Burning out alternators

[WotEver]

3 minutes ago, Tom and Bex said:

Our electric usage is quite low, 70-80ah a day max

Therefore absolutely no point in you having lithiums, surely?

The last paragraph in my previous post explains ‘the difference’ for more heavy users. 

[Tom and Bex]

Advantages would be much shorter charge times, and not needing to get to 100% which still takes hours of charging, even with low usage. Would only be planing for small lithium bank, using 2nd hand 210ah cells, which should give 2 days between charges, and much shorter charge time. Plus could use washing machine without running engine or generator as we currently seem to have to (cold wash setting only).

We also seem to kill batteries in about a year! Current set were new last May, and are currently down to not much more than 100ah - badged capacity should be 405ah!

[ditchcrawler]

2 minutes ago, Tom and Bex said:

Advantages would be much shorter charge times, and not needing to get to 100% which still takes hours of charging, even with low usage. Would only be planing for small lithium bank, using 2nd hand 210ah cells, which should give 2 days between charges, and much shorter charge time. Plus could use washing machine without running engine or generator as we currently seem to have to (cold wash setting only).

We also seem to kill batteries in about a year! Current set were new last May, and are currently down to not much more than 100ah - badged capacity should be 405ah!

Probably because you only charge for an hour. I use a similar amount and run for about 3 hrs.

[WotEver]

10 minutes ago, ditchcrawler said:

Probably because you only charge for an hour. I use a similar amount and run for about 3 hrs.

Which explains why they want Lithium I guess. 

[Tom and Bex]

We generally charge for 4+ hrs every 2 days, and at least an hour on days in between. Depends on solar though, not needing much additional charging now spring is finally here. Generally tail current is down to 2-3a at 14.8-15.1v when we stop charging. 

Think we killed them early on though, as followed general advice on charging sealed batteries and only charged at 14.4v. Since charging at the higher voltage they seem to have stabilised and stopped deteriorating, even improving slightly. Have mentioned this on here before.

And yes, that's why we're interested in lithiums. Fed up with hours and hours of engine/generator running with very little load, and batteries that are not fit for purpose

[MtB]

42 minutes ago, Tom and Bex said:

The example with sander and vacuum was just to demonstrate the alternators were quite happy producing 150a for 3hrs, so can't see why they won't charge lithium batteries for about an hour a day? Our electric usage is quite low, 70-80ah a day max so easily replaced in 1 hrs charging or less, yet some people insist our standard alternators will overheat and burn out if used for charging lithium batts. Just can't understand the difference.

 

I don't think there IS any difference. If you know for a fact your alternators are happy running at full chat for hours on end running a sander and vacuum cleaner, they will probably be fine running at full chat charging Litium batteries. Bear in mind doing this successfully once doesn't mean they will cope doing this every day for ever. 

The thing is, automotive alternators are not designed to run at full output indefinitely. Some will, some won't, and this is the reason for you being told it won't work. Sloppy advice really. It may or may not work, but if it does work you are still using your alternators beyond their design parameter and eating into the designed safety margin. 

 

[WotEver]

47 minutes ago, Mike the Boilerman said:

Bear in mind doing this successfully once doesn't mean they will cope doing this every day for ever. 

Which was exactly the point I was attempting to make. 

[Steve Neale]

Update on my original problem. I took the alternator into a reputable auto electric place with a view to replacing it and left it with them so they could source one with correct fittings etc.

Called in there today to be told there is nothing wrong with the alternator! They had tested it and it works fine. When I get a chance I'm going to fit it and see if it's behaving itself. Looks like I'm going to need an expert to get to the bottom of this. Thanks for the tips.

[WotEver]

1 minute ago, Steve Neale said:

Update on my original problem. I took the alternator into a reputable auto electric place with a view to replacing it and left it with them so they could source one with correct fittings etc.

Called in there today to be told there is nothing wrong with the alternator! They had tested it and it works fine. When I get a chance I'm going to fit it and see if it's behaving itself. Looks like I'm going to need an expert to get to the bottom of this. Thanks for the tips.

Can you be specific with the fault? We might be able to help (although it’s always difficult at a distance). “It’s stopped working” as per your OP doesn’t give much to go on. 

Does the ignition light come on? Does it go out? What battery monitoring do you have? Do you have a multimeter? Is it the clamp type for D.C. amps? The more you tell us the more likely we will be able to assist. 

[Steve Neale]

Ok, more info. On pre heat the alarm sounds and the warning lights come on. Once the key is turned to start, the engine turns over, fires and runs. The lights go out. On checking with the multi meter (this is our only battery monitoring) the alternator is pushing 14 volts into battery. Everything fine and dandy for a time with no problems . Then perhaps a couple of weeks later once you have started the engine you hear the pre heat alarm and see that the warning light is on. No output to the battery.

We suspect that this is a problem preceding our ownership as some months after buying the boat we twigged that the alternator wasn't working and spotted that the spade end connector to the warning light on the back of the alternator had been disconnected so there were no warning lights (and therefore it wasn't charging). 

We have one starter battery and two domestic separated by a manual switch. 

We have been told that this could be caused by turning the key to OFF before pressing the stop button, but the last time it did it, we are sure that we pressed the stop button first.

Any help would be appreciated. 

[WotEver]

Is this a Vetus engine with the multipin plug at the back of the engine? Or indeed any other engine with a multipin plug?  If so, (with engine stopped and everything off) pull the plug apart and back together a few times to clean the contacts. 

[Taslim]

^^^^ as above but don't spray it with WD40 or similar.  The plastic really dosn't like it.

Serviceol Super 10 is good.