Twin Battery Isolating switches

[Spaniard_King]

Just currious,

How does one know if they are getting an Isolation from battery 1 and battery 2... ie what if both batteries where actually linked when the switch is on either battery 1 , 2 or both. how would it be possible to tell if this was happening.

I only ask this as I have found this to be the case on my own boat::)

[peterbo3]

Garry,
Remove cable from terminal 1 at the back of the Perko. Select Batt 1 & try to start the motor. If it starts then you have a problem. Do the same with terminal 2. You could do the same with a multimeter if you don't want to start the motor.
You could also remove the pos cable from each battery in turn. Probably easier than pulling off the Perko.

[Spaniard_King]

Peter,

I found my issue.. but if you wernt looking.. how or what would indicate you had this???.

You see.. if your not looking.. you wouldn't know :

[Spaniard_King]

By the way.. It was a HD Bep switch.. not a perko

[peterbo3]

Garry,
I have never heard of this happening before but I don't get out much ;D ;D. The only way to check would be as described. What was your actual problem?

[Hamish73]

a tong tester will tell you in a few seconds without removing any wires..
A tong tester is a device that clamps onto a cable and measures current flow.

[Spaniard_King]

peter, as I have described.. couldn't isolate one battery from another... didn't know it was like that....no indicators

[FNQCairns]

You could try measuring voltage and check for the change in singular for each and the average (if you know what I mean, assuming both batterys have different Voltage at the time.

cheers fnq

[Spaniard_King]

You could try measuring voltage and check for the change in singular for each and the average (if you know what I mean, assuming both batterys have different Voltage at the time.

cheers fnq

FNQ, this ia all good, but what if your not looking for it.. How would you know.. giving what most boaties have in the way of instruments???

[frank100]

Guys,
About the only thing I can think of that would tell you that the problem existed, and you were'nt looking for it would be:
If you have either 1 or 2 selected on their own for an extended period ( say overnight) and subsequently found both batteries were run down.

Frank

[Spaniard_King]

Frank,

You have come up with our first answer.. has anyone else got a method to determine this fault??

[frank100]

OK heres another one:
With the selector in either pos.1 or pos.2 disconnecting the battery lead (either pos. or neg.)from the the battery which is supposedly not in use, will produce arcing as the lead is removed or replaced , as long as there is some sort of load connected to the battery supply.
To explain , the selector is in "battery 1" position & you remove a lead from either the + or - of battery 2. The terminal will arc as the lead is removed. How much arcing will be determined by the amount of gear switched on at the time and what sort of gear.
Of course if the power from the battteries is isolated & no electrical equipment is connected, you won't know there is a prob.

Just thought of another:
Battery selector either 1 or 2 (same as above). Then disconnect + lead off the batt. which is not selected and short to neg. or ground ie fibre glass boat, removing both leads from batt. not selected & touching together. OR aluminium boat remove + lead from batt. # not selected & touch the boat (neg) with the terminal lug.
I am sure the resultant "bang" would be scary.

Frank

[Spaniard_King]

Frank,

your getting away from the question, disconecting the lead is not an option because your not looking for a fault because you don't know you have a fault..hope that makes sense

[frank100]

Garry,
Yep, strangely that does make sense. BUT I was thinking along the the lines that the battery removal was for some other reason , not because you were looking for a fault you did'nt know existed.

Frank

[FNQCairns]

FNQ, this ia all good, but what if your not looking for it.. How would you know.. giving what most boaties have in the way of instruments???

OK then I guess you cannot because selecting 'both' just makes a bigger battery and 1 or 2 divides it:-[

cheers fnq

[frank100]

Garry,
I assume that the fault was not evident when the selector was in the "off" position.
Since the selector switch links "batt1" or "batt2" to a common terminal another syptom of the switch not isolating either battery from each other is also not to isolate the battery at all. ie with the selector in the "off" position you would have power available at the bus bar / switches / fuses.


