Help! Electric problem..

[Arthur Marshall]

This possibly should be on the maintenance section, so please move it if nec, but I'm in urgent need of advice so thought I'd put it here first.

 

Broke down yesterday - stopped to pick up gas and noticed that the charging light had come on. Didn't go off when i revved, so thoguht I'd stop engine and start it up again (IT training!). No start - nothing - no reaction from the starter at all except the charging light going out when I pushed the starter buton. Then discovered that both domestic & starter batteries were flat, whcih they hadn't been when I set off (charging light had gone out normally then, 3 hours cruising). Phoned RCR, he's checked the starter and says that that has failed and had taken it away to get it refurbished. But surely that wouldn't have flattened both batteries? I had assumed initially this was an alternator problem, but again, why would both batteries be flat?

 

I get a 12v reading with the voltmeter from both batteries, but there's no power to run the water pump. Small bit of light from the flurescent lighting, but if i turn the water pump switch on that goes out. The other oddity is that the battery isolating relay clicks if I turn any domestic power on, which I would have thought it shouldn't. RCR bloke tried replacing the relay but made no diference to anything.

 

It is possible that the starter battery is too small for the engine (Lister SR2)- could that be a factor?

 

I don't know anything about the electricas really, so am flailing about in the dark - any advice? I'll try to give ay more info that i can.

[bizzard]

This possibly should be on the maintenance section, so please move it if nec, but I'm in urgent need of advice so thought I'd put it here first.

 

Broke down yesterday - stopped to pick up gas and noticed that the charging light had come on. Didn't go off when i revved, so thoguht I'd stop engine and start it up again (IT training!). No start - nothing - no reaction from the starter at all except the charging light going out when I pushed the starter buton. Then discovered that both domestic & starter batteries were flat, whcih they hadn't been when I set off (charging light had gone out normally then, 3 hours cruising). Phoned RCR, he's checked the starter and says that that has failed and had taken it away to get it refurbished. But surely that wouldn't have flattened both batteries? I had assumed initially this was an alternator problem, but again, why would both batteries be flat?

 

I get a 12v reading with the voltmeter from both batteries, but there's no power to run the water pump. Small bit of light from the flurescent lighting, but if i turn the water pump switch on that goes out. The other oddity is that the battery isolating relay clicks if I turn any domestic power on, which I would have thought it shouldn't. RCR bloke tried replacing the relay but made no diference to anything.

 

It is possible that the starter battery is too small for the engine (Lister SR2)- could that be a factor?

 

I don't know anything about the electricas really, so am flailing about in the dark - any advice? I'll try to give ay more info that i can.

Any battery from 70 amps capacity upwards in good nick and charged should start that engine. Check all the battery terminals for cleanliness and tightness,. then check alternator drive belt tension. To start with.

[Arthur Marshall]

Any battery from 70 amps capacity upwards in good nick and charged should start that engine. Check all the battery terminals for cleanliness and tightness,. then check alternator drive belt tension. To start with.

Done that - that's all OK but some of the wiring was a bit ancient and we've replaced that. What i can't understand is why both batteries have gone flat - the garage suggested a short in the alternator could have that effect? But it seems a coincicdence the starter motor dying at the same time, and I don;t trust coincidences.

[jonathanA]

don't think there is much you can do until RCR bring back your starter. once the engine is going make the RCR fella check that the start battery is being charged.

 

I don't think RCR cover domestic faults so he'll probably leave at the at point or start costing you money...

 

in the meantime i would start gathering info such as

 

1 or 2 alternators fitted.

is there a split charging system or a switch for connecting the starter/domestics together

engine type

trace the wiring from the alternators to the batteries and draw a diagram so that others can help you if there is still a problem

 

could it be you got something wrong when you'e been re-wiring ?

[bizzard]

Sounds like it could be an alternator or charging fault and probably not a starter motor fault.

[Pete & Helen]

Done that - that's all OK but some of the wiring was a bit ancient and we've replaced that. What i can't understand is why both batteries have gone flat - the garage suggested a short in the alternator could have that effect? But it seems a coincidence the starter motor dying at the same time, and I don;t trust coincidences.

I don't believe in coincidences either. nor do I think that there is anything wrong with the starter motor. What made him think that if your batteries are flat??

