Simplified Battery Management

[BlueMan]

I'd like to bounce an idea off the 'experts' here.....

I have a new (6 month old yacht) with two battery banks - 80Ah for engine starting and about 200Ah for domestic use. All the batteries are of the 'leisure' style so a compromise between engine starting and deep cycling. Alternator charging management is via the dreaded 1-BOTH-2-OFF style rotary switch. I also have a Sterling mains charger installed with separate outputs attached directly to the two battery banks.

I have been struggling with/worrying about the chances of someone in the family not getting the switching right when under power and blowing the alternator by accidentally selecting or passing through the OFF position.

If we are normally in a marina each night, and hooked up to shore power, can anyone see any reason why I can't just leave the rotary switch in the domestic position all the time? The domestic bank should be more than adequate in terms of CCA capability, unless severely run down which is quite unlikely (shore power almost every night) and we then always have the fully charged engine battery to get out of jail if required.

Am I missing something or would this take all the worry away while doing this style of day hop cruising?

 

[peteandthira]

I have a similar setup to yours with the addition of Sterling's battery management panel. I leave my batt switch to domestic almost permanently, and whenever I have shore power I leave the charger on. I have had no problems and have not yet had to add water to the battery cells in my first year.

I am not certain about the advisability of leaving the charger running all the time (I mean ALL the time, even when away from the boat) so perhaps an expert electrics man might suggest better advice.

I have been happy with the above so far!

Pops

 

[pappaecho]

Passing through the "Off" position is unlikely to cause any damage to the alternator. Leaving the switch in the off position may do so, depending on how the system is wired.
If the battery bank for the engine has simple two very heavy cables onto the battery terminals, then you may have a problem. On the other hand on my boat the alternator exciting wire, comes directly from the battery + ve via the ignition switch, which means that even if the battery rotary switch is in the 'off' position a running engine via the alternator and ignition switch, is still charging the battery. The downside of this, is if you leave the ignition on, it still draws a small amount of current, and not everything is truely isolated

 

[Talbot]

The reason for two battery banks is that the engine starter battery is supposed to be a car style device that is designed for high Cold Cranking Ampage for a short period, whereas the standard leisure battery is designed to deliver low ampage over a considerable period. Use of the leisure battery as an engine starter will very much shorten their life unless your batteries are specially designed for this (e.g. carbon fibre reinforced cells on Elecsol batteries). similarly the use of car batteries for domestic will also shorten their life as they are not designed for deep discharge.

If you are really concerned about switching through the "Off" and blowing the alternator, there are alternative methods using straight on/off switches on each bank, but there is still the danger of switching both off simultaneously.

 

[Guest]

Batterys ....

a) I do not allow another to touch the switch without first asking / telling me first ....
b) Leisure batterys are not designed for engine starting - depsite what some may say .... the plates are too soft and collapse with the high currents demanded on starting engines - particularly diesel's

You need a HD Diesel Battery or at least a good car battery .... breakers yards can often supply a good HD van or truck battery.

Domestic battery should be leisure deep cycle type .... any caravan shop will supply. BUT in fact in value - the old breakers yard again ... cheap and cheerful .... throw away more frequently ... still cheaper than 'designer' batterys.

The switch is so common and in fact as an alternator service guy told me .... most alternators nowadays are protected against diode blow on switch off .... but as he also said - don't trust it !!

The switch should be ....

Batt A Both Batt B with Off opposite the rest ... NOT between two settings that you would use .... get into habit of start battery ..... leaving there for a while to regain lost charge from starting, then 2 clicks to other battery .... charge up and then to both till engine switched off. Switch off enine and return switch to only domestic then .....
I make it a point to not use start battery for domestics unless ABSOLUTELY necessary ..... for obvious reasons.

The fear associated with the switch .......... many boats used them still have them and will have them for years to come !!

Sterling and other charge boosters ..... many use them, many don't use them, many have no trouble with them, many have trouble with them ...... Me - I don't want one .... cause I have cheaper way to do it .....

Was passed for a drink a split diode job ... but need extra voltage to compensate ..... so will do this :

Fit a bridging diode on back of alternator - as per Alstair Garrods book .... to cheat the alternator to up its voltage enough to cover loss across diode splitter .... cost ? Pennies ....

But you already have Sterling .... keep an eye on it ... one cooked my mates batterys and he very nearly had a fire .... he ripped the whole lot out and reverted to old fashioned way and never had problem again ... in fact it is where I got the splitter from .... he has a serious boat HR42 and is now on his way south .... happy knowing his batterys will not be cooked !!

/forums/images/graemlins/tongue.gif

 

[BlueMan]

Re: Batterys ....

