Battery charging issue

[Tony Brooks]

Thanks for the feed back and well done.

[ditchcrawler]

55 minutes ago, Ewan123 said:

Well, since I left that hanging I thought I'd just update with the resolution from today! A bit embarrassing really after all of that, especially as I think the answer was here all along... I think it just took me a few months to get confident poking around in there.

 

After playing with the multimeter a few times, giving up a few times, I went back to the beginning and checked the wiring connections. I think I did a lazy one when I first checked... because one connection was clearly corroded (can't seem to a upload a pic on mobile but I think this is that W connection @Tony Brooks)

 

So WD40, wire brush, scrubadubdub and all appears to be well! No fluctuation in engine revs (sound) and no bouncing needle on dial (first time I can reliably read revs on this!). The charging input now goes as expected.

 

Hoorah.

 

Thank you for all of the patient advice!

And are the batteries charging OK?

55 minutes ago, Ewan123 said:

Well, since I left that hanging I thought I'd just update with the resolution from today! A bit embarrassing really after all of that, especially as I think the answer was here all along... I think it just took me a few months to get confident poking around in there.

 

After playing with the multimeter a few times, giving up a few times, I went back to the beginning and checked the wiring connections. I think I did a lazy one when I first checked... because one connection was clearly corroded (can't seem to a upload a pic on mobile but I think this is that W connection @Tony Brooks)

 

So WD40, wire brush, scrubadubdub and all appears to be well! No fluctuation in engine revs (sound) and no bouncing needle on dial (first time I can reliably read revs on this!). The charging input now goes as expected.

 

Hoorah.

 

Thank you for all of the patient advice!

And are the batteries charging OK?

[Ewan123]

44 minutes ago, ditchcrawler said:

And are the batteries charging OK?

And are the batteries charging OK?

 

As far as I can tell from looking at the 'amps in' from a quick run this evening, time will tell, though I think the battery charging was more just the symptom that made me take heed. Need to watch a few cycles, though to be honest the solar has had them floating most days recently so it's not been a big issue anyway for a while.

Edited August 20, 2021 by Ewan123

[Ronaldo47]

A good smear of Vaseline on the contacting surfaces, as well as over them, can help prevent corrosion. Vaseline is very different from lubricating grease. Unlike lubricating grease (which is designed to stay put), Vaseline will flow readily under pressure when clamping up battery terminals and so  does not affect contact resistance.

Edited August 20, 2021 by Ronaldo47

[Tracy D'arth]

2 hours ago, Ronaldo47 said:

A good smear of Vaseline on the contacting surfaces, as well as over them, can help prevent corrosion. Vaseline is very different from lubricating grease. Unlike lubricating grease (which is designed to stay put), Vaseline will flow readily under pressure when clamping up battery terminals and so  does not affect contact resistance.

Better still if you can still find it is Holts Nocrode battery grease for terminals.When I built communication centers, the backup battery suppliers sent sachets of this stuff out with the batteries. It worked very well, many years later when the batteries were tested the connections were perfect.

[ditchcrawler]

13 minutes ago, Tracy D'arth said:

Better still if you can still find it is Holts Nocrode battery grease for terminals.When I built communication centers, the backup battery suppliers sent sachets of this stuff out with the batteries. It worked very well, many years later when the batteries were tested the connections were perfect.

We used that all the time Offshore on our batteries

[Alan de Enfield]

 

[ditchcrawler]

1 minute ago, Alan de Enfield said:

 

So, I gave the same answer to another question, is that a problem?

[Alan de Enfield]

Just now, ditchcrawler said:

So, I gave the same answer to another question, is that a problem?

 

Not at all, I posted it at the same time as you posted it - I did not know that you were going to post it - it is called 'co-incidence'.

[ditchcrawler]

20 minutes ago, Alan de Enfield said:

 

Not at all, I posted it at the same time as you posted it - I did not know that you were going to post it - it is called 'co-incidence'.

OK I thought it was in reply to me posting it and took it the wrong way, Sorry.

[Col_T]

With apologies for hijacking the thread, how does the alternator W terminal / rev counter thing actually work? Is it really as basic as a pulse per revolution, or is it more sophisticated than that?

[ditchcrawler]

18 minutes ago, Col_T said:

With apologies for hijacking the thread, how does the alternator W terminal / rev counter thing actually work? Is it really as basic as a pulse per revolution, or is it more sophisticated than that?

AC voltage taken before the rectifiers 

[Col_T]

 

4 minutes ago, ditchcrawler said:

AC voltage taken before the rectifiers 

 

Thanks for that, Brian. Unfortunately you have completely under-estimated the depth of my ignorance, for your reply makes no sense at all to me! sorry.

[Alan de Enfield]

11 minutes ago, Col_T said:

 

 

Thanks for that, Brian. Unfortunately you have completely under-estimated the depth of my ignorance, for your reply makes no sense at all to me! sorry.

 

An alternator does not make DC (battery) electricity, it makes AC (Alternating current, like in a house). The rev counter picks up the AC and measures the number of 'waves' in the AC and converts it to a RPM reading.

The AC electricity then proceeds to rectifiers to change it from AC to DC (suitable for charging a battery)

 

The process is the reverse of how an Inverter works, so the whole process is :

Engine turns over alternator

Alternator makes AC

It is changed to DC to charge the batteries

The DC is taken from the batteries and fed into an Inverter

The inverter takes the DC and converts it into 'mains' AC to power your microwave, TV etc etc.

 

And then folks wonder why there are so many energy losses between running the engine and making mains electric.

[Tony Brooks]

8 hours ago, Col_T said:

With apologies for hijacking the thread, how does the alternator W terminal / rev counter thing actually work? Is it really as basic as a pulse per revolution, or is it more sophisticated than that?

 

Most alternators are three-phase machines, that means they have three generating coils in them. Each phase produces AC at the frequency determined by the speed its turning and the number of magnetic poles on the spinning part called the rotor. As said above, the AC from each coil is passed through a pair of diodes to produce DC.

 

The W terminal connects to the phase at one diode connection, but that leaves the other diode in circuit. This produces half-wave rectified DC, so as you say, a series of pulses ranging between zero and a higher voltage. The frequency varies with speed and number of poles. So as you say just pulses but not one per revolution.

 

To get engine revs from the pulses, the rev counter has to be set for the number of poles PLUS the alternator to engine pulley ratio. Nowadays, this is done by setting the engine speed with an independent rev counter, often the strobe type, and then pushing a setting button on the alternator until it reads the correct speed. Somewhere on the forum, there are instructions on how to convert a cheap cycle speedometer into a rev counter.

 

Bet you wish you had not asked now!

 

 

[Col_T]

Thanks for that, chaps. 

 

@Tony Brooks - yup, you're right again! 😀

[Ewan123]

13 hours ago, Ronaldo47 said:

A good smear of Vaseline on the contacting surfaces, as well as over them, can help prevent corrosion. Vaseline is very different from lubricating grease. Unlike lubricating grease (which is designed to stay put), Vaseline will flow readily under pressure when clamping up battery terminals and so  does not affect contact resistance.

Thanks, I think I'll do just that.