Charging regime while on shore power

pcatterall

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We are marina based and have shore power at all times.

Most of our electrics are battery powered so the shore power charges the batteries which power our equipment.
I tend to run the charger until there is 100% charge making sure that they have the last amp squeezed in.
I then switch off the charger and use the batteries down to around 60% then start the regime again.
I believe that it is better to keep the batteries working/cycling but I may be completly wrong,
what do the experts think?
I find it useful to monitor usage of the various equipment and gain confidence in the capacity available using my BM2 monitor.
 

David2452

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No, battery life is related (among other factors) to the number of cycles, assuming you have a good quality charger that will maintain as well as bulk charge better leave it connected.
 

Plevier

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Lead acid batteries like being fully charged and don't like being discharged.
You are shortening your batteries lives very significantly.

PS They don't suffer from memory effect either, not cycling them will not reduce the available capacity.
 

lw395

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There is informed opinion which says there is some merit in not continually float charging, it is good to stop charging and draw a bit of current frequently, but I think that ideally means small excursions around 99% charged.
The fewer occasions a battery is less than 95% charged the better.
Of course the advantage of the OP's regime is that he knows what his capacity is, and let's face it, milk floats run like this for years, cycling every day.
The key thing is getting the charger on as soon as possible after discharging.
 

Pye_End

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I rarely see a need to use a charger except when cruising and wanting to keep the fridge running. Otherwise, with a small solar panel they are always fully charged. With the batteries switched off they lose little before the next visit, even without a solar panel. What have you got running that takes them down to 60%?
 

pcatterall

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I rarely see a need to use a charger except when cruising and wanting to keep the fridge running. Otherwise, with a small solar panel they are always fully charged. With the batteries switched off they lose little before the next visit, even without a solar panel. What have you got running that takes them down to 60%?
Just fridge, water pump and lights.
 

Norman_E

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I have considered leaving my new Sterling Pro Charge charger connected permanently, which I never dared do with my old Waeco charger in case it failed to go down to float mode and cooked the batteries. My reason for not doing so is that it is a three output charger with two outputs linked together as recommended in the instructions, to charge three identical new house batteries. The third output charges the older starter battery. My fear is that if the older battery were to fail, and therefore never reach the voltage that causes the charger to drop into float mode it could well damage the other batteries. All that runs when the boat is left is the ultrasonic antifouling (unless the bilge pump were to run) so I leave the charger on a seven day time switch that turns it on for about 4 hours, once per week. That is easily enough to replace current used and natural self discharge without the level of charge ever falling very much, and the charger will usually drop into float mode well before it is switched off.
 

Plevier

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There is informed opinion which says there is some merit in not continually float charging, it is good to stop charging and draw a bit of current frequently, but I think that ideally means small excursions around 99% charged.
The fewer occasions a battery is less than 95% charged the better.
Of course the advantage of the OP's regime is that he knows what his capacity is, and let's face it, milk floats run like this for years, cycling every day.
The key thing is getting the charger on as soon as possible after discharging.

Milk float and other genuine traction batteries are so different from the overwhelming majority of boat batteries (even T105s although excellent are not real traction batteries) that they are not relevant to this discussion. In any case, if not cycled, they would last a lot longer than they do when cycled!
Do you have any references for your first suggestion about frequent shallow discharges? It's certainly not an idea that had any acceptance in the years I was in the battery manufacturing industry, but ideas can change.
 

Plevier

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I have considered leaving my new Sterling Pro Charge charger connected permanently, which I never dared do with my old Waeco charger in case it failed to go down to float mode and cooked the batteries. My reason for not doing so is that it is a three output charger with two outputs linked together as recommended in the instructions, to charge three identical new house batteries. The third output charges the older starter battery. My fear is that if the older battery were to fail, and therefore never reach the voltage that causes the charger to drop into float mode it could well damage the other batteries. All that runs when the boat is left is the ultrasonic antifouling (unless the bilge pump were to run) so I leave the charger on a seven day time switch that turns it on for about 4 hours, once per week. That is easily enough to replace current used and natural self discharge without the level of charge ever falling very much, and the charger will usually drop into float mode well before it is switched off.

