Tested generator not charging; vsm422 volt reading variation; ground connection quest

[ketchcng]

I am trying to figure out a charging issue i have been having for a year. I think i have my batteries grounded wrong, but wanted to run it by you guys before i start changing things again...

I have a 20 amp generator, not an alternator (its old, but been rebuilt and tested) and an external regulator. When i run the engine the rebuilders mentioned voltage should be at 14.6. I only get 13.2.

I have starter battery ground/negative terminal wired directly to house battery ground terminal and then house ground terminal wired directly to blue seas vsm422 shunt side one terminal and then shunt side two terminal wired to main negative bus bar. Engine ground wire near solenoid connects at this same main negative bus bar. Generator is grounded directly to external voltage regulator ground post.

Should i break the ground connection from start battery to house and run the ground start connection directly to generator? Or to regulator? Or to both?

Should my engine ground wire go to the main negative bus bar as it is now or to somewhere else?

Last part of puzzle...my vsm422 displays voltage slightly higher than what the batteries are actually when i check them with a multimeter. Start battery with multimeter is at 12.6, vsm displays 13.06. Amp use of vsm seems to reflect accurate draws though, as i know my gps draws 500ma and vsm displays .5amp draw, etc.

Thanks a lot.



Christian Gould
S/V Sea Dog; Rhodes Chesapeake 32
Lake Superior, Apostle Islands

[model 10]

If the shop tested the generator then it must be the regulator. Take the cover off and hold the field contact closed ( watch your voltmeter!) You can play with the contacts and bend the arm a little to adjust the voltage or maybe there is an adjustment screw.
Get an alternator.

[ketchcng]

The shop tested the regulator too. I think I have my grounds wired wrong. The regulator is only grounded directly to the generator ground. The engine is then grounded to bus bar which is wired to vsm amp shunt then wired to the batteries common negative terminals. Seems like I should have a wire directly from battery negative to generator ground?


Christian Gould
St. Paul, MN
S/V Sea Dog
Apostle Islands Lake Superior

[model 10]

Or to the regulator and to the gen.

[hzcruiser]

A wiring diagram would be helpful, to you in general and other forum members to understand what is happening.

There is a good chance you'll notice a problematic wiring yourself once you draw it with some simple drawing software, doesn't have to be anything fancy.

[ketchcng]

From battery to regulator and then to generator in series? Or battery to regulator and from battery to generator again?




Christian Gould
St. Paul, MN
S/V Sea Dog
Apostle Islands Lake Superior

[transmitterdan]

The generator cannot make more voltage than the battery or regulator will allow for a particular charging voltage. How long do you let the generator run with the voltage holding at 13.2V? What does the VSM say the charging current is when at 13.2V? If the current is close to zero at 13.2V then the regulator is most likely telling the generator to hold there. Some regulators will do this once they think the battery is charged. They call it the "float" voltage. So 13.2V float voltage may be the regulator's programmed value. In which case nothing is wrong.

It's possible your multimeter is not calibrated. Do you have another way of checking it.

[model 10]

[QUOTE=ketchcng;1833491]From battery to regulator and then to generator in series? Or battery to regulator and from battery to generator again?

Don't be cheap with the wire. Everything should be grounded. There is no "series" with a ground. Ground everything with it own wire. Usually the gen is grounded to the block through the mount.

[ketchcng]

The generator shop said the regulator was set to 14.4 volts. I also have a clamp on amp gauge and I was only reading .8 amps on my regulator to battery line. The generator had been warmed up too.

What is strange as well is that with the engine off I can read voltage at battery of 12.6. I then check voltage at regulator and it is the same 12.6. If my grounds were not complete wouldn't those readings be different?

How does adding a ground wire help when I already read 12.6 through the system?


Christian Gould
St. Paul, MN
S/V Sea Dog
Apostle Islands Lake Superior

[ketchcng]

Christian Gould
St. Paul, MN
S/V Sea Dog
Apostle Islands Lake Superior

[model 10]

You are not doing something right. If my memory serves me right, 2 wires to the gen and 4 wires to the reg. The regulator has a field, an armature and buss terminals and of course a ground. If you apply field current to the generator through the field relay in the regulator you will get the set voltage on the A terminal, you ain't getting that. Measure the field output at the reg first.
It's good to know that it all worked at the shop, it's you or your boat that's messed up.

[transmitterdan]

Christian,

I don't understand the diagram. The solenoid should have 4 wires. 2 control the solenoid and 2 wires go to the main contacts. Is this an automatic charging relay that is suppose to charge the start and house batteries? If so then the diagram is not correct as it shows no connection path from the generator to the house bank.

Another issue I see is that the diagram suggests that the VSM is measuring the current in both the starter and the house bank battery. This doesn't seem right. Which battery voltage is the VSM monitoring?

[ketchcng]

The bat connection from regulator attaches at solenoid common stud where a wire runs also to battery.

The vsm measures voltage from each battery where a lead connects to each batteries + terminal. The drawing is showing the amp gauge function of vsm where the grounds run through the shunt to measure amperage.

My hunch is I should disconnect the wire connecting the - battery terminals and connect start - to the regulator gnd post. Also connect new wire from regulator gnd post to main negative bus bar.

Sound like that will help?

My vsm shows voltages that are higher than the batteries actually Are in voltage when measured at battery with multimeter. I think the regulator is getting the same false reading and that is why I only get 13 volts with engine running from regulator because it thinks the batteries are already over and charged, when they are not. But if I check system voltage with engine off, the connection at bat and gnd on regulator reflects actual voltage, 12.6.


Christian Gould
St. Paul, MN
S/V Sea Dog
Apostle Islands Lake Superior

[ketchcng]

I have no problem starting over...how would you wire a voltage regulator to charge two batteries?

[Stu Jackson]

Originally Posted by transmitterdan

Another issue I see is that the diagram suggests that the VSM is measuring the current in both the starter and the house bank battery. This doesn't seem right. Which battery voltage is the VSM monitoring?

Agree.

Originally Posted by ketchcng

I have no problem starting over...how would you wire a voltage regulator to charge two batteries?

The regulator can only control the charge to one bank. Based on the above, you have combined the banks through the grounds to the shunt. Separate them so the start bank doesn't touch the shunt and goes to ground.

Charging of secondary banks is accomplished with the use of a 1-2-B switch (on B but ONLY when charging is present), echo chargers or ACRs (auto combining relays - Blue Sea or Yandina combiners).