Alternators, Charging Circuits

[mikeyboy1966]

One of my projects this year is to upgrade the battery bank,and look at the charging system on the boat.

everything has worked fine through the summer once I’d replaced the domestic batteries.

5 day cruising no problem with no shore power.

but,,,,,,

the batteries are stuck in any gap.

the wiring is a mess.

so a centralised bank of batteries and simplified wiring is the order of the day.

ill be upgrading to 3 domestic 1 starter.

all of the wiring is getting on a bit so I’ll rewire all of the supply side of things.

all battery +ve side of things is currently brown.

this In itself does my swede as in my world brown is earth/return.

anyways.

I couldn’t get any pics as the light was fading, and all the electrics associated to the charging/engine are virtually inaccessible,which,again is a big issue for me.

question #1

im guessing this is the rectifier/diode 

 

[mikeyboy1966]

Any info on the above is welcomed.

the alternator looks to have been replaced.

poor photo,

I just can’t get near it.

[mikeyboy1966]

Also mounted on a plate bolted to the engine in the same area.

a black box with CAV on it,glow plug relay??

a solenoid,starter??

another relay and a black box with alternator controller.

[mikeyboy1966]

When I start the engine after a full load night away (fridge,lights,heater,toilet)

the charge light stays lit till I rev the engine to @ 1500rpm

then it extinguishes and the ammeter immediately flicks up to @25 amps.

this suggests there is an electronic device controlling the alternator.(see above post)

after a while it settles at prob 8/10 amps.

im guessing the alternator is a minimum of 50 amps so any recommendations of an upgrade is welcome on the control side of things.

[Smoggy]

The finned device is a blocking diode that charges both battery banks with no back flow to kill the engine battery,  if the alternator has no external controller you won't be getting fully charged as diodes have about 0.7v drop across them.

Do you have a working charge light at the helm? Normally the alternator is excited by the 12v through the charge light bulb to the field coil and it goes out once charging as  it's a route to ground till it starts charging then there's 12v to both sides hence the light goes out, no voltage differential. 

If someone has replaced ignition lights with led lamps you need a resistor across charge light to excite alternator,  often a rev will kick it in due to residual magnetism. 

Read it 3 times and ask again as I've been drinking....

[BrundallNavy]

The black box looks like a split charge relay. 

[Vaughan]

8 hours ago, Smoggy said:

The finned device is a blocking diode that charges both battery banks with no back flow to kill the engine battery,  if the alternator has no external controller you won't be getting fully charged as diodes have about 0.7v drop across them.

Do you have a working charge light at the helm? Normally the alternator is excited by the 12v through the charge light bulb to the field coil and it goes out once charging as  it's a route to ground till it starts charging then there's 12v to both sides hence the light goes out, no voltage differential. 

If someone has replaced ignition lights with led lamps you need a resistor across charge light to excite alternator,  often a rev will kick it in due to residual magnetism. 

Read it 3 times and ask again as I've been drinking....

Whilst what you say is quite right, I think we will find that the Prestolite alternator is self exiting, and that the warning light will have been added as an extra.  It is quite normal that a Prestolite will need to be revved up before it cuts in.  The photo is a bit hazy but I assume the alternator is 110 amp, which will be fine for a bank of 3 domestic, 1 starter, but I would recommend a more "intelligent" charge splitter than the basic blocking diode, as Smoggy says above.

Your engine is a Perkins if I remember, so no glow plugs to each cylinder and therefore no need for a relay.  The preheat is one glow plug, in the air intake of the induction manifold.  It does have a separate solenoid from the starter though, so that is maybe what the black box is. More photos will help!

[Vaughan]

10 hours ago, mikeyboy1966 said:

then it extinguishes and the ammeter immediately flicks up to @25 amps.

Have just realised you talk of an ammeter, which is an old fashioned way of doing it, as it means the wiring has to go up to the dashboard and pass through the ammeter before it goes anywhere else!  If you are re-wiring the boat you can do away with all that and simply fit a voltmeter, wired from the ignition "on", to ground.

Normally the feed to the dashboard will come from the battery side terminal of the starter solenoid, while the domestics will go to the main fuse box.  Both of these will go through  battery isolator switches which ideally, will be outside the engine compartment.  I much recommend circuit breakers rather than fuses, since fuses blow on a surge of amps, but are not sensitive to volt drop.  The starter battery will feed the ignition key and will also feed any appliances that are only used when the engine is running, such as horn, wipers and nav lights.  So you may want a small breaker box under the dash, fed from the key.  Everything else will come from the domestic batteries except the bilge pump, which is fed from the starter and does not need to pass through the battery isolator.

You can buy battery chargers for shore power with 2 or 3 outputs for the seperate batteries and I recommend at least 40 amps DC output.  Chargers give off heat and need good ventilation, so install them near a hull vent if possible.  Same applies to inverters.  This is the main reason why both will fail.

[Vaughan]

8 minutes ago, Vaughan said:

 Same applies to inverters.

And fridges!!

[mikeyboy1966]

Thanks for the replies,

As I said,it’s all working fine,but I’m going to upgrade anyway,

as things stand if there was any issues with the wiring it would just be a pain to gain access and effect a fix ,

I guess this is normal for a boat of this age as previous owners upgrade and modify ,in my experience and from what I’ve seen up to now with the boat there are quite a few “bodges” and a fair amount of redundant wiring which I will remove.

