Alternator battery charging - Which way to go?

Cardo

Cardo

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www.yacht-tinkerbell.co.uk
So, our current setup has the 60A alternator going into a split charge diode and then off to the engine and domestic battery banks. Needless to say, the domestic bank charging is pitiful, even when motoring along at a hefty set of revs.

So, some kind of device is required to keep us juiced up.
There seem to be two main types -
An advanced regulator, such as this one:
http://www.marinesuperstore.com/item/07519/sterling-alternator-regulator-pro-digital

Or this fancy A2B charger:
http://www.marinesuperstore.com/item/99197766/sterling-alternator-to-battery-charger

Now, aside from the £110 price difference, what is the actual difference between them at the end of the day?
My skills with soldering irons and stuff are good enough to fettle, so installation isn't a concern.

The advanced regulator only has one output, which then needs to go to a split charge diode. The A2B has two separate outputs. How can the former bulk charge the domestic bank whilst only applying a float voltage to the very little discharged engine battery?

If you were in my position, which would you go for?
 
You need a Sterling Advanced Alternator Controller plus a ducted fan on to the back of the alternator. A voltage sensitive relay if you have more than one bank of batteries would also save the drop in voltage associated with splitter diodes. If you just want to convert to battery sensing without boosting then an Adverc is for you.
 
Steve C Cronin said:
You need a Sterling Advanced Alternator Controller plus a ducted fan on to the back of the alternator. A voltage sensitive relay if you have more than one bank of batteries would also save the drop in voltage associated with splitter diodes. If you just want to convert to battery sensing without boosting then an Adverc is for you.
Click to expand...

I'd agree totally with Steve, about the need for a well-cooled alternator. My most recent addition (alternators die regularly, so I always carry a spare) has done away for the need for the Adverc, as its on-board controller charges at a steady 14.1 volts @ the battery. I've always fitted a larger than standard alternator, between 90 - 120 amps - tiddlers like your 60 amp one can't cope with a modern cruisers' thirst for power. I do have a conventional 3-way splitter diode, @ start the input on this is 15.1v soon dropping - there's about 0.6v drop between diode input and output.
As my system was installed over 20 years ago, I've not bothered with new fangled items like voltage-sensitive relays or a microprocessor controlled external regulator.
Incidentally, the alternator (90 amp) cost €79 at the wholesaler in Agrinio - it's a local make designed to substitute for a Yanmar Hitachi ( which 60amp variant lasted 1 season before melting - no external fan) and because of the big fan behind the pulley is larger than the Hitachi.
I also have 328w of PV panel, feeding @ 24v through a BZ500 MPPT controller. That effectively means that during the summer months in Greek waters (May, June, July) I can lie at anchor indefinitely with the computer and fridge working away happily.
Normally, on connecting to shore-power the charger never has to put in a bulk-charge, but goes happily into the absorption phase.
 
Check if your alternator will accept external control from an advanced regulator. The Hitachi alternator that came with my new Yanmar did not, so I went the Sterling A to B route.
It does take care of the starter battery separately from the domestic bank, so I ended up with a redundant VCR.
 
Cardo said:
So, our current setup has the 60A alternator going into a split charge diode and then off to the engine and domestic battery banks. Needless to say, the domestic bank charging is pitiful, even when motoring along at a hefty set of revs.

So, some kind of device is required to keep us juiced up.
There seem to be two main types -
An advanced regulator, such as this one:
http://www.marinesuperstore.com/item/07519/sterling-alternator-regulator-pro-digital

Or this fancy A2B charger:
http://www.marinesuperstore.com/item/99197766/sterling-alternator-to-battery-charger

Now, aside from the £110 price difference, what is the actual difference between them at the end of the day?
My skills with soldering irons and stuff are good enough to fettle, so installation isn't a concern.

The advanced regulator only has one output, which then needs to go to a split charge diode. The A2B has two separate outputs. How can the former bulk charge the domestic bank whilst only applying a float voltage to the very little discharged engine battery?

