Voltage reading a bit low?

[stuarto49]

I purchased a 2008 FJR last Nov, with about 25,000 miles, totally stock. The battery had just been replaced by the dealer. I was able to contact the dealer where most previous maintenance work had been done by PO. Was confirmed that the 'sub-harness' and ignition key (?) recall had been done but no other significant work (like valve check). Bike has been perfect, have added about 4000 miles in just a few months.

For electrical accessories I added a fuse block fed by a power relay connected directly to the battery with 10 ga wire and fuse. Grounds for all accessories connected to ground bar on this fuse block, also with 10 ga wire to battery neg. terminal. The power relay is triggered by the tail light feed (typical setup). The fuse block feeds the GPS power, aftermarket heated grips, powerlet for my Gerbing gear, two sets of Denali LED driving lights (D1 plus the newer DX Extreme), each set controlled by Denali toggle & relay, and better dual horns thru a relay, etc. An SAE connection is also wired in ahead of the power relay - so I can charge or use air compressor with key off. More recently I added a digital voltmeter in a small plastic box just above steering stem. Also fed by this accessory fuse block.

When riding along, between 3000 and 4000 RPM the meter shows 13.6 volts, +/- 0.1. (I've seen higher on several other bikes, like maybe 13.8-14.0) I've double checked the accuracy of this meter with one of my Fluke meters and it is spot on. When I turn on the D1 Denali LEDs (which I always run to be seen better) the voltage drop to 13.5. With the second set of Denalis voltage reads 13.3. With the single Denalis and my Gerbing jacket (with or w/o heated gloves attached) the meter is down to 12.6, +/-. If I then add the heated grips I'm down to 12.0, definitely NOT good. I rarely use the battery tender and the bike starts instantly, even if it sat unused for a week or two.

Yesterday I checked the battery connections - they were clean and OK but I tightened about 1/8 turn each. I suppose I need to check other grounds in the system?

Where are the connections to and from the rectifier/regulator? These connections have been the cause of voltage issues on some of my previous bikes.

Stuart, Richmond, VA

Iron Butt Assoc. #11000

 

[stuarto49]

I purchased a 2008 FJR last Nov, with about 25,000 miles, totally stock. The battery had just been replaced by the dealer. I was able to contact the dealer where most previous maintenance work had been done by PO. Was confirmed that the 'sub-harness' and ignition key (?) recall had been done but no other significant work (like valve check). Bike has been perfect, have added about 4000 miles in just a few months.

For electrical accessories I added a fuse block fed by a power relay connected directly to the battery with 10 ga wire and fuse. Grounds for all accessories connected to ground bar on this fuse block, also with 10 ga wire to battery neg. terminal. The power relay is triggered by the tail light feed (typical setup). The fuse block feeds the GPS power, aftermarket heated grips, powerlet for my Gerbing gear, two sets of Denali LED driving lights (D1 plus the newer DX Extreme), each set controlled by Denali toggle & relay, and better dual horns thru a relay, etc. An SAE connection is also wired in ahead of the power relay - so I can charge or use air compressor with key off. More recently I added a digital voltmeter in a small plastic box just above steering stem. Also fed by this accessory fuse block.

When riding along, between 3000 and 4000 RPM the meter shows 13.6 volts, +/- 0.1. (I've seen higher on several other bikes, like maybe 13.8-14.0) I've double checked the accuracy of this meter with one of my Fluke meters and it is spot on. When I turn on the D1 Denali LEDs (which I always run to be seen better) the voltage drop to 13.5. With the second set of Denalis voltage reads 13.3. With the single Denalis and my Gerbing jacket (with or w/o heated gloves attached) the meter is down to 12.6, +/-. If I then add the heated grips I'm down to 12.0, definitely NOT good. I rarely use the battery tender and the bike starts instantly, even if it sat unused for a week or two.

Yesterday I checked the battery connections - they were clean and OK but I tightened about 1/8 turn each. I suppose I need to check other grounds in the system?

Where are the connections to and from the rectifier/regulator? These connections have been the cause of voltage issues on some of my previous bikes.

Stuart, Richmond, VA

Iron Butt Assoc. #11000

 

[RossKean]

While it is possible that you have a problem, I would want to check the voltage a little closer to the battery. Perhaps check it at the SAE connector or (ideally) right at the battery. When you are drawing lots of power, especially across a relay, some voltage drop is expected.