It's not crystal clear what's best in this situation.
I certainly agree with switching the charger off when the batteries are fully charged and are totally isolated and the boat is being left.
However in your case the batteries are not isolated and are discharging - I don't know by how much in a week.
The charger's switching to float does not mean that the batteries are fully charged; it just means it has reached a state where further charging at the higher voltage will produce gas and heat but only a slow increase in state of charge, hardly any quicker than at a lower voltage (with a floor of 13.8V below which you will maintain state of charge, offsetting self discharge, but won't go to full charge.) I don't know the switching criteria that this particular charger uses, but commonly it equates to 80-90% SoC.
Reaching really full charge at 13.8V takes many hours.
So you are actually ensuring that your batteries are never fully charged.
What battery capacity do you have and how much does the a/f take?
 

concentrik

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We turn everything off when we leave the boat - shorepower, wind, solar and switch out all batteries. When we're on shorepower we have a dedicated 60A switchmode power unit which provides all our 12v items. At the same time the batteries are connected to the charger, which only 'sees' real batteries and never any parallel loads - motors, lights, instruments etc, inductive or otherwise. By the same token these 12v devices never encounter any charger-related jiggerypokery like desulfation pulses (whatever they are) no matter how beneficial they may be to the batteries. So far it has worked well. We had a battery 'cook' once on charge but it was an old one.
 

Richard10002

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Milk float and other genuine traction batteries are so different from the overwhelming majority of boat batteries (even T105s although excellent are not real traction batteries) that they are not relevant to this discussion. In any case, if not cycled, they would last a lot longer than they do when cycled!
Do you have any references for your first suggestion about frequent shallow discharges? It's certainly not an idea that had any acceptance in the years I was in the battery manufacturing industry, but ideas can change.

What makes and models are milk float genuine traction batteries?

I've just bought 4 x Trojan T105s on the basis that they are true deep cycle batteries, or at least much more able to cope than "usual leisure batteries"

I actually thought they were traction batteries... Now I'm wondering what is the difference between T105s and genuine traction?
 

VicS

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What makes and models are milk float genuine traction batteries?

They are not battery powered are they

d-horse-milkcart-19501.jpg
 

Plevier

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What makes and models are milk float genuine traction batteries?

I've just bought 4 x Trojan T105s on the basis that they are true deep cycle batteries, or at least much more able to cope than "usual leisure batteries"

I actually thought they were traction batteries... Now I'm wondering what is the difference between T105s and genuine traction?

In honesty traction battery is not a very tightly defined term (but not as loose as "leisure"!).

The best most long lived traction batteries have what are called tubular +ve plates. Instead of a pasted grid, there is a set of parallel spines surrounded by paste enclosed in polyester mesh tubes. They are big, heavy, expensive and mainly used in fork lift trucks.
image026.png


Other than that you are looking at conventional pasted flat plate construction but greatly beefed up - thicker plates with more lead framing in them. They also tend to have higher antimony content for greater plate strength at the expense of higher gassing, water loss and self discharge rate. Lead calcium is inferior here in terms of cycle life and temperature resistance.

I think I was a bit harsh and should concede that T105s are traction batteries, but at the lightest end of the scale. Their main applications are floor scrubbers and light golf type buggies (including hotels, airports, hospitals etc.) Milk float batteries would be heavier (but probably flat plate rather than tubular). Milk floats range from around 48V up to 130V or so and of course capacity required is inversely proportional to voltage.

Who makes them? All the big European manufacturers used to do them - Oldham, Exide (Chloride), Fiamm, Varta, Banner and so on, and some Eastern European stuff e.g. Balkancar in Bulgaria. I expect now you can get them from Korea, China etc but I'm not up to date. I've no doubt there are many producers in the US - some US battery makers are huge but don't export.

I can't imagine there are many sailyboats operated by forumites that would want anything bigger/heavier than T105s.
 
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