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Posted

Is it true that when you turn the key on the volt meter will show the voltage in the battery? If it is true of need a battery mine is showing less than 10 on the guage.

 

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Posted (edited)

If you are talking about the OEM voltmeter in the bike don't put a lot of faith in that. A long ways from being accurate. If you are seeing 10 volts when you turn the key on that is enough to spin the motor, but from my experience not enough to get the old girl to fire up to start. These old bikes like their spark. And as you crank that motor over that "10" reading is going to drop like a rock.

 

A while back I did a bunch of mods to the bike from changing to a DEKA AGM battery, new heavier battery cables, a 4 brush starter, a Shindigen rectifier and HO stator. I figured as long as I was at it I might as well install a digital voltmeter to monitor the system.

 

I left the OEM voltmeter installed but wired a new power supply system completely independent of the bikes harness. Just the wiring for the battery, R&R, HO stator and then the Digital voltmeter direct to the battery. The difference in the readings on the two meters was quite a bit. About 1.5 to 2 volts difference. The new digital gave me instant readings on the voltage activity at all times. I knew instantly if I was having a problem after sitting, during starting and running down the road. Saved my bacon a couple times.

 

With an accurate reading with a voltmeter at the battery you should see at least 12.6 volts with the bike off, while cranking you should still show around 11.0 then around 14.0 to 14.4 volts running around 2,000 RPM and above. dbtgallery (7).jpg

Edited by Snaggletooth
Posted
Yah!! If you can start the bike cold and it turns over normal, your battery is probably still OK!!

It turns real slow. Even slower when it's warm

 

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Posted
It turns real slow. Even slower when it's warm

 

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This is one reason I like being a member of this website. Great answers for just about any problem. I will start with the my volt meter. & see where it goes from there. Thanks for the help.

 

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Posted

Well then, chances ARE your battery is on the way out!! Keep in mind though, unless you have upgraded your battery cables to larger gauge cables and swapped your starter out for a 4 brush one, it is normal for 1st gens to start sloooow when hot...

Posted
it is normal for 1st gens to start sloooow when hot...

 

See, this is where the old joke, "While you're in there" came from. First it's the slow cranking when cold. Then it's the slow drag when hot. Then it's the engage clutch popping off.......... Then it's might as will get a new battery. Then ohhhh cool cables. Then the it's better Stator.... then a better rectifier.... then.... then... then... ah damn.

 

I used to say I'm not restoring an old bike. I'm building a new one. Not always so far from the truth. But is the shortest path to success.

Posted

Quick check of the battery showed 12.4 volts with nothing on. So I'll pick up the 4 brush starter & so on

 

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Posted

Just a voltage check does not necessarily mean the battery is good. What you need to do is remove the battery, put it on a charger to insure a full charge, then take the battery to Auto Zone, etc and have then load test the battery!! It may read 12.4 volts with no load but if a cell or cells are weak it will dip much lower under load! I mentioned Auto Zone because I know they do it for free...

 

4 brush starters and thicker battery cables help the HOT starting issue but do not make a huge difference cold starting. Notice I stated HUGE, they do make some difference cold.

Posted
Quick check of the battery showed 12.4 volts with nothing on. So I'll pick up the 4 brush starter & so on

 

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12.4 volts ain't that good if it is an Agm Battery.

 

voltage.jpg

Posted
12.4 volts ain't that good if it is an Agm Battery.

 

[ATTACH=CONFIG]105466[/ATTACH]

It is an agm battery

 

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Posted
12.4 volts ain't that good if it is an Agm Battery.

 

[ATTACH=CONFIG]105466[/ATTACH]

It is an agm battery

 

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Posted

It's an agm battery. I'll charge it & take it to autozone.

 

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Posted

On have it on my battery tender. Then I'll test it. I found my father in laws battery tester in a box of tool I got after he passed away last year.

 

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Posted
If you can, sloooow charge it overnight at 2 - 5 amps or so. AGM's charge better at a slow rate, but they do not like float chargers either...

 

Yep, Tenders are good for keeping a good battery in a decent state of charge, but will never get a deep charge into it. It takes a good old fashioned charger a full overnight charge at 2 amps to usually bring them back to full power.

 

From my experience with the DEKA AGMs over the last 7 years is a Tender is really not even needed if the bike is ridden even weekly and the charging system is working correctly. That picture is posted earlier of my voltmeter is after sitting over a weekend before starting it. Mine has sat a month and never dropped below 12.6 volts. Shelf life volt power on a healthy AGM is months, not days. The first DEKA was 5 years old and never saw a charger or a Tender. Just didn't need it.

Posted

Ok so I checked the voltage this morning 12.9 do a load test it drops to 10.9 I don't think I have a battery problem.

 

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