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Old 07-11-2014, 02:40   #1
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New Alternator Need Ext Regulator?

Hi Folks

12v refrigeration going in now. My solar panels have been able to keep up with the load so far but I'm sure I'll need more charging after the frig is hooked up. Currently have 35 amp alternator.

I'm planning on an alternator between 60 to 80 amps. My house bank is 440Ahr. Start battery is about 60 Ahr. All lead acid. The controller for the solar panels splits charging between house and the start batteries.

Do I need to do the same with the alternator output as in split the charging current? Seems with the different Ahrs the start batt will charge quickly and the house more slowly.

Is here an external regulator that does this? Is it necessary?

Would also appreciate advice on a good brand alternator.

Thanks

Brian
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Old 07-11-2014, 05:42   #2
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Re: new alternator need ext regulator?

Hi Brian,

The key issue to remember is that under normal cranking, the start battery is only slightly discharged. Yes it is putting out a lot of amps but only for seconds. So in maintaining charge in your systems the start battery just needs topping off while the house batteries will need serious charging.

The ideal solution, direct all charging directly to the house batteries and use one of the devices (ACR or automatic charge relay) that automatically connects the start battery for charging but only when the house batteries are being charged. This simplifies the system and removes the complication of split charging outputs.

This setup has a few advantages. First, you connect the charging systems directly to the house batteries (with a fuse) so there is always a load on the charger. This is particularly important with alternators that can blow the diodes if it disconnected from the batteries while charging. Second the start battery is always automatically disconnected from the system by the charging relay so it is never accidentally left connected and run down.

There are several companies that make these auto connect charge relays. The Combiner from Andina, Duocharge from Balmar, Echocharge from Xantrex, Bluseas systems makes one but I can't remember the name.
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Old 07-11-2014, 06:01   #3
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Re: new alternator need ext regulator?

To your questions about the alternator.

Not sure what's available in your part of the world. If available Balmar alternators are excellent but expensive. If these aren't available or just to pricey then look for a truck or bus alternator from a local shop. Leece Neville is an excellent, heavy duty unit. They usually come internally regulated but can be modified for an external regulator. Balmar also makes a good external regulator.

Regarding capacity I would say 60-80 amps would be the bare minimum. Most alternators are rated at max capacity and cannot really output anywhere close to that continuously. Also as the batteries charge state increases the alternator can put less charge in so higher capacity alternator to charge more initially can help reduce charge time.
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Old 07-11-2014, 06:45   #4
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Re: new alternator need ext regulator?

Re is an external regulator necessary, no, but an external smart regulator will do a far better job of charging. This will not only benefit you on a daily basis, but will be better for the batteries long term. Internal regulators are typically very simple devices designed more for just topping up start batteries.
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Old 07-11-2014, 11:45   #5
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Re: new alternator need ext regulator?

An external reg does not split the charging. It just cintrols the alt, which is still only wired to one batt. they are nice to have. But not really needed. Plus you need an ant that is external reg. you can't just add an external reg to any alt. ( without internal modification by a shop)

Sharing the charge is totally different. And needs to be done with or without external reg


There must be something there that does it now. Maybe a diode box.

There are many different ways to do it.
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Old 07-11-2014, 13:23   #6
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Re: new alternator need ext regulator?

Leave the alternator connected to the starting battery and put a Voltage Sensing Relay between the alternator out put and the house batteries. When the starting battery is recharged the VSR will then switch the alternator to charging the house batteries.

Limiting the charging current can be a bit of a problem as alternators are rated for their maximum output for only a limited time period. I have used a resistor (short length of SS bike spoke) in the cable from the VSR to the house batteries to achieve this. You need to protect it somehow as it gets pretty hot.

I have pretty well standardized on the Bosch 85 amp universal alternator and they are cheap and available pretty well anywhere. The internal regulator and brushes are in a unit fastened with two screws which can be readily removed and replaced and if you want to fit an external regulator a unit with brushes only and external connections is available.
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Old 07-11-2014, 21:09   #7
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Re: new alternator need ext regulator?

