Fried Alternator?

[SimonP85]

I think I may have damaged my alternator (on a Beta 20hp) today by, rather stupidly, connecting the battery up the wrong way round.

There was definitely a bit of smoke coming out of the alternator and some of the insulation on one of the wires to it has melted. However, the engine started fine and no warning light lit on the control panel. I didn't have the meter with me today to check but will have a look tomorrow. Is there any chance I have got away with this? What readings should I take to see how much damage I have done? We've got two batteries with a diode splitter.

TIA

 

[VicS]

I think you will need to get your alternator checked out. Very highly likely that you have blown one or more diodes.

You may well have also blown the diode splitter,at least the side that battery was connected to.

With luck, a lotta luck, the diodes splitter burnt out first and saved the alternator rectifier.

You'll need not only to check that its is giving the correct volts output but that its is still capable of giving the full current output, which it wont if just one or two diodes are blown.

A job for your nearest auto electrician I think.

 

[SimonP85]

Hmm yes I had a feeling that might be the response! If I need to take it for repair, how easy is it to remove and then refit? Many thanks.

 

[earlybird]

[QUOTE If I need to take it for repair, how easy is it to remove and then refit? Many thanks.[/QUOTE]

Removal/replacement is straightforward if fiddly.
Based on my B622, same block as B722, and Lucas alternator:-
Remove all wires from rear of alt. remembering / photographing where they go.
Slacken top adjusting bolt, swing alt. towards block, remove belt.
Alternator pivots on 2 lugs on underside, on my engine the single pivot bolt is ~150mm long and passes through both lugs with a cylindrical spacer between them and with a nut at rear, 13mm hexagons with possibly awkward access. NB, it's possible that your set-up might have 2 shorter bolts, I don't know. Remove this/ these pivot bolt(s) and the upper adjusting bolt.
Lift off alternator,replacement by reverse procedure. Make sure no wire is likely to chafe when the engine runs.
Just thought, it might be sensible to disconnect batteries first!

 

[VicS]

Just thought, it might be sensible to disconnect batteries first!

Essential I would say. Although the diode splitter, if not shorted, should protect you.
If you need to reconnect for power on board then well insulate the main output lead if it cannot easily be disconnected at the other end as well.

 

[Stu Jackson]

Before you take the wires off the alternator, make sure the power is off. Either assure your 1-2-B switch is off, or disconnect the battery.

 

[VicS]

Before you take the wires off the alternator, make sure the power is off. Either assure your 1-2-B switch is off, or disconnect the battery.

wake up at the back there Stu ...

 

[SimonP85]

Been down again today. Definitely no output from the alternator - not a great start to the season!

Managed to remove it without too much hassle and will get it down to an auto electrician in the week - fingers crossed.

There were 5 connections to the alternator - 3 thin wires to separate terminals and 2 fairly thick cables going to the same screw terminal (one of which goes to the charge splitter and one from the wiring loom). I presume this sounds about right.

Thanks for advice.

 

[VicS]

Would have expected only one wire on the main output terminal and that going to the splitter. I wonder where the other one goes?

Three thin ones: warning light, maybe one to ignition switch if negative regulated, sensing wire if battery sensed (to go with the diode splitter),
signal to tacho from the W terminal

I'll have to look at the wiring diag.

 

[SimonP85]

Having looked at the manual on the Beta website the wiring looks as though it's correct (see page 42 of the pdf here).

It's certainly worked up till now anyway!

 

[VicS]

Yes i had a quick look at the wiring diagram yesterday evening but was not absolutely sure I had the right one, so I am now looking at the diagram on page 41 of your link as 42 is just the panel wiring diagram.

It should have been modified a bit when fitting the diode splitter.

I'd expect the alternator output to go to the common terminal of the splitter only instead of to the terminal on the starter solenoid.
Then the two batteries to be connected individually to the two output terminals of the splitter.
Id expect one battery to remain connected also to the starter solenoid, (not really shown very clearly on the diagram) with the feed still taken from there to the engine control panel (via the 40amp fuse and pin 1 of the 11 pin connector)

Id expect all the domestic services to be connected to the second battery, unless you are devotee of Nigel Calder.
If you are then I'd expect to see all the domestic services also taken from the above battery and the second retained just as a reserve battery.

No panic if all is working correctly but I think I would check out just how it is connected. From what you say it sounds as though one side of the diode splitter is possibly being bypassed.

There seems to be no provision for the alternator to be battery sensed. With adidoe splitter it should be or the batteries will be under charged due to the volts drop across the diode splitter.

