Battery wiring (new question)

[Mudhook]

More queries on battery wiring - no shouting please!

I'm rewiring with an Adverc charge controller. My original system had both starter and services +ve taken from the output side of the 1/2/Both switch. The Adverc schematic recommends the starter to be wired direct to the starter battery, and in a conversation with one of the Adverc chaps I was advised never to run heavy starter-type currents through the 1/2/Both switch.

However I rather like the redundancy of being able to use the service battery to start the engine if need be, but in my new Adverc-inspired schematic (not yet fitted) I could only do this by having the 1/2/Both switch on 'Both'.

Can the knowledgeable members of the team advise?

Regards, Mudhook

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[halcyon]

Get a single isolater switch and wire the starter to the engine battery via new switch, agrees with adverc. Wire sevices through terminal 1 on your rotory switch, and 2 to the engine battery. Us off and 1 for your normal service, switch to 2 and you can start of the service battery.

Brian

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[LadyInBed]

On my current boat and on previous boats the 1/2/both switch was wired direct from the batteries as below. Charging/Starting is also via the switch.

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[Chris_Robb]

another alternative:

Look at the west marine site:
<A target="_blank" HREF=http://www.westmarine.com/webapp/wcs/stores/servlet/WestAdvisorDisplayView?storeId=10001&langId=-1&catalogId=10001&advisor=464-465.htm>Click here</A>

They suggest that you should use simpler on off switches.

I don't think you should not worry too much about Steve Cronins problem with the Split Charge Relays, so long as you have the heavy current devices all off the engine battery, and the alternator charging the engine battery. I use a relatively cheap splitter from KDD in Cornwall (had it for 7 years on 100 amp alternator) tel 01326 376938. (£68)








<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by kimhollamby on 09/02/2004 09:16 (server time).</FONT></P>

 

[halcyon]

Chris
Nice to here it's still going strong.

Brian

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[pvb]

Fully agree...

If possible, get rid of your 1-2-Both switch. These things are just accidents waiting to happen.

You need to consider in what circumstances you're ever likely to need to use the service batteries to start the engine. Your engine is tiny in automotive terms. What's likely to stop your engine battery starting it?

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[Mudhook]

Re: Fully agree... well

Thanks for all the info so far folks...

>These things [1/2/Both switches] are just accidents waiting to happen.

Surely not if you have some kind of foolproof split-charging system? Can you be more specific as to the risk?

>You need to consider in what circumstances you're ever likely to need to use the service batteries to start the engine.

Well I've already had recourse to this (my engine is a weary device). Twice last season fuel supply gremlins have exhausted the starter battery. I think it's no bad thing to have a backup source of cranking power.

Regards, Mudhook.

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[Aeolus_IV]

Re: Fully agree... well

Fool proof split charging systems: A split charge diode block.

Especially if you are already installing the Adverc alternator regulator. This means that you can then relegate your off/1/both/2 switch to being only the method you choose to supply the electrics in the boat.

If you're engine will not start with one batteries worth of power, then you probably have a rather serious problem with it. Will flattening your service battery help you out now? But you could use the "both" position, but only if you have somehow disconnected the flat starter battery first - otherwise you'll simply drain your fully charged house batteries into your started battery. Result: two 1/2 charged batteries and possible damage to house batteries and wiring as currents could be quite high. This is where the idea of an emergency battery isolation switch is a good idea - it needn't be easily to hand - but would probably be easier than digging into the battery area to physically disconnect the battery.

Regards Jeff.

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[pvb]

1-2-Both switches...

Over the years, there have been lots of posts on this and other forums about problems experienced when 1-2-Both switches have been incorrectly set. Sometimes, it's a well-meaning crew member who changes the setting. Sometimes, it's the skipper who forgets to change the switch. Often, the result is a flat starting battery.

If you have a properly designed split-charging system, there's no need at all for a 1-2-Both switch. It can be replaced by two simple on-off isolator switches; one for the starting battery, one for the domestic battery bank. That way, there's no opportunity for getting it wrong.

If you do need the facility to start the engine from the domestic batteries (and let's hope your fuel system problems are over) you can simply wire in a third on-off switch to link the domestic batteries to the starter circuit. Be careful, though, as if the starter battery has been flattened, connecting the domestic bank to it will result in a high current flowing between them. This will also reduce the charge in the domestic bank which can be used for starting. To prevent this, the link from the domestic bank should go to the starter side of the engine isolator switch, and the engine isolator should be switched off before the link switch is switched on. As on-off switches usually have handles which can be removed when in the off position, one solution is to discard the handle from this third switch. If you need to start the engine with the domestic bank, you then remove the handle from the engine isolator (thus ensuring it's turned off) and use it to operate the link switch.

Sorry if that's a bit of a long explanation - it would be easier if I could include a diagram.

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[Mudhook]

Re: 1-2-Both switches...

I can make sense of this (and of Aeolus's comments). I can see that separate on-off switches are more foolproof that 1/2/Both and I like the idea of only having one key - the opposite of firing off an ICBM in your lunchbreak! The 'rather serious problem' is at least as much to do with the operator as the engine, but it does happen. I will commence yet another schematic before I go down to the boat with cable and crimpers next weekend!
Regards, Mudhook

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[TonyBrooks]

As long as you join all the battery negatives together with "starter" cable (as I think you should) all you need is a very good blow arround the batteries to expel possible explosive gases and a decent jump lead to join the possitives in an emergency - just like jumping a car.

I would question why the engine battery should ever be flat, except when its at the end of its life.


Tony Brooks

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[Krusty]

Re 1-2-Both switches to allow engine start from domestic battery. I have started my engine through a Vetus switch of this type for 15 years and 50,000 NM (roughly 1500 starts) before having to replace the switch for wear/pitting. (Inferior switches may not give the same service, of course.)
My Adverc ensures the battery always spins the engine for a quick start, so the switch contacts do not overheat. If you have an engine problem, sort it out: do not murder the electrics. Unless you are going to live aboard, or start up five times a day when cruising, fit a Vetus switch and forget it!
Piota.

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