Eng. battery charging

[Ocean Hound]

I have had a problem for some time with the engine charging circuitry in that the engine batteries 2x150amph do not hold their charge. They are receiving a charge from one of three sources, the engine itself, a seperate Vetus generator and shore power. These three sources have all been tested show the batteries to be receiving a full charge, but even with new engine batteries there is usually insufficent charge to turn the engine over, a Perkie 4108 80hp and usually I have to switch on the generator and/or switch the domestic batteries to parallel to get enough power. The domestics (4x150amphr), are I assume on completely seperate circuit and thus only come into play if in 'parallel' which to my simple non electrical mind means that the power is seriously shorting out somewhere between the engine batteries and the control switches for engine/service/parallel switch near the bus bar and/or the bus bar to the solenoid, starter motor or engine switch. I've recommended to get a Mastervolt 12/50-3 that will keep all the batteries evenly charged but that to my mind does not resolve the fundemental question of where is the engine battery power disappearing to. Has anyone in the forum had a similar experience and can shed some light on my dilema and where I might look for possible 'shorts'.? The boat is a Moody 471 1990. Many thanks

 

[claudio]

You may need to check where the voltage is going

Set a voltmeter to DC Volts, Check the battery voltage drop whilst cranking the engine (connect the probes to the terminal posts) If the voltage goes down more than about 20%, there is a problem with the battery. If the voltage is OK whilst cranking, it is probably the connections. Connect one probe to the negative terminal post on the starter batter, the other probe to the engine block, crank the engine. If the voltage is above 1 volt you need to check the earth connections. Repeat the test with the positive lead, one probe on the battery positive terminal, the other probe on the starter solenoid (thick wire), again if the voltage is greater than 1 volt whilst cranking, you have a problem with that cable. Make sure that you connect the probe to the actual battery terminal (not the clamp). If the cables are at fault, check all connections including the clamp on the terminal post.

 

[Ocean Hound]

Many thanks for the tip. The boat is in Sweden at the moment so it may be a week or two before I can test.
Edward

 

[ms1]

seems to me you have 2 x engine batteries and 4 x domestic of 150ah. I would suggest that is the start of your problem.

Surely one alternator is never going to be able to charge up that lot. ?
Even so I would start with taking each of these batteries out, charging them fully and getting them tested.
You only need one battery to start the engine. Clean terminals and try start the engine on one fully charged battery. Once you have resolved that matter put the other batteries in being careful to clean all terminals.
Bear in mnd that a 'bad' battery will just suck the life out of others to which it is connected.

Finally you need to check exactly what you are charging when you have 240 volts. if you have separate circuits for starting and domestic you probably are not charging all 6 of them simultaneously when you have 240 volts. Actually it would take a hell of a charger to charge that lot.

 

[Refueler]

This sounds like dud connections.
My 4-107 refused one time and I had to remove starter cables and clean up, along with earth cable on engine. Once done - Bingo.

It's not unusual for connections to look OK - batterys as well - but when you take apart and check - they are corroded or dirty enough to create very high resistance - enough to prevent starting.

4-108 at 80HP ? Interested to know what RPM max you have on that engine ....

 

[Ocean Hound]

Thanks - will try. Note your are in the Baltic. We will be leaving after spending 3 seasons there. Brilliant sailing particulalrly if you can get up to the Stockholm Archipelago and Aland. Weather and accurate forecasting always a problem though - just had a duff ten days, but when the sun is out it is some best saling in world. If you want any advice or assistance - pls do not hesitate to get in touch.
Edward Wain
Ocean Hound

 

[Cliveshep]

I agree, too much battery! You need to look again at total of batteries and total of what you have available to charge 'em with. Meaning your 50AC or whatever on a Perkie 4.108 ain't gonna do it - no way brother! However, on a separate note, try starting, crank for a bit, then quickly put your hand on all battery/starter motor/earth connections. If you find a warm one that's your problem one.

 

[Refueler]

[ QUOTE ]
Thanks - will try. Note your are in the Baltic. We will be leaving after spending 3 seasons there. Brilliant sailing particulalrly if you can get up to the Stockholm Archipelago and Aland. Weather and accurate forecasting always a problem though - just had a duff ten days, but when the sun is out it is some best saling in world. If you want any advice or assistance - pls do not hesitate to get in touch.
Edward Wain
Ocean Hound

[/ QUOTE ]

mmmm I've been out here over 15 yrs ..... and exploring more and more each year.

Archipelago and Alands - have to agree ... amazing cruising grounds. I have bilge keel and 1m draft - so I'm able to get into places and coves that most cannot.

July 21 - Aug 5 .... I'm on an anti-clockwise trip fromn Ventspils north, Alands, Archipelago, Gotland and back home to Ventspils ... tight schedule - but do-able.

Shame you're leaving here ... pity we didn't meet. I'm HLR for Cruising Assoc for Latvia West Coast .... (Ventspils, Pavilosta .....)

Back to your charging ... you do seem to have a lot of batterys to charge up ! Do you have an upgraded alternator or the standard one ? If standard it's probably only capable of 45A max if you're lucky.

Still trying to find out about 4-108 at 80HP ... maximum figure I've found so far is 48HP, at 4000rpm - and then it's a land engine....... most marine are cut back to 3000 - 3600rpm and 42 - 45HP. Interested to learn more about your engine.

 

[Cliveshep]

Your right, I noticed that. Most 4.108m's are around the 40 mark.

 

[Ocean Hound]

My mistake - its an M90, or is it M80. Unfortunately all manuals on board

 

[Refueler]

[ QUOTE ]
My mistake - its an M90, or is it M80. Unfortunately all manuals on board

[/ QUOTE ]

I do apologise - I wasn't trying to be smart or upset ... just trying to get good idea of what you had .. with a 4-108 - if you had the standard alternator - it would struggle to keep up with your battery set-up.
It's worth once you have confirmed that all connections are clean and good - if still you have charging problems - to consider whether to upgrade your alternator - which may need a double belt drive if you go to high levels.
Another possibility of course is that starter motor may be in need of a good clean-out !
My starter was doused from a small leak on fuel return line that ran over top of it. Silly design mistake that allowed pipe to vibrate against engine corner - finally causing a pin-prick hole. The starter basically needed more "OOOMPH" to get it to turn ... once leak stopped and starter cleaned - it span easily on a small battery !

Good luck and hope you make it to Baltic again ... and if you visit Ventspils - I'm always ready to help ...

 

[halcyon]

Sounds a bit like trying to cure the symtom, not the illness.

I think it is start by checking the starter motor on a bench test, is it pulling the correct amps for output. If it is then check input volts plus earthing and work back to batteries, because with that size battery bank it should have enough power.

Not until I could prove that everything is working in spec, and it is low battery capacity due to bad charge system would I invest time and money in battery chargers.

Brian