450 AH vs 675AH charging question

[brianlara 3]

Well, WOTNAME, FWIW, I'm known in certain OZ gov departments as ACTUALLY "certifiable" so maybe, as one to another, you'll trust me.
Having once supervised some splendid mechanics, I've often advised boat owners to "at least select reverse if you must insist on raising the SOC of your batteries on you mooring/hook".
Either on the hook or on a mooring what YOU do is almost as good as going for a good run.
Having never seen the cut of the gears in your box I can't tell you if selecting reverse causes more wear than when motoring (forwards).
Probably no difference other than less load with prop spinning in reverse.
In a perfect world...the reverse trick wouldn't be recommended by the manufacturers. The stuff of lawyers!!!
But, what you're doing is a lot less risky than what most others do.
Not many boxes were designed to tolerate high loads.......for long periods, in reverse.
IMHO, keep it up.
That said, 50% revs, when in reverse (that's the caveat) isn't the same as in fwd, there being less thrust.
And diesels must be loaded (well) or most will glaze the cylinder walls...eventually....whilst producing very little ring or bore wear & glazing = oil consumption, smoke and poor performance/starting too.
Could have gotten seriously technical but some cages shouldn't be tempted.
Keep it up and good luck with the sanity.

[brianlara 3]

Good to hear that story Pinguino.
I learnt from it.
Cheers.

[brianlara 3]

There are people who don't know this so....you've warmed the engine a bit and run it up to, say 1200rpm. They you turn on your freezers or HF or your inverter or whatever and as you do you hear the motor load up right? It's loaded! ......wrong!
Alternators and water pumps etc are NOT loads in terms of what diesel fuel MUST have to burn efficiently.
A diesel at idle or lightly loaded at higher revs isn't breathing much more than you are, stress wise.
SO, unless loaded to around app 30% minimum, the fuel burns poorly, does not produce gas & heat.
Piston rings are designed to keep combustion gasses above the piston producing downward thrust.
If you throw a match into diesel fuel it goes out...out!
On cold days, no wind, even gasoline will do the same thing.
The only reason diesel fuel ignites is because of the incredible heat produced by extreme compression ratios.
If a diesel engine is running, and ticking over charging batteries @ 2000rpm it IS NOT working, and then there is very real risk of combustion chamber inefficiency which will produce a bit of heat/energy and way too much soot.
Piston rings sit in grooves and these rings move at virtual light speed trying to conform to cylinder wall irregularities. And don't think cylinder wall are smooth, they aren't and are not meant to be. If cylinder wall was mirror finished like the face of a piston ring the the gasses would NEVER be trapped above the piston.
Google the words "clyinder bore cross-hatch" and go to images. those x'ing lines are intended to be dams of oil but can become soot traps which when saturated with enough wet/sooty/carbon will clog up and you then have glazed cylinder walls and a pretty sick/expensive to repair diesel.
It won't need a rebore or even new rings etc.
Usually honing the cylinders is a good fix and you toss it back together with nothing more than gasket & seal kit.....and you then tell yourself.... "drop the mooring line and "let's get that shaft turning".
" And from now on let's keep the cobwebs out of this thing".
Some, have been fortunate....many haven't.
If the water pump/alternator is turning, so should the PROP.
AND, as as an addeded benefit this annoys the hell of things which consider your prop a nice place to live......
It's about as far from rocket science as chewin' gurm.
Hate notepads.
Cheers.

[conachair]

Question for those in the know - are industrial generator diesels designed differently? I did a job this year with about a dozen running constantly 24/7 for 6 months under no load almost all of the time. Sorry for the slight drift.

[brianlara 3]

No they aren't!
But like taxis which often run 400,000 miles those engines are ALWAYS hot, hot, hot.
AND ...those industrial generators run flat out, fully loaded and sitting on the governor.....forever!
And boat diesels could too if we treated them properly.
A friends fishing boat, 4 cyl non turbod Lehman, used to do 40,000 hrs between overhauls...little motor, working hard, always hot.
How would you like to be an ONAN aux?
Start up, boil the Billy for a coffee, turn off....over & over & over.
Most yacht engines, trying to get the battery banks SOC up.....ditto.
Would you want to be one?
And frankly I don't care how many feathers I ruffle.....if it saves money and heartache.

[conachair]

Originally Posted by brianlara 3

No they aren't!
But like taxis which often run 400,000 miles those engines are ALWAYS hot, hot, hot.
AND ...those industrial generators run flat out, fully loaded and sitting on the governor.....forever!

That was the question, they are not loaded at all, hardly any power getting pulled for 99% of the time for over 4,000 hours just on one job.