Thanks for the advice everyone. I know this type of question is almost as inflammatory as colregs.....

Fortunately my Sterling device is just a mains charger, not an alternator charge regulator so I think it should be relatively safe.

I asked the question as I had been thinking about replacing the switch with one of the BEP clusters that has isolators for each bank, a paralleling switch for emergencies and a VSR for alternator charge distribution. I figured that would mean it would normally be totally hands-off but then I recall that there were some heated debates over VSRs some time ago.

Oh well, I guess I'll just keep on worrying that the helmsman is up to the job as I scurry down to do the switching!

Thanks again for taking the time to reply.

 

[Stemar]

Re: Batterys ....

I have a very simple system that seems to work fine for me, though my domestic needs are modest. I have a simple charging circuit much the same as on a million cars to the starting battery - an ordinary car type. The domestics are completely isolated from this, so I can't run the starter battery down. I use a cheap relay - not a posh VSR - to switch the domestic battery in parallel with the starter battery. This relay is energised by the charge warning light circuit, so it only makes when the alternator is charging, and if the charge drops, the relay will break the domestic out of the circuit.

It ain't sophisticated, and the experts, especially those with something to sell, will promise all sorts of dire consequences, but it works, I understand it and I can fix it at sea. Also, you can't switch it to off and blow the alternator, because there's no need to touch any isolator switches until you leave the boat.

If anyone wants more info and a circuit diagram, PM me.

 

[cliff]

Re: Batterys ....

[ QUOTE ]
Domestic battery should be leisure deep cycle type

[/ QUOTE ]No, no, no. The vast majority of people are under the same impression but IMHO leisure batteries should really be traction batteries. They will take real punishment from high current drain (running a 1.8KW inverter ~165amp), are true deep cycle (6~8v)and will tolerate repeated fast recharging - downsides are cost, availability and high maintenance - do they drink water or what? Well mine do but they get abused frequently and are recharged either via the engine alternator fitted with a Sterling controller or from shore power via the inverter / charger or even sometimes both (chargers boosting to 15.8v!)

I do agree though that standard car type batteries are NFG for leisure use and a reasonable substitute would be the common Leisure/marine batteries punted around by most caravan centers, swindleries and general battery merchants.
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“Artificial intelligence is no match for natural stupidity”
Skype id:cliffillupo

 

[Ships_Cat]

Re: Batterys ....

I agree.

Any boat that is used seriously away from the marina should really consider traction batteries for all the reasons Cliff gives. Our current set (Trojan) are now 9 years old and don't seem much different to when new (but that cannot last) even though used every week all year around.

Occasional jaunts around the harbour/occasional weekend type boat, boat sitting unattended week after week, etc then suggest cheap batteries as whatever one installs will probably die from neglect under those circumstances.

John

 

[Stoaty]

Re: Batterys ....

A set of proper traction batteries should last you 15 years if you look after them. I have known well used fork lift lift batteries to last over 20 years. A proper traction battery charger these days will give equalising charges as required and may well extened the life by upto 30% . An equalising charge is a charge of 1/20 of the amp hour capacity of the battery applied to an already fully charged battery for 6 hours. It will bubble quite strongly. This is where your water goes, but sulfation is removed. I would have traction batteries in my boat if I could justify the weight and cost. I doubt if I would ever own a boat longer than the life of the batteries. My choice these days are normal flooded batteries as found on lorries suitable for tail lift and cab heater operation. Varta do a 150AH one for around £75 in motor factors and battery specialists.

 

[William_H]

Re: Batterys ....

I think you will find that the leasure battery you have will be a lot greater in amp hour capacity that the minimum cranking type care battery that could do the engine job. ie the leasure battery is probably so big that the cranking current will not greatly trouble it cos it is so big. (assuming you don't have a huge diesel to crank)
As for 1,2 both switches if you have one consider a plastic guard or stopper that will allow it only to be used in one or off position. Such that in an emergency you copuld force it to both.
Move the power take off to your domestic services to your services battery via a separate medium current switch. Add then a voltage Sensing relay or a relay driven by some circuit which is only activated when engine is running (as already suggested) or a separate paralelling switch to ensure charge of the leasure battery.
This arrangement means that the only normql use for the 1,3 both switch is to turn battery on to operate the engine. and is not touched until youturn engine off and leave the boat.
If however both your batteries are identical it would be advisable to at least occasionally check that your leasure battery alone will start the engine. It is there partly as a standby if engine battery fails so make sure it can do the job.
As for leaving the shore charger on continuously I would hate to do that. There is the possibility of electrolytic corrosion from stray earth currents and the possibility of fire although granted the charger is intended to be left on and forgotten. regards olewill
PS it is unlikely the alternator will be damaged if you accidentally go to Off.

