the battery and calculate the actual capacity of the battery. It does this by precisely measuring the voltage drop over the time that the 15 amp load is applied
The battery is then allowed to recover for 5 seconds The tester plots the recovery curve of the battery once the load is removed. Characteristics of problem batteries can be identified by how the battery recovers.
HDF Community Team
Joined: Dec 2005
Posts: 5,419
Likes: 2,621
From: NC USA
I’m just going by the spec sheet of the tester used at advance auto, the Spectre HP. They also put it in an analog load tester and it was also 12.5 down to 11.5 or so.
i did also take it to autozone but the practice squad there barely knew how to hook their tester up and didn’t give me much confidence they knew what the hell they were doing anyway. But, they said it tested good also.
...........
The first load is 1.5 Amps and is applied for 5 seconds, this load
.........
The second load is 15 Amps and is applied for two seconds
i did also take it to autozone but the practice squad there barely knew how to hook their tester up and didn’t give me much confidence they knew what the hell they were doing anyway. But, they said it tested good also.
...........
The first load is 1.5 Amps and is applied for 5 seconds, this load
.........
The second load is 15 Amps and is applied for two seconds
I certainly didn't know they used that stuff where you are. The one's around here use the 300 amp carbon pile testers that'll actually load and test one like ya have to.... Like Rip said, 15 amps is nothing. That's only 2x what the head and tail lamps and ign pull when you switch it on.
Can't say it's bad, but I can say - it's not been load tested properly yet....
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,586
Likes: 6,435
From: Honah Lee
Test it on the bike like I said. I keep having odd problems with my 3rd battery years back. I carried it to check. All good. Few months latter same thing. I finally just replace it. All was good.
SInce then, I only use maintenance charger if it sits a lot. I don't want the last start when I leave home.
I keep an eye occasionally on that 9.7 or so at cranking.
Once it has a little hesitant on hot starts or bangs, I replace it.
SInce then, I only use maintenance charger if it sits a lot. I don't want the last start when I leave home.
I keep an eye occasionally on that 9.7 or so at cranking.
Once it has a little hesitant on hot starts or bangs, I replace it.
Advanced
Joined: Nov 2018
Posts: 66
Likes: 20
From: michigan
I had my battery load tested after charging it up all night. It's a 310 CCA AGM battery that tested good. It dropped from 12.5 to 11.7 on a 15amp load, then back up in the recovery period.
Your battery test was incorrect in my opinion, If using a carbon pile load test, the battery is checked at 1/2 CCA, your case 150amp for
15 seconds and the voltage should not fall below aprox 11 volts at the end of the 15 second test.
in my opinion, if your dropping to 11.7V with only a 15amp lode your battery is done.
I got about 50 AC volts at around 2000 rpms.
Your AC volts seems good
As suggested I guess the next step is replacing the regulator anyway. Frustrating since I maybe have 100 miles on the current one. But that's what I get for riding a classic I suppose. If there are any other stones I haven't turned over I'm all ears. Thanks much.
Your battery test was incorrect in my opinion, If using a carbon pile load test, the battery is checked at 1/2 CCA, your case 150amp for
15 seconds and the voltage should not fall below aprox 11 volts at the end of the 15 second test.
in my opinion, if your dropping to 11.7V with only a 15amp lode your battery is done.
I got about 50 AC volts at around 2000 rpms.
Your AC volts seems good
As suggested I guess the next step is replacing the regulator anyway. Frustrating since I maybe have 100 miles on the current one. But that's what I get for riding a classic I suppose. If there are any other stones I haven't turned over I'm all ears. Thanks much.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,586
Likes: 6,435
From: Honah Lee
Interesting but I tried to attach this yesterday and all I got was Memory Error on my phone. Now it works. Sure wish someone could explain that.
Last edited by Jackie Paper; Mar 20, 2021 at 10:01 AM.
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Seasoned HDF Member
Joined: Oct 2005
Posts: 7,499
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From: Santa Klaus County, Cali
Any chance it could be a bad ignition switch? Just a 3 position switch...off...on...(on) & lights. Don't know how to test those switches but it doesn' seem that the OP has ruled that out or eliminated that as a potential source of the problem. I may have missed that tho.