[brianlara 3]

Conachair, you're right, I didn't read you properly.
Even thought these engine are on standby, they are running hard, and when the load comes on they don't start screaming because they are already well and truly working, even on standby. Massive electrical loads require a huge rotational inertia otherwise the revs would drop and then theres no electricity.
An, eg, ONAN, simarly does no tick over like a boat diesel ticking over at only 1500 revs doing nothing more than drive water pumps &
alternators (= not loaded, not getting hot). That genset is already working at speed awaiting a massive demand from the kettle or cooking range.
A car engine, sitting in the workshop, can run to max revs on even 5% throttle valve opening as many will have noticed in traffic. Gets as hot as in traffic.
Not a great analogy but consider that gasoline engines produce more heat per unit of fuel than diesel and if abused as described above would run forever because there are very low levels of combustion by-products. Naturally we aren't talking at max speed but plenty fast, say 3000rpm. And, by the way, that gas engine won't love what you did but it won't crap itself like a diesel because both the working tolerances are reduced, very important, AND the oil is hot. If oil isn't h o t then it doesn't reach the important places.
The genset you see may be on stand-by awaiting load but they aren't ticking over like a boat engine @30% revs doing nothing more the running a 140amp alternator.
Imagine in your mind, that alternator spinning over being driven by a couple of Vbelts. You wouldn't want to try stopping it.
Think now what it takes to spin a 2 or 3 foot prop.
Spinning alternators etc doesnt require much energy (heat) but a prop??
Yes, I know, thermostats are there to get the engine to temp but unless there is load there is crappy combustion which of'ntimes will bite you.
Surely, doubters......!
Yep, Pinguino has had great results...not all motors are created equal but I'm not going there because this tablet is becoming a pain to drive.
FWIW, I've taught this stuff and seriously more complex at Technical College.

[conachair]

Originally Posted by brianlara 3

Conachair, you're right, I didn't read you properly.
Even thought these engine are on standby, they are running hard, and when the load comes on they don't sta.................

Not disagreeing in any way, I much prefer to have a honda suitcase in the cockpit running a sterling procharge ultra than use the main engine.
Just interested.
I recently fitted a couple of thermometers to my Beta 35, one day I'll run just for charging and see just what does go on with the temperature.

Interestingly, it gets colder when the revs are increased and presumably the thermostat opens.

[El Pinguino]

Well I think I am doomed...doomed I say!!! Over the last three days I have done about 1400 k in my little diesel limo.....
She red lines just under 5000 RPM...idles at about 700
A steady 60kph on Beach Road in 5th sees her sitting on about 1100rpm....100kph on Olympic Way in 'overdrive' about 1700 and 110 on the Hume Freeway about 1900 so she is never driven hard and spends a lot of time barely above idling....

Moving right along... temperature is down to the thermostat and as shown above an idling engine isn't running 'cold'.

Let us consider a simple case.... A yacht with no solar , wind or anything but the alternator as fitted.
Bin out sailing for a few days, now at anchor, windy enough to blow a dog of its chain so not moving on the morrow but the batts are at 11.9 volts and the lights are dim.

So the engine is as built - mine is a Volvo MD17D and came with a Valaeo(sp) alternator...about 60 amp but 'automotive' and machine sensed and I imagine most of the era were the same .. probably the same today. No dedicated ammeter so the skipper has no idea what is going on.
Skipper starts engine... the alt does what it does in your car... a big kick in the the guts at start up and then goes back to just trickle charging...only putting out more amps if you turn on the headlights/fire up the freezer.....
4 hours later engine off and we are well on our way to glazing the bore.
Now.... do the same with a battery sensed alt ( not perfect but what is ?) and it will work hard at charging the batts....and the engine will be under load ....doesn't matter what end of the engine the load is on... load is load.

I don't think glazing the bore or not is down to luck ... its down to batt or engine sensing from the alt.

I do however think that while many will spend $$$$$ on their wind/solar/shore charging systems they just accept their engine system as it is....

[Salty Mike]

Question: Would it help the batteries at all to rotate their order of charge?
As in say you have 6-6v in series (the numbers are arbitrary at this point) seams to me the ones on each end receive the most abuse so would rotating them on occasion be worthwhile? Been trying to wrap my thick head around this for a while now any insight will be appreciated.

