Do We Really Need Electric Posts ???

[Guest]

3 hours ago, LondonRascal said:

I am having some 'battery woes' currently. On Trixie, she has two 110Ah batteries to domestics and one 125Ah starting battery. One the face of it, that sounds plenty - but in fact she only has 55Ah of usable battery capacity. That is not a great deal when you consider that there is a fridge to power, heating, lighting, water pump and shower drain pump and that is before a TV is plugged in and so within a 24hr period you really ought to run the engine to ensure that you are not eating into more than 50% of the capacity in Lead Acid batteries.

Normally the answer would be to fit some more capacity - but with a small boat you hit the issue of where to put them, and not only that where to put them that will keep the boat 'on an even keel' and not listing. It also is easy to get carried away with number of batteries verses ability to recharge them. When you have a battery monitor installed (I think very one should hire or private) you see just how long it can take - especially that last 15% where you are putting relatively few amps in - more a 'trickle charge' to full. Without a monitor it is like a toilet tank with no gauge, you just guess and hope.

Because Trixie is not going to be a long term keeper there is not much point going 'mad' with batteries be it in number, fitting a second Alternator, or changing the chemistry of the batteries. I am going to keep it simple and hope to add an extra 110Ah (giving me 165Ah domestic capacity) and running the engine for longer to recharge them fully.  Solar Panels are not the be all and end all, but you can see how these can help a lot - especially with fridges, which on the average boat is the single highest continuous drain on the batteries. In hot weather they need to work more often to maintain a set temperature - if you can have solar power of just 2 or 3 Amps that will go a long way to taking away almost all the drain during the day the fridge will take from your domestic battery bank - and when you are not about using the fridge (e,g, it is off) will keep the batteries topped up too.

I really think now for the majority of boaters it is time to at least move up to AGM batteries - they cost more than the usual Lead Acid, may need some re-configuring of your chargers and Alternator regulators, but will last longer (more cycles) and can be discharged to a greater degree before damage is caused than standard Lead Acid batteries. You could get a Leoch branded AGM battery of 110Ah capacity for £140.00. Not bad really and are not the silly pricing of Lithium where you are looking at £1,400 for 150Ah battery (equivalent to 258Ah Lead Acid).

 

 

Really can you charge agm battery's as fast as lead acid.  Answer is no you can't which equals extend running times and that if yiu have arrived at your destination means running at the quay heading , stick to tried and trusted and proven to work .

[dnks34]

The biggest concern for me with an off grid power supply is the obvious one of battery cost/longevity. 

We have 5 x 110amp batteries and what do they last, 4/5 years if your lucky.  Its a more or less a rolling replacement of batteries.  

I always buy the most attractively priced ones so I dont feel so anoid when an expensive one lasts less time than a cheapo!

Someone may well have a nice big battery bank that will run a washing machine for the day but what will you do the day after when its flat, run your engine or plug it in!

Shore supplies make life so much simpler (and cheaper) for people who like their home comforts and I would like to see more.

 

[BrundallNavy]

During the early / late season I like to plug in where possible so I can run a small oil filled radiator and leave it on overnight without worrying something I won’t do with the diesel heater. We only have one 110 amp battery so we have to be thrifty with the power. 

[Broads01]

Interesting discussion. Ive never hired a boat with an electric hook up facility although at some stage I will and I can see the benefits of not having to run the engine. Having said that, as I tend to cruise plenty of hours, the majority of the time I find I don't need the engine and the heating and microwave work fine without, even when I need the heating on for a few hours in the evening. I do think people run engines far more than they actually need. 

I wouldn't want to be in the situation of restricting myself to moorings with electric though (which I've been surprised by on some recent threads). I like to wild moor sometimes. 

[LondonRascal]

3 hours ago, Ricardo said:

Really can you charge agm battery's as fast as lead acid.  Answer is no you can't which equals extend running times and that if yiu have arrived at your destination means running at the quay heading , stick to tried and trusted and proven to work

You are correct that AGM batteries are more sensitive to charge voltage and current - put too much in too fast and you damage them, use too much out of them and leave them in a discharged state without promptly re-charging and you damage them. They are not the quite the perfect battery some might think.

