Multimeter reading of 17v

[MtB]

 

Afraid so that is one of the living aboard costs charging the batteries and 6/8hrs a day is not unusual in the winter.

 

 

I have to say, this is simply not true.

 

Liveaboards who charge for 6/8 hours a day are very unusual, and those who do are a bloody nuisance to all around them.

 

(Unless by "6/8hrs a day" you actually mean 45 minutes per day )

[Chewbacka]

Lots of batteries gives you plenty of capacity for running stuff and reserve for days when you can't recharge before for the next day if you see what I mean.

The downside of having lots of batteries is that if you consistently undercharge you will destroy lots of batteries in one go which are expensive to replace.

So before buying a big bank of batteries you need to learn how to look after them including having the tools to measure (volt meter, current meter, smart gauge) and the time and equipment to recharge - shore power, engine running, generator etc.

[Jak]

I would think it totally depends on usage over evening / night how much needs to be charged next day, no?

[ditchcrawler]

I wonder how long it takes to reasonably recharge a single 110Ah battery with an engine driven alternator

[WotEver]

I wonder how long it takes to reasonably recharge a single 110Ah battery with an engine driven alternator

What's your definition of 'reasonably'?

 

If you want to get it to 80% you can probably do that in 2/3 hours. If you want to get the last 20% then another 5 hours probably.

[hackenbush]

Hi Hackenbush. I have a pair of 110ah leisure batteries. I understand that that is seruiosly minimal even for my minimal 12v lights, telly and only running fridge with the engine. And no, if you will be buying a new bank of batteries best they are same.

 

Budget means I've got no choice but to go with one battery for a while, but based on what you say I need to get up to at least 2 asap

I wonder how long it takes to reasonably recharge a single 110Ah battery with an engine driven alternator

sounds like you already know the answer

[WotEver]

 

Due to something called 'The AmpHour Law' (which isn't a law at all, just an observable fact), a battery will more or less demand a current equal to the Ah needing to be replaced. So for instance if you take a 100Ah battery at 80% SoC it will take approximately 20A charging current. At 81% SoC that drops to 19A etc.

 

You can therefore see that the more charged a battery becomes the longer it takes. That's why it's impossible to actually get a battery to 100% SoC. You can always squeeze a bit more in, it's just uneconomical to keep going.

 

Where you stop is your own judgment call of fuel and time plus wear and tear versus battery life.

[Geo]

OK, that sounds pretty awful. I'm guessing it's not a good idea to buy a new battery and connect it with the old?

 

A definite No. The bad battery will pull down and kill the new battery

[Geo]

 

Budget means I've got no choice but to go with one battery for a while, but based on what you say I need to get up to at least 2 asap

sounds like you already know the answer

 

The answer to the charging time question is that it depends on how big the alternator is, i.e. how much current it can push out into the battery. If the batteries need say 50Ahs. If the alternator only gives out 20 amp it will take longer than an alternator that will give out 50amps. Basically you would expect it to take between 6 and 8 hours to charge a battery that needed 50Ahs to the level that will give a reasonable balance between battery life and expense.

[ditchcrawler]

The reason I asked the question is how many boats do we know of that only have one domestic battery,

[Jak]

Yes. I'd understood my 2x110ah was entry level.

[Alan de Enfield]

The reason I asked the question is how many boats do we know of that only have one domestic battery,

 

Until this evening my answer would have been 'none' (now it is 'one')

[Geo]

Lots of batteries gives you plenty of capacity for running stuff and reserve for days when you can't recharge before for the next day if you see what I mean.

The downside of having lots of batteries is that if you consistently undercharge you will destroy lots of batteries in one go which are expensive to replace.

So before buying a big bank of batteries you need to learn how to look after them including having the tools to measure (volt meter, current meter, smart gauge) and the time and equipment to recharge - shore power, engine running, generator etc.

 

This ^^^^^^^^ and

 

Most important, the buckets or power (batteries) have to be filled and refilled. Batteries do not make electricity they only store the electricity that you put into them with a charger or alternator.

Edited November 27, 2016 by Geo

[WotEver]

The reason I asked the question is how many boats do we know of that only have one domestic battery,

Quite. With a reasonably large alternator it doesn't take much longer to replace 200Ah from a 400Ah bank than it does to replace 55Ah from a 110Ah bank. Maybe only an hour or two more.

 

But if you don't charge them properly it's cost you a lot more in broken batteries.

[Geo]

Quite. With a reasonably large alternator it doesn't take much longer to replace 200Ah from a 400Ah bank than it does to replace 55Ah from a 110Ah bank. Maybe only an hour or two more.

 

But if you don't charge them properly it's cost you a lot more in broken batteries.

 

With the right size of alternator dependant on the battery size those two batteries should charge within a hour of each other.

[WotEver]

 

With the right size of alternator dependant on the battery size those two batteries should charge within a hour of each other.

Absolutely.

[ditchcrawler]

 

 

But if you don't charge them properly it's cost you a lot more in broken batteries.

That is why I said reasonably charge, if I had said fully charge a third of you would have said 3 days and another third would say its impossible.

[Geo]

That is why I said reasonably charge, if I had said fully charge a third of you would have said 3 days and another third would say its impossible.

 

And those that know would have said fully charge and if you don't the battery will gradually become sulphated and die earlier than it should. The majority of battery failures are due to batteries not being fully charged and becoming sulphated. While the plates underneath the sulphate are perfectly good the charge cannot get into or out of the battery and it is dead.

[WotEver]

As I said several posts back, Charging in the winter is a compromise between battery life and engine/generator life. When you don't have Solar you have to get the batteries into the 90%+ area regularly if you want them to last at least 2 seasons. Get them into the high 90's daily and they can last you several years. Never get them above 80% and they'll be dead in a few months.

