Underperforming alternators

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neilbatcheler

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I have a catamaran with two engines to which I have just fitted two Balmar 100A alternators with Balmar ARS-5 regulators. My battery monitor tells me that the battery bank (520ah AGM) is only 60% charged yet when I start one engine (either one) the alternator / regulator only delivers 50A or so, for a short while, before tailing off over a period of an hour or so to "float" mode and 10 amps or less. This is less effective charging than the original Hitachi 60A alternators without smart regulation, so something's wrong somewhere! Balmar haven't yet responded to my email queries but then it is Christmas! Does anyone have any ideas?
 
Have you checked the voltage at the battery terminal, and at the alternator output stud ?
Sounds like your droping voltage some where, and the alternator is seeing a high voltage, and the batteries a lower voltage, hence the low charge amps. It could just be a low alternator voltage.
Check volts first.

Brian
 
Forgot to say, use a common negative point, do not measure using the earth at each end, or check for a volt drop between earths.

Brian
 
Its impossible to answer your question accurately on the basis of the desciption you have given of the system, but as a first reaction I would have thought that two 100amp alternators for that size of battery bank is way over the top. There is a ratio between battery bank size and max charge rate - I cant remember what it is at the moment and google yields no results.

You might say "so what". But the charge rate is controlled by the controller and that in turn responds to the voltage of the battery itself. So if your batteries are reasonably charged, it wouldnt matter if you put a 1000 amp alternator on the engine, it wouldnt give up any more current. I only used to use one yanmar 60 amp jobbie on a bank of the same size and never had battery problems as a result.

Anyway, what you dont know at the moment is how fully charged your batteries really are. If you let them rest for a few hours and then measure the voltage, you will get an idea. 12.7 volts equals fully charged and then your capacity meter would be wrong. 12.4 or so is half charged so your meter is right and the system isnt charging fully. At which point you check the circuitry to ensure the controllers are sensing the true battery voltage at the battery terminals and not some much higher figure at the alternator output.

Best bide your time and talk to bamar who have far more expertise than me. Meantime, your charge rates dont really surprise me.
 
Thanks for your reply. I think you're right, I'll bide my time and wait for Balmar, but to answer your query at the beginning of your reply, my understanding is that normal lead-acid batteries will happily accept up to 25% of the ah capacity in amps, i.e. 520ah would accept a chage of 130amps. In my case with AGM batteries they should accept up to 40%, i.e. 208 amps. I'm sure that my two 100A alternators will never produce anything like that anyway.
 
Thanks for that Brian. I've just checked voltage at both the alternator end and the battery terminal end and they tally exactly (currently 12.7V). I was using the negative available to me at either end though so I'll do as you suggest and use a common neg and try again.
 
The voltage is low, may be worth while letting the battery level drop a little, then run up engine and make a note of the voltages, you want to see 14.2 - 14.4 volt before regulation / cut-back. Either way the voltages will probably be needed by Bulmar.
You can just twist a length of 1 sq mm cable onto your neg probe to extend it for a quick check.

Brian
 
Besides several good points already made, also consider the battery monitor itself. You dont say what one it is, but bear in mind that they are always an estimate of charge level, and whilst that can be a very good estimate, it can also be an inaccurate one for many reasons.

Also what condition are the batteries? They may not be taking / holding as much charge as their specification due to wear and tear etc.

Anthony
 
You should do the check with the alternators running. Preferably while supplying a good current so if possible discharge the batteries a bit first or put as much load on as possible.

Doing it with no current flowing as you must have done to only get 12.7 tells you nothing. BUT if the batteries had not been on charge for say 12 hours 12.7 indicates that they are fully charged regardless of what your condition meter is saying.

(I use 12.7 = fully charged, 12.2 = half charged & 11.7= discharged but all after a 12 hour rest)
 
Anthony,

The monitor is by Mastervolt and I think it works by measuring the amp drain versus charge to work out the remaining capacity, having been initially programmed with fully charged batteries and told the capacity, 520ah.
Currently it's showing 12.7V, status 63%, ah consumed 199.
The voltage may be showing slightly higher than true as the solar panels are charging (I'm in Trinidad).
The AGM batteries are 18 months old so should be fine?
 
