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2 alts better than 1


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#21 Crazyhorse

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Posted 23 April 2019 - 06:31 PM

From what I understand:
Current is the only indicator of charge acceptance/ SOC whilst charging.
Bulk = increasing voltage, constant current, Absorb= constant voltage Vset decreasing current. Bulk is usually over quickly.
Time at bulk to Vset  only indicates how flat your batteries were.
240Ahr batteries at 0.01C indicator means a tail current of 2.4A for 100%.( Probably < 0.01C to holy grail!)
How long is it going to take to get your acceptance to that rate?
Otherwise you are doing a partial soc charging.
Which LA batteries don't like.
Correct me if I'm wrong.


You forget we are talking alternators. There is also a 400 watt wind turbine (more like 200w unless a cyclone is passing by) and 120w of solar panels.
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#22 Crazyhorse

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Posted 23 April 2019 - 06:34 PM

I would imagine that Yanmar would not be keen to put that much load on the front end of the crank. Unless the engine is designed to take that load, it isn't going to last long if you start swinging on the front of it.


That's the idea behind a gradual increase in power output so we don't need foot pounds of belt tention. Belt is still great (now 2 years). The alternator bearings would wear before the big end.
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#23 ricka

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Posted 23 April 2019 - 06:40 PM

Thanks IT good advice and from others ..make the best of what I have. I shall get an expert to check the volts
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#24 Crazyhorse

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Posted 23 April 2019 - 06:44 PM

This is what Balmar says about belt sizing;
 
"Ensure that the belt or belts driving the alternator are capable of handling the alternator’s horsepower load. As a rule, a single 3/8" belt is capable of supporting up to 80 amps@12 volts, and a single 1/2" belt can support 100-amp@12-volts. Dual belts will typically support alternator outputs of up to 300+ amps/12 volts. Driving an alternator on an undersized belt will substantially increase the risk of belt slippage and premature belt failure. All 24-volt Balmar alternators require a minimum of dual 1/2” belts for optimal performance. Balmar offers a wide selection of AltMount serpentine pulley kits for marine diesel engines. Visit the Balmar website for more information and application charts"
 
Not far from what I said before


All that's fine if you are running a V12 etc. This is a 18hp 2 cylinder long stroke diesel and running the alternator where we needed multi belts will overload both the alternator and engine. If the power output is kept at a controlled level where temperature is monitored and wattage slowly increased as the batteries reach a SOC where the current starts tapering off, wheres the problem in that? So far it's working very well.
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#25 lateral

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Posted 23 April 2019 - 10:02 PM

You forget we are talking alternators. There is also a 400 watt wind turbine (more like 200w unless a cyclone is passing by) and 120w of solar panels.


Better still. Instead of two alternators, just one decent one & top them up with solar and wind.

Still need shore power once in awhile for an equalize.
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#26 vesper1

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Posted 24 April 2019 - 07:03 AM

The beauty of two alternators is the redundancy offered, this is a good enough reason on it own. I've had a 120 amp alternator charging house batteries plus original Yanmar alt charging dedicated engine battery for almost 20 years and have never had a problem starting the engine. It's a simple system and 100 % redundancy you won't regret it.
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#27 wheels

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Posted 27 April 2019 - 07:36 AM

IT is correct with what he has posted.
The reason why ALTS over 85A require twin belts is for two reasons. Firstly, belts have a natural efficiency where slippage vs wear comes into the equation. The unit being driven by a belt may seem to be spinning OK, but if the load is too great, excessive wear of belt and pulley is taking place.
I get what the poster is saying re budgets etc, but one needs also to factor in the time of charging which equates to engine run time, resulting in engine wear, fuel use, noise and so on.
Then there is the charge into the battery bank. It is always best to try charging close to the charge limit of the battery type. It is not critical charging a bank with a low current, but getting a good hit stirs up the electrolyte and means you do not have to do an equalisation charge so often. Over charging is death to batteries. So do not use too large an ALT to do the work. ttt


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#28 Crazyhorse

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Posted 27 April 2019 - 08:18 AM

IT is correct with what he has posted.
The reason why ALTS over 85A require twin belts is for two reasons. Firstly, belts have a natural efficiency where slippage vs wear comes into the equation. The unit being driven by a belt may seem to be spinning OK, but if the load is too great, excessive wear of belt and pulley is taking place.
I get what the poster is saying re budgets etc, but one needs also to factor in the time of charging which equates to engine run time, resulting in engine wear, fuel use, noise and so on.
Then there is the charge into the battery bank. It is always best to try charging close to the charge limit of the battery type. It is not critical charging a bank with a low current, but getting a good hit stirs up the electrolyte and means you do not have to do an equalisation charge so often. Over charging is death to batteries. So do not use too large an ALT to do the work. ttt


All well and good when you have either no control over the alternators output (internally regulated) or your external regulator puts the alternator into full output. Belt wear will take place, slippage etc. Being able to soft start and build voltage/current means the output comes up over time, a little longer than full grunt but we are still able to get up to maximum current output within 5 minutes of starting and alternator has no slippage with a temp of less than 50deg which makes a system that will work if you know what you are doing. FLA does require a boot now and again but usually a 16v desulphating cycle. Leaving batteries uncharged for long periods and running them down below their recommended state of charge also builds sulphate on the lead.
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#29 wheels

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Posted 28 April 2019 - 06:27 AM

 

Leaving batteries uncharged for long periods and running them down below their recommended state of charge also builds sulphate on the lead.

Actually, Sulphation starts as soon as the battery drops below full charge. The speed of sulphation increases proportionally to the level of discharge. The time that the battery is left below full charge goes into the hardening of the Sulphates on the plates. Soft Sulphate can be removed during a good hard charge. But once it becomes too hard, nothing will remove it. Nothing. Not even those charging devices that say they rejuvinate the battery.


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