Generator Dilemma

[sfellows]

Our generator saga continues:

We have a 30 yr old Onan 3cyl 1500rpm Generator which keeps failing. We suspect it is on the control side, and have spent a large sum so far (~£1000 with Onan engineers). I believe the time has come to:

1) Bin it and get a new model (variable speed, much smaller/lightweight) - e.g. Fischer Panda 5000i/Pagero etc.
2) Get it rebuilt including new controls (e.g. DeepSea)
3) Ignore & get a "suitcase" one as we only use the generator for battery charging and water heating

The big issue for 1 & 2 is getting the old one out., and for 2, getting it back in. It's big, it's heavy and the main propulsion engine is in the way. We could in theory take it out in bits, but that makes option 2 very challenging.

In addition, access to the "old" generator is pretty awful with the starter motor almost inaccessible, but I don't think there's anything currently wrong with the mechanical side of it. When it works it works!

Finally, if we did have it refurbished, how to get the lump back in?

(One well known south-coast yard suggested to get it out they would cut a hole in the fibreglass and get it out though that! - I wasn't convinced).

Any advise gratefully received....

 

[davidej]

Using a generator to heat water sounds to me very wasteful and un-green. There must be a better way.

 

[jwfrary]

How many hours have you done? If its say sub 15000 you have good compression then just service it in place, Heat exchanger, injectors, fuel pump water pump etc. No need to take it out unless its bottom end is worn....even taking the head off is a fairly simple job.

The control system can be a bit over sensitive on the ONAN's especially when it gets a bit older.

The looms not all that sophisticated, it wouldn't take a competent engineer long to retrofit for example a DSE 3110, I think they are about 100 quid.

Depending on the model the regulators separate but if it isn't then again it isn't overly hard to retrofit a DSE AVR regulator.

I consider a ONAN needing a rebuild at about 25000 hours and that's usually not much more than an oil pump and some new bearings and rings.

 

[jwfrary]

PS. If you do bin it.

you could take it out in bits.

and Install a smallish DC generator (Which are small enough you can practically lift them into place by hand!) , Battery bank (Or potentially your existing house bank), and inverter to power your water heater. Would mean less time with a generator running and silent AC power overnight at anchor.

Polar Power link > 8080VP-13 – Polar Power < Make some very small lightweight sets based on Perkins/Volvo. or there's the fisher panda (Not that I could recommend those for durability)

For example a rough system could be:-
5 kw DC Polar Power, - I'm guessing at 6 k not priced one (just oggled)
3KVA Victron Multiplus 1.2k
200 Ah 24v Lithium Battery. 4k
other related Victron bits bits (BMS, Cerbo, Lynx, Shunt) 1 k
Wiring 0.5k

Approx cost in bits = 12.7 k

Gen can charge your domestic bank via its alternator as well as the inverter bank via the main winding. which could make for quite a tidy system.

I'm not saying it would be a cheap way to go but it would be a very modern way to go and has its benefits the system I suggest above would give 2 hours runtime at 1500 watts on battery. More batteries more runtime and the water heater doesn't run all the time, so I recon you would get thought the night if your not too greedy with the power.

 

[rotrax]

Using a generator to heat water sounds to me very wasteful and un-green. There must be a better way.

Well, when on a mooring or on the hook without shore power, that is what we use our genset for. We get a tank of hot water, First Mate does like her shower every morning.

But it is not only the calorifier powered up - we get an hour of charge into the batteries, all the devices get charged, breakfast coffee made and First Mates new 'Instant Pot' - a small boat sized one - will make a meal for later that day - beef goulash in 45 minutes. Look them up, absolutely brilliant cooking device.

We have a Westerbeke 8KW genset in its seperate generator garage, access through the pilothouse sole.

Whatever you do, dont get a Fischer Panda 3,000 RPM one, or one with a small engine.

First thing I did with our Westerbeke - it was an ebay bargain - was to deep six all the sensors and wiring that stop the generator. If it has oil in the sump and water coming out of the exhaust that is good enough for me.