 

[MedMan]

When I fitted out my boat for long-term cruising I was, like you, concerned about blowing the diodes on my alternator. Given that there will be times when you have been on watch for 30 hours in a rough sea, having a system that depends upon you thinking straight and not turning the switch the wrong way with a £100 penalty and no power until you can fix it if you get it wrong, IMHO 1-2-both switches have no place on a cruising boat.

In re-wiring my batteries I completely separated the domestic and engine circuits and fitted the following:

Three separate on/off switches, one on each bank and one to parallel the two banks together for emergency starting.

A pair of blocking diodes between the alternator and the battery banks.

An Adverc 'smart' regulator. As well as providing a highly efficient charging regime, this compensates for the voltage drop across the blocking diodes so removing the main argument against them.

A built in battery charger (I now have a Stirling) with outputs for two banks.

This system is idiot-proof and has worked extremely well over the eight years I have been in the Med.

 

[Guest]

Info is that latest VSR\'s are good ...

The old trouble appears to be history and I'm told are better than Diode jobs now .....

Price is atrractive as well.

 

[Guest]

So with greatest respect ... we will change Caravan shop literature.

Leisure batterys are not designed for starting duties .... I know that from Caravan Dealers ... having had a number of vans over years and also trying to use one to jump a car years ago ......... battery was knacked by it. When I returned it under it's warranty - tried to is better term - they asked if I tried to start a car ... - it null and voids the warranty.

I was told many times that a leisure battery is called a Leisure battery for that very reason - supply of domestic in caravan ... so thats a lot different to a boat ???

Starting duties are best left yto starter batterys - ie HD car or truck stuff.

I really don't see the reason for fancy expensive stuff unless you are subject to extended cruising / away from power extended periods etc.

Average yottie plugs in often enough to get away with car battery's across the board ... so why the hoo-hah ??

Sorry for my style here - but I am posting based on information given to me over years and what appeared to be confirmed by experience. I don't bother with leisure battery's anymore .... cheaper to buy s/hand out of breakers and discard later for another .....

 

[cliff]

Re: So with greatest respect ... we will change Caravan shop literature.

[ QUOTE ]
I was told many times that a leisure battery is called a Leisure battery for that very reason - supply of domestic in caravan ... so thats a lot different to a boat ???

[/ QUOTE ]Yes actually - my "at anchor" drain on the batteries is 15~20 amps depending on which fridge is running, who is watching TV or playing a Video/DVD, etc. I don't think many caravans pull that amount of power continuously of their DC supply.
[ QUOTE ]
Average yottie plugs in often enough to get away with car battery's across the board ... so why the hoo-hah ??

[/ QUOTE ]No hoo-hah at all Nigel just simple statement of fact - not personal opinion. Traction batteries are the ultimate in deep cycle/leisure batteries and are "serious pieces of kit". The popular "leisure/marine deep cycle" batteries would not stand up to the punishment I give my batteries for very long and standard car batteries will not stand up to continual deep cycling not do they hold their voltage as long as the mid-range leisure (semi deep cycle) batteries on slow discharge.

I agree starting batteries are for starting engines and the ordinary car or truck type HD high CCA batteries is perrfect for that job but not for leisure use.

If you are happy going to a scrap yard and buying old batteries for your boat then, fine, that is your choice. I personally value my time more then than cost of new batteries and have no intention of changing batteries every year or two. When I hit the starter I expect the engine to start. I do not need the worry of a duff, secondhand battery suddenly giving up the ghost on me. Nor do I intend to have to drink warm beer because the leisure batteries are duff and I cannot run the fridges. I do like ice in both my G&Ts and my Whisk(e)y. My choice I admit but I would rather spend a few 00's once every 10 years or so and have piece of mind (and cold beer and ice).
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“Artificial intelligence is no match for natural stupidity”
Skype id:cliffillupo

 

[DaveS]

Re: Batterys ....

The complete 4 way BEP cluster is impressively neat and on a shiny new boat I might well be seriously tempted.

Having an older boat, and being generally tight, I was faced with a similar situation (but with separate isolators rather than a 1/2/both/off switch). I installed a BEP VSR and retained the isolators when separating the cranking / domestic circuits. I also have a jump lead which I could use for emergency paralleling. No longer having to remember to juggle switches is great, and the real bonus is no electronics-upsetting voltage dip when I press the starter button.

Like you I have a multi-output Sterling "smart" mains charger which is left on while the boat is plugged in to the pontoon. No problems so far - except when some clown trips the main pontoon supply then does nothing about it...

