dynastart

[mipak]

i have a 1971 4 berth cruiser with a 2 cylinder 25hp volva penta diesel engine which uses a dynastart.

the 2 batteries aren't being charged so the dynastart was stripped and found to have a worn commutator ... the 4 brushes were reasonable.

it was all cleaned and re-assembled. when it was started, the batteries began to be charged once more but after about 10 minutes, the charging stopped.

again, the dynastart was stripped etc. and re-assembled. the result was as before.

ideally, i would like to try and get hold of another dynastart but they're not exactly readily available!

has anyone got any suggestions please?

i'm happy to go into more detail on this via email if need be.

 

[oldharry]

Dynastarts are pretty tough things, so did you find out why it had stopped charging? If the coils, commutator, and brushes were good, then the fault is more likely to be in the control box.

Having Dynastart engine myself I too would be interested to know where spares can be obtained, other than picking them up via Ebay etc.

 

[jerryat]

I agree with old harry, check the control box. They are extremely crude by todays standards, and do wear out. I had this (Dynastart) on my old 10hp Bukh diesel many years ago, and experienced similar problems to you.

Luckily I had a chat with the guys at Lucas Marine, who said whip the control box off and we'll test it. It was faulty (worked sometimes then not for ages) and they offered a new replacement for about 1/3 of the cost of the Bukh 'spare'!!

You may even be able to get one from a car scrap-yard which is what a friend of mine did not long after. Cost him a pound!!

 

[mipak]

Yes indeed they are. I and a colleague came to the conclusion that it must be the dynastart because there was no voltage coming out of the D+ terminal and the ammeter wasn't working when the engine was running. This lead runs to the L+ terminal of the ammeter and on from its B+ to the D+/61 terminal on the regulator.

I recently re-wired the circuits but I'm sure I didn't alter any relating to the charging circuit. Mainly, I just added some gauges and a new 4 terminal ignition switch which replaced the original 3 terminal switch and starter button.

Under the dashboard, there are 2 metal boxes ... one with 6 terminals: D+/61, DF, 50, B+/30, 30H & earth and the other, slightly smaller, has 5 terminals: D+, an unmarked term. connected to DF on the reg, another unmarked term. connected to B+/30 on the reg, one terminal not connected & earth. There are 2 relays in each box but I can't remember what positions the contacts are in when it's running and not running.

I stripped the dynastart and found that the commutator grooves were clogged so these were cleaned out and the darkened faces lightly sanded. The faces are also worn. The brushes were cleaned up as well.

Once it was all connected up, I started the engine, the result being that the red charging light went out and the meter was showing a good charge of around 16 to 20amps at the start. The voltage on both new 12v 60aH batteries indicated just over 14v.

After a while, the red charging light came back on and the ammeter dropped to zero so I re-did the whole exercise again with the same result.

When I was last out on the boat, it was October 2004 and everything was running just fine then so have to admit that I find it quite strange that the d/start is at fault. Perhaps I did connect a wire to the wrong terminal ... I don't know.

And that's pretty much it really.

I can send you the updated wiring diagram if it would help.

As regards looking for spares, there seems to be precious little on the net except, as you said, in eBay. I just typed in 'Dynastart' into Google and went through each listing with little result. I suppose there is always the alternative of doing away with the dynastart etc. and converting the system to an alternator, starter motor and a cogged wheel to replace the flywheel but that would be a major job at a major expense.

Hope all the above makes sense and my thanks in advance ... Michael.

 

[mipak]

thanks jerryat ... but how do I check the control box?

Out of the 2 boxes under the dashboard, I think the larger one with the 6 terminals all along the longest side is the charging regulator so is the other smaller one, with its terminals situated at each corner, the control box?

Inside it, there are 2 relays ... one with 2 contacts which the metal strip flips between the two and the other relay just has one contact. It all looks very shiny and new ... no corrosion or anything.

Michael.

 

[VicS]

Older Dyna-starter control boxes (made by Siba) had the solenoid for the starter function built in. Later boxes (made by Bosch) did not include the solenoid which is fitted as a separate unit.

