Battery switch wiring

[qetoo]

I have a conventional starting battery plus a 450 AH domestic bank. I charge the domestic bank directly from the alternator. To charge the starting battery, I use a "Heart Echo Charge", which has given me excellent service for several years. I have posted a diagram at:

http://carlten.tripod.com/Electrical_system/electrical.html

Cheers,

 

[TheBoatman]

Re: One last time...

Stig
You don't have to anymore switching with your set up as with the other way. The only thing is you have 2 batteries feeding a common bus bar?

Go on board - turn on cracking bat switch
Start engine
Turn on domestic bat switch - both bats now being charged
When you stop engine turn off engine cranking bat switch (to protect it) and run on domestic.
If you want to be a purist then before you re-start the engine turn on cranking battery before you turn off the domestic
Re-start engine - then turn the domestic back on to charge it. Simple ain't it /forums/images/graemlins/wink.gif

FWIW I don't bother /forums/images/graemlins/tongue.gif /forums/images/graemlins/tongue.gif /forums/images/graemlins/tongue.gif, I have the same system and turn both bats on and start up because I've got 200+AH of bat power and a quick jolt from the starter of a 20 hp engine doesn't really make a great deal of difference. I do however have an "intelligent" charging system which is worth it's weight in gold - I have instant readout of power in each, voltage in each and can see when I need to charge them up to maintain good battery life and if one is a little down on the other the system points the alternator power in that direction.
I'm not an electrician so only understand it from an engineers point of view, but the guy that fitted it said that with most alternators they start on high output but very quickly drop to low, but with this system it keeps the alternator running on high to replace the energy into the starting bat and it attempts to balence the charge between the 2 bats.

Peter. /forums/images/graemlins/smile.gif

 

[nealeb]

Simple solution?

I had to replace a faulty 1-2-both switch recently and used a prebuilt switch+VSR unit from Merlin. Two battery switches, each dedicated to their own battery. Turn on both when I open up the boat. The engine starts from its own battery and the domestic battery runs everything else and at this point they are completely separate. The alternator is connected to the engine start battery, so once the engine starts charging this one "fills" first. Once the battery voltage has reached a preset level, the Voltage Sensitive Relay automatically switches both batteries in parallel so both charge. Once the engine stops, and the battery voltage falls from its "charging" level, the VSR drops out to separate the batteries again. There is also an emergency "parallel" switch for manually connecting both batteries if needed. I was able to replace my original switch with no wiring mods needed except to run a negative wire back to the battery busbar to get the VSR to work.

Especially as I am usually single-handed, this removes all up-and-down-the-companionway on engine start/stop. Next job is to fit the intelligent charge regulator to make both batteries charge a bit quicker.

This seems to be what the original poster wanted.

 

[Guest]

Re: Simple solution? .....

From what is said generally - these smart systems appear very good and I would not disagree.

My only concern is connecting two batterys together ... if one should fail and the VSR then puts both on after engine battery comes up ... what happens then ... if domestic is faulty ? Does it drag the engine battery down or does VSR click out ? If engine start battery fails - does VSR keep plugging away at engine battery - leaving domestic to fend for itself ?

I may be hanging on to old fashioned technology and risking duff batterys from forgetting switch overs etc. - but I like being able to decide myself what happens and when it happens .... Second I do not have a high output alternator - which I know from a friends experience with a smart system - he had to change to higher output to get the benefit of the system.
I know I have a faulty Domestic battery - that will only start engine if its just come off charge etc. I am well aware and that will be changed next time back ... But it runs my domestic needs ok for a few days .... topped up by engine alternator during engine runs .....
I am happy that I know my engine battery is not being dragged down by the domestic ....

So if the smart system copes with this - great ... I don't know ...

 

[Ben_e_Toe]

Re: Simple solution? .....

Here's another suggestion.....

I have four isolator switches, neutral, batt 1, batt 2 and 'charge'. Initially I switch on the first three, this links the engine batterry to the engine and fires up all of the domestic systems, but with the 'charge' switch open, both circuits are separated. Once the engine has started and run for 10 minutes I close the 'charge' switch and bridge the two batteries to charge. Then all I have to remember is to open the charge switch again before I stop the engine.

It's much easier to explain to the crew as the charge switch is coloured green and cannot be confused with the other switches.

That said if I knew where I could get a voltage sensing relay for £50 I'd buy one instead!

 

[Guest]

Re: Simple solution? .....

The funny thing is the old 1 - both - 2 - off switch is not as bad as people make out ....

1) It has make before break - so that changing batterys doesn't involve blowing the diodes etc.
2) It is a simple device that even my SWMBO can understand - remember she is a Russian with limited english and not boaty at all ... not electrical engineer etc. etc. - I told her #1 is for cabin lights, #2 is for engine. Rest forget but NEVER switch to off without asking me first.

I have various e-mails and PM's (well my PM's have been emptied last few days so lost those !) about interlocked switches, dual pole, 3-way, 2-way switches etc. etc. But they all seem to be introducing extra switches and thought ....

The system I wish to fit in all respect and consideration after thinking about it ... is as per Electronics afloat ... That is cheat the Alternator senser with a small diode to increase the output, then I can connect up the splitter diode unit I have ... which so far has been redundant due to the voltage drop etc. Once I have that done - I can stop thinking about charging and still use my old-fashioned switch to choose which battery does what etc.