Alternators

[rickngill]

Hi

I would like some advice on our altenator, we have 3x110amh Leisure batteries and the altenator is 70 amp, but after talking to a chap at a chandlers and boat builders we were informed that we need to increase the alternator to one that supplies around 120 amps or more. Is this correct advice or will we be ok by leaving things as we are. We leave the boat an a towpath with no hook up and we start the engine every week or so and leave running for a couple of hours, but we have had a few problems of late and the batteries are less than a year old.

All advice will be gladly taken on board

Many Thanks

Rick n Gill ( Notts o Swift)

[steelaway]

It will only become an issue if you find you are running out of electrical power overnight.

If you have a small consumption and travel a few hours every day the alternator will be quite adequate.

 

Alex

[onionbargee]

The chandlers didn't sell 120 amp alternators by any chance ?

 

He's talking out of his stern gland. Don't run the engine just to charge batteries full stop.

[nicknorman]

Hi

I would like some advice on our altenator, we have 3x110amh Leisure batteries and the altenator is 70 amp, but after talking to a chap at a chandlers and boat builders we were informed that we need to increase the alternator to one that supplies around 120 amps or more. Is this correct advice or will we be ok by leaving things as we are. We leave the boat an a towpath with no hook up and we start the engine every week or so and leave running for a couple of hours, but we have had a few problems of late and the batteries are less than a year old.

All advice will be gladly taken on board

Many Thanks

Rick n Gill ( Notts o Swift)

 

With a 330 AH bank, a larger alternator would only charge at more than 70A for perhaps the first hour from around 50% state of charge. After that, the batteries can't take that much current and it will gradually decrease. So installing a larger a larger alternator is an expensive way to shave a fairly short time off the required charge time.

 

If you are having problems, it may be because 2 hours isn't enough to charge the batteries, though I'm not clear if you are using the boat during the intervening 2 weeks or whether its just left with everything switched off. If the latter the 2 hrs should be more than adequate and enlarging the alternator would definitely make no difference since you will be starting with well charged batteries. Maybe they need an equalisation charge?

[Captain Fizz]

Are you living aboard or is your boat left unattended?

If unattended, is there any electrical load?

Charge your batteries by cruising with the boat or at the very least, with the engine under some load (in gear) Diesels are not improved by being left on tickover for long periods.

[dmr]

Of course a 120 amp alternator would be better than a 70amp alternator (as long as your engine and belts can take the extra load), but a 70 amp alternator is good enough.

If you are not using the boat then an engine run once a week is fine to keep the batteries full, a small solar panel might be even better. However if you are spending time on the boat an engine run every day might be more reasonable.

 

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

 

ps unless chosen correctly a 120amp alternator might actually be worse than your 70 amp alternator!

[trackman]

We only have a single 70A alternator for 4 x 110Ah domestic batteries and a 90Ah starter.

We managed for 4 years with this setup, and our batteries all lasted for about 6 years.

However, we live aboard most of the time, and run the engine daily to charge the batteries. Most of the power goes in running our fridge, and we use very little else of significance off the 12V system. We have a Travelpower set on our engine that produces 3.5kVA of mains power for the washing machine etc.

It is possible, then, to survive with such a setup as yours, but it depends totally on what your power usage is.

Your current charging (sorry, bad pun not intended) regime sounds far from enough to keep your batteries in good heart however little power you use.

Even with our very low demands I'd say we ran our engine for at least 2 hours every day, with a longer charge, say 8 hours, every few weeks if we weren't cruising for long hours anyway.

When the boat is not in use, and all electrical items isolated, the batteries will still lose power. I think the figure is about 10% a month. This means hours of charging regularly to keep them in good stead, unless you have a mains supply and a good marine battery charger in use all the time. Remember that letting domestic batteries go below about 50% charge will damage them unless they are special, expensive deep discharge ones. I doubt yours are from your description.

We have now added some solar panels and a controller for them. This makes a big difference in summer, but much less in winter. I'd say our engine running has roughly halved in summer with 136W of panels fitted. In winter the benefit is likely to be barely noticeable though.

[Grace and Favour]

Are you living aboard or is your boat left unattended? If unattended, is there any electrical load? Charge your batteries by cruising with the boat or at the very least, with the engine under some load (in gear) Diesels are not improved by being left on tickover for long periods.

