Combining Alternator, Solar Panel, Shore Power Charger

[Zen Zero]

I even spent 16 quid on the RYA Electrics book but can find precious little about how to connect these things together.

My current system has 2 batteries ("motor" & "house") and 3 manual isolators (motor on/off, house on/off, batteries connected in parallel/batteries isolated from each other). The solar panel has it's own controller and has separate connections to each battery.

Thus when motoring we connect both batteries in parallel and they both get a charge from the alternator, at rest, the solar panel keeps them topped up. When at anchor or under sail the batteries are disconnected from each other (if someone remembers to do so) and the house battery is depleted for lighting and the VHF. We generally motor for an hour or so each day.

I want to add shore power charging and at the same time make the above system more automatic and less reliant on faulty memory.

I can envisage the scenario where we're connected to shore power, the sun is shining and someone starts the motor, and therefore where 3 sources are emitting at the same time; will this upset the alternator?

I'd really like to keep the two batteries separate as much as posible. The solar panel does this with its snazzy controller (it's got loads of LEDs that flash and change colour in meaningful ways). I'd happily consider installing two mains power battery chargers. But what's the best way of splitting the alternator charge (surely not 2 alternators?!)? And of ensuring that the 3 sources don't interfere with each other?

 

[VicS]

Keep the existing solar system, connected directly to the batteries.

Get a dual output charger. Connect directly like the solar panels ( You may end up with a triple output one with two outputs paralleled to the house battery)

Connect the alternator via a Sterling "Alternator to Battery" Charger. That will give enhanced charging of the house battery at the same time as bog standard charging of the starter battery ( Prob best connected via the isolators)
Aternatively an "advanced alternator regulator" ( Sterling again perhaps) and a diode splitter. That'll boost charge both batteries though.


OR

chuck it all out. Get a small solar panel , a small leisure battery and an outboard with rope starting.
Go sailing instead of managing a power plant.

 

[Scotty_Tradewind]

When motoring or on shore power, you may need to have fitted diodes to stop a 'back feed' of current going the wrong way to things like solar panels and a wind genny???

I'm no expert but my marine electrician just fitted my SP's and WGy with them as/the instructions on the controller/regulator.
These are 5 year old panels now all rewired and on a horizontal gantry and in the bright sunshine I was getting at best just over 5 amps charge from them this last weekend, but mostly around 3 amps +.....

 

[dt4134]

At the risk of sounding like a salesman for Sterling's Alternator-to-Battery Chargers, it sounds like that is what you want.

I connected the outputs of mine directly to the relevent batteries and am very happy with the arrangement. I really dislike the idea of the output of the alternator going through a switch. A couple of times I've had a clumsy crew member turn off the batteries accidentally (the switches are in the aft cabins), with my current set up that will cause no damage at all even if the engine is running.

IMHO there's no need to connect the starter and domestic banks together (my link switch switches the domestics into the starter motor so if the starter battery doesn't work I can switch out that and switch in the domestics - no point in pulling the domestics down with a duff starter battery - using both banks in parallel would be the real last resort.)

Don'y worry too much about the separate charging inputs to the batteries combining. If they're intelligent chargers they won't boil the batteries.

 

[Zen Zero]

Go sailing instead of managing a power plant.

That's exactly what I'm trying to achieve!

 

[mcframe]

I even spent 16 quid on the RYA Electrics book but can find precious little about how to connect these things together.

Replace switches with BEP VSR.

Plumb alternator (+Sterling)/solar/wind through VSR (*after* solar/wind reg/controller).

Plumb each of the two outlets from shore charger direct to batteries (via shunt for battery monitor if fitted) - if single output charger, then bung that through the VSR too.

Turn on fridge/heating/radio/ipod/etc

Go sailing.

 

[VicS]

Replace switches with BEP VSR.

Plumb alternator (+Sterling)/solar/wind through VSR (*after* solar/wind reg/controller).

Plumb each of the two outlets from shore charger direct to batteries (via shunt for battery monitor if fitted) - if single output charger, then bung that through the VSR too.

Yes VSR system is another way to go. Perhaps with a two way VSR

Then you only need a single output from the alternator ( rather than two as from an A-B charger). Connect so that the VSR gives the starter battery priority charging from the alternator

A single output shorepower charger connected so that the house battery has priority.

I guess you can keep the existing solar system with its dual output.

Battery monitor if fitted would require its shunt connected directly to the house battery.. Things like the BM1 connect to the negative side

 

[mcframe]

Yes VSR system is another way to go. Perhaps with a two way VSR

Battery monitor if fitted would require its shunt connected directly to the house battery.. Things like the BM1 connect to the negative side

What's a two way VSR?

As I've got a BM1, 'always live' things like the Webasto (and maybe electric bilge pumps if fitted) are connected directly to the upstream, non-battery side of the shunt (unswitched, but through a fuse), so they don't depend on house switch being on.

 

[VicS]

What's a two way VSR?

Dual sensing is what I should have said.

A "normal" vsr senses one battery when its volts rises to the VSR operating setting it connects the other battery

A dual sense one senses both batteries. When either rises to the operating voltage the VSR connects the other.

It means you can connect your charger to the house battery so that charges first before the VSR operates to connect the starter battery and your alternator output to the stater battery to recharge that before connecting the house battery.

No big deal but just something it enables you to do.

 

[Zen Zero]

This all sounds rather expensive! Is it because the item descriptions have the word "boat" in them. Why should a Sterling kombi - charger/inverter for example cost £800 when an office UPS (uninterruptible power supply) does the same job (and has its own battery in it!) for £50-100? I'm sure I'm missing something, but I can't put my finger on it.

 

[nimbusgb]

This all sounds rather expensive! Is it because the item descriptions have the word "boat" in them. Why should a Sterling kombi - charger/inverter for example cost £800 when an office UPS (uninterruptible power supply) does the same job (and has its own battery in it!) for £50-100? I'm sure I'm missing something, but I can't put my finger on it.

Yes you're missing 'boat' in the office UPS. They do do the same thing in fact the office UPS has to be very tightly regulated and a good sinewave generator. The difference is that marine companies are selling to a much smaller market and adjust their prices in compensation.

A lot of contributors will swear they there are real differences in 'marine' equipment and then go out and buy an iPad for use on their boat