Alternators....

[MtB]

 

I do not think fitting cheap batteries while you learn how to maximise their life is in any way crazy. far better ruin a £150 set than a £400 or more set.

 

Except that a cheap set actually costs £300 (4 x £75) and a set of Yuasa semi tractions costs about £400 and is infinitely better.

[Dave Payne]

3 x £50 for el cheapo for me.

 

So an ideal.shopping list is a smartguage, amp meter thing with shunt and a portable voltmeter.

 

Then.i can start seeing what's happening better?

[WotEver]

3 x £50 for el cheapo for me.

 

So an ideal.shopping list is a smartguage, amp meter thing with shunt and a portable voltmeter.

 

Then.i can start seeing what's happening better?

In brief I would say, in order of priority (although there's not much in it):

 

1. Ammeter or Ah counter which will give you more info.

2. SmartGauge or Voltmeter.

3. Multimeter with DC Clamp Ammeter function.

 

1. Will tell you when to stop charging.

2. Will tell you when to stop discharging, with SmartGauge being much simpler and requiring no experience to use.

3. Is useful for tracking down all sorts of gremlins.

[Tony Brooks]

I would rather say:

 

2. Will tell you when to START charging, with SmartGauge being much simpler and requiring no experience to use.

 

but it amounts to the same thing.

[alan_fincher]

14.4v doesn't significantly damage the batteries unless it is kept on 24/7. Even on a long cruise it's likely that the batteries will only just about be fully charged. So cruising for 12 hrs and then using the batteries for 12 hrs, repeat next day, isn't bad for the batteries. Having them on 14.4v 24/7/365 will shorten their life due to plate erosion, but it will take a while. Also it will cause them to gas and lose water.

 

Modern cars do tend to reduce the alternator voltage once the batteries are charged, but even without that it's pretty difficult to drive more than say 12 hours per day on a repeating basis.

 

 

 

Its not really a significant problem and the batteries don't get damaged. If they are "open" then they might loose just a little water which will need topping up from time to time. Obviously if you don't top them up then they will get very damaged.

Sealed batteries are a bit more of a risk but these most likely have calcium in their plates which reduces water loss. Car batteries will also be calcium so don't loose water. So boats and cars don't really need a float mode on the alternator. Float mode is only needed on a mains battery charger that is left on indefinitely, and most chargers go into float to soon anyway which does more harm than good on a "cruising" boat (rather than one that lives in a marina).

 

I guess that trucks that are in use for very very long hours might be a bit different, dunno if anybody builds a float capability into those.

 

.................Dave

 

To play devils advocate here, some people specialise in fairly complex boat electrical installations take a quite different view.

 

I had always gone along with the popular view that most batteries get killed by persistent undercharging, (or at least a failure to regularly get to near fully charged), but a long conversation with someone who does this as a day job managed at the time to convince me that a modern high output "standard" alternator that never reduces the voltage it is trying to charge at can actually do more damage than you might imagine.

 

His argument was that some kind of external controller is not just important to try and make the early part of the charge happen faster, but also to ensure that the current is reduced to a float charge once the batteries genuinely need no more.

 

To be clear he was talking about the situation where you have a large high output modern alternator being spun at a good speed, you cruise for many hours a day, but where you actually do not place large power demands on the battery bank, (i.e.maybe most use is all LED lighting, pumps, and limited use of electronic devices that use much current, with zero or little need for 240 volts).

 

Note I am, of course,not suggesting that more battery banks get killed by too much charging than too little, and nor of course was the person I talked with. However I think he was probably correct to suggest failure to reduce or stop charging in some situations with long cruising days might do some harm. You would not connect your battery bank to a mains charger that was not designed to eventually go into float, but many of do so with an alternator that does not have the same sophistication.

 

I have no doubt several will not dismiss any of the above as nonsense, but if so, I'm interested to hear a well constructed argument for that being the case.

[nicknorman]

To play devils advocate here, some people specialise in fairly complex boat electrical installations take a quite different view.

 

I had always gone along with the popular view that most batteries get killed by persistent undercharging, (or at least a failure to regularly get to near fully charged), but a long conversation with someone who does this as a day job managed at the time to convince me that a modern high output "standard" alternator that never reduces the voltage it is trying to charge at can actually do more damage than you might imagine.

 

His argument was that some kind of external controller is not just important to try and make the early part of the charge happen faster, but also to ensure that the current is reduced to a float charge once the batteries genuinely need no more.