Terminals are similarly marked.
DF to DF,
D+61 to D+ (Via ammeter and fuse maybe )
51/30 (On Siba ) to battery +ve (and starter switch)
B+ (on Bosch) to battery
50 (Siba) from starter switch.
A (Siba ) to A or A/30

On a separate solenoid

87 from battery +ve
85 to earth or negative
86 from the starter switch
30 to A/30

One of the coils in the regulator is the voltage controller and has to be adjusted to control the volts to the specified value. The other is the cut out which has to be adjusted to cut in when the volts have risen to a specified value just above battery voltage and to cut out when they fall just below normal battery volts. But sorry I do not have details of how to adjust these for a Dyna-starter. Unless you can obtain precise details it would be sensible IMHO to get a good auto electrician who knows what a Dyna-starter is to check/adjust it for you.

(had there been a third coil in there it would have been the starter solenoid)

 

[William_H]

Just a little theory if I remember it all.

The generator (part of the dynastart) requires a cut out coil. This is a relay which has a high resistance winding (many turns of fine wire) connected between the output (brushes) and ground. Around this coil is a few turns of heavy wire. The output current flows through this coil. Such that current flow out aids the field of the voltage coil. The contact on this relay connects the output of the generator to the battery and system.
Should the generator stop charging (when engine stops or slows to idle) the power from the battery will tend to flow back into the generator to the current flow being in the opposite direction will oppose the field made by the voltage coil so releasing the relay and disconnecting the gen from the battery. (In a modern alternator the diodes stop this reverse flow.) The light may be connected from the battery via the ignition switch to the gen output so that if the gen is not generating and the battery voltage is ok the light will glow until the gen starts charging.

The second coil of the regulator is the voltage regulator. This is a coil also connected across the output of the gen. The relay contact is made when the coil is not energised and opens when the coil is energised. This contact connects the output voltage of the gen to the field coils which are the stator coils around the inside of the body. The spring tension of the relay is carefully adjusted so this coil only pulls in enough to open the contacts at 14 volts. So when the output reaches 14 volts the relay operates to disconnect power to the field coils so stopping the charging. This stopping reduces the output voltage so the relay relaxes to again feed power to the field coils which increases output again. The relay is in a constant state of make and break the end result is an output regulated to 14 volts. A resistor is fitted across the contacts so that field current rather than be cut off completely is reduced to a low amount when the contact is open.
Some generators have current regulator which is a somewhat similar relay with a coil of heavy wire through which the output current flows such that if the current becomes high enough the contacts operate again to reduce the field current hence output voltage.

Now in a dynastart the generator must be converted to operate as a starter. The armature may carry another commutator with seperate heavy brushes to carry the obviously high current of starting a bigger engine or may simply use the generator armature and brushes to carry max current through the one set of armature windings. At the same time full current must be fed to the field (outer stator ) coils to give max torque. Again this may be via separate field coils or the one set. An examination of the dynastart should determine if there are extra heavy windings for starting.

In any case relays must redirect the current to the dynastart to make it motor.
I reckon if dynastarts were still popular we would see some very simple smooth electronic regulators to replace these unreliable contacts on relays

Don't despair Starter Gens (dynastart) are used on most smaller gas turbine aircraft engines where the starter may crank initially at 1000 amps at 24 volts and then generate a max 200 amps at 24 volts.
They sometimes have a standby alternator for single engined aircraft. Which may give you a hint that a separate alternator may give more charging power on your boat. I hope this may give some understanding of what the relays do ...olewill

 

[mipak]

Thanks for all that. Obviously I'm not at the boat right now to check but I can't remember seeing any name on either of the 2 boxes. From your description, I think the regulator ... the larger of the 2 ... must be a Bosch because it only has 2 relays inside it.
The wiring connections you described are much the same as mine but just to clarify ...