Frank

[Spaniard_King]

OK then I guess you cannot because selecting 'both' just makes a bigger battery and 1 or 2 divides it:-[

cheers fnq

FNQ, you see I am saying what if when you selected battery 1 is was still connected (via the switch somehow) to battery 2... how would you know if you wernt looking for a problem.. This happened to me.. no matter what position the 4 position switch was in both bateries were connected at all times... How would you notice this if you wernt looking for it?

I wonder how many people have found both batteries flat and taken for granted the second battery is stuffed when in fact it had been dragged down with the first battery:o

[Dan5]

Well it would be near impossible to find that problem unless you specifically were doing an isolation test,the way i was shown to set up twin's with iso switch was to have a crank and house so everything powered would say run off batt 1 and engine only on batt 2 so my sounder etc would not work if ran on batt 2 and vise versa i could only start with electronic's on while in both pos and could do nothing with either while in off pos, ofcourse you just have to remember to switch to house when the engine is not running. Sound right? Dan...

[Chimo]

Hi Garry

This may be way of the mark but are we talking about an incorrectly wired setup or is there a design fault with the type of unit being used?

When my boat was rewired after I bought it (the original setup was a disaster) we used the one isolator switch for each of the motor batteries.

We used a third one to link the two motor batteries for use only if one motor battery dies and the dead motor has to be started. This is to be done with the good motor off and its isolator off and the pin out and the dead battery "plugged" in. Once the "dead" side motor is up and running the link switch is turned off, and the pin removed and the good side connected as normal and we are off with both motors running. The house battery charges off one motor battery with an Auto Battery Coupler contolling the charging process.

You only have the one motor I think but the concept would, I think, still apply in your situation. I was not sure about the swiching units so went the simple way we did.

Cheers
Chimo

[Spaniard_King]

Well it would be near impossible to find that problem unless you specifically were doing an isolation test,the way i was shown to set up twin's with iso switch was to have a crank and house so everything powered would say run off batt 1 and engine only on batt 2 so my sounder etc would not work if ran on batt 2 and vise versa i could only start with electronic's on while in both pos and could do nothing with either while in off pos, ofcourse you just have to remember to switch to house when the engine is not running. Sound right? Dan...


Dan,, you have hit the nail on the head. The only reason I found this problem was because I recently direct wireed my sounder to the port battery. When I was running on the stbd battery the port battery Was taking charge at 14.1V when it should have been isolated and only powering the sounder.. at around 12.5v

The batery switch had failed and no matter what position the switch was in.. both batteries were joined at all times::) ::) If I had not wired the sounder to this one battery I would never know the switch had failed in the way it had... even if I had both batteries go flat most likely I would have blamed one battery for beeing sick instead of the switch beeing bad and dragging both batteries down together to a failed state.. makes me wonder how many systems are like this.. a quality BEP switch to I might add:-/

[Spaniard_King]

Hi Garry

This may be way of the mark but are we talking about an incorrectly wired setup or is there a design fault with the type of unit being used?

When my boat was rewired after I bought it (the original setup was a disaster) we used the one isolator switch for each of the motor batteries.

We used a third one to link the two motor batteries for use only if one motor battery dies and the dead motor has to be started. This is to be done with the good motor off and its isolator off and the pin out and the dead battery "plugged" in. Once the "dead" side motor is up and running the link switch is turned off, and the pin removed and the good side connected as normal and we are off with both motors running. The house battery charges off one motor battery with an Auto Battery Coupler contolling the charging process.

You only have the one motor I think but the concept would, I think, still apply in your situation. I was not sure about the swiching units so went the simple way we did.

Cheers
Chimo

Problem with system chimo if the main battery being charged never reaches the pre-determined level the other battery nwill never receive a charge.. the auto battery coupler is good muntil this scenario occurs but then its too late:'(

[frank100]

Garry,
So was I correct in assuming that you had a faulty switch and that power was always available ? even with the switch in the "off" position ?