Untidy wiring messes with my head.

 

[mikeyboy1966]

Whilst on this subject,

have any of you got a recommendation for charge control upgrades?

if my ammeter is telling the truth,10 amps is not a huge charge rate for batteries that have been running lights ,heater , fridge etc for 12 hrs.

given the alternator is 50amps +,

poss 110 amps if Vaughan is correct

[annv]

Hi Micky Also in addition to what Vaughan said when you wire battery up take the pos cable from the first batty then the neg from the last battery, see dig. this spreads the load over all the battery's equally rather then just the first battery John

[annv]

Hi Micky i use a sterling advanced charger this fools the alternator into charging the full amperage while it also monitors the battery temp as well reducing the the charge until temp drops then up too full charge until battery is fully charged, see there web site for more info. John

[mikeyboy1966]

I’ll take a looksee

[Vaughan]

23 minutes ago, mikeyboy1966 said:

if my ammeter is telling the truth,10 amps is not a huge charge rate for batteries that have been running lights ,heater , fridge etc for 12 hrs.

If a 90 amp alternator ran for more than a minute or two at that rate, it would burn out.

What actually happens, when you are charging batteries that have been used overnight, is that the volts start low (maybe 12.2) but the amps are high. The amps will very soon settle on about half the capacity of the alternator, and will soon drop, as the volts start to come up. Once the battery is near to a full charge you will see 13 or more volts, but only about 5 amps. This is quite normal.

The intelligent regulator fools the alternator into providing a few more amps than it wants to, to complete the final charge of the batteries.

Not a technical description but I hope it is understandable!

[Regulo]

The  Sterling advanced charge regulator is highly recommended by me, but it does involve getting into the alternator. Also the very high charging rate obtained will require careful and regular checking of your battery electrolyte levels. As stated there is the option to fit the temperature sensor (supplied), and I'd strongly advise it to be fitted. I do like to have an Ammeter at least on the domestic battery bank, it can give immediate indication of problems. Modern digital ammeters use a shunt locally to the battery, and light gauge wiring to the instrument itself, thus no long runs of heavy gauge cable, with the associated losses. 

[MauriceMynah]

Are amps green?

[annv]

Hi Mikey just a thought a volt meter is of more use than a amp meter as it gives you the state of the battery and if being charged rather than how much you are putting in or taking out, if alternator is charging volts will go up to near 14 volts if battery is low standing voltage is 12volts . John

[PaulN]

20 hours ago, mikeyboy1966 said:

One of my projects this year is to upgrade the battery bank,and look at the charging system on the boat.

everything has worked fine through the summer once I’d replaced the domestic batteries.

5 day cruising no problem with no shore power.

but,,,,,,

the batteries are stuck in any gap.

the wiring is a mess.

so a centralised bank of batteries and simplified wiring is the order of the day.

ill be upgrading to 3 domestic 1 starter.

all of the wiring is getting on a bit so I’ll rewire all of the supply side of things.

all battery +ve side of things is currently brown.

this In itself does my swede as in my world brown is earth/return.

anyways.

I couldn’t get any pics as the light was fading, and all the electrics associated to the charging/engine are virtually inaccessible,which,again is a big issue for me.

question #1

im guessing this is the rectifier/diode 

 

Looks like you are planning to revamp your battery storage and wiring. No doubt you are aware but you have to consider the BSS requirements for your next inspection (battery section attached). This varies for lead acid batteries or sealed AGM and Gel types. Also location, engine bay or seperate. Attached are photos of my battery storage box, sorry it's a bit out of focus.

The batteries are sealed AGM and in October this year I replaced all 4 with sealed Rolls S12 230 AGM's (ouch). In the photo the lid is off which is on the left of the photo and the engine starter battery can just be seen at the bottom of the photo with it's lid on. You can also see the flange of the vent going to the hull fitting.

I also use a Sterling intelligent charger which I would recommend, however, the charge rate needs to be set via the dip switches according to the battery type, Lead Acid, AGM or Gel, details attached.

Sorry if you know all this already, but maybe of help. Hope all goes well.

BSS Batter Storage.pdf Sterling Pro Charger D Digital.pdf

[mikeyboy1966]

Linky no worky

[annv]

Hi Pauln your battery's are not wired up for best performance see di above. John

[PaulN]

On 06/12/2022 at 09:06, annv said:

Hi Pauln your battery's are not wired up for best performance see di above. John

Hi Annev

Batteries are connected as 2 banks of 2 and the battery isolator allows me to switch between Bank 1, Bank 2 or Both, as installed when the boat was built by Swancraft. Batteries are AGM 230 Ah each, so plenty of power. Not sure why this format is inefficient but would be a major job to change. However I accept any advice, but not sure what you recommend I should be doing.

[PaulN]

On 05/12/2022 at 17:00, mikeyboy1966 said:

Linky no worky

Sorry about that. Will try loading pdf docs again.BSS Battery Storage.pdfSterling Pro Charger D Digital.pdf

[Regulo]

Are these 4 batteries all for domestics? Can't work out why they're split into two banks? Do you have the isolator on "both" usually? 

[Vaughan]

14 hours ago, PaulN said:

On 05/12/2022 at 18:00, mikeyboy1966 said:

Linky no worky

Sorry about that. Will try loading pdf docs again.BSS Battery Storage.pdfSterling Pro Charger D Digital.pdf

Linka still no worka.

Whata mistake-a to make-a.