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Old 23-12-2013, 10:16   #31
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Re: Battery configuration

Quote:
Originally Posted by Charliemciver View Post
Hi, thanks for all comments so far.

I prb should have made 3 points clearer in my original post:

1) the two bow thruster batteries are currently at the front of the boat (rest at the back-ish). The previous owner didn't have them wired to the domestic bank (though it was clearly intended. not sure why. there is evidence of something going quite wrong and it being dismantled, and hence no charging currently). There is substantial cabling that goes between the front and the back of the boat already to make this join, so reconnecting it is easy. Bizarrely the switch gear for the windlass is mid-ship with the intended battery at the back. Moving the switch gear forward and sharing the 2 bow thruster batteries for the windlass is doable relatively easily - I have no idea why they put the windlass battery at the back. It only makes sense to me if they needed the capacity of a 3rd battery on the bow thruster /windlass. Which in the UK seems less likely than the med, say.

2) I currently have a 115A alternator so it can charge reasonably hard.

Yes, but you don't want to run it at full output for long. Best to de-rate them by about 20-25% in order to prevent overheating and burnout of the diodes.

3) I was proposing 3 banks (not 4) - ie starter x 1, domestic x 3, and then a combined windlass/bow thruster set x2

That will work just fine.

Maybe I can ask a few more questions to help clarify what I am learning from this and maybe my questions expose my understanding which may need 'adjusting'


People have criticised AGM batteries because they don't like a 'hard charge' from the alternator (ie when Alex uses on bow thruster and only engine charges). So this would be the case when out at sea for a few days and after some hard domestic use and we fire the engine up.... So should I discern from this that AGM is only good if you back in port super regularly and hooked up to the shore-power so the fancy charger used?

AGM batteries need to be fully charged frequently, and it takes quite a few hours to reach a truly full charge, no matter how much charging capacity you have. Your intended use for the thruster and windlass is just fine, provided you can find a way to fully charge them frequently. I have just such a setup....two golf-cart batteries in the forward cabin (225AH) with short cables to the windlass. The breaker is located right beside them. This works very well. I have a dedicated smart charger (Iota DLS-55/IQ4) also in the forward cabin which runs 24/7 at dockside, and which is powered from my AC generator when on trips.

People seem to worry about using sealed marine batteries for starter use.... Not enough CCA vs a basic flooded lead acid I guess. Yet I hear a Diesel engine is a light start load and hence doesn't need much charging ?

A diesel draws LOTS of amps while actually starting -- sometimes 150-200 amps or more -- but only for a few seconds. If you figure out how much energy that actually takes out of the battery, it's typically less than 1 AH.

So why is sealed marine battery with lower CCA bad here? Surely if the load isn't bad, marine battery is better as the CCA will be lower but adequate and the overall capacity (RC?) is higher which will give you a longer ability to start?

Sealed batteries are marginally OK. They just don't seem to last as long as regular flooded batteries. And, there's no way to check the level of the electrolyte, and if some gets boiled off there's no way to replace it.

Re golf car batteries - what are they inside? I don't need war and peace - short explanation is fine.

Six-volt golf-cart batteries -- so-called because they're basically designed to power electric golf-carts -- are true deep-cycle batteries. They have thicker plates than do most 12 volt batteries. They're great for boats because they're rugged, take abuse pretty well, and weigh only about 60-70 pounds apiece, so they won't break your back like a 4D or 8D or other large battery. Two of them in series will give about 225-250AH at the 20-hour discharge rate. Great for house batteries. Can also be used for starting if necessary. They're ubiquitous around the world, and are relatively lower cost.

Really appreciate everyone's comments.

I'll look into SWR meter - I've just fitted AIS with an antenna sharer and have a ham radio background too, so this is familiar turf. I have my SWR meter ready to test my own system this week

Good for you! What's your callsign? Mine is WA6CCA. Among other things, I install SSBs on boats. In my opinion, EVERY SSB installation should have a cross-needle power/swr meter installed in-line all the time.

