Blue Sea Isolator

[Hightower]

I have one of these fitted to my boat its a 1 or 2 or both type.

When in off, the battery + terminals become common. Is this correct? I'd have thought you'd have got complete battery isolation.

The reson I ask is because one of my batteries is dead and the other is OK and I know for a fact I have isolated the batteries after each outing.

[Hightower]

Ok just checked a bit more thoroughly and found what's in the attached photo. A resistance across terminals 1 and 2 of 105 Ohms, this is clearly discharging battery number 1.

Is this normal or a fault with the Isolator switch? Have I got my wiring right?

Andy

[Hightower]

Oh, hold on a min, the resisance is comming from the batteries

I hate electronics and electrical work.....

But why would one battery be flat, I've only ever run the boat on the Both setting Interestingly it's the larger capacity battery thats dead.

Any suggestions anyone, this has got a JW feel about it

[jwalker]

You called sir?

If you've definately always run on the two batteries and you're sure your wiring is fine, nackered battery comes to mind.

[Hightower]

Well I'm charging it up right now. I guess time will tell.

Andy

[jwalker]

Originally Posted by Hightower

I have one of these fitted to my boat its a 1 or 2 or both type.

When in off, the battery + terminals become common. Is this correct? I'd have thought you'd have got complete battery isolation.

Dunno about your switch but mine is; off - 1- Both - 2 - off as the large knob turns. It is the output connection which turns and it's wide enough to bridge 2 contacts so it first rotates to connect with contact 1 then it bridges both 1 & 2 and finally it connects with contact 2 and then back to contacting with nothing so it's off.

[Hightower]

Dunno about that Jeff, is all hidden under plastic.

However it does however seem like the battery is nackered, I get the required voltage from the terminals, but even the charger doesn't want to know

That means I must have been running my boat on the smaller 85Ah one. More expense.

[jwalker]

Connect your meter across the terminals and leave it connected. If the battery is in the boat, switch it into circuit on its own and turn the start key to crank the engine. Read the meter as you do this.

If its not at the boat, connect something with a highish load, a head lamp or whatever else you might have that'll draw a few amps, watch the voltage on the meter. It should drop a bit but not too much.

Do you have an 'always on' circuit for, say, your VHF or bilge pump. If so, which battery does it connect to?

If you've got a modern automatic battery charger, it may be that it can't get going if the battery is completely flat. One of mine is like this and it can be started by connecting a good battery also. When the charging starts you can then disconnect the good battery.

[Hightower]

My charger has all kinds of buttons on the front panel, if you turn it to manual you should be able to get enough charge into a completely flat battery and then after an hour switch to auto.

I think the batteries had it, I'll remove and make some checks in the garage later. BTW the negative battery terminal is turning a bit about 1/4 turn)

[jwalker]

Originally Posted by Hightower

BTW the negative battery terminal is turning a bit about 1/4 turn)

Oops.

[jyasaki]

Hightower;

Sounds like your suspect battery is already out of the boat? Take it to a local mechanics, and have them run a load test on it. Over here, most will do it for free (anticipating sales of new batteries, most likely.) They may be able to shock charge it as well, which may get a little more time out of it (not really something I believe in, but some do.)

BTW, what you have is commonly called a battery switch, rather than an isolator. What is commonly called an isolator is an electronic module that senses a charge-capable voltage at one terminal, and opens to allow both batteries to be charged. If it doesn't sense a charging voltage, it remains closed, allowing drain off only one battery (depending on how your load is wired up.)

I have 2 batteries and a switch, much like your setup. One of these days, I'll drop an isolator in as well, so I don't have to remember to hit the switch to get a charge on both batts. I subscribe to the " 'Both' only in emergencies" school of thought.

jky

[Hightower]

When charging both batteries at the same time which battery will charge first if the batteries are of different amperage capacities?

[jwalker]

There may be reasons for this not being true but, if the batteries are of the same type, I think they will charge together and become fully charged at pretty much the same time.

[jyasaki]

Originally Posted by jwalker

There may be reasons for this not being true but, if the batteries are of the same type, I think they will charge together and become fully charged at pretty much the same time.

If you have the two paralleled, the voltage will be the same on both by default.

Whether or not they reach full charge at the same time is another matter, but the charging voltage they see will be the same. Assuming they are equally drained, and in roughly the same condition, then yes, they should attain full charge about the same time.

If they are not equally drained, setting the switch to "both" will equalize the condition (based on voltage and assuming again they are both in similar condition), and we're back to square one.

There may be an issue if you have one fairly flat battery and one fairly charged; there will be nothing to limit the current from one battery to the other (other than internal battery resistance and whatever is in the cables and switch), so the surge can be pretty dramatic.

jky

[bedajim]

Originally Posted by jyasaki

Hightower;

Sounds like your suspect battery is already out of the boat? Take it to a local mechanics, and have them run a load test on it. Over here, most will do it for free (anticipating sales of new batteries, most likely.) They may be able to shock charge it as well, which may get a little more time out of it (not really something I believe in, but some do.)

BTW, what you have is commonly called a battery switch, rather than an isolator. What is commonly called an isolator is an electronic module that senses a charge-capable voltage at one terminal, and opens to allow both batteries to be charged. If it doesn't sense a charging voltage, it remains closed, allowing drain off only one battery (depending on how your load is wired up.)

I have 2 batteries and a switch, much like your setup. One of these days, I'll drop an isolator in as well, so I don't have to remember to hit the switch to get a charge on both batts. I subscribe to the " 'Both' only in emergencies" school of thought.

jky

I used this set up for mine

http://bluesea.com/category/2/productline/overview/329

[tinker]

Check your drawing, the batteries are not connected in 'series'
You need the negative of the first to be connected to the positive of the other battery.

ie

- (Batery one) + - (battery two) +

This would double the voltage of your two 12 volt batteries
12 volts + 12 volts = 24 volts

if you connect in parallel it would stay at 12 volts but the available power would be double (roughly), I have used this on many old cars/vans.

[Chris]

Andy,

I thought you were only supposed to have the switch set to the "both" setting in an emergency when you need to parallel the batteries together in order to get a boost,

I may be wrong on this but leaving the switch set to both when you are running is not good.

I would speak to Merlin Electronics 01202 697979 . They sell Blue Sea stuff so could help.

Chris

[Nos4r2]

Have you got a pic of the isolator Andy?

[jyasaki]

Originally Posted by Chris

I may be wrong on this but leaving the switch set to both when you are running is not good.

I don't think that it's "not good" in the sense that you'll damage anything, but it defeats the purpose of having two batteries (assuming you have two for redundancy rather than additional cranking capacity.)

Generally, you should leave the switch set to one battery or the other such that if you drain the thing to where it won't crank the motor, you can simply switch to the other battery and still get the motor started.

If you run set to both and run them flat (which will take twice as long, theoretically), you're dead in the water (so to speak... hopefully.)

jky

[tinker]

On his drawing he has connected the negatives on the batteries togethor, this is wrong? IMHO Or is it right? IYHO