The KISS principle - Keep It Simple Stupid.

 

[TernVI]

A budget of over £10k seems a lot for what you get from a generator.
Hot water can be had from an eberspacher.
In conjunction with a big alternator, maybe running the main engine to charge batteries might take many years to put £5k's worth of wear on the main engine?
Particularly if one invested a bit in solar?

Maybe the sums people are spending on the 'Lithium Battery' thread look a lot more reasonable if you consider a mixed Lithium/Lead Acid battery system might avoid the need for a generator.

OTOH, it's hard to believe it can't be mended.

 

[jwfrary]

A budget of over £10k seems a lot for what you get from a generator.
Hot water can be had from an eberspacher.
In conjunction with a big alternator, maybe running the main engine to charge batteries might take many years to put £5k's worth of wear on the main engine?
Particularly if one invested a bit in solar?

Maybe the sums people are spending on the 'Lithium Battery' thread look a lot more reasonable if you consider a mixed Lithium/Lead Acid battery system might avoid the need for a generator.

OTOH, it's hard to believe it can't be mended.

True enough, if your only interest is hot water a hydronic or thermotops quite a good way to go.

 

[ip485]

I cant answer your opening question, other than there comes a point when it has probably had its day and if Onan's own engineers cant get it running reliably perhaps it is on its last legs (although I would ask them for an opinion, especially having spent so much money).

I do have a Genset, and I am not sure I would be totally without it, but I have tried to make it redundant because it does make some noise, and it is a terrible way to heat water and make DC power. Unfortunately it is the only way to do some things (like run a diving compressor, the A/C, and very occasionally give the batteries a short boost if they have been hammered).

The two biggest challenges are making DC power and hot water off mains.

Both can be achieved.

I have 800W of solar which keeps up with DC power needs almost always (and would do always if I was more sensible with power use).

Heating was the big problem, because running the engine to make hot water was also for me silly. An Ebber hydronic heater dedicated to heating hot water has solved that problem completley.

It can therefore be done, and less than the cost of a new Generator (even including fabricating an arch), as long as you dont have any power hungry AC kit.

 

[Zing]

I have replaced almost every component on my Onan genset control system. It is very simple. In fact apart from the AVR you can manage without it all. I have got it working with a few simple by-pass wires. So, if the engine is sound, keep it and replace the bits you need. They are also very cheap, just relays and basic electrical/electronic parts.

 

[garymalmgren]

Generator which keeps failing. We suspect it is on the control side,

Can you elaborate, please?

gary

 

[sfellows]

To answer Gary:

At the moment it will not start. Completely dead. Battery is fine. We ran it last year for an hour and then we stopped it (manually). On trying to (immediately) re-start it, it was "dead" that is, not turning over, no clicking from the solenoid. Previously to this we had two different engineers, (both Onan branded engineers) one who eventually got it working, the other gave up . It's possible a fuse has blown (I think this has happened before), but the only one we can find is not blown).

I believe the mechanical side is fine (it's currently not seized), I don't believe it's done more than 5000 hours, but we've spent money on it and it's still not reliable. My preference would be to replace the current analogue controller with a Deep Sea controller (and probably the voltage regulator), but my skills are nowhere near good enough (even if this is possible on an old generator - I don't know - I'm assuming you can.....) . An electro-mechanical engineer in the Gosport area would be good to find!

The biggest issue is for me is access - although it's in an Engine room, access to the rear of the generator where the starter motor is is very poor.

I like the idea of a "re-build" in situ and making it simple (if there's oil and temperature is correct then don't stop it) with digital controllers. Is this realistic?

 

[TernVI]

Starter motor not turning should be pretty basic to diagnose.
You could have had a fair idea of the problem in the time it took to type the last post.

Are the volts getting to the motor? Are the volts getting to the solenoid?

Possibly the other problems with the generator may not be within the generator but in the rest of the installation?