Is my alternator to battery charger now redundant?

dgadee

dgadee

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I have installed a Beta 20 with a 70 amp alternator and just completed test wiring up to a battery and firing today. On the old Vetus I took the output from the alternator to a Sterling Alternator to Battery Charger (this one: Sterling Power Alternator to Battery Charger 12V 80A – AB1280 – Battery Megastore). The Beta just seems to lead the alternator output to the starter positive lead.

My questions:

(1) Is the Sterling box now over spec? I had it there to increase the output from the lowish power alternator to feed start and house batteries. Do I need it on this new engine? Has alternator design moved on? The other boat (Yanmar 29hp) has a VSR and seems to be ok in terms of charging batteries.

(2) If I am to keep it, do I just take a lead to it from the starter or would the alternator have to be disconnected from the starter wiring.

I would call up Sterling but he unfortunately makes me feel like the electron fool that I am and I am none the wiser at the end of the call.

Incidentally, what a difference in noise levels! Wouldn't have thought it would have made so much difference.
 
In addition to post #2, if you did decide to fit it, you remove the connection between the alternator and starter cable and fit a new cable from the alternator to the AtoB charger.

Personally, i wouldn't fit it.
 
The alternator to battery charger has a number of advantages over the relatively dumb alternator regulator fitted to most marine engines.

These main advantages are the incorporation of a correct multi stage charging profile that will charge the house bank accurately. This is combined with an alternator temperature sensor that will reduce the chance that the alternator will suffer a hissy fit trying to charge a depleted battery.

Personally, my preference for most applications is an advanced external alternator regulator, but if you already have a alternator to battery charger there are a lot advantages incorporating this technology into your new system. The alternator to battery chargers are expensive, but if you already have this equipment and it is a suitable size for your new installation (which it is) i would certainly use it.

Sterling have some good wiring diagrams and these should be followed. If you run into problems with the installation the expertise on this forum should be able to help.
 
Last edited:
noelex said:
The alternator to battery charger has a number of advantages over the relatively dumb alternator regulator fitted to most marine engines.

These main advantages are the incorporation of a correct multi stage charging profile that will charge the house bank accurately. This is combined with an alternator temperature sensor that will reduce the chance that the alternator will suffer a hissy fit trying to charge a depleted battery.

Personally, my preference for most applications is an advanced external alternator regulator, but if you already have a alternator to battery charger there are a lot advantages incorporating this technology into your new system. The alternator to battery chargers are expensive, but if you already have this equipment and it is a suitable size for your new installation (which it is) i would certainly use it.

Sterling have some good wiring diagrams and these should be followed. If you run into problems with the installation the expertise on this forum should be able to help.
Click to expand...

There is a solar panel which keeps the house batteries fully charged when I am not onboard - that wasn't there when I installed the alternator to battery charger. Would that mean I don't really need anything sophisticated when I am onboard - just putting power into batteries for the primary user, the fridge? House batteries are (or were at purchase) 2 x 150 amps. It's not a liveaboard.
 
dgadee said:
There is a solar panel which keeps the house batteries fully charged when I am not onboard - that wasn't there when I installed the alternator to battery charger. Would that mean I don't really need anything sophisticated when I am onboard - just putting power into batteries for the primary user, the fridge? House batteries are (or were at purchase) 2 x 150 amps. It's not a liveaboard.
Click to expand...

Solar panels are great and can supply most if not all of the power consumed from the house bank in some installations. Our system is set up this way. It still helpful to have the maximium output from the alternator. This will help suppliment power when the solar panels production is inadequate.

To reliably extract the most power from a marine alternator either an extenal regulator or a alternator to battery charger is required. There are pros and cons of each of options, but if you already have a suitable alternator to battery charger it would be silly not to use this option.

