Topic: Battery dying: differential diagnosis?

[medic09]

Have been riding my bike without particular problems.  A few days back I blew a fuse while sorting some wires in the headlight bucket.  Replaced the fuse without thinking twice.

Today went for a good ride with my wife, then did some maintenance.  Valve clearances, timing.  No big deal.  Went for a test ride.  Rode okay.  Stopped for gas, and the starter wouldn't kick over; not enough juice.  The turn signals didn't work, either.  Kick started, and went home.

Checked the battery, and it's showing 8+ volts!  What happened to 12+?   

This is a fairly new (last fall) glass mat battery.  Am I correct in thinking that my daily commute (130 miles/round trip) should be recharging my battery?  That I shouldn't ordinarily need the charger?  That something is wrong here, as of today?

The only other recent changes have been that I've put PIAA bulbs in the headlight and signals, and Tailblazer (name?) blinking bulb in the taillight/brake light.  As far is I know, I have not significantly increased the amps drawn down here.  The rectifier and voltage regulator are new components from Oregon Motorcycle that I put in over the winter.

I've been riding the bike since late February/early March.  Having put it on the charger because I haven't needed to.

Can anyone help with my differential diagnosis?

Thanks!

[750goes]

what are the power consumption ratings (watts?) of the headlight and flashing lights ?? - if its a high powered light you could be draining the battery as you ride ??

apart from that  - give the battery a charge and then do a test with the bike runnning and measure the voltage drops as you turn on the offending items (just wind your idle up to say 3500 for the experiment)

[medic09]

The demand of the new bulbs is within the range of the standard stuff; or so the manufacturer claims.  I didn't do the arithmetic, but with claims of no additional drain, I didn't anticipate problems.

I charged the battery last night, so that I can check it before I dare ride on my commute this morning.  I *really* don't want to take the car...

[medic09]

Well, this AM it starts right up.  ~12.5 volts resting, ~13.5 volts (?!) at about 3,000.  Shouldn't that be more like 14?  The charger didn't showed 'finished' yet, so I put it back on while I get ready to leave.

[bryanj]

You are right that isnt enough. resting volts, fully charged, shouold be 13.2 (2.2 volts standard per cell x 6 cells) charging volts shoult be 14 -14.5.

You have one of three faults.

(1) disconnected wire(s)

(2) bad connectors

(3) bad regulator/rectifier---just cos its recently new dont mean its still OK

[SteveD CB500F]

"Resting" is with the ignition off, right?

You certainly won't get 13.2V with the ignition on (no engine running)

[bryanj]

Yup Steve that is fully charged with no drain at all, because they are "nominally" a 12v battery and described as such people think 12 is fully charged, its only when you go back to the school physics basics and remember that the acid cell gives 2.2 volts and there are 6 of them in series you get the 13.2 volts that our batteries should be at when fully charged and of course you need a differential to charge them, without going so high as to boil of the fluid, so thats where the 14.2-14.5 that most electonic regulators are set at comes from (28.4 on HGV with 24 volt system)

[medic09]

Well, Bryanj, if those really turn out to be the only likely possibilities for a differential dx, that won't be so bad.  I did my morning commute (~65 miles, mostly highway speed), and packed along my multimeter.  When I go back out later, I'll take a quick look at the battery again.  I've got the old reg and rec, so I can do a little experiment when I have time at home.

Anything else I should be looking for?

[SteveD CB500F]

Make sure the battery earth (-ve) strap makes a good connection with the frame. It doesn't matter how good your reg/rec is, if this is anything other than "good" you'll always have problems.

[medic09]

Make sure the battery earth (-ve) strap makes a good connection with the frame. It doesn't matter how good your reg/rec is, if this is anything other than "good" you'll always have problems.

That's why I ask you guys!    I wouldn't have thought of that...

[bryanj]

An easy check with a voltmeter is at any "hot" connection check the voltage between it and the battery ground terminal direct and also betwen it and the engine---shound be the same, if not you have a bad ground point, you can also put a probe on each end of the ground wire and see if there is a voltage, if there is there is a problem--used this for years on Fiats which had notoriously bad ground cable connections which caused flat batteries

[eldar]

13.2 when off? I never have had a battery read that even when fully charged. 14.5 volts is getting into the dangerous range for charging the battery too. Gets close to boiling after a while. 14 is ok but anything in the 13 range is ok. Even cars I have had never charged at anything above 14 and this includes metros, nissans, hondas, or even old fords. My nissan did it once, when the vr was bad.

[SteveD CB500F]

As Bryan says, the 13.2V is a theoretical maximum. Even brand new batteries will fall a little below this.  My bikes (including my modern ones), sit at about 13V when off.

[SteveD CB500F]

Just measured my Triumph.

12.9 off
12.5 on
14.2 at 3k rpm

That's solid state electronics and modern gel battery (same chemistry though!)

