So it Begins

[Stemar]

Well, Jissel is sold and Jazzcat is paid for. Now comes the time to start a project plan that I might, just possibly, live long enough to see through to the end, though I suspect that my liking for lazing with a glass of rosé on a sunny afternoon may mean some of the less urgent items get postponed sine die...

Anyway, the first of many questions is about charging batteries. JC has twin engines, with twin starting batteries ~80AH each, one alternator charging one battery. No domestic battery. There's a spare battery the same size as the starters that isn't connected. I want to add a solar panel or panels.

I want to have a separate domestic battery. No question about that, but how best to do it? Would it make sense to have both engines started by one battery, charged by one alternator, with the domestic system - they other starter battery and the spare in parallel - charged by the other alternator, or is there a better way to do it?

It's been suggested that running one engine is more economical when not in a hurry or motorsailing. If I do this a lot, one battery may not get the top up I'd like, so could I use a VSR to connect the two, or should I just rely on the solar panels to even things out?

When I put solar on Jissel, PWM was what was available at a sensible price and, to avoid big losses from the boom shading the panels, they were wired in parallel. The ideal place for panels on Jazzcat is on the cabin roof, so shade from the boom is inevitable, so I've got the same problem. With an MPPT controller is there a better way to do it? Can anyone recommend a sensibly priced dual battery MPPT controller

Last question (for now!) JC has a small caravan-style gas and 12v fridge. Does anyone know what sort of current consumption I should expect? I'm interested in peak current and AH in 24 hours, as this would have a bearing on the wattage of the solar panels.

Thanks in advance

 

[PCUK]

I always had one starter battery for two engines, plus two domestic batteries. I used a two in, three out diode but VSRs will do just as well. My old combi caravan fridge would drain a 200 ah battery to nothing in about 20 hours. It was also not thermostatically controlled so would freeze everything until the battery was dead. Yours may be different.

 

[Tranona]

Definitely go for decent size domestic battery. From what you have said before your domestic demands are not high - the big consumers are fridge (typically 30-40 amps a day, instruments and autopilot and lights at night (either nav lights or domestic). I would think 100AH capacity would be a good basic start. A deep cycle FLA would be around £90 , but AGMs are falling with cars increasingly using them, particularly stop start models. I have 95AH AGMs used for Jaguars and Land Rovers which cost around £130. Advantages greater charge acceptance, lower self discharge and longer life.

For wiring you may find this system useful bepmarine.com/en/p/717-140a-dvsr ignore the "outboard" bit the essential is that it is pre-wired for twin engines so really simple to install. Bit more expensive than buying all the bits individually but neat and idiot proof. I have installed two in the past, although for single engine. You have so much redundancy with twin engines you are unlikely to ever need the emergency parallel, but the neat thing is that if you have one engine start battery fail you only need to parallel that engine to start, the other still has its own battery.

Don't know much about solar but sure others will offer suggestions. However with the level of usage you are likely to have and the fact that you are likely to be using the engines more than a typical saily boat, not sure you will need a lot of additional charge capacity. Different if you have a full set of instruments, autopilot, big fridge and night time sailing. Think I would try for a year with just the basic battery and perhaps a small solar for the domestic and see how you go.

 

[duncan99210]

An absorption fridge (12v and gas) is a greedy beast if you’re running it off the battery. A typical fridge of that type uses 75 watts or about 6 amps at 12v and that’s on all the time, not cutting in and out like a compressor fridge. One way round that is to set up a relay so that it only works on electricity when the engine(s) are running.