With an alternator to battery charger your house bank will be charged correctly with a propper three stage algorithm even if the solar power is inadequate. In addition the alternator will be protected from a high temperature failure which can occur in some instances if the batteries are heavily depleted.
 
noelex said:
To reliably extract the most power from a marine alternator either an extenal regulator or a alternator to battery charger is required.
Click to expand...
That's confusing. With a modern alternator with regulator set to , say 14.6v ( like mine :) ) and a fairly discharged battery won't it just give all it's got until that's enough current to push the battery voltage up it 14.6v, then the battery will accept less and less current as it nears fully charged. How can an external regulator change that if set to the same 14.6v? How can it extract more power?

Seems like less reliable, another point of failure.

Going to float has been discussed in the past lots, imho it's more likely that the regulator won't know enough to fully charge the batts before switching to float. Most regulators get it wrong.
 
GHA said:
That's confusing. With a modern alternator with regulator set to , say 14.6v ( like mine :) ) and a fairly discharged battery won't it just give all it's got until that's enough current to push the battery voltage up it 14.6v, then the battery will accept less and less current as it nears fully charged. How can an external regulator change that if set to the same 14.6v? How can it extract more power?

Seems like less reliable, another point of failure.

Going to float has been discussed in the past lots, imho it's more likely that the regulator won't know enough to fully charge the batts before switching to float. Most regulators get it wrong.
Click to expand...
That's 'modern' in a 1990s way.
Modern car alternators are controlled by the ECU.

Some cruising boats do sometimes motor for 23 hours a day for several days, over charging has been known to be an issue.
As it commonly was on 90s tech cars when they were used as taxis etc with many hours running, day in, day out.

Overcharging won't happen often on most yachrs, but if it does, it's likely to be at a very awkward time.
 
How many boats are built with alternator to battery chargers ?

Are all of the Bavs, Jens, Benes suffering with flat batteries or over charged batteries as a result ?
 
Slightly OT, but hopefully still relevant. If you have a standard, 'dumb' engine alternator, and you link it up to a house battery, what actually happens when the battery is fully charged? Is there no voltage difference between alternator and battery, so it just happily sits there? Or can it overcharge? Is there case for installing an on-off switch on the positive charging cable, and if so will an alternator be damaged spinning all day whilst not linked to a circuit?
 
GHA said:
That's confusing. With a modern alternator with regulator set to , say 14.6v ( like mine :) ) and a fairly discharged battery won't it just give all it's got until that's enough current to push the battery voltage up it 14.6v, then the battery will accept less and less current as it nears fully charged. How can an external regulator change that if set to the same 14.6v? How can it extract more power?

Seems like less reliable, another point of failure.

Going to float has been discussed in the past lots, imho it's more likely that the regulator won't know enough to fully charge the batts before switching to float. Most regulators get it wrong.
Click to expand...


It is a good point that an external alternator regulator or an alternator battery charger is an added point of failure. KISS has a lot of merit on a sailboat. However, it is impossible to charge a lead acid battery bank quickly and accurately without a proper multistage charger.

The typical “dumb” alternator regulator undercharges the battery, leading to long charging times and reduced battery life. It is possible with some “dumb” alternator regulators to increase the voltage, but then when motoring with near fully charged batteries or motoring for long periods, the batteries will be overcharged, shortening their life. For most flooded lead acid batteries a single voltage set point of 14.6v is too low for rapid charging, but on the other hand if maintained for too long it will overcharge the batteries. This depends on the battery chemistry.

The answer is a proper multistage charging algorithm. This is available with either marine external alternator regulators or alternator to battery chargers. Both of these technologies accomplish a similar goal (albeit at a reasonably significant cost).

Given that Dgadde already has an alternator to battery charger installed, I would suggest it is sensible to use this with his new installation.

If programmed correctly (and external regulators or alternator to battery chargers are usually adjustable over a wide range of parameters) there is no reason why they should charge incorrectly or switch to float early.

