Battery charging

[Solent sailer]

hello all
i have a Mitsubishi alternator (A7TA0171B (last letter may be an E the label has been partly painted) 12v 40A), we had been having problems with our leisure batter so i fitted a Stirling regulator, this didn't seem to be having much effect, so i made further investigations and the alternator regulator puts out 14.6 volts the whole time no matter how long the engine is running, this overrides the Stirling controller.
i think this has been boiling my leisure battery and could explain why one failed early.

as the controller and brushes are all one unit i cannot disconnect the internal controller, i would like to disable it but don't want the charge alarm on my engine control panel sounding the alarm the whole time or not working at all.

any suggestions?

 

[halcyon]

hello all
i have a Mitsubishi alternator (A7TA0171B (last letter may be an E the label has been partly painted) 12v 40A), we had been having problems with our leisure batter so i fitted a Stirling regulator, this didn't seem to be having much effect, so i made further investigations and the alternator regulator puts out 14.6 volts

any suggestions?

The first thing is to sort out the problem, before making more changes.

Running at 14.6 volt regulation is not bad, unless you are motoring for 24 hours a day.

What is the problem you have with the batteries ?


Brian

 

[rob2]

I'm not up to speed on alternators myself, but it sounds as though you have a problem with the original controller. Probably the most cost-effective solution would be to take the alternator to one of the many garden shed, one man automotive repairers. Our local guy will rebuild alternators and starters for a very reasonable fee. Whilst he has it, you may as well ask him to install the extra brush wires for the Sterling controller. He may be able to test the unit with both the original controller and the Sterling unit, so you only have to refit it with the certainty that it is functioning correctly in itself.

Rob.

 

[VicS]

First question has to be to confirm what sterling regulator have you fitted.

You do mean one of the "advanced digital alternator regulators" rather than an "alternator to battery charger" ?

If so then you must have the basic alternator operating correctly before you install the Sterling regulator.

Once fitted the Sterling regulator operates in parallel with the internal one.

If the alternators own regulator is leading to an output voltage that is too high ... 14.6 ?? ... then you will not get less.

ITYWF that the Sterling does not reduce the alternator output below the level at which the internal regulator operates. It boosts it and controls it, falling back to the internal regulator at the float stage.

I would suggest, as above, that you disconnect the Sterling and sort out the basic alternator, before reconnecting the Sterling.

 

[halcyon]

If the alternators own regulator is leading to an output voltage that is too high ... 14.6 ?? ... then you will not get less.

ITYWF that the Sterling does not reduce the alternator output below the level at which the internal regulator operates. It boosts it and controls it, falling back to the internal regulator at the float stage.

I would suggest, as above, that you disconnect the Sterling and sort out the basic alternator, before reconnecting the Sterling.

But what is the OP's battery problem and how does he charge them, he could be under-charging, then discharging, thus getting sulphation and surface charge.

Which would be the same result, seeing high voltage and boiling battery, but caused by under rather than over charge.

Brian

 

[blackbeard]

Can you tell us:
capacity of battery bank
what kit is being supplied by battery bank ie lights (filament/fluorescent/LED), instruments, autopilot, 'fridge (type?) etc, and rough proportion of time that engine is running
whether you have had a problem with engine battery (which is presumbly being charged with same voltage but not discharged so much)
whether battery which failed was down on electrolyte levels (assuming not sealed)

Also - if batteries are isolated (main switch off) overnight (or longer), what volts do you see on them before main switch is switched on?

As has already been said - it doesn't necessarily follow that failure was due to over charging and it's possible that battery failed due to under charging.

A leisure battery might not be expected to have a very long life anyway. Especially if left slightly under charged.

14.6 v from the alternator (how accurate was the voltmeter?) might be a bit on the high side but not by much, and might not be a problem especially if engine is used only part of the time.

 

[Solent sailer]

The Stirling controller is the advanced digital charge controller and I fitted it to attempt to give the battery a better quality of charge, when I found the charge remained at 14.6v I disconnected the Stirling unit, as VicS said it runs in parallel to the existing alternator charge controller and only takes control when the alternator charge controller reduces it charge rate.
The problem came to light when my Leisure battery bank failed earlier than I expected at around 2 years (2x70Ah batteries), I now have one 105Ah leisure battery fitted and I think it may have been leaking electrolyte as the enclosure was wet last time I looked and very acidic. The problem really came to light when we were on passage in a flat calm to the Isles of Scilly from Poole 30 hours of continuous motoring; the battery was very charged at the end of this trip! If I had been using a battery I could top up it wouldn’t be much of a problem but these “maintenance free” batteries are a bit of a problem in that respect.
I has wondered about just fitting a new regulator to the alternator as this would probably cure the problem, but if this is a marine alternator with a boosted output (continuous high charge rate) I would be replacing one regulator with another identical one!

 

[mitiempo]

14.6 is a little high. As posted the problem is when running under power for long periods.

I think a good external 3 stage regulator would be a good addition - the alt is modified so its internal reg has no effect. The third stage in a 3 stage reg is float (13.2 - 13.4 volts) and will not boil the batteries.

Here's a link to how a Leece Neville alt is changed. It is not hard to do and if you wish any alternator shop can do it for little money.
http://www.pbase.com/mainecruising/alternator_conversion

A good external 3 stage regulator would be the Balmar MC-614.
http://www.balmar.net/PDF/regulator info s/MC-614.pdf

 

[Solent sailer]

14.6 is a little high. As posted the problem is when running under power for long periods.

I think a good external 3 stage regulator would be a good addition - the alt is modified so its internal reg has no effect. The third stage in a 3 stage reg is float (13.2 - 13.4 volts) and will not boil the batteries.

Here's a link to how a Leece Neville alt is changed. It is not hard to do and if you wish any alternator shop can do it for little money.
http://www.pbase.com/mainecruising/alternator_conversion

A good external 3 stage regulator would be the Balmar MC-614.
http://www.balmar.net/PDF/regulator info s/MC-614.pdf

i think this would be a good solution, the Stirling unit is in effect the computerised regulator and would perform this function if the existing regulator would let it. The charge controller in the alternator is very difficult to remove! i have disassembled the alternator to install the connections to the brushes for the Stirling controller and i cannot see how it could be adapted to disable/remove the controller and still have the brushes retained correctly. If i could remove it and let the Stirling controller work i would just do that, i do still want the charge alarm on the engine control panel to work.