 

[RaYzerman19]

This all sounds fairly normal to me, although the Datel seems to be a couple of tenths low. To compare, take voltages with your Fluke at the battery with accessories on and off, and compare to your Datel. Chances are it's just a difference, the voltages taken at the battery will be higher. Then you know how much low the Datel reads and you can just go ride and don't worry about it. Check charging voltage at the battery say above 3000 rpm and you should be seeing 14.

 

[Donal]

If you have some time on your hands you may want to work your way through D Carver's odyessy with his charging system here . I would suggest the ideal starting point would be to hook up a DVM on the battery and the output terminals on the RR simultaneously, to see if there is a significant difference. You will need to do this with all the loads you described above and at similar RPMs.

It will normally be easier to detect voltage drops than slightly abnormal resistances.

 

[Fred W]

More recently I added a digital voltmeter in a small plastic box just above steering stem. Also fed by this accessory fuse block.
When riding along, between 3000 and 4000 RPM the meter shows 13.6 volts, +/- 0.1. (I've seen higher on several other bikes, like maybe 13.8-14.0) I've double checked the accuracy of this meter with one of my Fluke meters and it is spot on.

Stuart,

I'd caution you that the way that you've setup your volt meter may not be the best way. The Datel voltmeter itself draws very little current. It will fairly accurately read the voltage at the point that it's own wires are attached to, in this case your Accessory Fuse Block.

The voltage at the Fuse Block can, and will, be reduced from actual battery voltage, often significantly, depending on how much of a load you have on it at the time. As the devices draw current there will be voltage dropped on the finite resistance of the wiring between the battery source and the Fuse Block. The greater the load, the greater the voltage difference.

You should not really care what the voltage at the Fuse Block is. What you should really care about is how much charging voltage you have at the battery terminals.

To get that reading from your Datel panel meter you need to have wiring that is dedicated (to the voltmeter alone, nothing else) all the way back to the battery terminals. Any resistances of those wires and connectors is insignificant since the meter never draws any appreciable current, so it will show you the true battery/charging voltage.

Some folks will wire their Datel directly to/from the battery using just small gauge wires and an appropriately small inline fuse. The Datel draws so little current (only a few milliamps) that it will not draw down your battery much, even over several weeks of storage time. Other folks will add a switch inline so they can turn it on at any time, but also shut it off when not being used. I have mine wired with a dedicated 12V power switched relay so the meter comes on automatically with the bike, but also have a manual switch, so I can turn it on when the bike is not switched on, to check the ambient battery charge state.

So, before we get into what might be causing your low voltage problem, is the voltage at the battery terminals actually drooping under the described conditions? You say that you have verified the Datel with a DVM, was that at the battery terminals? Did you see that the voltage at the battery is actually as low as the reading you initially noted?

If so, it is probably due to the distributed resistances between the Alternator and the battery. You may want to check out this thread for extensive troubleshooting information and the final solution. (note: Seems Donal beat me to the punch by a few milliseconds)

 

[Chuck35]

13.8 was the best I ever saw (no acc loads) before I installed Jacks harness. Since then I have added lights and heated gear, typically I see 14.0 to 14.3 now.

 

[Denver_FJR]

I'll throw out a couple (incomplete) bones...

• Looking at wiring diagram, the rectifier connection connects to battery through the 50 amp main fuse, and this fuse is located just ahead of battery. There's a picture of main (and other) fuses in the owner manual and you can download from yamahamotorsports.com under the "Parts & Service" link.
• The ground connection is to engine block on the front, right hand side. Have to take fairing off but other then that easy to see/check out.

Since your meter is connected through the accessory block, wondering if it could be cause of drop. Have you checked voltage at battery?

 

[Benhur]

if you have access to the service manual it specifies that the charging voltage at 5000 revs is 14v for the 2008. this is specified on page 8-250 of the service manual... this to me would imply that 13.6 at 3000-4000volts is probably correct....so that part of the electrical system would be functioning ok....I would be concerned that you have too many accessories draining the system at 3000revs?

R.

 

[Donal]

I thought I had replied to this once but.............

If you have the time you might like to review D Carver's epic tale about charging woes here. Basically you need to start with two DVMs; one on the battery and one on the output from the RR. Then with all the loads you mentioned earlier, check to see how close the voltages are. This will give you a good idea if there are resistances between the RR and the battery. Rather than spend a lot of time trying to reduce any resistance you might be better taking the same route as others and installing additional wiring between the RR and the battery.

 

[Fred W]

There are currently two identical threads running on this topic.

@benhur - No. Regardless of how they wrote the spec, the alternator is also capable of putting out 14.1-14.2 volts (to a fully re-charged battery, meaning you have to wait for the battery to recharge after an engine start) at idle speed of 1000 rpm, with no added accessory loads on it.