Merry Xmas everyone. Blowing a gale here in south UK today!

Merry Xmas to you; hope the New Year goes well, too!
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Old 23-12-2013, 10:25   #32
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Re: Battery configuration

Golf cart batteries are 6V as opposed to 12V, but two connected in series will give you 12V.
The are a lead acid battery with thicker plates than the so called deep cycle leisure batteries, and can take many more discharge/recharge cycles.
In the UK, best price/deal I have found is with Tayna Batteries.
A popular battery for marine use, is the Trojan T015,
T-105 Trojan Battery Deep Cycle (T105) - Trojan Batteries - Trojan Batteries - 6 Volt
Another advantage is the size, being smaller than 12V batteries, much easier to handle.
In my case, I presently have 2 x 200 Ah 12V batteries, which I will replace with 4 x T-105's, total space taken up is pretty much the same, although the T 105 is slightly taller than the 12V batteries in place.
Happy Xmas
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Old 23-12-2013, 10:33   #33
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Re: Battery configuration

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Originally Posted by sailinglegend View Post
I am always dumbfounded by people who ask for help and then say they can't be bothered to make any changes.

On a boat one small change to something can mean a major re-working of other systems. You have to make the choice between following best practice, or living with a bad installation that will ultimately mean your batteries will die prematurely. One bank killed early - and then the next one will soon die too. The cost and the effort of correcting the problems will always be worth it in the long run.

Sorry to have a go at you but if you know you have a problem - fix it.
Ok
A few things seem to have surfaced particularly re my charging regime

Feel free to have a go anytime , if you think its justified , I'm a big boy and can accept it , you wont be the first I assure you; my field of expertise is mechanical engineering and machining so I relish hearing informed debate on this subject
I have already accepted that my system has some short-comings in respect of charging and I am going to very accurately check voltages at the batteries as part of this
What I cant/wont accept is that the system is fundamentaly wrong .
There seems to be many issues re batteries that no-one seems to agree on so I have tried to take the best shot at finding out where my system can be improved , but whose standards do I apply .........................
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Old 23-12-2013, 10:37   #34
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Re: Battery configuration

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Originally Posted by alexandlorna View Post
... There seems to be many issues re batteries that no-one seems to agree on so I have tried to take the best shot at finding out where my system can be improved , but whose standards do I apply .........................
Apply my standards!!!

If you've got 13.8-14.0 volts at your batteries your system is fundamentaly wrong!
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Old 23-12-2013, 10:51   #35
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Re: Battery configuration

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Originally Posted by sailinglegend View Post
Apply my standards!!!

If you've got 13.8-14.0 volts at your batteries your system is fundamentaly wrong!
Ok so what should I have then starting from a new Beta with twin 120A alternators
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Old 23-12-2013, 11:16   #36
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Re: Battery configuration

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Originally Posted by mitiempo View Post
Lets assume a run (there and back) of 60 feet. Let us also assume an alternator of 80 amps without any voltage drop splitters. Alternator output 14.4 volts.

With the engine running and all batteries aft in one bank (except for the separate start battery) and 95mm cabling (between 3/0 and 4/0 Awg) the voltage forward for thruster and windlass will be about 13.8 volts. This works well for both thruster and windlass.

Now if we place batteries forward the wire size required to charge them at a proper voltage will be larger. If the forward batteries are charged by alternator alone they, as posted, will never be fully charged. Even the 20 hours of motoring suggested might not do this. Voltage is pressure and it is just too low. I would expect a short life for the forward Agm bank.

Also not using the Victron to charge the forward Agm batteries is a mistake. The difference between flooded vs Agm requirements is very small, and Agm batteries are happy at the same setting. But with the voltage drop you get charging over such a long run it really makes no difference anyway as the output voltage at the alternator or Victron will be lower forward anyway.

I try to size charging cables for zero voltage drop. It charges much faster and is easy to achieve with a short run, often impossible with a run to the bow. Electronics issues shouldn't occur if the engine is running when thruster or windlass are in use as the alternator is at maximum output at this time.