Dynastart:
30H >> 30H on Regulator
DF >> DF on Regulator

D+ >> L+ on ammeter then from B+ >> D+/61 on Regulator
D- >> earth

Charging Regulator(larger box):
30H >> 30H on Dynastart
B+/30 >> main batteries switch
B+/30 >> battery terminal on ignition switch via fuse
B+/30 >> unknown terminal on unknown smaller box (control box?)
50 >> starter terminal on ignition switch
DF >> second unknown terminal on unknown smaller box
DF >> DF on Dynastart
D+/61 >> ignition terminal on ignition switch via amp warning light
D+/61 >> B+ on ammeter
D+/61 >> D+ on unknown smaller box

Unknown smaller box (Control Box?):
3 of the corner terminals are as above.
The only other terminal, apart from earth, is not connected to anything.

I was sort of hoping I'd wired up incorrectly which, once corrected, might have solved the problem but as far as the regulator is concerned, it seems to have been done the same as yours.

I wasn't aware that regulators were able to have the voltage etc. adjusted so if need be, I'll look for someone here who knows how to do it.

I don't know where the solonoid is ... could it be in one of the relays in the smaller box perhaps?


... and to William_H ...
Your description of how it all works is most interesting although it's part of an electrical circuit with which I'm not really familiar. Hopefully I'll improve.

Assuming I need to get both boxes, I expect I can get them online somewhere unless I can find a scrapyard here without having to go to the mainland.

My thanks to everyone for all your help so far. It is really much appreciated.

Michael.

 

[misterg]

Are you sure the brushes aren't sticking / at the limit of their travel? That would have given the burnt commutator in the first place.

0.02p

Andy

 

[VicS]

[ QUOTE ]
but just to clarify

[/ QUOTE ] Try again. difficult without a diagram

I'll assume you have a Bosch Dynastart (I think Dynastart is actually Siba's name ) because you mentioned an earth connection and the Siba did not have an earth terminal and a separate starter solenoid.

Dynastart terminals:

30 to 30 on solenoid
DF to DF on control box
D+ to D+ on regulator (via ammeter* and fuse if fitted)
D- to earth/battery negative (sorry I missed that before)

Control box terminals:

B+ to battery via isolator (and maybe fuse and ammeter*)
B+ also possibly to starter switch
DF to DF on Dynastart (as above)
D+/61 to D+ on Dynastart (as above)
- or the case to earth/battery negative (I missed that first time as well)

The solenoid terminals

30 to A/30 on the dynastart (This is a heavy wire that carries the starting current)
87 to battery + via the isolator (this is also a heavy wire carrying the starter current)
(30 and 87 may be interchangeable)
86 to the starter switch
85 to earth/battery negative
(86 and 85 may be interchangeable)

* these are alternative positions for the ammeter. In the D+ to D+ wire it will only display the Dynastart output but in the B+ to battery position it may also show battery discharge if the other electrical circuits are connected to the regulator B+ connection.

Most of this has been derived from a circuit for a Stuart Turner engine with a Siba control box and Dynasart that I was helping someone at a distance to rewire using a replacement Bosch Control box and separate solenoid. It also incorporated a run/charge switch.

I notice there is no provision in the above for a charge warning lamp which on the circuit I am working from was part of the supply to the ignition system via the run charge switch (or an optional key switch)

It will however have to be connected from battery + connection somewhere via an "Ignition switch" and then to the D+ to D+ connection.

Using the circuit i have the engine could still be cranked without switching on the key switch, but it would not require a huge alteration to change that.

Sorry this is getting confusing. I am supposed to be painting and varnishing my dinghy.

 

[mipak]

forgot to mention when i emailed the diagram ...
the main switch to the B+/30 charging regulator terminal link is a thick heavy red cable.
the 30H charging regulator to the 30H dynastart terminal link is a thick heavy red cable.
the battery to earth link is a thick heavy black cable bolted to the engine.

the main switch is shown set to both batteries but can be set to any of the 4 positions.

i don't know what the box marked '???' is (the control box?) or what it does.

the ammeter has always been linked with thin (2.5mm) wire. if it was connected in line from the B+ regulator terminal to the main battery switch, would it not need to use thick cable or did you mean it could be in line (2.5mm wire) to the battery terminal on the ignition switch? i can easily do that. i can confirm that when it activated for those few minutes in its present position, it only showed positive readings, no negative ones.

michael.

 

[William_H]

Almost certainly your amp meter should be connected with heavy cable. The current flows through the meter. Not to be confused with the type where a remote shunt carries the current with only a little going to indicate to the meter.