Anything less is of significance.

 

[RichDoyle]

FWIW:

I have mounted a Datel digital VM that I can connect either directly to the battery or the voltage available from the accessory plug (not while driving, but by moving from one SAE connector to another). Steady state riding (after startup recovery) at anywhere from 2000 RPM up, the battery side seems to always be at 14.2-14.3 volts, while the accessory voltage stays at 14.0 volts. Remember that every wire, relay and connector adds resistance to the circuit, requiring a voltage drop across the interface. It adds up and is a function of the amps being pumped through those interfaces at the time.

Different settings on the handgrip heaters affect the accessory voltage, but not the battery-side voltage. Hitting the brakes causes a 0.2 volt drop in accessory voltage, again with no noticeable effect on battery-side.

 

[dcarver]

+1 jacks harness. I still see 14+ Vdc all the time, with load. But verify first it's needed.

 

[blassoff]

Interesting. I too have a fuze block with relay, but wired directly to the battery. My datel is also wired direct to the battery. At idle I'm seeing 13.8. At 3000 rpms with minimal load (grip heaters and gps), I show 14 volts. I'd wire the volt meter direct to the battery. Also put your fluke directly on the battery terminals to test voltage. Lastly, I always wire my tender leads direct to the battery. Don't know why I wouldn't (or why id want my fusebox to intervene). All of my hardware is from Eastern Beaver and I don't recall ever seeing a substantial voltage drop when checking power at the fusebox. Check at the battery!

 

[stuarto49]

Yes - somehow I've started two threads. But replies are still coming in on both.

I've rechecked voltages right at the battery terminals. Key OFF - 12.89V at battery. Healthy and well charged!

Running at 3000 RPM -13.5V with no accessory loads. Datel off acc fuse block reading 13.3.

Running at 3000 RPM - 13.2 V with both sets of LED lights + heated grips on 100%. In this condition the Datel is reading 12.6. Aha!

So I've rewired the Datel directly from the battery terminals, thru an in-line fuse, and a lighted rocker switch just below the meter. Also mounted and wired in an additional Powerlet outlet on this circuit. So if I want to charge something I can run from this circuit with the Key off. And the Datel reads much higher with various loads.

Thanks for all the comments.

Stuart

 

[stuarto49]

Hi - see my reply on the other thread. I've re-wired the Datel directly to the battery and have higher readings with various loads. Still not quite 14, however.

When I ride up to your tech gathering I"ll show you what I've done under the driver's seat. Fuse block, 40A relay, #10 leads from the battery thru an in-line main fuse.

Stuart

 

[stuarto49]

Now below is the same reply I added to the OTHER thread. How can we combine them into 1 ???

Yes - somehow I've started two threads. But replies are still coming in on both.

I've rechecked voltages right at the battery terminals. Key OFF - 12.89V at battery. Healthy and well charged!

Running at 3000 RPM -13.5V with no accessory loads. Datel off acc fuse block reading 13.3.

Running at 3000 RPM - 13.2 V with both sets of LED lights + heated grips on 100%. In this condition the Datel is reading 12.6. Aha!

So I've rewired the Datel directly from the battery terminals, thru an in-line fuse, and a lighted rocker switch just below the meter. Also mounted and wired in an additional Powerlet outlet on this circuit. So if I want to charge something I can run from this circuit with the Key off. And the Datel reads much higher with various loads.

Thanks for all the comments.

 

[Fred W]

Stuart, based on the voltages at the battery it does appear that you have a charging issue. And I agree, the battery is taking and holding a charge fine, so it won't be that easy.

My bet at this point would be that you are dropping the missing voltage on the harness between the R/R and the battery, much as Don Carver found in the previously linked thread. There have been a number of second gen owners who have found similar circumstances. You can confirm that by using your DVM to measure that drop directly. Just put one lead on the R/R output and the other on the positive battery terminal and you will measure the drop. Ideally it should be zero, but in reality you'll probably get a small drop, maybe a tenth of a volt or two, on a good wiring harness. Anything more than a half a volt is cause for concern.

 

[stuarto49]

Fred:

I'll be checking this out this evening. I've had several machines over the years which exhibited similar 'low' charging voltages due to poor connections in and out of the R/R/. And I've replaced more than one unit and had the voltage jump right up to 14.0 just above idle.

I see some units (new) on eBay but only a few specify that they are the upgraded MOFSET type.

Thnx, Stuart