How do you get the most of of your alternator

[geem]

if I have a 60amp alternator and I want to get 60amps out of it, what do I need to do? I have a sterling alternator regulator and 400 amp/hr of domestic battery bank all at 24v. Is possible? Main reason for asking is that as a back up to my generator I want to run the 1.5kw watermaker motor through my 3kw inverter without taking too much out of the batteries. Theoretically the alternator output is about the same as the watermaker motor load. It would be nice if the load and output balanced.

 

[lpdsn]

You'll only get maximum output when the battery voltage is very low. Doubt you'd get the theoretical 60A anyway.

If you're taking 1.5Kw out of the battery (say 25.2V X 60A with your 24V system) then your voltage will drop and the alternator output will increase, but I reckon you'd need a bigger alternator to reach a steady state.

 

[sailorman]

if I have a 60amp alternator and I want to get 60amps out of it, what do I need to do? I have a sterling alternator regulator and 400 amp/hr of domestic battery bank all at 24v. Is possible? Main reason for asking is that as a back up to my generator I want to run the 1.5kw watermaker motor through my 3kw inverter without taking too much out of the batteries. Theoretically the alternator output is about the same as the watermaker motor load. It would be nice if the load and output balanced.

Fit an Adverc, it has transformed our power generation

 

[prv]

You'll only get maximum output when the battery voltage is very low.

Or if you have a smart booster which lies to the alternator about the battery voltage.

Pete

 

[TQA]

The redneck route is to have a switch that provides battery voltage directly to the field terminal. The alternator then will be on max output at all times.

Now there are some risks to this. The alternator may overheat. 200c is about the max case temp for a modern alternator. Maybe you can fit a temp alarm. Many modern regulators have the option of a case temp sensor, maybe you can do something with that.

The drive belt will take a hammering. Watch the tension like a hawk.

Back in the 90s when lots of cruising boats had the early unreliable 'smart' regulators I fixed up several boats with a 3 way switch and a stop light bulb. This gave you charge rates which you selected manually.

WARNING Do not do this with anything other than conventional wet cell lead acid batteries.

 

[pvb]

if I have a 60amp alternator and I want to get 60amps out of it, what do I need to do? I have a sterling alternator regulator and 400 amp/hr of domestic battery bank all at 24v. Is possible? Main reason for asking is that as a back up to my generator I want to run the 1.5kw watermaker motor through my 3kw inverter without taking too much out of the batteries. Theoretically the alternator output is about the same as the watermaker motor load. It would be nice if the load and output balanced.

If you're drawing 60A from the batteries, the alternator should supply most of that, depending on engine revs. Alternator output capability increases with revs, and peak output is usually only reached at perhaps 5000rpm (alternator rpm) which perhaps equates to 3000rpm (engine rpm) depending on pulley ratios. You should be able to find an output curve for your alternator, which will show you how fast you've got to spin it to give 60A output.

 

[pvb]

Fit an Adverc, it has transformed our power generation

What, in addition to his Sterling alternator regulator, or instead of it?

 

[GHA]

if I have a 60amp alternator and I want to get 60amps out of it, what do I need to do?

Run your alternator at high enough revs so it's producing full output and have something which will accept 60A t or below the voltage the regulator is set at. Might be more engine revs than you really want though..

 

[lpdsn]

Or if you have a smart booster which lies to the alternator about the battery voltage.

Pete

Got one, it lies quite happily to the alternator, but the absolute max I've seen out of a 55A alternator is 49A (that's 49A into the battery, the alternator might've been producing more current at the lower voltage, but obviously stepping up the voltage reduces the current - if it didn't you could string a whole series of them together and power the world ).

 

[William_H]

I think OP idea is fraught with problems. Manufacturers are generally very optimistic in quoting alternator amps capability found under ideal conditions of RPM and voltage out. So for the OP I think a bigger alternator with associated drive belts etc driven at enough speed to get the required amps to run the inverter. A far better idea is a water maker pump driven directly from the engine but that may not be practical. good luck olewill

 

[geem]

I think OP idea is fraught with problems. Manufacturers are generally very optimistic in quoting alternator amps capability found under ideal conditions of RPM and voltage out. So for the OP I think a bigger alternator with associated drive belts etc driven at enough speed to get the required amps to run the inverter. A far better idea is a water maker pump driven directly from the engine but that may not be practical. good luck olewill

This is not my primary method of operating the watermaker. I am looking at what I do in the situation when my generator fails. I only really use the generator to run the watermaker. In addition to the alternator running with a smart regulator, I have 460w of solar and a wind turbine. I can cope with the batteries being depleted to some extent but I am trying to understand what is realistic from a 60 amp alternator under the situation I describe.
I intend to install a CT meter so I can see what the alternator is producing. In addition. I will install a CT meter on the inverter so I can monitor that as well.