My money would be on the charge circuit as J above said more info would be of use. This must have been like this for a while as 3 hrs wouldn't kill your domestics and using the starter may just had enough to fire up the engine last time you started it.

Good luck hope your sorted soon

[Sir Nibble]

All the symptoms point to a failed connection on the +ve side. In fact I would bet on it and I would not be surprised if there was nothing wrong with the starter. I would suggest you let your man re fit the starter and see, if it's all good then shame on me, if it makes no difference then tell him "never mind at least you tried" and send him away. There should be no bill to pay consequent on HIS wrong diagnosis. Then get your meter and check voltage at the alternator THEN TRY THE STARTER If I am correct then you may have volts that will disappear when you try the starter. Check back down the line a bit at a time and you will almost certainly find a bad connection. The bad connection may well be at the starter itself and removing and refitting may well cure it. Visually inspect for signs of heat such as discoloured plating on terminals or melted insulation. The problem will be at a terminal and not halfway down a cable.

[Arthur Marshall]

in the meantime i would start gathering info such as

 

1 or 2 alternators fitted.

is there a split charging system or a switch for connecting the starter/domestics together

engine type

trace the wiring from the alternators to the batteries and draw a diagram so that others can help you if there is still a problem

 

could it be you got something wrong when you'e been re-wiring ?

1 alternator, split charge relay fitted, Lister SR2. Been working fine for a year and a half, which is why it's all a bit odd. I'm suspicious of the split charging relay - why should it react when I turn one of the domestic things on? I wouold have thought it should only react to the ignition switch.

Sounds like it could be an alternator or charging fault and probably not a starter motor fault.

That's what i thought, but he linked the starter up to a new battery and got no reaction.

[Laurie St Lyon]

I am no expert but my immedediate thought (from having had campers/caravans) is the alternator.

As already said above get a meter and see if it charges when you get the starter back.

 

I also think you need to check the wiring. Not only for bad conections but also for whether there is a diode or other device fitted that stops you drawing power from the starter battery for the Domestic side and vice versa. Better you have a flat domestic bank than a flat starter battery IMHO.

[Sir Nibble]

It shouldn't but that doesn't point to a bad relay, at first thought it smells of a dud earth connection. Difficult to diagnose at a distance but check those connections!

Because I've not been around for a while I will take the trouble to point this out. Hope no one thinks I'm being conceited.

35 years auto and marine electrician.

[Chalky]

If you have a spilt charge relay how is it energised? If it's off the ignition key then here's a possible scenario.

 

When you run the engine the starter and domestic batteries are both connected together. They are charged off the single alternator and both experience the same voltage / charge. When the engine is off the domestic battery only supplies the domestic loads. If there's a fault in the starter motor this will drain whatever is connected to it - if the ignition is off then it's only the started battery, if the ignition is on then it will drain both batteries. As a scenario it would fit the description you've given.

 

Ideally you want a split charge relay being energised off a voltage sensitive switch - it will only energise the coil once the starter battery is being charged by the alternator and stops this kind of issue affecting the domestics.

[Arthur Marshall]

All the symptoms point to a failed connection on the +ve side. In fact I would bet on it and I would not be surprised if there was nothing wrong with the starter. I would suggest you let your man re fit the starter and see, if it's all good then shame on me, if it makes no difference then tell him "never mind at least you tried" and send him away. There should be no bill to pay consequent on HIS wrong diagnosis. Then get your meter and check voltage at the alternator THEN TRY THE STARTER If I am correct then you may have volts that will disappear when you try the starter. Check back down the line a bit at a time and you will almost certainly find a bad connection. The bad connection may well be at the starter itself and removing and refitting may well cure it. Visually inspect for signs of heat such as discoloured plating on terminals or melted insulation. The problem will be at a terminal and not halfway down a cable.

I've got heat affected insulation on the cables going from the battery to the isolator switches, melting showing at the switch end. We've replaced all these cables. I'll see what happens when I get the starter back - no word from RCR yet. I'll print this out and take it with me when he gets back with the atarter.

But there's still the puzzle of the flat batteries?

[Pete & Helen]

It shouldn't but that doesn't point to a bad relay, at first thought it smells of a dud earth connection. Difficult to diagnose at a distance but check those connections!