 

[FullCircle]

Re: So with greatest respect ... we will change Caravan shop literature.

Now now boys.
Cliff and Nigel, you both have a point, but you are coming from the different ends of the usage scale.
I dont think there are many anythings that sit and draw 15-20amps at anchor all the time.Wow.
My use on the jeanneau 35 seems to be about 5 amps tops with the fridge and lights, but I dont have a TV.
Also, having been a skint yottie for years, I always got my batteries from the breakers,as they seemed to last only marginally less time than a 'proper' battery, whatever that is. A fiver a pop. Bargain. Also have used Batman.co.uk for a 'Leisure' battery for my Jouet laast year - 30 quid, also a bargain, but i dont expect it to do the duty cycle you are talking of. PS my Jouet alternator was only 8 amp!
Nigel, we must learn to appreciate that there are people like Cliff who need a nuclear generator, whilst we have spent our free time dreaming up ways to keep the seepage of wiggly amps to a trickle.

In other words you are both right /forums/images/graemlins/grin.gif

 

[Guest]

Problem here is crossed terms and useage ....

In fact many caravans will pull large amps ... when not pugged in to sites. When I did 'field' vanning without mains supply - it was common to have to connect car and charge van every couple of days etc.
That is why the leisure battery was for the job ... would survive steady ampage drain and also deep cycling. Loads such as yours and the vans are not the "BANG" that a starter exerts on the battery ..... normally it's a load that increases as you switch things on .....
A van will often have a 3-way fridge, TV, gas heater system etc. etc. on it - plus of course the water pumps and all.

Traction battery's as you quote are a mean battery !! I have a Mercedes 7 ton truck with tail-lift we use on additive work and it has average battery's .... for that work and I would have difficulty fitting them to my boat ........... second they cost and weigh a ton !!

So my system of breaker yard batterys for both gives me reasonable domestic capability .... I rarely do more than 4 days on the boat ... with probably plug in each two days ... my engine gets run a reasonable amount between berths so charging is adequate.
I've had old batterys literally since the day I bought her - with only one change - thats now 7 years .... so I think I've done well .....

I may later this year splash out on another breakers yard job and try and remember to quote on that to the forum .... !!

Concusion is - we all have different requirements and put different solutions to them ... one is noit necessarily correct or acceptable to another ...... makes for interesting world !!

/forums/images/graemlins/tongue.gif

 

[timevans2000]

Re: So with greatest respect ... we will change Caravan shop literature.

I used cheapy caravan batteries for 3 years on my boat. I had 110 amp hour batteries costing £45 each. I had 3 in parallel giving me 330 amp hour on the domestic bank. They are used for engine starting and everything else you can think of.
The reason I had no problems was cos they are about 4 times the load inposed by the starter motor(excluding the inrush current) ie 80 amp starter motor. I have always worked on this formula and have had no problem. My emergency battery is a 26 amp hour agm engine starter should I flatten the main bank. This has never happened.
If you keep to this formula you can have dirt cheap batteries with the whole domestic bank costing less than one specialist marine battery. Forget the hype just get on with it!
Current duty bank is 350 amp hour. Purchased in Caribbean. Cheapest I could buy. still running everything from one bank. Batteries are never turned off when living aboard so no switching issues.

Here is one thought about battery isolation. Whilst crossing Biscay last year my newly refurbished starter motor jammed in the engaged position. I heard a strange noise and suspected the problem. I quickly looked at my battery monitor which advised I was putting 250 amps into the batteries by vertue of the starter motor turning at high speed by the engine. Pulling the engine stop cable didnt stop the engine cos it was being turned by the starter!! The only cure is to cut the supply to the engine. This has to be done by the battery isolation switch. The result was a blown alternator but a saved starter motor! Diode protection would have saved the alternator. Make sure your battery islolation is just that. If I couldnt have isolated the starter I would likely have had an engine fire as the starter motor cooked!

 

[cliff]

Re: So with greatest respect ... we will change Caravan shop literature.

[ QUOTE ]
we must learn to appreciate that there are people like Cliff who need a nuclear generator

[/ QUOTE ] Wow, I never thought of that - any idea where I can pick one of them up cheap? - would they stand shock loads like when SHMO decides to switch on the microwave (wrong side of 1kw) and She Who Never Obeys (daughter) decides it is time to blow dry her hair (wrong side of 600w) at the same time. Real punishment for the batteries to go from 15~20amp to ~240amp albeit for a few minutes only - enough to bollox a "car" battery!.
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“Artificial intelligence is no match for natural stupidity”
Skype id:cliffillupo