Quote:
Originally Posted by RaymondR View Post
Leave the alternator connected to the starting battery and put a Voltage Sensing Relay between the alternator out put and the house batteries. When the starting battery is recharged the VSR will then switch the alternator to charging the house batteries.
It is likely that the alternator output is connected to the starter and from there to whichever battery is selected by the position of the main battery switch, commonly 1/2/both/off.

The better choice for the alternator output is the large house bank. This bank will always be the most in need and it doesn't make sense to send the current through the start battery first. This is especially important if an external regulator is added as it will alter settings based on the sense wire that should be on the house bank.

Whether you need an external regulator may depend on how much charging you need from the engine. It will certainly add to the price.

This link may help you make your decision on an external regulator.
Musings Regarding External Regulation - SailboatOwners.com

I agree a VSR (ACR in North America) or an Echo Charge should be purchased and will take care of the start battery automatically when a charge source is present. Ideally all charge sources will go to the house bank.
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Old 09-11-2014, 01:01   #8
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Re: New Alternator Need Ext Regulator?

Thanks for the replies. Looks like I will not get an external regulator as I do not want to run my engine so long as to achieve the "float" charge. My solar panels keep the house bank around 13v. With the new refrigeration load I'll just want to boost the volts with the alternator and let the solar keep everything topped off, although the solar controller doesn't do float.

From your replies it does look like the VSR (ACR) is a good idea. I will check out the internet for a single line wiring diagram. Any suggested brands???

Many thanks

Brian
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Old 09-11-2014, 01:12   #9
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Re: New Alternator Need Ext Regulator?

Looks like a Blue Sea SI-ACR will do the trick. (?)
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Old 09-11-2014, 08:13   #10
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Re: New Alternator Need Ext Regulator?

Quote:
Originally Posted by BriRich View Post
Looks like I will not get an external regulator as I do not want to run my engine so long as to achieve the "float" charge......
Here are lots of reasons you should fit an external regulator if you can afford it and are doing some cruising, not just weekend sailing out of a marina.

1. It should have multi-stage voltage settings for different battery types.

2. It should also be custom programmable to match the alternator and battery bank sizes. There are so many ‘new’ batteries now that don’t fit the standard charging profiles. Balmar's regulators allow all charging parameters to be changed, for example they can be programmed to stay longer in the absorption stage without dropping down to float too early to get the batteries close to 100% charged.

It is worth noting that with sealed batteries most battery manufacturers recommend that you use a multi-stage regulator to drop the charge down to float mode at 13.2-13.8 volts to avoid gassing and overcharging. This is a condition of the warranty on some batteries.

3. It will delay the charge current for about a minute at start up until the engine oil is well distributed. A 100 amp alternator draws 4 HP which is a heavy load on an engine when starting with a weak battery.

4. It will also accept a sensor to measure the alternator temperature and control the charge rate. Even a 100 amp alternator could be providing 15 amps to the boat systems, another 25 amps to say a watermaker or an inverter, and then a heavily discharged bank may be demanding 50 or 60 amps. In this situation the batteries may not get charged and the alternator will overheat and burn out from continually trying to deliver its maximum output if not protected by a temperature sensor. It is too easy for the alternator on a boat to get too hot if used for long periods.

5. It will also accept a sensor to measure the battery temperature which will rise with a heavy charge current. At 25ºC batteries start to gas at 14.4v, at 40ºC they gas at 14v so the external regulator will reduce the charging voltage automatically to compensate for this. If batteries are fitted in an engine compartment it is very easy for them to get too hot and lose water. This is fatal for sealed batteries. Sailing in high temperature regions may mean the batteries are already at 30C before charging starts.

6. It will have a voltage sensor at the batteries not at the alternator. This will
compensate for split diodes or losses on cable runs to the battery and always maintain the batteries are the right charging voltage.

7. A Balmar regulator has a “small engine mode” that allows you to cut the output to 50% with a switch to reduce the alternator load on the engine when you suddenly need extra power in a big sea. It also has belt manager to reduce the load on the alternator so when set to 70% will run cooler and produce 70 amps at a lower speed.