 

[sailorman]

What, in addition to his Sterling alternator regulator, or instead of it?

Im told the Adverc is a far better bit-o-kit

 

[fisherman]

I'm told an alternator will only charge a battery to about 70% capacity without a management device. Then it's down to revs. My 40 amp only reaches 28amp, (more with batteries flat) which is the requirement to power everything in the boat, at 1100 engine revs, which is about 3000 on the alternator. Bigger alternator will make no difference, still needs the revs. Smaller pulley means more belt wear. The answer is Adverc.

 

[GHA]

I'm told an alternator will only charge a battery to about 70% capacity without a management device ................. The answer is Adverc.

Told wrong I'm afraid, for newer alternators anyway. Mine runs at 14.6v which will get to full charge just the same as a mains charger. Still takes a while with either source.

 

[halcyon]

Told wrong I'm afraid, for newer alternators anyway. Mine runs at 14.6v which will get to full charge just the same as a mains charger. Still takes a while with either source.

Not 100% nearer to 95%.

You need to monitor volts and net amps, when volts stop going up and amps or at the bottom, you have the best charge level you will get, what ever % it is. Running longer will only burn fuel, once voltage levels out, amps will fall to milliamps, so effective charge level increase.

Brian

 

[geem]

Bearing in mind I am on a 24v system. When I have run the watermaker via the inverter with the engine running I see a voltage on my batteries of 25.2v. This was before I added the Sterling regulator. if the voltage is down at 25.2v then surely I should be able to get lots of amps into a 400 amp hour (800 amp hour at 12v) battery bank? I trying to understand how hard my alternator will work. Its a 60 amp alternator at 24v (120amp at 12v) so will it get any near 60 amp under these conditions?

 

[charles_reed]

A 60 amp alternator is too small (from my experience of 11 alternator failures) for a liveaboard - external controllers like the Adverc (I've had one for 25 years, updated) will overheat the alternator and shorten battery life I've found that constant operating temperatures in excess of 140C, inevitably lead to alternator failure.
The OP should thank his lucky stars he's never getting 60 amp output from his alternator and I'd suggest not even trying.
It's difficult to ascertain whether he needs this sort of alternator output or it's wishful thinking.
If the latter I suggest he thinks about something with a greater chance of success.

Subsequent to starting the post I see a further post, shining more light on his situation - I'd suggest that everything is working OK with his 60-amp alternator and he should be giving thanks that he's not seeing more amps our of the device.
I doubt that even changing the alternator for a larger would see much greater output.

 

[pvb]

Bearing in mind I am on a 24v system. When I have run the watermaker via the inverter with the engine running I see a voltage on my batteries of 25.2v. This was before I added the Sterling regulator. if the voltage is down at 25.2v then surely I should be able to get lots of amps into a 400 amp hour (800 amp hour at 12v) battery bank? I trying to understand how hard my alternator will work. Its a 60 amp alternator at 24v (120amp at 12v) so will it get any near 60 amp under these conditions?

This raises lots of questions. First, how long were you running the watermaker with the engine running to end up with 25.2v? And was 25.2v the voltage after the engine stopped? Second, 25.2v isn't particularly low, so you may not see 60A charge, even with the Sterling regulator, but will your engine be revving fast enough for the alternator to theoretically be capable of producing 60A?

 

[RobbieW]

Bearing in mind I am on a 24v system. When I have run the watermaker via the inverter with the engine running I see a voltage on my batteries of 25.2v. This was before I added the Sterling regulator. if the voltage is down at 25.2v then surely I should be able to get lots of amps into a 400 amp hour (800 amp hour at 12v) battery bank? I trying to understand how hard my alternator will work. Its a 60 amp alternator at 24v (120amp at 12v) so will it get any near 60 amp under these conditions?

I reckon you'll get closer than most other ways. I have a 12v alternator capable of 130a, Ive experimented with running the inverter (2Kw) on various loads up to SWMBOs hairdryer (which the alternator couldnt keep up with) at about 1500w and noted an increase in output to try and match the load. If the Sterling doesnt try to current limit, cant see why it would, you should get a similar result. You'd still have to experiment with engine revs to increase output though.

 

[halcyon]

Bearing in mind I am on a 24v system. When I have run the watermaker via the inverter with the engine running I see a voltage on my batteries of 25.2v. This was before I added the Sterling regulator. if the voltage is down at 25.2v then surely I should be able to get lots of amps into a 400 amp hour (800 amp hour at 12v) battery bank? I trying to understand how hard my alternator will work. Its a 60 amp alternator at 24v (120amp at 12v) so will it get any near 60 amp under these conditions?

You need 26 volt to get any charge into flat batteries, to get reasonable recharge levels you need to see 29 volt. Putting a high load on while charging, can drop battery voltage dramatically limiting recharge.

Brian