Battery Charging Problem

S

sailor211

Well-Known Member
Joined
17 Oct 2007
Messages
1,724
Location
Gosport : Boat Soon to be Gosport
Visit site
Setup :- Working happily for 10 years plus.
Engine Start battery 70Ah
Two domestic 110Ah batteries as a single bank
Adverc BM control unit
90 Ah Leece Neville alternator
Boat lives on a mooring. Air X wind charging when not running the engine.

Problem:-
With the ADVERC in circuit the charge commences OK rises to 14V and all appears to run through the charge cycle. However after a while the voltage will climb to 15 then 15.6 V

With the ADVERC unplugged the charge voltage is 12.8 – 13.2 consistent.

ADVERC returned and checked by ADVERC, and found to be functioning correctly. I assume this is correct.

The ELECSOL domestic batteries are, past their best after 5 years and not holding charge to an acceptable level. ( Charged by the sterling 3 stage charger they charge at 14.1V then drop to 13.2V float after ½ an hour) Are the failing batteries the root of the problem?

If I fit new batteries will all be well, and the problem disappear, or will I knacker the new batteries the first time I start the engine by over voltage?

I cannot see why the voltage rises? Unless the ADVERC is failing . I am assured the unit tested OK

Engine revs should not affect anything. The only effect can think of is that with increased engine running time the ADVERC is getting warm however there has not been a change since installation.

Any suggestions as to cause or what to test ?
 
After installing my Sterling it occasionally used to go overvoltage, causing the warning light to light and charging to stop. Sterling advised that the problem was a fault on the earth side. After a great deal of searching I found that this was correct, a poor connection between the alternator and engine ground. Once fixed the problem has never recurred.
 
I think a little more information is needed. Do you have a blocking diode? Where is the Adverc red lead connected? The red lead is the voltage sensing connection and, if there's a poor connection, this could cause the Adverc to progressively increase the alternator voltage. You also said the charge "rises to 14V" with the Adverc - I'd expect the voltage at the batteries to be higher than this.
 
I would suggest that you check the batteries individually for capacity. Charge the battery till you are sure it is charged fully. Then connect a load like a headlamp or several with a discharge current of around 10 amps. You should get about 5 hrs of lamp discharge at 10 amps while maintaining a voltage above 11.5. Don't worry too much about accuracy here it will become very obvious if the batteries are cream crackered. Even good batteries might be pressed to provide more than 60% of the claimed AmpHour rating.
good luck olewill
 
Dodgy earths can have even worse effects than Vyv described in post #2. A few years ago an intermittent earth (worse, I think, than Vyv's "poor" earth) developed on my Sterling regulator. My later assessment was that each time the earth lost contact, the regulator began again as if starting its timed cycle from scratch. The result was a battery bank boiled half-dry. I managed to nurse the batteries for another year, but it was still an expensive (and potentially dangerous) failure. In time-honoured stable-door fashion, I rewired with an independent second earth.
 
macd said:
Dodgy earths can have even worse effects than Vyv described in post #2. A few years ago an intermittent earth (worse, I think, than Vyv's "poor" earth) developed on my Sterling regulator. My later assessment was that each time the earth lost contact, the regulator began again as if starting its timed cycle from scratch. The result was a battery bank boiled half-dry. I managed to nurse the batteries for another year, but it was still an expensive (and potentially dangerous) failure. In time-honoured stable-door fashion, I rewired with an independent second earth.
Click to expand...

I have a Sterling regulator too. Can I just confirm that the "independent second earth" was for the alternator? I plan to follow your advice... :)
 
Tony Cross said:
I have a Sterling regulator too. Can I just confirm that the "independent second earth" was for the alternator? I plan to follow your advice... :)
Click to expand...
It was the earth going directly from the alternator to the sterling regulator, which I doubled up, using a 5mm ring terminal on one of the alternator case through-bolts. The first earth succumbed to vibration.
 
Last edited:
Interesting because since removing my alternator, replacing the regulator and refitting I too have had voltages c.15.2 according to my Nasa BM1.

Maybe i havn't fitted the earth correctly or am I barking up the wrong tree ? Where does the earth go from the alternator ? Which is the earth ? Engine = VP2030

Sorry for sounding so vague but when I removed the alternator I just noted where everything went and put it back the same. Guess I may not have put it back quite the same ?

Any tips appreciated, thanks
 
macd said:
It was the earth going directly from the alternator to the sterling regulator, which I doubled up, using a 5mm ring terminal on one of the alternator case through-bolts. The first earth succumbed to vibration.
Click to expand...

Sorry for being dim, but you're talking about doubling-up the two black wires that go from the Sterling regulator to the B- on the alternator? Would it not be just as good to add an extra earth wire from one of the through-bolts on the alternator case to the engine block? As I understand it from Vyv's post, the problem arises if the alternator case looses it's earth connection with the engine block for whatever reason?
 
ospreyk30 said:
Interesting because since removing my alternator, replacing the regulator and refitting I too have had voltages c.15.2 according to my Nasa BM1.

Maybe i havn't fitted the earth correctly or am I barking up the wrong tree ? Where does the earth go from the alternator ? Which is the earth ? Engine = VP2030

Sorry for sounding so vague but when I removed the alternator I just noted where everything went and put it back the same. Guess I may not have put it back quite the same ?

Any tips appreciated, thanks
Click to expand...

For "earth" read DC negative..... your MD2030 may have an isolated DC negative return ( ie does not use the engine block, that being "earthed" to the DC negative during starting and preheating by an earthing relay) but it depends upon the version A , B, C, or D. Look at the wiring diagram in the owners manual.
 
Tony Cross said:
.....Would it not be just as good to add an extra earth wire from one of the through-bolts on the alternator case to the engine block?....
Click to expand...
It is always best practice to take a new earth directly to the negative battery busbar to avoid any high resistance in the engine earth connection to the battery. 100 amps or more going through an engine block should be avoided if possible.
 
sailinglegend420 said:
It is always best practice to take a new earth directly to the negative battery busbar to avoid any high resistance in the engine earth connection to the battery. 100 amps or more going through an engine block should be avoided if possible.
Click to expand...

Thanks for this, I will see about replacing the existing B- connection to the engine block with one all the way to the battery negative. I've spent this morning cleaning up the B- terminals and the engine block connection.

Thanks for the advice! :)
 
pvb said:
Why? It works fine in cars & trucks.
Click to expand...
You can't make comparisons between auto and marine batteries/charging/engines. On a boat the salty environment is going to cause corrosion and build up resistance. 100 amps for two seconds to start a motor is fine - 100 amps for 30 minutes = 1800 seconds is eventually going to cause problems.

Best practice is often ignored because of "old wives tales". Do some tests and see the difference. Measure with a clamp meter the current from the engine block negative to the batteries, and then wire in an extra negative wire directly from the alternator. In an old installation with corrosion building up this direct wire may well pass much more current than the engine earth wire.
 
Thanks for all the tips. Went to boat last weekend, examined the alternator and found that the yellow wire on the same stub as the red but on the inside of the first nut was loose. Removing and refitted correctly and the voltage when charging now reaches a maximum of 14.4v. Problem solved. Hope the OP managed to solve his charging issue. Bestest, Pete
 
You must log in or register to reply here.

Share this page

Top