[TwoTired]

For lead acid batteries, 13.2 V is the peak surcharge reading you should get just after you disconnect the charger.  A fully charged battery that as "normalized" after about an hour or two is 12.7 Volts.

http://www.yuasabatteries.com/faqs.asp?action=1&id=14

Vehicle charging systems usually try to maintain an operating battery at about 13.8 V with 14.5 Volts being the upper limit, above which electrolysis starts separating hydrogen and oxygen from the electrolte (looks like boiling).

Cheers,

[eldar]

Yeah my Batt sits at about 12.6 or so a couple after riding. Around 13.3 or so when above 3000rpm, maybe slightly higher but not above 13.7.

[medic09]

Okay, so I charged the battery overnight.  It showed about 12.5v key off, and about 13.5 @ about 3000 rpm.  I rode my commute, about 65 miles, mostly on the highway.  Parked the bike for about 7 hours.  Ambient temp reached about 30 C, 50 in the direct sun.  Before I started off, I checked the battery.  It showed 12.77v without key, and 15+  at about 3500 rpm.  Rode home.  The battery showed 12.94 without key, 12.53v initially at idle, 15+ at about 4000 rpm, and 13+ at fast idle.

I guess I should switch out my voltage regulator?  Presently I have a fairly new solid-state unit; but I have still have the old original.

 

[eldar]

You might want to do that and see what happens. I would rather have a battery go dead from not enough charge than fry it from too much.

[TwoTired]

Okay, so I charged the battery overnight.  It showed about 12.5v key off, and about 13.5 @ about 3000 rpm.  I rode my commute, about 65 miles, mostly on the highway.  Parked the bike for about 7 hours.  Ambient temp reached about 30 C, 50 in the direct sun.  Before I started off, I checked the battery.  It showed 12.77v without key, and 15+  at about 3500 rpm.  Rode home.  The battery showed 12.94 without key, 12.53v initially at idle, 15+ at about 4000 rpm, and 13+ at fast idle.

I guess I should switch out my voltage regulator?  Presently I have a fairly new solid-state unit; but I have still have the old original.

 

I don't know what color wires your new regulator has.  But, the old one used the black wire to sense what the battery voltage was and made decisions on controlling the alternator based on that.  Were I you, I would check to see that the black wire at the regulator had the same voltage as the battery.  If not, find out why and fix it.

Cheers,

[medic09]

Okay, so I charged the battery overnight.  It showed about 12.5v key off, and about 13.5 @ about 3000 rpm.  I rode my commute, about 65 miles, mostly on the highway.  Parked the bike for about 7 hours.  Ambient temp reached about 30 C, 50 in the direct sun.  Before I started off, I checked the battery.  It showed 12.77v without key, and 15+  at about 3500 rpm.  Rode home.  The battery showed 12.94 without key, 12.53v initially at idle, 15+ at about 4000 rpm, and 13+ at fast idle.

I guess I should switch out my voltage regulator?  Presently I have a fairly new solid-state unit; but I have still have the old original.

 

I don't know what color wires your new regulator has.  But, the old one used the black wire to sense what the battery voltage was and made decisions on controlling the alternator based on that.  Were I you, I would check to see that the black wire at the regulator had the same voltage as the battery.  If not, find out why and fix it.

Cheers,

Thanks for that tip, Lloyd.  The Oregon Motorcycle reg uses the same wires; it is plug and play.  Where would I put the probe to check this?  Do unplug the black wire from the reg while the engine is running, positive probe to black wire, black probe to ground?  Like all my other problems, this is learning as I go along.

[medic09]

Methodology question:

How do I read the meter?  It shows an immediate reading, then very slowly continues to creep up over more than a minute or so.  It starts in the low to mid 13s, and creeps up over two minutes or more.  So what value am I actually using?

I unplugged the black wire from the reg.  With the red probe to the black reg wire, and the black probe grounded to the engine, it showed 11.54.  The batter showed mid 13.   

[TwoTired]

Ideally, you want to measure the black wire while it is under load and carrying current to the alternator.  It won't do this while disconnected from the regulator.  Simply turn the ignition switch on and measure the black and green wires at the regulator terminals without the engine running, and then quickly make a measurement at the battery terminals as your battery voltage will be falling due to the ongoing drain.

The battery voltage slowly rises as it is being charged with the engine running fast enough to make more power than being used by the bike.

The electric stater motor draws about 1800 watts per second out of the battery.  The stock bike electical load is about 120 watts per second.  Your alternator will make about 40- 50 watts per second at 1000 RPM-ish, and can make 210 Watts per second at 5000 RPM if the regulator allows it.  At some RPM, specific to your bike, the alternator output will be exactly what the bike uses.  Higher RPM will begin charging the battery and the voltage should rise.

If the regulator can properly sense the true battery voltage, it should react by limiting the alternator output so it can't over charge the battery  (above 14.5 V).  If the battery is at 15.5 V but the regulator only "sees" 12.5 (for example) on its black wire, it will think the battery isn't fully charged yet and allow full output of the alternator at cruise speeds.  Battery life will diminish.