Because I've not been around for a while I will take the trouble to point this out. Hope no one thinks I'm being conceited.

35 years auto and marine electrician.

I would tend to agree. The Earth is the common point and would explain a lot. A jump lead from the battery (The lead that should go to earth) to the chassis should save having to check the cable in great detail

[Arthur Marshall]

I would tend to agree. The Earth is the common point and would explain a lot. A jump lead from the battery (The lead that should go to earth) to the chassis should save having to check the cable in great detail

Did that - didn't seem to make any difference. Edited August 15, 2013 by Arthur Marshall

[Sir Nibble]

I've got heat affected insulation on the cables going from the battery to the isolator switches, melting showing at the switch end. We've replaced all these cables. I'll see what happens when I get the starter back - no word from RCR yet. I'll print this out and take it with me when he gets back with the atarter.

But there's still the puzzle of the flat batteries?

Almost certainly if there is heat damage to the connections the switch is knackered. Try byepassing that switch either by temporarily moving the cable or by holding a spanner across it whilst someone operates a water pump or something and see what happens.

[Arthur Marshall]

Almost certainly if there is heat damage to the connections the switch is knackered. Try byepassing that switch either by temporarily moving the cable or by holding a spanner across it whilst someone operates a water pump or something and see what happens.

Thanks - will do. I did wonder about the switches - they've failed before. I'll bypass them until I can get them replaced - I think they only get used when i lay the boat up for winter anyway.

PS don't know what the hell I'd do without this forum... even if people do yell at me sometimes...

Edited August 15, 2013 by Arthur Marshall

[nb Innisfree]

Check split charge relay, it could be stuck in the on position and draining all batts through faulty starter motor?

[Arthur Marshall]

One other question. The only new bit of kit I've been using is a midifile player which I've been running from a cigar lighter socket via an adapter. It uses 9 volts at 3000 ma. Is this putting too high a load on the wiring, and could it have been a cause of the overheated cables?

[kevinl]

The same thing happened to me a while ago, it (eventually) turned out to be the isolator swich had corroded and burnt out. All the symptoms were the batteries were flat but there was nothing wrong with them the or the starter motor which as here somehow got the blame. Try connecting a jump lead from the neg side of the battery to something metal and unpainted, see if it does anything, that is if like me it's negative earth and all goes through one isolator switch, just a possible.

K

[bassplayer]

One other question. The only new bit of kit I've been using is a midifile player which I've been running from a cigar lighter socket via an adapter. It uses 9 volts at 3000 ma. Is this putting too high a load on the wiring, and could it have been a cause of the overheated cables?

Definitely not unless there is a short in the wiring on the cigar lighter socket when you pushed the plug in Have you got an amp meter in circuit? That should show you if any current is being drawn. It should also help check that the batteries are being charged when the engine is running. It does sound like you have an alternator fault to me but won't be helped if your batteries are old or/and have a current leak somewhere. I hope you get it sorted soon.

[bizzard]

You could by-pass everything on the charging circuit by running a heavyish cable from the alternators main pos+ terminal direct to your engines battery's pos+ terminal pos. and connect a jump lead from the battery neg- post to the engines mass. Start the engine and set it to fast idle and put a voltmeter across between the battery's two terminals and you should get a reading of 13 volts plus and rising if the alternator is charging the battery.

[Arthur Marshall]

Many thanks to everyone for their help. RCR have just rung to say they are picking up the starter tomorrow and will be down to fix it - person I spoke to didn't know what if anything they'd done to it. I've got a printout of a load of your replies to take with me for referencem both for me and the engineer... if I'm not back here on Saturday I'm off floating down the Weaver with a working engine. Fingers crossed...

[Sir Nibble]

I've got a printout of a load of your replies to take with me for referencem both for me and the engineer

Poor sod! Been there, everyone with an internet connection becomes an expert.

[bassplayer]

Poor sod! Been there, everyone with an internet connection becomes an expert.

It's the nice side to this forum though.

[Arthur Marshall]

Poor sod! Been there, everyone with an internet connection becomes an expert.

Wouldn't dream of quoting anything directly at him - but it's given me some things to check out and suggest to look at if he doesn't think of them. He's said that he's an engineer, not an expert on electrics, so every little helps...