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CB72/77 Battery

Charging System, Wiring, Lighting
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Tim Allman
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Joined: Tue Dec 02, 2014 9:25 am
Location: Guelph, Ontario, Canada

CB72/77 Battery

Post by Tim Allman » Wed Aug 07, 2019 6:58 pm

I have been trying to buy a battery for my CB77 and find that the venerable 12N9-3A is no longer made and as far as I can tell has been superseded to the YBL9-B. My local dealer has a YBL9-A2 in stock which also seems to be a possibility although the terminals are a bit different. I am wondering what the rest of you use for batteries these days.

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brewsky
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Joined: Wed Jul 23, 2008 5:21 am
Location: Princeton, WV

Post by brewsky » Thu Aug 08, 2019 5:26 am

I have been buying brands similar to these, labeled 12n9-3a, but they don't have the terminal "ears".....just made my own "ears" to attach to the ground strap etc

Just have to watch pole and vent tube orientation shown in pics shown online as they sometimes show them reversed for 3a and 3a-1


https://www.ebay.com/itm/New-12N9-3A-Ho ... Sw29Jb~u0v
66 dream, 78 cb750k, 02fz1, 09 wing

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jleewebb
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Location: travis county, tx

battery

Post by jleewebb » Thu Aug 08, 2019 11:49 am

A Motobatt MB9U will last at least twice as long as a lead-acid YUASA and is worth the price in my opinion. Google around for best price, you'll probably find it on eBay.

I use red loctite on terminal screws and tighten the heck out of them as they tend to vibrate loose.
'62 CB77. "It's a rider."

DJM
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Joined: Thu Oct 09, 2003 1:54 pm
Location: Chesterfield UK

CB77 battery

Post by DJM » Thu Aug 08, 2019 4:40 pm

I also use the Motobat MB9U, the terminal arrangement can be configured to match the CB77's existing wiring and of course the vent tube location isn't an issue as there is no vent tube! Great batteries too which I believe in the US come with a two year warranty.

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Tim Allman
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Joined: Tue Dec 02, 2014 9:25 am
Location: Guelph, Ontario, Canada

Post by Tim Allman » Thu Aug 08, 2019 5:40 pm

The Motobat looks like a good option. Thanks for the replies.

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brewsky
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Location: Princeton, WV

Post by brewsky » Fri Aug 09, 2019 6:08 am

I've been hesitant to use a sealed battery with an unregulated charging system.

Recent testing on my Dream showed it was putting out in excess of 16 volts at 55 mph with the headlight on. (That was with the original rectifier replaced with a simple bridge rectifier.)

I have since replaced it with a Kohler type regulator/rectifier and the rate appears to stay below 14V at speed, but falls below battery rest voltage around town.

Just FWIW
66 dream, 78 cb750k, 02fz1, 09 wing

DJM
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Posts: 553
Joined: Thu Oct 09, 2003 1:54 pm
Location: Chesterfield UK

Sealed batteries.

Post by DJM » Fri Aug 09, 2019 8:45 am

I've used the Motobat batteries on both my CB77 and CL77 for several years and many thousands of miles with no problems, Both run standard charging systems although the CB does have a cheap 'modern' solid state rectifier, the CL is still running the original rectifier and neither have any form of regulators fitted.

Seems to me that the Honda charging system comes in for some undeserved criticism as, mine at least, work well enough. I always run with the headlight on, often for 100 miles trips and both bikes have turn signals with standard filament (not LED) bulbs fitted; never had a problem with the batteries going flat.

Question, If the standard charging system was so poor why did Honda fit a Low Output version to later bikes??

As far as measuring battery voltage while the engine is running and charging, I would be wary of drawing too many conclusions from the results.

What you are trying to measure is the DC voltage of the battery with a half wave rectified AC charging voltage superimposed over the top, this AC component varies from zero to perhaps 30 volts many times per second dependent on engine speed.

Few multimeters can measure this accurately, in fact do you set the meter on DC or AC voltage range?

A far better way is to start off with a cold engine, turn on the headlight for a while to partially run down the battery, wait a few minutes for the battery to cool and then check and record battery volts.

Go for a long run, say 50 - 80 miles. Let the battery cool down overnight and check the battery volts again. If it's higher than previously you'll know the system is charging OK,

If you break down on the run with a flat battery you'll know it's not charging!

Works for me anyway!!

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