You are sure you have diode splitter and not a VSR. The more I think about it the more I am think you may have a VSR not a diode splitter.

 

[halcyon]

Yes i had a quick look at the wiring diagram yesterday evening but was not absolutely sure I had the right one, so I am now looking at the diagram on page 41 of your link as 42 is just the panel wiring diagram.
.

It is also possible that the alternator charges the engine battery direct, and the service battery via the diode splitter.

Not ideal, but it will be possible to check when the alternator is sorted, and refitted simply with a voltmeter. If this is the case, then a good case to chaneg to a VSR, and gain some extra charge.

Brian

 

[SimonP85]

Thanks for the replies everyone. The smaller cable that ran off the main (B?) terminal on the alternator ran to the diode splitter, which has one output going to the domestic battery and the other to the starter. We have a Off-1-All-2 selector switch that each battery is connected to and this then runs to the engine and domestic board. I don't believe there's any type of battery voltage monitoring.

If this myterious large brown cable is also conected to the starter solenoid, could this bypass the diode and charge back through the battery selector switch? I think I'll have to give Beta a call tomorrow as it seems rather baffling. Over the last 2 season both batteries have been fine (and certainly changed by the alternator) but it just seems like an increasingly odd setup!

 

[halcyon]

Thanks for the replies everyone. The smaller cable that ran off the main (B?) terminal on the alternator ran to the diode splitter, which has one output going to the domestic battery and the other to the starter. We have a Off-1-All-2 selector switch that each battery is connected to and this then runs to the engine and domestic board. I don't believe there's any type of battery voltage monitoring.
!

What size cable goes to the splitter ?

If nothing else, it stops you doing damage to the alternator if you operate the 1, 2 both switch, with the engine running.

Brian

 

[SimonP85]

Er... possibly not very helpful but it's not huge, perhaps 5mm diameter (including insulation).

I'm guessing I've most likely damaged the diode splitter too in this process - any recommendations for a better system, perhaps a VSR?

 

[halcyon]

Er... possibly not very helpful but it's not huge, perhaps 5mm diameter (including insulation).

I'm guessing I've most likely damaged the diode splitter too in this process - any recommendations for a better system, perhaps a VSR?

As you have a 1, 2 both switch, the diode splitter is doing very little, the charge current will go via the switch. Assumming you start on bank 1 ( engine ), and switch to both or bank 2 ( service ) for charging, the diode will only provide a bleed charge to give a maintanance charge to the engine battery.

If the diode splitter is ok, and you have not had any problem for a number of years, keep it as it is, but do not connect the battery the wrong way round again.
The diode splitter you have will stop damage to the alternator if you change-over the switch, with the engine running, so a resonably safe system.

If you want to go automatic operation, keep the 1, 2 both switch, remove the service feed from the switch output, but leave the engine feed on it.

Buy a simple battery isolator, wire this to the service battery, and reconnect the service feed to the output side.

Now fit a VSR between the output terminal on the 1, 2, both switch, and the output of the isolator.

You now select 1 on the switch for engine start, and turn isolator on for service supply. If you start the engine, it will charge the service battery via the VSR when the charge voltage come up.

If you have a flat engine battery you select 2, and start from the service bank.

Not as complicated to do, as to write.

Brian

 

[SimonP85]

I've just spoken with Beta (very helpful as usual) and having looked over the wiring diagrams with them they believe that having the large brown cable (in addition to the cable going to the charge splitter) is superflous and, as suggested, will just result in charge being given to whichever battery is selected on the 1,2,both switch. With this in mind I see no reason to connect it back up to the hopefully soon to be fixed alternator!

Can anyone see any problem with this? Surely this would then mean both batteries would get an equal charge and no longer have the problem of the batteries charging via the 3 way switch?

 

[halcyon]

Can anyone see any problem with this? Surely this would then mean both batteries would get an equal charge and no longer have the problem of the batteries charging via the 3 way switch?

Yes, unless you have a battery sensed alternator, you will loose around 30% of your battery capacity. The 1, 2 both switch was by-passing the diode volt drop, and you will still need to use the switch to select the battery.

So you gaining nothing, and loosing a lot.


Brian

 

[SimonP85]

Ok I'll leave it as it was previously!

I took the damaged alternator to my local auto electrician earlier in the week and they called earlier to tell me its not repairable and that a new one would be ~£170 and that he'd then have to solder on the tacho connection. Does anyone have any other suggestions?

 

[VicS]

its not repairable

Thats tough. I'd have expected just a new diode pack , and maybe regulator would have fixed it.
Any idea what the problem is? Damaged windings?

Id have budgetted £80 or so even then.