 

[jwfrary]

Sterling make the pro split r which takes outputs from 2 engines and splits to multiple banks,might be worth a look

 

[William_H]

I would go so far as to say never use the fridge on battery. Perhaps ok with engine running charging but at perhaps 10 amps continuous no good. Suggest if you want to run on battery change to compressor style fridge. Running on gas is not very good requiring good ventilation. Not recommended for boats. (arguable)
Re battery arrangement. Presumably your engines are at present wired as per standard for one engine. Each separate. This is probably quite OK ie not worth changing. You should have facility to jump start one engine from the other's electrics if a battery fails. You could just run domestics off either engine battery quarantimning the other for engine start. Jump start if necesary or.....
For domestic battery a separate battery system charged from either engine vie 2 x low volt drop FET diodes or schotky diodes not so good (.25v drop) or by 2 VSR. Interesting that 2x VSR would also connect the 2 engine batteries together while charging which may be a concern. (not sure) ol'will

 

[Refueler]

An absorption fridge (12v and gas) is a greedy beast if you’re running it off the battery. A typical fridge of that type uses 75 watts or about 6 amps at 12v and that’s on all the time, not cutting in and out like a compressor fridge. One way round that is to set up a relay so that it only works on electricity when the engine(s) are running.

I fitted a standard car headlight relay on my boat - so once engine is running and alternator fires up - the relay cuts in and powers my coldbox. I can also switch over to power the box direct from battery when on shore power ....

 

[penfold]

It's been suggested that running one engine is more economical when not in a hurry or motorsailing. If I do this a lot, one battery may not get the top up I'd like, so could I use a VSR to connect the two, or should I just rely on the solar panels to even things out?

Run stbd engine one day, then pt engine next; also evens out running hours.

 

[Tranona]

Run stbd engine one day, then pt engine next; also evens out running hours.

Really not necessary from the point of view of charging a separate house battery if the BEP switch cluster is used as whichever engine is running will charge the house as well through its VSR.

That is part of the reason why I suggested that solution as it gives maximum flexibility. Each engine has its own start battery plus can be paralleled with the house for emergencies without affecting the other engine and the house will be charged when either or both of the engines are running (after the start batteries are charged. All automatic and idiot proof.

Personally not sure solar other than low power to top up the house when the boat is not being used is really necessary for coastal cruising unless energy consumption is high (Nav, autopilot, fridge, night time running). Better to increase capacity to cope with the variations as plenty of alternator capacity to charge larger bank and small solar for in week top up. Power audit needed once the boat gets used, but installing +/- 100AH battery is a good start adding another if typical daily usage discharges to 50% or so.

 

[Mudisox]

My Cat has separate systems each side but they can be connected with a switch. I have 2 x 105Amhr service batteries each side and separate 50AmpHr starter batts each side that can be linked to domestic. I only have 3 small old solar panels but they keep the batts topped up when left alone. 70 amp alternators both sides.
I alternate the engines when on passage to keep hrs roughly equal, and rarely use shore power except for hair dryer use! Fridge on most of the time when onboard. Seems to suit me and the way I use the boat.

 

[Neeves]

Mudisox beat me to it - but we have similar ideas and design, so there is a bit or repetition

We have one start battery 80a/hr, once one engine is running we start the other - has worked well for 20 years. We have 2 x 200a/hr AGM house batteries. Be careful with the batteries they are very heavy. The alternators are 60amp and 120 amp. We can switch the batteries to become all engine start or all house - but never have had the need. Basically the engine start is only used for the engine.

I don't like to contradict Tranona but I think 100a/hr house will be a bit small - you will need to constantly run the engine(s) every 24 hours, with a fridge and autopilot, assuming you only discharge to 50% - remember you have lights (even if LEDs, windlass) a computer ++ if you have an inverter it will use 0.5a/hr.

Both or either alternators charge both the house and engine start. Ours is a BEP system, but the details I forget (as after 20 years I have never needed to remember). I suspect the BEP system we have has been replaced by something more modern . We motor on one engine but cycle them, to keep the engine hours roughly equal - then I service both engines together (one lot of mess, not twice)

We have solar and a wind/hydro gen as well - all feeding into the BEP system.

We have a Xantrex (I think that is the spelling) monitor.