This is just not true. The cables needed to properly charge the forward batteries can be much smaller than cables needed to run the windlass/thruster from aft batteries. The problem with your calculations is that you assume the maximum amperage of the alternator when you figure the voltage drop. This simply not the case. As the charging current tapers off, the voltage at the forward batteries will rise to the proper level. If the cables have a bit of a voltage drop, this will also have the effect of limiting the alternator output, which as Btrayfors says, is not a bad thing.
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Old 23-12-2013, 11:55   #37
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Re: Battery configuration

Quote:
Originally Posted by Charliemciver View Post

1) the two bow thruster batteries are currently at the front of the boat (rest at the back-ish). The previous owner didn't have them wired to the domestic bank (though it was clearly intended. not sure why. there is evidence of something going quite wrong and it being dismantled, and hence no charging currently). There is substantial cabling that goes between the front and the back of the boat already to make this join, so reconnecting it is easy.
You can connect the banks together, with one caveat. The substantial cabling between them needs to be quite substantial (I'd recommend 1/0), and should have a fuse which limits its current to the ampacity of the cable (250 amps for 1/0). Both sets of batteries are capable of putting out well over 500 amps, and could cause a fire if you have a short or bad battery at either end. Most commonly, the cables can be heavily loaded if the forward bank has failed and you use the windlass/thruster, but you can do the same thing by running the inverter off a failed domestic bank.
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Old 23-12-2013, 12:27   #38
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Re: Battery configuration

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Originally Posted by nigel1 View Post
While all the battery experts are here, I have a somewhat similar situation, but want to combine two banks into one.
Original from factory was a house bank and a starter battery.
Previous owner had a bow thrust fitted, and the installers fitted an independent battery bank forward for the BT.

Present set up is
1 x 125Ah 12V Start Battery
2 x 200Ah House Battery
2 x 125Ah 12V Bow Thrust battery

After 4 years ownership, I reckon the BT see's about 5 minutes use per years, and then in only 1 to 2 seconds bursts of use.

To me, that 250AH up forward is wasted, and I would rather include that in the house bank.
When the time comes, I want to replace the house and BT banks with Trojan T105, two forward, 4 aft.
Ideally would have all 6 in one place, but no space available aft for the BT batteries.

Can I safely parallel connect the BT bank and the house bank (using suitable sized cable)
Second question:
The 3 banks are independently charged by alternator and battery charger. The alternator goes through a Sterling zero loss splitter, and the sterling battery charger has 3 outputs.
If I can combine the BT and house banks, is it OK to leave the charging set up as it is, with a charge output to the aft batteries, and a charge output to the forward batteries, in effect, one bank but with two charge in puts, but to different battery posts.
Welcome any suggestions.

Oh, and regarding large cable's, in the UK, 95mm cable is very expensive, but using 2 x 50mm cable is a lot cheaper.
Nigel, no one seems to have answered you question, we seem to have about three different queries going on at the same time.

If you combine the BT and house banks how are you going to charge a 650 AH bank? Why does the engine have a 125 AH battery? my Diesel Ford Focus runs off a 75 AH battery, something to think about when its due for replacement. Do you have an electric anchor winch by chance? but the idea of 250 AH of batteries just for the BT is as you say barking.

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Old 23-12-2013, 12:47   #39
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Re: Battery configuration

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Nigel, no one seems to have answered you question, we seem to have about three different queries going on at the same time.

If you combine the BT and house banks how are you going to charge a 650 AH bank? Why does the engine have a 125 AH battery? my Diesel Ford Focus runs off a 75 AH battery, something to think about when its due for replacement. Do you have an electric anchor winch by chance? but the idea of 250 AH of batteries just for the BT is as you say barking.