Cheers,

[medic09]

Ideally, you want to measure the black wire while it is under load and carrying current to the alternator.  It won't do this while disconnected from the regulator.  Simply turn the ignition switch on and measure the black and green wires at the regulator terminals without the engine running, and then quickly make a measurement at the battery terminals as your battery voltage will be falling due to the ongoing drain.

The battery voltage slowly rises as it is being charged with the engine running fast enough to make more power than being used by the bike.

The electric stater motor draws about 1800 watts per second out of the battery.  The stock bike electical load is about 120 watts per second.  Your alternator will make about 40- 50 watts per second at 1000 RPM-ish, and can make 210 Watts per second at 5000 RPM if the regulator allows it.  At some RPM, specific to your bike, the alternator output will be exactly what the bike uses.  Higher RPM will begin charging the battery and the voltage should rise.

If the regulator can properly sense the true battery voltage, it should react by limiting the alternator output so it can't over charge the battery  (above 14.5 V).  If the battery is at 15.5 V but the regulator only "sees" 12.5 (for example) on its black wire, it will think the battery isn't fully charged yet and allow full output of the alternator at cruise speeds.  Battery life will diminish.

Cheers,

I'm showing 11.38 at the green and black wires, and 12.38 at the battery terminals.

[TwoTired]

Okay, rev the alternator till the battery voltage peaks,  (or goes above 14.5)  and then read the black and green wires and then the white and green wires while the alternator is still reving.  At that battery voltage the regulator should provide reduced voltage on the white wires.  If not, try another regulator.

Put, a window fan in front of your engine.

Cheers,

[medic09]

Okay, rev the alternator till the battery voltage peaks,  (or goes above 14.5)  and then read the black and green wires and then the white and green wires while the alternator is still reving.  At that battery voltage the regulator should provide reduced voltage on the white wires.  If not, try another regulator.

Put, a window fan in front of your engine.

Cheers,

The black/green showed around 11.38 again, the white/green showed 0.  I tried three times.  0.

[TwoTired]

The white and green wires are supposed to be power to the alternator.  Zero volts means it is shut down completely, and can't charge anything.  How is your battery getting over charged?

What is your battery voltage with the alternator reved?

[TwoTired]

What's on the white and green with the ignition on and the engine not running?

[BobbyR]

If you are speaking about your 78K I have the same bike and was having a dying battery problem. I dug into the factory manual and did their tests which all come down to adjust the regulator with the engine running at 3500. I cleaned the contacts and then adjusted the voltage to 14. Works good.

[medic09]

What's on the white and green with the ignition on and the engine not running?

I'm still getting 0.  Green/black show about 11.48, like before.

 

[medic09]

If you are speaking about your 78K I have the same bike and was having a dying battery problem. I dug into the factory manual and did their tests which all come down to adjust the regulator with the engine running at 3500. I cleaned the contacts and then adjusted the voltage to 14. Works good.

This is a solid-state replacement reg.  There's nothing to adjust.  Though I may have to replace it...

[TwoTired]

What's on the white and green with the ignition on and the engine not running?

I'm still getting 0.  Green/black show about 11.48, like before.

 

I don't think your regulator is working anymore.  Or, maybe you have an open circuit to the alternator field coil.  (I don't know the internal circuitry of your non-stock regulator.)

Can you measure resistance across the disconnected white and green wires.  S/B about 7 ohms.  If you get that, then replace the regulator.

Cheers,

[medic09]

What's on the white and green with the ignition on and the engine not running?

I'm still getting 0.  Green/black show about 11.48, like before.

 

I don't think your regulator is working anymore.  Or, maybe you have an open circuit to the alternator field coil.  (I don't know the internal circuitry of your non-stock regulator.)

Can you measure resistance across the disconnected white and green wires.  S/B about 7 ohms.  If you get that, then replace the regulator.

Cheers,

8.1, if I measure correctly.

[coyotecowboy]

It sounds like you've already ruled out the battery, but for future reference, we check batteries at the shop like this

1.  disconnect battery

2.  hook up battery charger (not just a trickle charger, a regular charger with a boost/start setting)

3.  hook up your battery tester on top of the charger leads

4.  turn it to fast charge, give it a few seconds for everything to come up

5.  turn the charger to boost/start for a few seconds only.  If it pegs your meter, your plates are shorted, period.  Replace the battery, put it on a low charge for a little while (45 mins to an hour so your alternator isn't having to work so hard to catch up), fire it up and check your output.

If your battery is even a little iffy, get rid of it, it'll only cause you troubles on down the road.

[medic09]

Well, I put the original voltage regulator back in.  At 4000 rpm the voltage across the battery posts peaked around 14.2.  I guess I stick with that for now.

Thanks guys!