A cautionary tale

[dor]

Talking to a friend tonight who was stumbling about on the back of his boat in the dark with a torch headset.....

 

He had been running his engine earlier to recharge his battery bank and happened to notice that his voltmeter was reading 15.5 volts. It seems that the cause was probably an internal short, possibly to do with the diodes, rather than a faulty regulator.

 

The alternator was a 110 amp prestolite, but the real problem was that the overcharging had caused his batteries to squirt acid into his engine bilge (trad stern). The acid has taken a lot of his hammerite paint off and he is having a real problem getting it to dry out - presumably because the water evaporates leaving conc. sulf. acid behind. I suggested he threw some bicarb in but he was not a happy bunny - especially as his boiler at home has just failed and he was hoping to stay on the boat for a few days whilst is was fixed!

 

Just out of interest - is Danboline bilge paint resistant to acid? I was surprised that the battery acid had been so effective at removing Hammerite.

[chris w]

He had been running his engine earlier to recharge his battery bank and happened to notice that his voltmeter was reading 15.5 volts. It seems that the cause was probably an internal short, possibly to do with the diodes, rather than a faulty regulator.

 

What's makes him think it's a diode problem? Why does he think it isn't a faulty regulator?

 

Chris

[Keeping Up]

There's a lot to be said for having a plastic battery box with a well-fitting lid

[dor]

What's makes him think it's a diode problem? Why does he think it isn't a faulty regulator?

 

I didn't say he thinks it is a diode problem.

 

The alternator was tested.

[Sir Nibble]

I didn't say he thinks it is a diode problem.

 

The alternator was tested.

Machine sensed unit, one field diode failed.

This is a 30p repair!

[dor]

Thanks for your input Snibble. It apparently was something to do with something shorting out internally and he has been told that the Prestolites are not repairable as there are no user-servicable parts. In your opinion would this be an easy repair if the internal damage was limited to a diode?

[Sir Nibble]

Thanks for your input Snibble. It apparently was something to do with something shorting out internally and he has been told that the Prestolites are not repairable as there are no user-servicable parts. In your opinion would this be an easy repair if the internal damage was limited to a diode?

Splutter! Choke! NO USER SERVICABLE PARTS?

Get me, a photo, part number, good description. If I can identify the type of unit I can probably talk you through a repair fairly easily. I can almost certainly get parts too.

[stuart]

Just out of interest - is Danboline bilge paint resistant to acid? I was surprised that the battery acid had been so effective at removing Hammerite.

 

 

From experience - no

[HYBRID]

Pour boiling water over the areas affected by acid, I was told this neutralises it.

[chris w]

It won't neutralise it (you need an alkali to do that like bicarb of soda) but will simply dilute the acid.

 

Chris

[Sir Nibble]

And a kettle full of boiling water is also an excellent way to shift any corrosion consequent on an acid spill. (Try it on a corroded battery terminal).

[Guest]

And a kettle full of boiling water is also an excellent way to shift any corrosion consequent on an acid spill. (Try it on a corroded battery terminal).

That was one of my tasks as an apprentice, servicing a fleet of battery forklift trucks. Cleaning terminals with boiling water was frequent.

[tidal]

For years (when I was still rebuilding landrovers or rolling them on their roofs and THEN rebuilding them) I had tins and tins of an american paint made for the aircraft industry that was totally acid proof.

It was brilliant stuff but I gave away my last quart tin to a friend with a steel ketch about 2 years ago.

 

I bet it is still out there. "Aircraft Finish Battery box paint"

 

I think in those day I spent $50 and got about 10 pints (including shipping) and it was worth every penny.

 

 

Boiling water does clean of the oxiidisation on terminals but I always carried bicarb for acid spills (even with the paint) I always disliked removing the skin from my hands when cleaning up.

 

Do NOT use it in a closed engine room though........tends (at best) to make your eyes water.

 

Seriously folks the fumes from a big spill can seriously affect your breathing

 

Also beware (those of you who go out to play in the brackish or salty bits) of geting a bucket of water from overside and washing acid spills down.

 

That really can put a crimp in your day------if not your whole life