With either engine running the voltage gets up to over 14v pretty quickly. In order to load the system I tried running our microwave oven via the inverter while running the engine. The alternator was providing around 37A, when we turned the microwave on I expected the regulator to sense this and increase it's output but it didn't - the ammeter reading showed minus 35A, which considering that the microwave via the inverter uses about 70A would indicate that the regulator didn't respond as I thought it would, or am I being naive?

Neil.
 
Sounds like two things.

Have you reset the battery monitor total amps when the batteries were at a known state of charge? i.e. Fully charged, reset the amp monitor to the 520a as 100%. Also chekc the Peukerts constant (in the instructions), as it is different to for Lead Acid batteries I think.
If this is true, then it means your batteries are fully charged already, and therefore your alternator/regulator is working - just the monitor is not showing correct battery amp state.


Second, it seems that, like me, your battery charger/inverter circuit is behind the sensing device, and will not show correctly the ampere harge or discharge. When you are on shore power, through the battery charger, does this show as positive amps, or do you just get a reading of about 13.7/13.9v as the circuit voltage? If so, the bank amperes will also get out of synch, as the monitor wont 'see' the battery charger ampage going in.

Just a thought, and one I have been battling with myself. /forums/images/graemlins/grin.gif
 
What does the voltage do when you switch on microwave with engine running ?

May also pay to let the batteries rest over night and do a voltage check in morning, turn of solar charge and loads till you check, it could be that the meter is wrong, and you have full batteries and no fault. But your microwave reading sound odd, check volts.

Brian
 
Hi. Can't remember the Peukerts thingummy but the battery monitor was reset to the new battery capacity when the batteries were replaced so should be correct. When on shore power (not often!) with the Mastervolt 80A battery charger running, the monitor will show the amps going in, often the full 80 amps for a short while before dropping down through the various stages - bulk, absorption, float. The monitor also appeared accurate with the original alternators, and the "Ah consumed" figure will drop as the charge goes in. So I have no reason to think the monitor isn't functioning, more's the pity!
 
In which case, with main batteries at 12.7 volts, your charge monitor thingy needs re-setting to 100%.

If it measures amp hours in and out, you must have to set both the total capacity and also the state of the battery when starting the monitor off. I dont know what you have run whilst connecting the new kit, but you may well have disturbed that base setting.
 
A battery charge monitor can drift out of synch over a period of time regardless of how accurately it has been set up. Some are worse than others - mine is terrible! You should re-set it from time to time. The Link 10 will re-set itself to read full if it detects a voltage over 13 and a current of less than 1% of the bank size for 10 minutes (figures approx as I haven't got the manual to hand). If yours hasn't got an automatic reset you should do it by hand.

It sounds as though you are expecting too much in the way of current into a charged battery. I have 330AH of battery and 2x55A alternators. I would expect 110A if the batteries were totally flat but as I never let them go below 50% I seldom see more than 30A on the ammeter.
 
Aha! Well despite the fact that this is going to make me look pretty stupid, I'll tell you what the problem was...having stated that my meter was correct and that the batteries were down around 200ah and should therefore be demanding more from the alternator, it would appear that I was wrong! We turned off all power sources (solar and wind), turned the fridge up, left a few lights on and went to bed. In the morning the battery voltage was down to around 12.4V, and on starting one engine the alternator was producing 65A, the highest yet seen. The other engine on it's own produced about the same, although with both running together there was no real difference. The microwave issue is still a bit odd though, running it through the inverter and one engine still results in minus 40A or so, although running both engines brings it up to +40A. The voltage drops to around 12.3V when running the microwave.
Further, having done a voltage drop test across both the negative and positive sides of each alternator/battery bank, it seems I have a drop of around 1v on the negative side - very bad according to Mr Calder. Cable sizes are fine so must be poor connections somewhere, that's tomorrow's job...
We're hauling the boat in a few days so will have mains power and can therefore fully charge the battery bank and recalibrate the Mastervolt meter.
Many thanks for everybody's help and opinions, and a very Happy New Year to you all!
 
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