Alternator regulator voltage

MarkJohnson12345

MarkJohnson12345

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www.markjohnsonafloat.org.uk
I have banged on a bit about Adverc, and alternators, so apologies for more.

Having fitted the Adverc system, I have not seen it switching between 14.4 and 14 volts as it is supposed to.

Have chatted to Adverc a couple of time, it appears that the little Sev Marchal alternator (35 amp/h), going on for 29 years old (I assume) is belting out about 14.3 volts.

Apparantly this actual makes the Adverc unnecessary!!

I also read that if the batteries are continually charged at 14.3 or above then it shortens their life considerably.

Having owned the boat since 2003, I am on my 2nd 110a/h domestic. I kind of expected it to last a bit longer than that.

Not being very clever with electrics, is the voltage regulator on the Sev set too high, or damaged?

Adverc have offered to reset the top voltage on their gadget, which allow the system to cycle between 14.5v and whatever the Sev regulator is set too.

In the longer term I would like to add another domestic 110amp/h so am wondering whether to relace the old alternator for a new larger capacity one.

But thats is not the immediate concern. What voltages are alternators usually set too??
 
[ QUOTE ]
What voltages are alternators usually set too

[/ QUOTE ] I think you will find they vary.

I would definitely not say that 14.3 is too high, some are higher

The merits of the Adverc BM system seem to be that it compensates for the voltage drop across a diode splitting system and uses battery sensing for charging the domestics battery.
 
Many modern automotive alternators are set at 14.4-14.6v, and don't cause battery damage. It's much more likely that the short life of your domestic battery is the result of excessive discharge. Adding at least one additional battery would be a good move.
 
I agree 14.4 is quite normal. This keeps coming up and the same people keep insisting 14.4 is too high. It isn't. Automotive systems where the alternator is running constantly have alternators set at anything between 13.8 and 14.4V
Car batteries last a long time and need lttle maintenance because with these voltages they are seldom more than 80% charged and don't gas very much. On a boat where the domestic batteries are lead acid refillable types we fit smart chargers to boost up to 14.8V to give near 100% charge but this does mean you need to check electrolyte more frequently. If you have sealed or gel type batteries 14.4V is about as high as you should go but with conventional lead acid types you can go higher. Also dont forget that it is the voltage AT THE BATTERY TERMINALS that matters. Diode bridges, long runs of cable or cable of low cross section will reduce the voltage at the battery.
 
Is this brushless alternator on an old Volvo engine? does it have extra diodes mounted on a subframe/heatsink at the back? As mentioned above, check the voltage delivered AT THE BATTERY. The extra diodes were built-in splitters and can be bypassed if only one battery is being charged, then you get more volts. To re-iterate, up to 14.8 is OK on open type batts, 14.4 on sealed.
 
Measured the voltage on the actual alternator/regulator output and quite surprised to find it reading 14.95 volts.

By the time it gets to the battery it is the 14.3 volts. But I do have one of these NASA battery monitors with the shunts etc.

Beginning to wonder whether I have wiring inthe wrong place!

MJ
 
[ QUOTE ]
to find it reading 14.95 volts..........By the time it gets to the battery it is the 14.3 volts. But I do have one of these NASA battery monitors with the shunts etc.

[/ QUOTE ] The volts drop is far too great (unless you have a diode splitter in there) The BM shunt will only drop 50mV at 100 amps.
14.95 volts at the alternator is too high as well. (Unless there is a diode splitter and battery sensing to compensate for it.)

Are you measuring the volts in one case from the alternator negative terminal/ case and the positive terminal and directly across the two battery terminals in the second.

You should be looking for the source of this volts drop. Check the negative as well as the positive but if it were the negative you'd probably be having starting problems
 
Are you measuring the volts in one case from the alternator negative terminal/ case and the positive terminal and directly across the two battery terminals in the second.

Yes, the 14.95v is measured at the back of the alternator, and the 14.3v was measured at the battery.

The other little puzzle is the green light on the Adverc system flashs at one second intervals for several seconds then stops. After another interval it starts again. The one second flash indicates overcharging. The batteries are certainly not being overcharged, but this 14.95v makes me wonder whether there is a connection somewhere.

I think I will take someone's advice on a previous thread and take off the alternator and get it checked out. Poor thing is probably nearly 30 years old!!

Thanks all for contributions.

Mj
 
Before removing the alternator, you need to find your volt drop. If you are measuring the terminal with the positive battery cable on, and get 14.95 v. Then 14.3 at the battery terminals, the volt drop must be external to alternator.

Can you physically follow the charge cable from the alternator to battery ? that is eyeball it all the way ?

Are you measuring voltage on the alternator output stud it's self ? can you measure the terminal as well ?

Brian
 
[ QUOTE ]

Apparantly this actual makes the Adverc unnecessary!!

[/ QUOTE ] Yup. And the Sterling equivalent. I've been going on about this for ages. They are boosters, not controller. If your alternator reg is in the mid 14s (as mine is) then what you really want is for the voltage to be reduced after a while, particularly after more than 12 hours at sea. The basic Adverc and Sterling cannot do that.
 
If you get yourself a few meters of 1 mm wire, strip one end and twist arount the neg probe of the multimeter, and tape over. Strip the other end and attach to the battery neg terminal.

Now you can measure anywere relative to a fixed point, i.e. all voltages are relative to battery neg. If you measure any neg connection it should be zero, any bad connection will appear as a positive value. If you attach wire to battery clamp, check voltage to battery terminal, may be a bad coonection on battery.

Get some paper and make a note as you work along both pos and neg cables, from battery to alternator.

This will give you a diagram of were you have volt drops, you can then decide what the problem is.

Best of luck

Brian
 
2 other measurements you can do is to test the voltage between the battery negative and the alternator positive and then between the alternator negative and the battery positive. That could indicate if the volt drop is in the positive connection alternator to battery or the negative connection alternator to battery.
 
[ QUOTE ]
2 other measurements

[/ QUOTE ] I'd have thought the simplest way of determining if the volts drop was in the positive or the negative connection would be to measure (look for) any volts between alt - and batt - and then between alt + and battt +. Then use the technique outlined by Halcyon to narrow it down.

Usually the alternator out put is connected to the rest of the system at the starter solenoid So if there is no trouble starting any poor connections are most likely to be between the alt+ and the solenoid or between the alt - and the engine block.

On the basis that we are looking for abt 0.6 volts at charging current we would loosing perhaps as much as 5 or 6volts under starter load if the trouble is between battery and solenoid or battery and engine block. That would make starting difficult!
 
[ QUOTE ]
Usually the alternator out put is connected to the rest of the system at the starter solenoid

[/ QUOTE ]

Not always if you have a single alternator driving a domestic and separate engine start battery the alternator would be connected to a splitter device and then to the engine start battery and the domestic battery. The engine start battery could also be connected via an isolation switch which is also a possible loss voltage.

The point I think we all agree on is to start to break down the current path and to check different parts for the volt drop to determine which element is causing the volt drop.
 
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