If the amp meter is between the gen and the battery (switch) then it will indicate charging current. If however the load lights etc is taken from the battery (switch) then that current will flow from the battery to the load nor t via the amp meter so no negative indications. For negative or total current indications the load needs to be taken from the gen side of the amp meter. good luck olewill

 

[VicS]

Will,
Mipak has emailed me his complete wiring diagram which I will study carefully later.

His ammeter is in the output from the dynastart (It does only show the charging current.) so the wiring will need to be heavy enough to take the output current but I am not sure what that is.

His reference to "heavy cable" is the cable that carries the starter current. Namely battery to control box, control box to starter and of course the negative connecton beteen battery and engine.

Later when i have studied his diagram I may PM you

 

[mipak]

hi ...
just read your post and also the one from will.

in the engine instruction manual relating to the electrical system, it says:
starter-generator md2b, md1b (md2 is the one i have)
generator output, max. w 135
continuous w 90
starter motor output, h.p. 1

does this help at all?

michael.

 

[mipak]

hi ...

at long last, the problem has been solved.

the dynastart is working as it should and has been pumping out a charge all the time but this has been blocked by the regulator ... or i should say ... both regulators!

the larger of the two with it's 5 terminals down one side is a bosch 0190219001 voltage regulator which contains the solenoid and regulator and the smaller box, type unknown, is also a voltage regulator without a solenoid (a separate solenoid would need to be wired in).

at some point in the past before i got the boat, a fault must have occured on the regulator side of the bosch and the second box was wired in to D+/61, DF and B+/30. the trouble was that the bosch wasn't disconnected from the D+/61 and DF leads so that both regulators were left to run together.

what should have happened when the second box was put it was that the leads to D+/61 and DF should have been disconnected and transferred to the new smaller box and just an extra lead wired in linking both B+/30 terminals on the two boxes. this would have allowed the new regulator box to do its job and the solenoid in the old box to start the engine.

perhaps the original fault was the totally burnt-out resistor(age and corrosion?) under the bosch which we found yesterday, perhaps it was something else but whatever cause was, what stopped the batteries charging was the non-working regulator coil in the bosch, one non-working coil in the second reg. box and both boxes effectively wired up in parallel!!

the result of all this was that when the engine was started, the ammeter immediately showed in excess of 30 amps for about 2 minutes before the charging system shut itself down.

and that's about it really. i've learnt a great deal from all this ... what, how and why etc. ... but it's thanks to all of you in the forum and to others here and on the phone who have enabled me to reach this point. it is really very much appreciated ... thank you.

once i get a new regulator wired in, i hope that that will end the problem so that i can go off and enjoy my trip to the orkneys!

michael.

 

[paul9]

Dear Mipak,
I have recently finished restoring my old Volvo Penta MD1 for my '19'0" Mirror Offshore during which time have spent many, many hours trawling the internet for spares, pistons,head gasket sets,dynastarts etc.
I now have wiring diagrams for the dynastart 2 models but they only give external connections, I also have the wiring diagrams how to connect to the boat loom including the regulator.
I have also found a supplier for Dynastart here in the UK not cheap but new approx £195.00.
If you want to e-mail me I will send you all the info I have

(paul.brennan9@btinternet.com)

 

[mipak]

a final update ...

things have moved on ... i wired the new regulator in and it worked very well. however, the batteries were still not getting charged and the cause of this was now clearly down to a fault in the dynastart. a few days after this, i was contacted by someone whose husband was ill in hospital and who had a boat with an engine that had a dynastart in good working order. this was offered to me on a long-lend basis as the boat was not going to be used for quite some time. I accepted this offer, installed it in mine ... and everything worked including the charging circuit.

now that the boat is ready to go, i've had to change my orkney plans due to running out of time and the high price of diesel ... even marine diesel is costing around 92p a litre in some parts of the west coast of scotland!

so instead, i'll stick to local areas which i'll enjoy almost just as much.

my sincere thanks to everyone here who've helped me with so much advice. i've gained a great deal of knowledge from it.

happy and safe sailing to all of you.

michael.