That said, they don't self discharge as much once fully charged as a standard flooded cell, and can provide more amps happily in a shorter time period than a flooded cell would - so are more suited for use where you may be using an Inverter and demanding a rather sudden, if short lived, amperage demand.

The real benefit most people see is that they generally have a longer cyclic life - I'd fit them on Trixie myself because of their advantages,  but because she has no Inverter let alone a big power demanding items, the old fashion flooded cells will suffice.

[quo vadis]

Oh

[Matt]

On Ranworth Breeze I personally will use a hook up when ever possible, we do not have an inverter, we do not have a microwave. But I like to keep the 2 x domestic & one engine start battery topped up.
We use an electric kettle & toaster the rest is 12 volt for the fridge, lights, pumps etc.
One of the issues can be that not everyone cruises enough to fully charge their batteries, on the canals they advise a minimum of 5 hours cruising per day.
Regards
Alan

Only 2 domestic batteries on RB?!


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[Meantime]

17 hours ago, ranworthbreeze said:

One of the issues can be that not everyone cruises enough to fully charge their batteries, on the canals they advise a minimum of 5 hours cruising per day.

Regards

Alan

Again the issue of cruising time is something that can be addressed to a degree through engineering. I have twin alternators on my boat which in theory means half the cruising time needed to charge any batteries.

2 x 24V banks at 110ah if discharged to 50% the advised maximum means I need to put back in 55ah to each bank, or 110ah total load. I have a 70a 24V alternator, so at reasonable revs a total of 2.5 hrs sees them topped back up again.

2 x 12V banks, one at 220ah and the other at 110ah for engine start. The engine start will be discharged very little so the main discharge will be the other bank. Again maximum advised discharge means I would need to put back in 110ah, plus a little for the engine battery. The 12V alternator is also 70a so again does the job in a little over 2.5hrs.

The above assumes the maximum discharge state. Anything less just means less time to recharge.

There are also some side benefits to twin alternators. Engines run better under a load and warm faster providing faster hot water. Even at reasonably low revs the alternators will provide a decent load on the engine if the batteries are discharged, meaning quicker hot water. If I put the invertor and immersion on, whilst running the engine I can have a full tank of hot water in about 20mins. All this is far better for the engine than running it on idle or just above when pottering up and down the Ant at 4mph, which can lead to the bores glazing.  

[vanessan]

Reading over this thread again, I have come to the conclusion that the answer to the topic question ‘do we really need electric posts???’ is - no we don’t. Had Charlie asked ‘do we really want electric posts???’ it seems to me that the answer would probably be yes. I don’t get the impression that anyone totally relies on them, cruising from post to post, rather that they find them useful in many circumstances. We all use our boats in different ways, for different purposes and for different lengths of time, the point is that we all enjoy our time afloat in a way that suits us. (Robin has proved that three times and I don’t think he’s finished yet!) Shore power is still a relatively new thing, particularly for hire boats but I get the impression that the all-singing all-dancing boats will remain popular for some time to come. 

With apologies to MauriceMynah who actually mentioned the ‘need and want’ aspect quite some time ago! 

 

[Guest]

Cruised from fisherman's burgh castle to reedham , total time 1.3 hrs all the power used last night by the inverter to run the TV for 7-8 hrs restored before I got here ,, 660 ah domestic bank ,170 ah starter battery bank all lead acid , 80ah alternator with advanced sterling regulator driven at a 2:1 ratio via a BMC 1.5 ,, what can I say it just works ,, will I be plugging in , er no absolutely no need to as solar panels will keep things topped up on this beautiful sunny day 

[vanessan]

My point exactly Ricardo - we all do things the way that suits us. This thread seems in some ways to have become something of a point scoring excercise!

[LondonRascal]

1 hour ago, vanessan said:

(Robin has proved that three times and I don’t think he’s finished yet!)

I could go on, but I won't.

This has to be a first, a woman telling me I have proved a point, but to have it in writing that I did it three times over? Well that is my life work achieved right there