Pete
Hi Pete
The start battery is a bit overkill but the beneteau original set up is that the start battery can be switched to the house circuit, some kind of back up I guess.
If I connect the BT bank to the house, such a large start battery becomes redundant, and a smaller battery can be used for the start.
Charging, there is a 60amp alt, plus 270 watt solar, and a D400 wind gen.
Also a 3 output sterling 60amp charger, which to date I have only used for equalising the batteries.
So far, the wind and solar has more than kept up with charging needs when cruising. Earlier this year over 6 week cruise, the battery charger was not needed.
The idea of combining the banks was to give that extra capacity for those days when it might be needed.
The windlass is electric, and usually used when engine is running. Being a wimp, I run the engine for 30 minutes a day to get some hot water.
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Old 23-12-2013, 12:56   #40
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Re: Battery configuration

Nigel, think you have this sorted, you just need 30 yards of heavy duty copper cable to link it all up. Are the 3 outputs for the Sterling linked together?

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Old 23-12-2013, 13:50   #41
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Re: Battery configuration

Hi Pete,
The three outputs from the sterling go to the 3 separate banks, as I keep the house and engine batteries seperate. Same goes for the alternator, which goes through a 3 output zero loss splitter (another sterling product).
I really wanted to know if I do connect the the fwd and aft banks, would there be any harm done if I left the charging set up as it is, with the fwd batteries being charged from one outlet, and the aft ones from another outlet, or, is it best to connect two outputs together at the charger, and have the +ve charge cable on the fwd battery bank, and the -ve return of the charger connected to the negative bus bar located close to the aft battery bank
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Old 24-12-2013, 09:25   #42
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Re: Battery configuration

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Hi Pete,
The three outputs from the sterling go to the 3 separate banks, as I keep the house and engine batteries seperate. Same goes for the alternator, which goes through a 3 output zero loss splitter (another sterling product).
I really wanted to know if I do connect the the fwd and aft banks, would there be any harm done if I left the charging set up as it is, with the fwd batteries being charged from one outlet, and the aft ones from another outlet, or, is it best to connect two outputs together at the charger, and have the +ve charge cable on the fwd battery bank, and the -ve return of the charger connected to the negative bus bar located close to the aft battery bank
It would be OK to leave it as it is, and you probably couldn't tell the difference in performance if you went with the other configuration. My previous post on the wires which connect the two banks together applies to your situation too.
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Old 24-12-2013, 13:29   #43
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Re: Battery configuration

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It would be OK to leave it as it is, and you probably couldn't tell the difference in performance if you went with the other configuration. My previous post on the wires which connect the two banks together applies to your situation too.
Thanks for the reply.
Looking at using 2 x 50mm2 cables to give equivalent of 100mm2 cable to make the connections between the two banks (works out much cheaper that way), with some thing like this on each end of the +ve
Dual MRBF Terminal Fuse Block - 30 to 300A - Blue Sea Systems

To get the best out of the system, I'll need to run the +ve supply to the house load from the forward bank.
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Old 24-12-2013, 16:03   #44
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Re: Battery configuration

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Ok so what should I have then starting from a new Beta with twin 120A alternators
guess I will just muddle by lol
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Old 24-12-2013, 16:41   #45
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Re: Battery configuration

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Originally Posted by alexandlorna View Post
guess I will just muddle by lol
Well, its not too clear what your question is, and this thread is now subdivided into at least 3 conversations...

In your case, you have two shiny new alternators on your Beta, probably internally regulated. Beta uses an Eastern European alternator and will sell you the "brush blocks" for these alternators so you can use them with external smart regulators. The voltage at the (internally regulated) alternators should rise to the 14.1-14.4 volt range soon after starting the engine, unless your batteries are seriously depleted.

The alternator outputs go to your 'splitter', which we don't know much about. The classic splitters are diode based, have big cooling fins on them, and drop the voltage about 0.6v There also some with more expensive diodes which drop the voltage about 0.3v. There are also some which are called 'combiners' which use relays and have no voltage drop. You need to measure the voltage at the alternators and then at the splitter output to see which kind you have. If you have a diode-based splitter, it will have the voltage drop regardless of the current, and you will need an externally sensed regulator in order to charge your batteries properly.
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