Bosch Dynastart, Worth Saving?

[Anthonyexmouth]

Just bought a boat that had been abandoned for 5 yrs. Dynastart was seized but with a bit of gentle persuasion it got spinning fairly freely. Found an old battery in the boat which appeared to hold a bit of charge when charged.

Today I connected said battery to the boat and turned the key, regulator/solenoid just clicked, hot wired +ive to dynastart and it started spinning but quite slow, but faded in speed fast. Putting it down to a battery issue.

Question is this,
1. would the low battery cause the clicking and none activation of the dynastarter

2. as the dynastarter spins is there hope for it? tbh, starting is my main concern over charging, happy to put a solar panel on the engine box to deal with charging.

 

[Seastoke]

Battery must be knackered

 

[Davy_S]

I had a Dynastart on an old MD6a, it would do as you describe with a low battery, i had a local leccy shop fettle it, it was years ago and cost me £25, it worked perfectly after that, but from what i remember, it only charged at around 8 amps, so solar top up a good idea.

 

[LittleSister]

Question is this,
1. would the low battery cause the clicking and none activation of the dynastarter

2. as the dynastarter spins is there hope for it? tbh, starting is my main concern over charging, happy to put a solar panel on the engine box to deal with charging.

Answer is this -
1. Yes.

2. Yes.

Almost certainly clapped out battery. Try it with a battery you know to be good, or just buy a new one. You have no indication there is anything wrong with the Dynastart.

 

[Anthonyexmouth]

Answer is this -
1. Yes.

2. Yes.

Almost certainly clapped out battery. Try it with a battery you know to be good, or just buy a new one. You have no indication there is anything wrong with the Dynastart.

I'll grab one of my big batteries off the other boat and give it a go.
So is the clicking a good sign for the solenoid/regulator not being dead

 

[LittleSister]

So is the clicking a good sign for the solenoid/regulator not being dead

Yes, that is likely the clicking you are hearing.

If the battery is more or less dead it would not be surprising that it would produce enough puff to operate the solenoid, but then not have enough left to spin the Dynastart. When you wired the battery direct to the Dynastart without the solenoid there was probably enough left to spin it slowly.

It could, of course, be something else, and you could potentially have more than one fault, but most likely with a good battery it will all be OK (or at least all be a bit clearer). Eliminate the easy and obvious culprit first.

 

[PeeBee]

Bear in mind though that Bosch Dynastarts mustn't be connected to a battery of more than 60Ah without a thermal cut out being fitted or there is a risk of buring out the Dynastart windings. I've just completed a total renovation of a 6m cathederal hull day boat with a Volovo Penta engine and Dynastart. I completely rewired the whole boat from scratch, wiring diagram attached which I thought might be helpful!

 

[Anthonyexmouth]

Thanks for that, ended up ditching the dynastart and getting a newish second hand one and rewired the boat. The original regulator and dynatart were too far gone with corrosion to save. All running sweet now. Too old for all that hand starting on cold mornings.

 

[PeeBee]

OK glad that it's all up and running now. I actually prefer Dynastart to an alternator/starter motor arrangement. They're simpler and more reliable.