Author Topic: Check your main Battery Ground  (Read 3983 times)

Online Kiwi_Roy

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Check your main Battery Ground
« on: March 29, 2016, 02:44:09 PM »
Most Guzzis have several ground wires connected to the battery Negative. I'm thinking in particular of Spine frames, EVs, Jackals and the like where the regulator or ECU case is wired back to battery Negative by way of small black wires.
If the main ground works loose when you next go to start the heavy start current (150+ Amps) looks for a way back to the battery this can cause the small ground to get red hot and melt into other wires shorting out the loom.

Here's a typical result, a spine frame where the main ground became loose, the regulator ground passed the starter current back to the battery and melted all the insulation off shorting a couple of other wires in the loom to chassis. Luckily in this case the owner was able to repair the damage with a new wire and a roll of tape.


This partial schematic shows first the normal current flow thru the main ground.
And then what happened when the ground connection was lost.

 
« Last Edit: March 29, 2016, 10:13:09 PM by Kiwi_Roy »
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Online Kiwi_Roy

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Re: Check your main Battery Ground
« Reply #1 on: March 29, 2016, 10:07:21 PM »
I also add a main fuse on my bikes to prevent a total melt down in the case of  short.
I add a 40 Amp in-line fuse in the main feed from battery to the ignition switch.
The fuse should never blow but is cheap insurance if the wire gets shorted to chassis

Note: on some bikes the feed to switch comes from the live terminal of the starter solenoid.
« Last Edit: March 29, 2016, 10:12:05 PM by Kiwi_Roy »
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Offline Bruce Reader

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Re: Check your main Battery Ground
« Reply #2 on: March 30, 2016, 03:16:00 AM »
Another good reason to run a heavy gauge earth wire from reg to battery.

Cheers

Bruce

Offline pikipiki

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Re: Check your main Battery Ground
« Reply #3 on: March 30, 2016, 06:42:15 AM »
Another good reason to run a heavy gauge earth wire from reg to battery.

Cheers

Bruce
It wont be the wire thats the week link unless it is freyed. It's the connection or connector. The high amp circuits are to the regulator and the starter.
If there's the slightest resistance in the connection that causes resistance. The resistance generates heat causing damage, worsening the connection and causing more resistance and yet more heat. Check battery, regulator, starter motor connections and any junctions in between regularly. Crimped wire connectors can quickly develop problems if handling high current and the crimping is not done to a very high standard. Soldering and sealing in shrink wrap I one method of making good connection although even solder can crack and cause problems of its own. Probably best to make a check list of important connections on your bike and check every 6 months.

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Re: Check your main Battery Ground
« Reply #3 on: March 30, 2016, 06:42:15 AM »

Online Kiwi_Roy

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Re: Check your main Battery Ground
« Reply #4 on: March 30, 2016, 10:32:39 AM »
It wont be the wire thats the week link unless it is freyed. It's the connection or connector. The high amp circuits are to the regulator and the starter.
 
While I agree a loose connection will overheat in this case if you look at the picture I posted the wire is fried far away from any connections, not by the charging current but by the miss-directed starting current. A wire sized for 20 Amps cannot carry over 100 Amps.
« Last Edit: March 30, 2016, 10:37:29 AM by Kiwi_Roy »
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Online Kiwi_Roy

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Re: Check your main Battery Ground
« Reply #5 on: March 30, 2016, 10:44:00 AM »
Another good reason to run a heavy gauge earth wire from reg to battery.