 

The choice really is that simple.

[Geo]

As I said several posts back, Charging in the winter is a compromise between battery life and engine/generator life. When you don't have Solar you have to get the batteries into the 90%+ area regularly if you want them to last at least 2 seasons. Get them into the high 90's daily and they can last you several years. Never get them above 80% and they'll be dead in a few months.

 

The choice really is that simple.

 

I would not agree from, personal experience of people who only charged into the 90% area. How do they know they are into the 90% area, well let us say it is your favourite the smartgauge. So that top 10% or so becomes sulphated, the smartgauge resets its self to a battery that only has 90% of its orginal capacity, because that is the level it is being charged to, Now the 90% is 90% of the 90% available capacity and gradually that next 10% or so becomes sulphated so the battery has lost something like 19% of its capacity due to sulphation, which by now is totally hard and immovable. And so it goes on until the battery is dead way way early, probably less than a year, could even be months in the case of a leisure battery.

 

ETA BTW the winter is what some 5/6 months of the year. I strongly suspect batteries under charged for five months or so will be very close to dead at the end of the five months.

Edited November 27, 2016 by Geo

[WotEver]

 

I would not agree...

I wouldn't expect you to. You argue just for the sake of it.

 

Nevertheless the point I made is completely valid. Charging is a balance between battery life and wear and tear and fuel usage.

 

Tony

 

Ps - I don't know why you have such an obsession with attributing an Ah counter's failings to SmartGauge. I never even mentioned a SmartGauge. What you described is what Ah counters do, which is why so many novice boaters who fit one experience terminally sulphated batteries in a few months.

 

I'm amazed that you don't know how to determine if the battery is charged above 90%. If a boater chooses to equip his boat with an ammeter then it would be the easiest thing in the world to know when he has charged to 90%+. (Please note the + that was in my post that you ignored in your reply.)

Edited November 28, 2016 by WotEver

[nicknorman]

I would not agree from, personal experience of people who only charged into the 90% area. How do they know they are into the 90% area, well let us say it is your favourite the smartgauge. So that top 10% or so becomes sulphated, the smartgauge resets its self to a battery that only has 90% of its orginal capacity, because that is the level it is being charged to, Now the 90% is 90% of the 90% available capacity and gradually that next 10% or so becomes sulphated so the battery has lost something like 19% of its capacity due to sulphation, which by now is totally hard and immovable. And so it goes on until the battery is dead way way early, probably less than a year, could even be months in the case of a leisure battery.

 

ETA BTW the winter is what some 5/6 months of the year. I strongly suspect batteries under charged for five months or so will be very close to dead at the end of the five months.

No it doesn't work like that. You don't know what you are talking about and I have to say it's a shame for OPs that on each and every such thread you repeat the same fallacious arguments ad nauseam, and drive them away.

 

http://www.canalworld.net/forums/index.php?showtopic=82022&p=1750795

Edited November 29, 2016 by Dave_P

[WotEver]

Tiresome, innit?

[alan_fincher]

Unfortunately although I'm sure most contributors to this thread are trying to be helpful, I think there has been quite a lot said in it that is either unhelpful to the OP, or isn't going to help them right now, given what they have said about their current circumstances, (including financial circumstances!).

 

Two things I would argue with, (but clearly expect to get told I am wrong!) are.....

 

I don't think anybody can prescribe what total battery capacity they actually need without knowing more than I have seen stated. I would say, (for example) a suggestion that a live-aboard must have 4 x 110AH minimum is just nonsense, and that many liveaboards who have taken the time to understand the issues manage with far less than that without problems, particularly if having only low demands, such has having all LED lights and not using a fridge in winter, (or having an LPG one), etc. Realistically you will not physically fit 5 large batteries, (I'm assuming a separate starter) in many narrow boats not designed for the purpose originally. Anyway, it doesn't matter how big the bank, you still have to find ways of putting back every amp hour you take out.

 

Several people have also repeated the commonly stated suggestion that you must not mix and match batteries of different ages in a bank, as you will have the new ones being "pulled down" by the old. However there are also many people who believe this is not true, provided we are talking only about batteries that have gone low in overall capacity, rather than actually having a shorted cell. I operated our last boat for many years using batteries in the bank of mixed ages, and those added to a bank seemed to have similar life spans to what I would have expected as if they were not connected to older batteries. On more than one occasion I separated the bank both to see if some batteries were low voltage because they were older, but also to see if current was flowing from the newer ones into the old when everything else was turned off. I could never measure any significant current, so I find it hard to see how new batteries were actively ruining old ones. It was also possible to prove, when charging, that in a bank of three batteries, each were taking a fairly equal share of the charge current. So whilst I would agree that if you have an older battery that you can't lift to a proper voltage it needs replacing, if it will actually charge to a good voltage, and deliver a share of the current, i can't see the problem with paralleling with newer ones that have an overall higher usable capacity.

 

I expect to get shot down in flames, but speak from practical experience over quite a few years of having ignored the most scaremongering statements, and having no great problems

Edited November 28, 2016 by alan_fincher

[WotEver]

I totally agree with your first point (about the number of batts required). Only an energy audit balanced with charging capacity can answer that question.

 

As for your second point, yes there is nothing wrong in principle with putting an old and new battery in parallel as long as their chemistry is the same, but there is a danger that the old battery could fail in a damaging way (soft short, cracked case for instance). If the 'old' battery is just a little down on capacity then sure, keep it in the bank; but if the battery is totally ruined (as I suspect will be the case for the OP) then there's no point. He might get a fiver from it at the scrapper and that would be a better bet than risking damaging the new battery.