 

To be clear he was talking about the situation where you have a large high output modern alternator being spun at a good speed, you cruise for many hours a day, but where you actually do not place large power demands on the battery bank, (i.e.maybe most use is all LED lighting, pumps, and limited use of electronic devices that use much current, with zero or little need for 240 volts).

 

Note I am, of course,not suggesting that more battery banks get killed by too much charging than too little, and nor of course was the person I talked with. However I think he was probably correct to suggest failure to reduce or stop charging in some situations with long cruising days might do some harm. You would not connect your battery bank to a mains charger that was not designed to eventually go into float, but many of do so with an alternator that does not have the same sophistication.

I have no doubt several will not dismiss any of the above as nonsense, but if so, I'm interested to hear a well constructed argument for that being the case.

No it isn't nonsense but it is a matter of degree. Would batteries last longer if they were never charged at 14.4v beyond when they are fully charged? Yes I'm sure they would. But how much, and to what extent do most boaters run boat engines for long periods after the batteries are fully charged? I suggest it isn't normally a significant factor.

 

It obviously is a bit of a factor for cars that generally don't use battery when parked up, use much less than 1AH to start, and then could spend 8 hours or whatever charging - this is why they have alternators controlled by the ECU that reduce the charging voltage once the battery is charged (they have a current measuring shunt on the battery terminal to monitor charging current).

 

Clearly if you had say a sea going motor launch that you regularly cruised round the clock to get to the Med or whatever, then fair enough. But for nearly all canal boaters the problem is the reverse, ie insufficient charging time rather than too much.

[WotEver]

I was about to write much the same as Nick. Certainly, if a narrowboat spends 8 hours a day every day cruising and uses very little power each day then yes it's a (minor) issue, but how many boaters fit that description? Not many, I'd suggest.

 

All LA batteries will die eventually. They will either die from sulphation or from plate corrosion. By far, the largest percentage that we hear about on here week after week are dying from sulphation due to under-charging.

 

Tony

[Señor Chris]

I was about to write much the same as Nick. Certainly, if a narrowboat spends 8 hours a day every day cruising and uses very little power each day then yes it's a (minor) issue, but how many boaters fit that description? Not many, I'd suggest.

 

 

I think it was your article that made me think it would be a problem! I can certainly see how in summer, my batteries would be charged for quite long periods with very little use overnight but as pointed out, this would be odd days rather than day after day. I'll just have to use the fridge more.

[WotEver]

 

I think it was your article that made me think it would be a problem! I can certainly see how in summer, my batteries would be charged for quite long periods with very little use overnight but as pointed out, this would be odd days rather than day after day. I'll just have to use the fridge more.

 

And if you're cruising for 8 hours, that's 16 hours that the batteries are either resting or being discharged. Not like a 24/7 battery charger, which was the focus of the article I think you;re referring to.

 

Cheers,

Tony

[dmr]

 

Except that a cheap set actually costs £300 (4 x £75) and a set of Yuasa semi tractions costs about £400 and is infinitely better.

 

Have just had a look at the data sheet for these (Yuasa).....

 

http://www.bblbatteriesonline.co.uk/product-pdf/Pro-Spec-leaflet.pdf

 

I suspect its wrong but it shows a cycle life (to 80% capacity) of only about 500 cycles with about 50% discharge, whilst Trojans and the like quote between about 1100 and 1600 cycles.

I rather suspect their graph relates to a total different battery from their range, but if its true its not good.

 

Trojans have got more expensive of late but £440 should still get a set of four.

 

...............Dave

[Mikexx]

 

Have just had a look at the data sheet for these (Yuasa).....

 

http://www.bblbatteriesonline.co.uk/product-pdf/Pro-Spec-leaflet.pdf

 

I suspect its wrong but it shows a cycle life (to 80% capacity) of only about 500 cycles with about 50% discharge, whilst Trojans and the like quote between about 1100 and 1600 cycles.

I rather suspect their graph relates to a total different battery from their range, but if its true its not good.

 

Trojans have got more expensive of late but £440 should still get a set of four.

 

...............Dave

 

 

You may be right, but my personal experience is not so clear cut. If there was a independent review of how these batteries behaved over a period of a year or 2 then I might be persuaded to pay for the name.

 

If a battery is well looked after and fully charged for most of the battery's life then that's about as good as it gets. I'd sooner get £400 of cheap leisure batteries on the basis they will have less onerous discharge and charge cycles from the increased capacity than £400 of expensive ones.