In short, single voltage set point charging from a “dumb” alternator regulator is simple and low cost. These are valuable attributes, but this has drawbacks compared to true multistage charging available from more sophisticated devices such as external alternator regulators or alternator to battery chargers. These devices can charge the batteries more quickly without risking overcharging the batteries. At the same time they can protect the alternator from damage (by monitoring alternator temperature and progressively reducing the alternator output if the temperature becomes high).
 
TernVI said:
That's 'modern' in a 1990s way.
Modern car alternators are controlled by the ECU.

Some cruising boats do sometimes motor for 23 hours a day for several days, over charging has been known to be an issue.
As it commonly was on 90s tech cars when they were used as taxis etc with many hours running, day in, day out.

Overcharging won't happen often on most yachrs, but if it does, it's likely to be at a very awkward time.
Click to expand...

I work on some commercial boats that run all day, everyday, they never switch the engines off whilst at sea. I've never had to replace the batteries on them because they have been overcharged and despite having lots of electrical equipment onboard, they don't have A to B chargers to squeeze any extra out of the alternators.

I wonder how all of the mobo batteries survive, their engines run all of the time they are at sea too.
 
dgadee said:
I have installed a Beta 20 with a 70 amp alternator and just completed test wiring up to a battery and firing today. On the old Vetus I took the output from the alternator to a Sterling Alternator to Battery Charger (this one: Sterling Power Alternator to Battery Charger 12V 80A – AB1280 – Battery Megastore). The Beta just seems to lead the alternator output to the starter positive lead.

My questions:

(1) Is the Sterling box now over spec? I had it there to increase the output from the lowish power alternator to feed start and house batteries. Do I need it on this new engine? Has alternator design moved on? The other boat (Yanmar 29hp) has a VSR and seems to be ok in terms of charging batteries.

(2) If I am to keep it, do I just take a lead to it from the starter or would the alternator have to be disconnected from the starter wiring.

I would call up Sterling but he unfortunately makes me feel like the electron fool that I am and I am none the wiser at the end of the call.

Incidentally, what a difference in noise levels! Wouldn't have thought it would have made so much difference.
Click to expand...
In 35 years of boat ownership, both mobo and sailboat, with "dumb" alternators I have never had an overcharging problem and have always had 8 years or more from batteries so I don't believe in modifying or adding complication to the original equipment supplied which could increase the chance of failure at sea. Keep it simple.

Www.solocoastalsailing.co.uk
 
dgadee said:
Incidentally, what a difference in noise levels! Wouldn't have thought it would have made so much difference.
Click to expand...

One question I don't see asked (though Noelex did mention it in post no 5) is about the house bank, how is this charged? An engine start battery used to power a new Beta 20 is going to use sod all battery power. However, there are some advantages depending on how the engine start house bank is connected or exists at all. Since the house bank could be quite discharged after a couple of days at anchor. An alternator to battery charger could provide a 3 stage charging profile whilst limiting the alternator if it gets a bit hot. Therefore since you already have it, I would fit it.

Pete
 
Looking at the spec of the Sterling I would suggest with your setup , and because you already have the Sterling, it would be well worth installing. It will significantly improve the time taken to charge the House batteries and do it in a much more effective way than just relying on the Alternator regulator. I suspect that the wiring will require the lead from the alternator to be disconnected from the starter and fed to the Sterling but you must find the Sterling wiring diagram and follow that. The Sterling has 2 outputs, and from the description on line the charging for the start battery is a very simple output but given the start battery will do very little trying to start a new engine that really isn't an issue and it will be the charging of the house bank that will be improved. The Sterling also has temperature sensors for both batteries and alternator so it will prevent the alternator being over worked.

Hope all goes well.
Yoda
 
The simplest arrangement would be to wire the engine battery as per tyhe engine makers diagram. ie alternator to starter main wire to engine battery. The house battery then should be totally isolated except it is charged from the engine battery via AtoB charger. Assuming here AtoB charger only operates when engine is running charging engine battery. VSR if necessary but Ia ssume AtoB has one built in. ol'will
 
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