Yes, ANOTHER DEAD BATTERY POST

R

rafanomenon

Been Around the Block
This shit is getting old... And expensive!

I'm on battery #4 for my 1977 CB750 F2. It's a newer model, sealed maintenance-free lead acid battery. 12V, 9.2 AH.

I dropped it in about a month ago, and all is well. I had this same problem with the first three batteries, but this time I gutted the wiring harness to check for any bad connections/bad grounds. Nothing. I even checked the voltage on the battery when running, and revved up to 4,000 RPM and higher. Battery spiked, but no higher than 14V - which shows a good regulator/rectifier that I also replaced.

This morning, the bike pooped out on me. No cranking of the starter motor, but it kickstarts and the lights work, and all appears well when running. I thought it could be a bad alternator/stator, but I tested the charge of the battery when revved and it looked good. Checked the fuses and fuse box. Good.

What. The. Fuck.

Help?
 
Only thing i can think of is what size is your headlight (and other lights)?

And do you plug it into any kind of battery tender?
 
Big Rich said:
Only thing i can think of is what size is your headlight (and other lights)?

And do you plug it into any kind of battery tender?
Click to expand...

Stock headlight, speedo with backlight, and tail light. That's it.

I'm thinking that since I've eliminated a lot of lights, the reg/rec can't handle the charge, and poops out?
 
rafanomenon said:
Stock headlight, speedo with backlight, and tail light. That's it.

I'm thinking that since I've eliminated a lot of lights, the reg/rec can't handle the charge, and poops out?
Click to expand...

That last comment doesnt really make any sense, you are now using less electricty, and thus should be keeping the battery at a good tend. sounds like a crappy honda charging system..... if you think it is too much juice that it is cooking the batterys,

get a couple of resistors in the 20+ watt range 3-5 dollars at radio shack, and and hook them up to the electrical loads, that should easly compensate for the removal of the extra lights.
 
Are you buying Yuasa or some cheap made in China battery?
Are you buying them pre-charged ?
It could be bad preparation
'Maintainance Free' batteries need very specific filling, 'soak time' and charging before being put into service.
If they are filled and put directly into bike, I've seen them fail in 7~10 days.
It also makes a great difference where you live, high temperatures kill batteries real quick (pretty much anything over 70 deg F reduces life)
I have seen a 'chart' giving expected lifespan reduction for every 10 deg over 70 but don't remember where
 
you are now using less electricty, and thus should be keeping the battery at a good tend.
Click to expand...

...until the battery is full and the system needs to dump excess electricity somewhere. It generally fries stator, neccesitating a $200+ stator replacment (or rewiring). Leaving the headlamp on during the day will generally help with this.

If you're charging at 14 volts, though, then this isn't your problem. How long is it between rides for you, and what is your general usage of the bike? For example: I ride most days, and use my bike as a commuter. My work commute is only about 7 minutes, but weekend rides average around 30 minutes to an hour.

Is your fluid topped up? Are your terminals clean and securely fastened?

Cheers - boingk
 
Couldn't be a fried stator. The reading at the battery spikes to 14v when revved. No higher, and no lower than 12v.

Lately, I've been riding it everyday. Home to work is about 25 miles each way, or 45 minutes in the commute. On weekends, it's generally longer. I bought the battery a month ago, fully charged and ready to go. Sat in the bike for a month without hooking a tender up to it, and that's when it pooped out. Assuming the stator and reg/rec are doing their jobs, I would think a brand new battery would last for more than a month.

It's a sealed, maintenanc-free lead acid battery, so no fluid to manage. Terminals clean and securely fastened. I'm thinking it's a bad reg/rec, so I ordered a new, solid-state one from OR Motorcycle Parts to see if that will fix the problem.

Maybe I've just gotta get better about taking my lazy ass to the garage to hook it up to a trickle charger ;)
 
Could be any number of things including a rectifier with a leaky diode. How is the battery mounted? If it's sitting on a steel base, it could be vibration breaking the plates.
 