Bruce, you cannot size the regulator ground for the starting current, besides it's easier to just make sure the main ground is connected properly.
I have thought of removing all of the additional grounds from the battery post and running them to the chassis, that way if the main ground falls off it won't crank over but I'm reluctant to do that for a different reason.
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Re: Check your main Battery Ground
« Reply #6 on: March 30, 2016, 02:39:43 PM »
I'm really trying to point out that these bikes have a serious flaw in the wiring that can lead to self destruction if the main ground works loose. I don't think this applies to the later bikes, at least not according to Carl's drawings, they show only one wire on battery negative i.e. no alternate path for the starter current, if there are 2 or more wires connected to battery Negative I would be worried.
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Offline Bruce Reader

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Re: Check your main Battery Ground
« Reply #7 on: March 31, 2016, 08:54:49 PM »
My point wasnt intending to be an answer to the main ground being loose-
but it does negate the current melting a stack of wires hidden in the loom.  Seeing as you need to improve the regulator earth anyway
you might as well run a larger seperate earth directly to the battery for the two problems.

Cheers

Bruce

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Re: Check your main Battery Ground
« Reply #8 on: March 31, 2016, 09:04:56 PM »
 Thanks Roy  :bow:

 Dusty

Offline Bruce Reader

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Re: Check your main Battery Ground
« Reply #9 on: March 31, 2016, 09:15:34 PM »
What are the all the earths on the battery from Roy ?

Cheers

Bruce

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Re: Check your main Battery Ground
« Reply #10 on: March 31, 2016, 11:19:28 PM »
What are the all the earths on the battery from Roy ?

Cheers

Bruce
Bruce,
There's the one from the regulator and another from the ECU (it doesn't show on the schematics), the point is if the main ground gets disconnected these small wires just go poof when hit by the starter current. To be safe you would need to run a very large wire from the regulator to the battery as David's has but it's a lot of work, he was starting from scratch, I don't expect owners will want to rewire their bikes.
If the extra grounds are terminated on the chassis instead of the battery they cannot pass current if the main ground falls off. The later bikes like Grisso or Breva show only one ground but I wouldn't trust the schematic without looking at the bike.

Another one that happens on the spine frames, the owners disconnect the battery positive and accidentally touch the wrench on the ECU case burning up the ground.
Always disconnect Negative first, reconnect last.

« Last Edit: March 31, 2016, 11:43:57 PM by Kiwi_Roy »
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Re: Check your main Battery Ground
« Reply #11 on: April 04, 2016, 10:33:43 AM »
This turned out to be a timely post for me.  Lately, when I go to start my Cali for the first time in the morning, I get a "click" similar to a dead battery.  When I turn the ignition switch back off and on again, it starts right up.  I keep the battery on a Tender and had recently replaced the starter with a new one from MotoElectric.  This weekend I removed my left side panel and inspected the main battery ground.  Sure enough there was enough corrosion to cause problems.  Cleaned it up with dremel wire wheel and retightened.  Starts right up!  Thanks Kiwi Roy!!

Offline Sasquatch Jim

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Re: Check your main Battery Ground
« Reply #12 on: April 13, 2016, 01:09:53 PM »
 Ah yes there are many possible misery battery drains.
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Offline AH Fan

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Re: Check your main Battery Ground
« Reply #13 on: April 13, 2016, 08:41:02 PM »
Bruce,
There's the one from the regulator and another from the ECU (it doesn't show on the schematics), the point is if the main ground gets disconnected these small wires just go poof when hit by the starter current. To be safe you would need to run a very large wire from the regulator to the battery as David's has but it's a lot of work, he was starting from scratch, I don't expect owners will want to rewire their bikes.
If the extra grounds are terminated on the chassis instead of the battery they cannot pass current if the main ground falls off. The later bikes like Grisso or Breva show only one ground but I wouldn't trust the schematic without looking at the bike.

Another one that happens on the spine frames, the owners disconnect the battery positive and accidentally touch the wrench on the ECU case burning up the ground.
Always disconnect Negative first, reconnect last.

Hi Roy.

Me just lurking........... are my 2004s also at risk on this ground connection issue.

Let me know.

Ciao

Online Kiwi_Roy

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Re: Check your main Battery Ground
« Reply #14 on: April 14, 2016, 07:47:06 AM »
Hi Roy.

Me just lurking........... are my 2004s also at risk on this ground connection issue.

Let me know.

Ciao
I believe so, ask me about it at coffee.
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