We have a new Dometic 80l compressor fridge and a 20 year old 60l compressor deep freeze. The big consumers are the fridge, freezer, autopilot and desal unit. But when we make long passages we use the hydro gen and it makes enough power to run the boat - everything. We run the fridge and freezer 24/7, so off the batteries. We are VERY power conscious - whenever the engines are running we make water, we turn the temperature of the fridges down (colder) and then return to normal when the engines are off etc. We charge computers, tablets etc similarly. We minimise opening the fridge and freezer. We are not purists and motor to an anchorage, maybe 30 minutes and same sort of thing in reverse (windlass only used with an engine running). In Tasmania we fish for crayfish and our pot will be 3-5nm from where we are anchored - we will motor, daily, to near the pot, I take the dinghy to collect the crays, Josephine motors round in circles or up and down a sheltered passage - all the time we are charging batteries, making water etc.

Take care, stay safe

Jonathan

 

[Neeves]

Mudisox beat me to it - but we have similar ideas and design, so there is a bit or repetition

We have one start battery 80a/hr, once one engine is running we start the other - has worked well for 20 years. We have 2 x 200a/hr AGM house batteries. Be careful with the batteries they are very heavy. The alternators are 60amp and 120 amp. We can switch the batteries to become all engine start or all house - but never have had the need. Basically the engine start is only used for the engine.

I don't like to contradict Tranona but I think 100a/hr house will be a bit small - you will need to constantly run the engine(s) every 24 hours, with a fridge and autopilot, assuming you only discharge to 50% - remember you have lights (even if LEDs, windlass) a computer ++ if you have an inverter it will use 0.5a/hr, water pumps - it all adds up.

Don't think you will steer by hand. Unlike a mono the steering is rough because on a mono you can steer though any seas, you cannot do that with a cat as if you miss a sea with one hull you will catch it with the other. Its not very satisfying. Much better to invest time in trimming sails - you get more benefit.

Both or either alternators charge both the house and engine start. Ours is a BEP system, but the details I forget (as after 20 years I have never needed to remember - it is all written down, on the boat). I suspect the BEP system we have has been replaced by something more modern . We motor on one engine but cycle them, to keep the engine hours roughly equal - then I service both engines together (one lot of mess, not twice)

We have solar and a wind/hydro gen as well - all feeding into the BEP system.

We have a Xantrex (I think that is the spelling) monitor.

We have a new Dometic 80l compressor fridge (its really the only item, apart from sails, we have replaced in 20 years) and a 20 year old 60l compressor deep freeze. The big consumers are the fridge, freezer, autopilot and desal unit. But when we make long passages we use the hydro gen and it makes enough power to run the boat - everything. We run the fridge and freezer 24/7, so off the batteries. We are VERY power conscious - whenever the engines are running we make water, we turn the temperature of the fridges down (colder) and then return to normal when the engines are off etc. We charge computers, tablets etc similarly. We minimise opening the fridge and freezer. We are not purists and motor to an anchorage, maybe 30 minutes and same sort of thing in reverse (windlass only used with an engine running). In Tasmania we fish for crayfish and our pot will be 3-5nm from where we are anchored - we will motor, daily, to near the pot, I take the dinghy to collect the crays, Josephine motors round in circles or up and down a sheltered passage - all the time we are charging batteries, making water etc.

In terms of solar power - you can never have enough! The limitation is the amount of space.

Take care, stay safe

Jonathan

 

[Stemar]

Thatnks for all the helpful suggestions.

The budget is fairly limited, I'm hoping to do the whole of the electrics apart from instruments for the cost of that BEP Marine gadget, and it looks like two VSRs and a few switches, so I reckon a DIY shouldn't be too hard.

Jazzcat will live on a mooring, and we rarely use marinas, preferring to anchor, so mains power doesn't enter into the equation, though I may put a basic system in for the rare times, especially at the end of the season for a bit of heat.

We only had 40w of solar on Jissel, our previous Snapdragon, but we didn't have a fridge. Somewhere to keep the rosé cold will be a new experience for us! All the same, it would seem that I can forget getting enough solar power to run a fridge, even a new one, without the budget of a million viewer Youtube sailor Maybe we'll just run it on gas when we aren't motoring. That wouldn't be too hard, but I can feel a little buzzer circuit coming on to remind us to switch, or maybe run it through a simple split charge relay, which would be a lot cheaper than a VSR. I used to have a gadget on Jissel that turned the cooler on when the voltage went over 14v, but gave the option of a 15 minute boost override, but they company seems to have gone out of business - shame, it would have been ideal.