[a64pilot]

Google either "wet stacking" or "Diesel slobbering" I feel this link is a good one,
www.dtic.mil/dtic/tr/fulltext/u2/a151273.pdf

My opinion is your not going to kill it, but it's not good for a motor and it's easy to not do it, so don't, it is as easy as people have posted as simply putting her in reverse while you charge batteries, or a better way in my opinion is a generator

[brianlara 3]

Conachair Sir. A few posts back along this thread I said suggested to the OP that he get a Yam or Honda, a Sterling Pro 12/60 (like mine) an stick em out back.
Diesel engines last longest when worked hard be they Cummins roaring up the interstate or a Volvo 17 pushing Pinguino's yacht into a contrary headwind for 2 days. Fact.
No alternator on ANY boat is big enough, relative to cubic capacity/rated output, to load a diesel such that it is working loaded as designed.
PING, Matey, you're right Boy, dooommed! Buggered!
You gotta get that Limo and push it to a dealer but stop just around the corner, get in start "er up and drive the last 100 yards into the yard for a trade-in valuation.
Ping, you are a deduction genius! On the face of it on of the brightest students I've ever taught.
And because it was ME who saved the last remnants of you cars value, you can send me a Gregory (on God! ...Gregory peck, ..cheque!....Jaysus!)...a Gregory for USD $1000.
And many on CF, though not Factor or physicist Cate, would agree that a grand is good value for you ( albeit rotten compensation for my stress) having had you butt saved with truckloads of professional advice. A bit more, Citroens, Renault's, Peugeots, crap. We mechanics never ever buy 'em. They're artists cars, academic physicists cars.
Saabs were good....Jerry Seinfeld (on my TV every night at 6:30 for an hour. Love Elaine, George is a dickhead but he kills me...I want to say that I'm sorry for the thread drift but I can't, just can't lie, not to you Ping. You may be the THE quintessential enemy of Dr Diesels design, you and Cate, but having read way too many of you old posts...you seem like a good bloke.
Seriously sick and war ravaged body...brain...leave my head alone...goin' back to bed...no chance of sleep thanks to you an' Conabloodychair.
Go away! For now.
This rotten tablet allows me to review this drivel only one line at a time with seriously blurred eyes (Lyrica 900mg daily) and so you've shed a little of you're popularity Pingbloodyguino.
Go away, you know I'm war neurosis.

[GILow]

Originally Posted by Salty Mike

Question: Would it help the batteries at all to rotate their order of charge?
As in say you have 6-6v in series (the numbers are arbitrary at this point) seams to me the ones on each end receive the most abuse so would rotating them on occasion be worthwhile? Been trying to wrap my thick head around this for a while now any insight will be appreciated.

6-6v in series would give you 36 volts. Not a common voltage on pleasure yachts.

Also, not sure where you get the idea that the batteries on each end somehow get a different workload but it does not happen that way. Whether the batteries are in series or parallel (or a combination of series and parallel as I would need to create 12v) they will all work just as hard. The only exception being if there were a mixture of different battery types.

Charging the batteries separately might have some advantages but I can't see them right at the moment. I can see many disadvantages such as different charge levels on each battery and a lot of bother keeping track of which is charged and which isn't.

Matt


Sent from my iPad using Cruisers Sailing Forum

[brianlara 3]

Salty, I'm going to offer you a great answer to your question in a few hours.
Pinguino's been playing " let's scramble the old bastards brain" with my mind and I'm goin' back to sleep.....Its 6:30am for Gods sake.
get back to ya Salt'. (promise me you won't try to "PING" ....new word, you read it here first....my brain.

[brianlara 3]

SALTY. Forget rotation. Not necessary if you choose one of the following.
Option A...Not perfect but almost.
Option B...Perfect but more difficult for me to have set up.
My set up:
Imagine 5x100ah batteries at your feet all lined up neatly & side by side.
Five negative terminals closest to your feet, and five pos's furthest.
Join all the pos with one common cable and then all the negs with another cable.
Here you now have a single 500ah battery agreed?
Furthest from you on your left is a positive terminal.
Put all of your loads and charging capacity positive leads onto that post/stud.
Closest to you on you right is a neg post onto which all of your neg leads go.
So, you have your two cables, a red pos and a black neg a few feet apart in two widely attached out hands yep?
This is the easiest way to achieve almost equal charge & discharge.

OPTIOB B: The perfect system has 5 EQUAL LENGTH cables joining all of the positives into, effectively, one positive input cable and then ditto the negs the same way.

Just using the two terminals of one battery for both pos and neg and then hanging the other batteries off the first one is, for this black duck at least, seriously not so good. Yep, it happens, some do it, don't bother telling me, not interested in beligerently motivated horses
who would prefer to dehydrate.
I NEED to hear of a better system if anyone can help. Truly.
Hope this was useful Salty.