But one shouldn't leave the boat tied to a mooring running the engine in gear - should one(?)

[Tony Brooks]

 

Hi

I would like some advice on our altenator, we have 3x110amh Leisure batteries and the altenator is 70 amp, but after talking to a chap at a chandlers and boat builders we were informed that we need to increase the alternator to one that supplies around 120 amps or more. Is this correct advice or will we be ok by leaving things as we are. We leave the boat an a towpath with no hook up and we start the engine every week or so and leave running for a couple of hours, but we have had a few problems of late and the batteries are less than a year old.

All advice will be gladly taken on board

Many Thanks

Rick n Gill ( Notts o Swift)

 

 

I am fairly certain that you may have ruined you batteries by sulphation caused by undercharging.

 

I agree the chandler is talking rubbish unless he discussed your situation in great detail.

 

Initially a battery will accept a lot of charge (amps) but then it gradually reduces what it will accept so it will take many hours to fully charge the batteries. To 80% is easy and done in a few hours but from then on it takes longer and longer to get that final 20% in and over the months I suspect that 20% has sulphate a bit like compound interest so if you batteries are discharging faster than they did then I suspect you killed them.

 

In you situation you can not take Onionbargee's advice not to ever run the engine to charge the batteries. His may be a council of perfection but needs must and all that. In any case some engines are far more tolerant of long periods of running at low loads than others.

 

The best solution for you (from what you say) is probably a 40 watt plus solar array and controller. The larger the better. This will both keep the batteries well charged when you are away from the boat and also charge them up again after a time away. It will NOT provide the needs of a livaboard boater. For that you need hundreds of watts and even then it may not be enough in the winter.

 

If you intend to stick with just engine charging either accept that you will ruin batteries and carry on as you are or run the engine until the charge (amps) is less than 2% of battery capacity. I would aim for about 5 amps but it would take a very long time.

[Captain Fizz]

I didn't suggest leaving the boat whilst it is running - did I ?

[Grace and Favour]

I didn't suggest leaving the boat whilst it is running - did I ?

No you didn't suggest that

 

Neither did I

 

But CRT forbid boaters to run our engines in gear whilst moored, because it damages the canal sides

[Arthur Brown]

Two hours is NOT enough charge time. You may put the bulk charge in but you cannot put the absorption and float charge in during that time.

 

Assuming that you use no power otherwise then a 10w solar panel should maintain the starter battery and a 30w panel maintain the house battery against natural self discharge. A better solar array will cope with power used, and may assist in keeping sulphatiion at bay.

 

A cruise of probably 8 hours engine time will set you on a good state of charge. 8 hours each day for a weekend will probably cure all your battery issues -til next time! Check that the batteries have the correct electrolyte level top up when required.

[Captain Fizz]

 

No you didn't suggest that

 

Neither did I

 

But CRT forbid boaters to run our engines in gear whilst moored, because it damages the canal sides

 

 

Then I stand corrected.

However, I would like to see the evidence to support the CRT stance.

[nicknorman]

 

 

Then I stand corrected.

However, I would like to see the evidence to support the CRT stance.

Flowing water is a very powerful abrasive, all the more so to soft banks. I doubt CRT want to provide the evidence you seek by deliberately damaging a canal - its all they can do to keep them vaguely serviceable without deliberately causing damage. However, not much imagination is required to see the problem.

[dmr]

   

 

Then I stand corrected.

However, I would like to see the evidence to support the CRT stance.

If the canal has a solid or piled bank then running in gear its probably not an issue, but a soft bank is easily eroded by running in gear, if you want evidence then go and visit Bugsworth basin...it was fine when boats had a horse, now its all restored and full of boats with engines and this has undermined the banks and the rock edging has fallen in!

 

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

[bottle]

If the canal has a solid or piled bank then running in gear its probably not an issue, but a soft bank is easily eroded by running in gear, if you want evidence then go and visit Bugsworth basin...it was fine when boats had a horse, now its all restored and full of boats with engines and this has undermined the banks and the rock edging has fallen in!

 

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

 

I think it probably is.

[dor]

to the OP: My situation is not so dissimilar to yours.