If you were in my position, which would you go for?
Click to expand...



A VSR as suggested already, would improve matters as it suffers no voltage drop like a diode splitter.

The diode system could be improved by making the alternator battery sensing if possible( If it is already battery sensed then I don't know why your charging is so pathetic.)


The Sterling advanced regulator will give better charging all round. It still uses a diode splitter ( or switched battery selection) but is battery sensed.
It will need a modification to the alternator!
It will deliver the same charging regime to both banks.

The Sterling AB charger will deliver enhanced charging of the house battery bank and standard charging of the starter battery.
It is a simple add-on device not requiring and modification of the alternator.

However if your current charging falls so far short of your needs a larger alternator, and possibly battery bank, may be what you really need.
 
There are variations available.
Adverc or Sterling are not the only alternator smart regulators - Merlin do one, for instance, the AMS. Installation similar/identical - with all three you need to open up the alternator and solder one extra wire in.
There is also an alternative to splitter diodes and VSRs - you can get a low/no loss splitter from Driftgate which does the job of a diode without the voltage drop.
My boat has the Merlin regulator and the Driftgate splitter installed, it has all worked faultlessly with a 60A alternator (without, incidentally, a cooling fan) for 5-6 years, maintaining a 220Ah service bank plus a 27Ah starter battery. We run a fridge 27/7 when cruising, and I am not a fan of motoring or marinas so this setup does work pretty well with maybe an hour's engine run per day.
 
Cardo said:
The A2B has two separate outputs. How can the former bulk charge the domestic bank whilst only applying a float voltage to the very little discharged engine battery?

If you were in my position, which would you go for?
Click to expand...

A battery will only take what it needs so whilst the domestic bank is charging, the charging voltage will be low enough not to overcharge the engine battery. As both reach the same state of charge, then again, neither will be overcharged.

When both are fully charged, the float voltage will be appropriate for both. If a load is now applied to either battery, the alternator will supply the current with little effect on either battery. (This applies provided both batteries are the same type (wet / agm / etc) and ideally should be the same age & make.)

Its this characteristic of LA batteries that allows multi output chargers whether mains or alternator fed to work without having to monitor and control each battery individually. So called 'multi station' mains chargers are available (used by the motor trade for simultaneously charging multiple batteries of different age, make, type and capacity) and are effectively multiple independent chargers in one casing and fed from one power supply.

I use a Sterling Digital regulator (the cheaper of the two they make) and it works fine. The A2B version is for alternators that cannot be modified or the owner doesn't want to do them or the vessel or engine is still under warranty.
 
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Cardo,
I have all inputs going to the Sterling A-B unit.

Solar and Wind Gen go through HRDi MPPT controller with output to A-B
Towed Gen will go direct (not completed installation yet)
Battery Charger 25a Cristec
Alternator 80a Hitachi
Still not got round to fitting the 2nd Alternator kit (60a standard Yanmar issue), which will also go to the A-B unit

Which is why I bought the higher input/output unit from Sterling.
The readout on the unit if easy and graphic.
The remote that goes with it is useful if you like that sort of thing. I do.
 
Cardo said:
So, our current setup has the 60A alternator going into a split charge diode and then off to the engine and domestic battery banks. Needless to say, the domestic bank charging is pitiful, even when motoring along at a hefty set of revs.
Click to expand...

Before spending money you need to sort out what your problems are.

The blocking diode will cause you big problems, take the service battery feed from it's terminal on the diode blocker and fit it on the alternator input terminal, by-passing the diode, this will allow you to see what the charge voltage is from the alternator and the charge current.

If the alternator voltage gets to 14.2 - 14.4 volt are okay and a booster is not going to do a lot.

Fitting a VSR will sort the volt drop problem, Durite do a cheap 140 amp one which allows up-rating the alternator if need be.