New alternator

If you are getting a newer alternator, make sure it has the field wire accessible. This will either need a positive or negative control voltage so make sure the regulator matches the alternator. If you can afford it get a marine "hot rated" alternator, not an automotive alternator.

So why is an automotive alternator not suitable for deep cycle batteries?

A car alternator is engineered to a price - cheap - because its main job is to charge a starter battery that has been discharged by about 1%, or about 1Ah, which it can do in about 10 minutes. Then it just has to supply power to the car systems. A 60 amp alternator can happily do this job, even when it gets hot, when it's maximum output may have been reduced to about 30 amps, and it's voltage may have been reduced to less than 14 volts by the built in temperature compensation. This is why car batteries don't gas and get overcharged.

A 'hot rated Marine Alternator', like the Balmar, is 'engineered' to provide its rated output current even at a temperature of over 100 degrees C, so it will maintain that output current and voltage and so charge the bank much quicker. Faster charging is what we all want.

This 'hot rated engineering' may mean:

- High temperature diodes mounted on big heat sinks
- Heavier gauge stator windings
- precision balanced rotor
- Copper composite brushes
- Heavy duty bearings with high temperature grease
- Corrosion resistant materials & coatings
- Dual cooling fans
- access to field windings
- tachometer output
- maybe an isolated ground terminal

All this comes at a much higher price!
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Old 09-11-2014, 09:31   #11
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Re: New Alternator Need Ext Regulator?

Just installed a "6" series Balmar alternator and a matching Balma ARS-5 multi stage regulator.. Gives me double options of running off the internal regulator of the alternator for a constant charge or flipping a switch to use the "smarts" of the multi-stage unit..
Its a simple plug and play unit with little mods for mounting.. all is working aqnd working well...
What was the pain was removing all that 30 year old complex wiring of the old "Tri-" regulator.. multipule wires running everywhere......
The new install is a clean system..............................
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Old 09-11-2014, 10:07   #12
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Re: New Alternator Need Ext Regulator?

Quote:
Originally Posted by BriRich View Post
From your replies it does look like the VSR (ACR) is a good idea. I will check out the internet for a single line wiring diagram. Any suggested brands???

Many thanks

Brian
Hi Brian,

Several good brands listed at the end of post #2.
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Old 09-11-2014, 10:11   #13
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Re: New Alternator Need Ext Regulator?

Quote:
Originally Posted by BriRich View Post
Thanks for the replies. Looks like I will not get an external regulator as I do not want to run my engine so long as to achieve the "float" charge.
Sailinglegend gave an excellent answer on all the benefits. Short answer addressing your specific objection to not run the engine a long time.

An external smart regulator will allow you to put more charge in the battery during a short engine run so is beneficial even if you don't plan to run the engine for long periods.
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Old 09-11-2014, 10:22   #14
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Re: New Alternator Need Ext Regulator?

Quote:
Originally Posted by skipmac View Post
Sailinglegend gave an excellent answer on all the benefits. Short answer addressing your specific objection to not run the engine a long time.

An external smart regulator will allow you to put more charge in the battery during a short engine run so is beneficial even if you don't plan to run the engine for long periods.
Whether you have an external regulator or not a full charge will take 8+ hours with an alternator as your only charging source. An external regulator does NOT make for a faster charge if the set voltage is the same (eg 14.4 volts). As the batteries get to about 85% state of charge their internal resistance increases and whether your alternator is 35 amps or 200 amps the batteries only accept a small amount of current. This is why cruisers discharge to 50% and charge with the engine to 80-85%, using solar or wind to fully charge.

External regs advantages of belt management, temp sensors, and a float voltage if you are running for many hours under power are advantages of course, but not totally necessary.

Sailinglegend's post does make very good reasons to add external regulation if you will be using the engine to charge most of the time, but it does come at a price. $800 for a 100 amp Balmar alternator, $350 - $400 for a Balmar MC-604 regulator - probably the best available.
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Old 09-11-2014, 10:40   #15
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Re: New Alternator Need Ext Regulator?

The little Andina and similar devices to charge your start battery work great. $50
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