Fitting a 100W solar panel and replacing the lights with LEDs has transformed my battery regime. Electric fridge probably takes 50% of usage, TV another 20%.

 

Battery voltage rarely drops below 12.5V and after a few days on the boat can return in 4 or 5 days to fully charged batteries.

 

Weekending without a solar panel is a guaranteed way to destroy batteries unless you cruise for 10 hours on the last day or have an electric hookup.

[by'eck]

 

I think it probably is.

 

Agreed - I saw a boat the other day moored against piling with engine running in gear so fast that the wash was churning up mud and throwing it into the centre of the cut. Absolutely unnecessary with an engine loaded by a good sized alternator, and a blatant waste of expensive fuel.

[vicafloat]

I have 550 amp hrs of domestic batteries and 90 amp starter battery,all charged by one 70amp alternator,which in theory would be working too

hard all the time. In practice,the batteries are trickle charged by a 30 watt solar panel when we leave the boat,usually for 10 days at a time, and the bank is fully charged when we return. The batteries are now entering the 4th year of service and are Lucas sealed (but not gel) The main drain whilst we are on board is the 12volt fridge and the reason why I need such a large battery bank is to cope with the heater cycle for my Candy Aquamat washer. There is a down side to this of course,my alternator seems to last about 4 years before requiring re-conditioning;but I regard this as more acceptable than trying to fit a second alternator within a very restricted space. The whole system is controlled by a

Smartbank and good quality relay.
I agree with Tony that your batteries are probably sulphated and I would recommend a solar panel and regulator first,then new batteries

if the charge from the solar panel does not improve matters. My little solar panel charges at 1.5amps on a good day and about

0.7amps on a dull day. I would advise buying at least 100 watts of solar power which would be ample in my experience as long as

you do not live-aboard. I rarely run my engine just to charge batteries,cruising is much more enjoyable!

[Tigerr]

On the RCR electrics course I recall being told that the load from the alternator itself often exceeds the load from the prop. Canalboats are pretty much working on unloaded deisels all the time.

[swift1894]

   

 

Then I stand corrected.

However, I would like to see the evidence to support the CRT stance.

Pity you weren't in Skipton a few years back then, when they drained the pool. You'd have seen a BIG hole in the bank where someone had been running their engine in gear whilst moored up.

You don't need the evidence, just be told by those who know something about canals!

[Cloudinspector]

If it's any help we have 4x110amp domestic and 1x90amp starter. All charged from a 90 amp alternator and 2 x 100w solar panels.

We liveaboard and spend 6 months in a marina with hook up and 6 months out on the cut. When out on the cut we run the engine for an hour each day for hot water/charging and and do a long 8hr cruise once a week.

This regime seems to work ok for us.

[OldGoat]

FWIW -

Provided you run the engine well above tickover speed - say 1100 rpm a modern plant type engine won't suffer. At tickover is not a good idea. That advice came from the manufacturer.

 

Ideally batteries should be charged at C/5 maximum for your boat that's 3 x 110 / 5 = 66 amps, so your alternator is about right.

 

What you should consider is a battery management system such as Sterling, Adverc etc. Should work out cheaper than solar panels.

 

[dor]

 

What you should consider is a battery management system such as Sterling, Adverc etc. Should work out cheaper than solar panels.

 

But a management system will only shorten the bulk phase of charging and will do nothing to get that all-important last 10% or so in. Really, all the management systems do is act as an external regulator and lift the charging voltage. If the OPs alternator is relatively new it is probably charging at 14.2V or higher so the external regulator will add little. The big advantage of solar panels is that it will give a small charge for a long time - just what is needed to get batteries up to 100% SOC. Couple that with a £15 alternator regulator off ebay that sets the alternator output to 14.4V or higher will be the most cost-effective way of extending battery life. One set of trashed batteries costs quite a bit more than a 100W solar panel.

 

What ruins the batteries of occasional or weekend users is leaving the batteries only partly charged.

[Tony Brooks]

Point of order!

 

An Adverc etc. will have no effect on the bulk charge because the design of the alternator is suppressing the voltage to below the regulated level. They will however shorten the absorption charge when they elevate the regulated voltage.

 

I have doubts if any of them will shorten the time required to get the last 10 to 20% into the batteries though because they normally shut down.