 

[Dellquay13]

a nylon net hung over the transom would be a very PBO suggestion for a wine chiller without excessive amperage demands on your batteries, at least in British waters

 

[Tranona]

If the original one is too rich for you (and is probably overkill anyway) then the simpler version bepmarine.com/en/p/718-140A-DVSR/Btery-Distribution-Cluster-Twin that only uses one engine to charge the house battery is a much more modest £150 or so. A little more than buying all the bits (of the same quality) separately but easy to install as the connections are done for you - just wire to batteries.

 

[Tranona]

I don't like to contradict Tranona but I think 100a/hr house will be a bit small - you will need to constantly run the engine(s) every 24 hours, with a fridge and autopilot, assuming you only discharge to 50% - remember you have lights (even if LEDs, windlass) a computer ++ if you have an inverter it will use 0.5a/hr.

This was on the basis of no fridge minimal electronics and no autopilot - as the boat is at the moment. I managed for over 10 years on my 26', even with basic electronics, autopilot and occasional use of an absorption fridge/coolbox with a 105AH AGM domestic, Red Flash AGM start charged by a Yanmar 1GM 35A alternator (and a BEP Marine cluster) - no solar or mains charging.

Would guess Jazzcat has 60A alternators so if heavy consumers are added it will support 200AH. However, if no fridge (at £600+ for the most basic!) and autopilot a single domestic battery will be fine.

Remember this is PBO and boating on a budget in the UK!

 

[fredrussell]

Sorry, off topic slightly Stemar, but did you post a pic & details of your new boat? Forum rules you know, give us a gander!

 

[northwind]

If you want to run the fridge using solar look at the victron solar controllers, they have an output you can use to power the fridge when there is enough power and it will switch off at a preset threshold

 

[Neeves]

Remember this is PBO and boating on a budget in the UK!

You are the first person I can think of who has posted out this salient fact - PBO and by inheritance this section of the Forum was about 'doing things' your self, hopefully with professional results.

I note that many of those who did do it themselves have disappeared, VicS, Coopec etc.

Jonathan

 

[Neeves]

Thatnks for all the helpful suggestions.

The budget is fairly limited, I'm hoping to do the whole of the electrics apart from instruments for the cost of that BEP Marine gadget, and it looks like two VSRs and a few switches, so I reckon a DIY shouldn't be too hard.

Jazzcat will live on a mooring, and we rarely use marinas, preferring to anchor, so mains power doesn't enter into the equation, though I may put a basic system in for the rare times, especially at the end of the season for a bit of heat.

We only had 40w of solar on Jissel, our previous Snapdragon, but we didn't have a fridge. Somewhere to keep the rosé cold will be a new experience for us! All the same, it would seem that I can forget getting enough solar power to run a fridge, even a new one, without the budget of a million viewer Youtube sailor Maybe we'll just run it on gas when we aren't motoring. That wouldn't be too hard, but I can feel a little buzzer circuit coming on to remind us to switch, or maybe run it through a simple split charge relay, which would be a lot cheaper than a VSR. I used to have a gadget on Jissel that turned the cooler on when the voltage went over 14v, but gave the option of a 15 minute boost override, but they company seems to have gone out of business - shame, it would have been ideal.

I know people sneer but I would look out for a cheap windgen, better one that will generate power from movement through the water, Ours is the Aero4Aquagen - surprisingly useful at night, when the sun does not shine and powers the boat when we are sailing (in a breeze).

I recall it was suggested you would sail to France, which to me seems at least to be a long weekend (or even longer). Thie idea of being without a fridge did not cross my consciousness (arrogance at its best, or worst). Without a fridge one battery, small, would be fine. You don't need instruments - DR and an iPad/phone should be more than enough. We sailed from Manilla to Hong Kong with only a trailing log and magnetic compass - and are here to make mention.....

Jonathan