Battery Isolator Question!

[nickjh]

Hi,

I have 2 leisure batteries and a starter battery..... My isolator allows me to select 1, 2, all or off&lock..

I thought that 1 and 2 would be the leisure batteries, however the other day I was anchored up with the radio on for about 3 hours.. I went to start the boat and it only just managed to fire...

So my question is what should the isolator actually isolate? Is there a standard way to wire them? Ideally the starter battery should not be affected.. unless someone has wired the stereo, GPS and VHF to the starter battery????


Cheers

Nick

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[boatone]

If three hours anchored up with a radio running gave you run-down batteries sounds to me as if u have a rather more serious problem than just a 1-both-2 switch issue.
What capacities are your batteries and whats the charging routine?

With a single alternator feed to the switch I would expect 1 to be the starter battery, and 2 the domestic batteries (prob parallelled together). On the other hand you may have some form of split charging system with a permanent feed to the starter battery and the 1-both-2 switch feeding the leisure batteries as you say.
Either way a few hours at anchor with a radio on shouldnt remotely lead to a run down battery unless the batteries are very low capacity or theyre not being charged up properly.

Quite possible someone has hard wired various stuff direct to the batteries but u should be able to suss that out by looking and tracing wires back

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[Sunnyseeker]

If your system needs any up dating a simpler smaller and better solution is to have three seperate isolator switches, one on your domestics to distribution/charge
one on your start battery to engine and the third that can lonk the engine battery to the domestics in the event that the starter battery dies for some reason, this switch is only used in emergencies so there is no chance that someone will leave the switch to both and run everything down.. I've been on boats more than once where weve had to resort to the old handle because someone had switched the rptary islotaor switch to both.
Only thing you need is a split charger that supplies to charging feeds.
We changed our boat to this system and were safe in the knowledge that no one could link the batteries and flatten the lot as the link switch has a cable tie on it, and its in a different place to the domestic isolator.

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[Bejasus]

Re: Battery Wiring & Switches

Look at this diagram from Ardverc and it shows a similar setup. Note the Isolation switch from the starter battery. The service batteries are paralleled to one pole of the 1/2/Both/0ff switch and the starter to the other. There is more stuff on here than you probably need (i.e. DCMIII) but the battery wiring is correct.

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[stephenmartin]

I am in the process of rewiring my batteries and isolator switches...I have two engines and start batteries and a large domestic bank (300amp/hr gel)....I was going to go for blocking diodes but was convinced to parallel the start batteries and charge off one engine and charge the domestic from the other engine...therefore only two isolator switches needed and crank batteries power only running loads....ie GPS and radio and some other light loads.....Oh...and scrounge a starter solenoid and push button (instead of a switch ten a penny from a breakers) to connect the domestic bank to the crank circuit if I ever drain the two large cranking batteries....nice and simple and no volts dropped over blocking diodes....Hope this helps.....even I can manage this

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[mercman]

If you dont know how they are wired why not switch battery isolator to batt 1 when you just listening to radio or using lights. Then you can flick to batt2 to start engine. If need be flick switch to all to use what juice is left in batt1 to help start. What is the other battery linked to? Has it a separate switch sounds to me like an inverter battery. Looking through your posts sounds to me like you could do with someone to run through the boat with you. PLEASE DONT TAKE OFFENCE! Sounds like its your first proper boat. Get some one in you trust like the dealer you brought it from if it was new or the old owner if second hand.

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