You now need to run the system and see if you are short of power, i.e. battery going flat quickly, if so you need to look at alternator output current and your battery bank size. You may have a battery problem due to sulphation from low re-charge levels, or the battery bank size is to small for your usage, or the available alternator output is to low.

What you cannot do is guess your problem or solution.

Brian
 
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I had the same setup and charging issues as you.

I fitted a Sterling AtoB unit, and have had fully charged batteries since.

Worth every penny and dead easy to fit.
 
Bobc said:
I had the same setup and charging issues as you.

I fitted a Sterling AtoB unit, and have had fully charged batteries since.

Worth every penny and dead easy to fit.
Click to expand...

Thanks, I too am looking at getting one. It's nice to hear a good recommendation.
 
IMHO there is NOTHING particularly SMART about these regulators. My basic Sterling regulator simply boosts the charge voltage at the battery terminals to 14.7v for precisely 1 hour and then drops the charge voltage to 13.8v (voltages for flooded batteries; different voltages for sealed or AGM). If you momentarily switch it off and back on again it simply repeats the sequence. For many years I achieved exactly the same manually by controlling the field current with a variable resistor. (OK it does also have a slow ramp-up function to avoid belt slip, but even that is not ideal).

Having said that, it is well made, neatly packaged, doesn't 'forget' and overcharge the batteries, and has proved reliable. Yes, you need to open the alternator and solder on one wire .... but that's surely a good opportunity to check the brushes, maybe grease the bearings, and generally get to know your alternator?

The much more expensive A-B devices have been developed for one reason only ...... so that people do not need to disturb their existing alternator.
 
Hi

+1 for the Driftgate which does the job of a diode without the voltage drop, the device is called an "X-split"

We have had one for 5 years, its a fix and forget device with no moving parts.

Good luck
 
As perhaps already said.. The simple option is to bypass the diodes ie a piece of wire connecting all terminals so there is no volt drop. This will prove if that is your problem. It does of course remove the isolation of the battery sytems so only for test. You could substitute switch to do the same job.(2 switches) or as said fit a VSR which will do the job automtically or fit the previously mentioned 0 volt drop splitter.
The above will give batteries the full ordinary charge voltage of the alternator regulator (about 14v or a bit less.)
To boost this for faster charging you can either replace the alternator regulator witha smart regulator which will boost charge voltage for a period until it thinks batteries are mostly charged when it reverts to normall lower voltage charging or fit the A2B type charger. This is in effect a smart charger that runs from the ships 12v system to charge domestic batteries. It has a switch mode power converter to convert 12v in to up to 15v out. (with some inefficiencies) so it sucks out more current at whatever the alternator can supply and feeds a voltage and current to the domestic battery in the smart type way to get a faster charge to the domestic battery.
My guess is that the engine battery is charged in the very ordinary way and the A2B runs off that the 2 outputs being for 2 domestic battery systems.
I would go for the alternator regulator if you are prepared to remove and add the necessary wires to the alternator.
It is all up to you as to how much money you want to spend and how badly you want to fast charge your domestic battery. good luck olewill
 
My alternator is on my list to look at this trip. Don't know if this is a good idea, but the previous owner solved the split charge question by fitting a second alternator. The original one charges the engine battery and the 140amp beast charges the 650 ah domestic batteries. No splitter required. The big one goes through a sterling regulator.

If the capacity needs increasing anyway is this a sensible solution?
 
Donheist said:
My alternator is on my list to look at this trip. Don't know if this is a good idea, but the previous owner solved the split charge question by fitting a second alternator. The original one charges the engine battery and the 140amp beast charges the 650 ah domestic batteries. No splitter required. The big one goes through a sterling regulator.

If the capacity needs increasing anyway is this a sensible solution?
Click to expand...

Two alternators is a good idea - its unlikely both would fail so its not difficult to manually connect the batteries together with a jump lead when the engine is running if one did.
The main engine is underutilised as a generator in my view - why go the expense of separate genny when a couple of large alternators can provide 2 or 3kw of mains power via an invertor as well as charge batteries...
 
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