OK... a few things caught my attention:

[quote author=rafanomenon]The reading at the battery spikes to 14v when revved. No higher, and no lower than 12v.[/quote]

So...it jumps up to 14v when you rev it. Does it stay there? It certainly shouldn't be showing 12v at more than idle. Hold the engine revs at 5k and see what the voltage does. If it isn't over 13.5v at 5,000rpm then something is wrong. My bet would be to check all the earths, starting with the regulator/rectifier - earth it directly to battery and see what the charging voltage goes up to.

[uote author=rafanomenon]Sat in the bike for a month without hooking a tender up to it, and that's when it pooped out.[/quote]

A month without use, or a month using the bike as you described? I would not let a battery sit that long without use, despite it claiming to be maintenance free. All that means is that when it f***'s up you can't fix it, and you pay for that privelidge. After a month, I would expect an overnight charge before using for daily duties. Whack it on a charger overnight (12hrs) and see how it goes.

Cheers - boingk
 
Idle shows 12v. Revved up, it spikes to 13.5-14v. In theory, this means that the charging system is working, as well as the regulator/rectifier...? I tested it once I got the new battery one, and not anytime after, so there's a huge chance that the reg/rec could have burned out within that time frame.

The bike sat for a month without hooked up to the trickle charger. I rode it for about 50 miles everyday or every other day at freeway speeds.

Teazer also has a good theory. The battery was tipped on it's side. It was sitting on the stock rubber grommets, so this should have prevented any vibration damage.

The new Oregon Motorcycle Parts solid state reg/rec shipped last night. I plan on putting that on asap.

Hooked the battery to a charger overnight, and it still holds a full charge. I'm still stumped.

I also checked the whole wiring harness. No leaky grounds or faulty connections. Also ordered a new harness JUST IN CASE. Covering all the bases here... And going broke while doing it!
 
You should check the battery voltage before your next ride, immediately after your ride, then again before your ride after that. This will tell you if your battery is charging properly during operation or if there is a draw while off. Did you test the diodes in the r/r?
 
If you have a fault it's possible to 'blow' electronic components in less than a millisecond.
Electricity moves pretty fast through wires ;D
If you have a sensitive meter you will almost always find a slight 'leakage' through diodes in reg/rect when using diode checker but won't find leakage with normal Ohm testing forward/reverse bias.
Personally, I would recommend getting Motorcycle Electrical Techbook by Tony Tranter, ( Haynes #3471)
 
Raf - you figure this thing out yet?


PJ - do those 400t reg/rec units need to be insulated like the stock 360 ones?
 
Nope, they are great.
They can cope with 20 amps for short periods without 'blowing up'
They work on any permanent magnet system (so if you have a CB500/550/750 or Kawasaki KZ, various Yamaha's your SOL)
I think I'm going to look for a couple more for my 360's, unless anyone has a CB/CM250/400 they are parting out ?
I don't want to pay more than $15~$20 though ;D
There are a bunch on eBay, just emailed seller of $15.00 one ;D
This guy has 6 available, I would ask if he'll do them cheaper
http://cgi.ebay.com/ebaymotors/SH532-12-FT-CM-CB-GB-400-450-500-REGULATOR-RECTIFIER-_W0QQcmdZViewItemQQhashZitem45e77b00f6QQitemZ300236341494QQptZMotorcyclesQ5fPartsQ5fAccessories
 
dp9 said:
Raf - you figure this thing out yet?
Click to expand...

Haven't figured it out per say, but I did replace the likely culprit with a solid-stat reg/rec from Oregon Motorcycles:
DSCN1392-525x393.jpg


It's adjustable, and the enclosed instructions say to not let the voltage at the battery go higher than 14.5v at mid throttle. I adjusted it to that, and all has been good so far. Like I said, I tested most of the connections and looked for a leaky ground. Nothing. Even rebuild the wiring harness. My guess is that it was a faulty stock regulator/rectifier. Lesson: Replace with a newer, more modern one asap!
 
It is possible that the old one was shorting out unuder load or due to vibration. My setup also showed periodic 13.5v charging, but then would go flat over a ride. Turned out to be a poor R/R earth connection.

And yes, electronics from this period have a tendancy to fizzle out. Hell, they're 30 years old and well past their designed lifespan, its to be expected

Let us know how you go - boingk
 
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