While I have not had this problem, I recently replaced my two single switches (one for ea. batt) with a 1 / 2/ both / off battery selector. This was due to the fact that the switches were falling apart due to the plastic sides becoming brittle.
On inspection I found that one of the switches had been making contact poorly due to the contact plate having a loose connection. ie badly pitted and slightly burnt.
Probably resulting in less than full charge to the battery & also probably some voltage drop. Although I never had a starting problem that was noticeable (a matter of time though I think ! )

Frank

[oldboot]

unless you have instruments in place to monitor the batteries or you check the function of the system by some other means......you wont know unless there is a problem......then you'll be left like a bobbing cork with two flat batteries.>:(


BTW a tong tester is a device for checking battery condition and is used ona battery only

a CLAMP meter is what you use to measure current in a cable without connecting.

common confusion.

The traditional tong tester looked leik an instrument ot torture with two spikes and a meteer in the middle....modern ones have jumper cable clips.

and yess a clamp meter would be a ver usefull device..... but it would have to be one that worked for DC...... lots of the clamp meters will only measure AC.

cheers

[Spaniard_King]

Garry,
So was I correct in assuming that you had a faulty switch and that power was always available ? even with the switch in the "off" position ?

Frank

Frank, when the switch was in the off position there was no power being supplied to the boat but both batteries were still in parallel with each other.

At no time could I acheive seperation of the batteries:'(

This is the point, At no time is it possible to know that you have actually got battery seperation ujnless you specifically have some measuring means in place to singularly measure each battery at all times. Not something that is standard in a dual battery setup:o

[Hamish73]

OldBoot, you comment had me worried there (I hate posting false info)
This is what I found on Wipipeadia:
A clamp meter (clamp-on ammeter) is a type of ammeter (http://en.wikipedia.org/wiki/Ammeter) which measures electrical current (http://en.wikipedia.org/wiki/Electrical_current) without the need to disconnect the wiring through which the current is flowing.
Clamp meters are also known as tong testers or Amprobes, (after one of the first vendors of such devices).

A simple electronic circuit could be designed that would give a pretty good indication of which battery was disconnected from the common if required, but I think this is a once in a lifetime fault situation.

[Dan5]

What happened to the switch? i hope it did'nt have a melt down that could have ended badly with a possible fire.I've only ever used the coles hersy switch's only beacause the larger boat's i have worked on have used them,some of the boat's have had up to a dozen extra large battery's running through them in series for 24 volt emergancy power.They are expensive but have been installed for many year's with no problem's and to get a good run like that out of anything electrical on a boat they would have to be well made you would think.Dan.......

[Spaniard_King]

Dan,

The switch physically worked fine, no evidence of any overheating warpage etc.

[Dan5]

Well it must have been bridging somewhere if the switch is making an open point,i suppose you have checked everywhere for it pullin ya hair out trying to find it.

[Dan5]

Hey mate just a crazy thought but a while ago you said that you were going through bilge pump's left right and centre is there anyway somehow they could make a bridge back to the battery? Stranger thing's have happened.(like a honda 40 starting by the trim switch after a service!)

[Spaniard_King]

Dan, the bilge pum p problem was more the poor quality of the plastic.. I have sorted the switch issue but I recon there are a lot more people out there with my problem but they don't know it.

[Fed]

What was the cause Garry?

[dnej]

This is what I did. As previously posted,the house battery,is only connected in an emergency,via the 2 switches.
If the switches went crazy,I would be unlucky for them both to go.
David

[Spaniard_King]

What was the cause Garry?

The battery switch had an internal fault::) causing both batteries to be parralled at all times.

My point of the whole thread is that this situation is undetectable in normal circumstances (even your system dnej) unless you have a digital volt meter on each battery it is very unlikely you could detect a faulty battery switch like mine.

Another point is when both batteries fail, we assum the batteries to be faulty but how do we know the switch isn't faulty (like mine) and in fact instead of flattening 1 battery you drag both to failure:o

Anyway, I hope this has opened a few peoples eyes that all may not be rosy down around ya battery switch;)

[Spaniard_King]

This is what I did. As previously posted,the house battery,is only connected in an emergency,via the 2 switches.
If the switches went crazy,I would be unlucky for them both to go.
David

David, how often do you charge the house battery and what swtich selection do you use??

cheers

Garry

[Chimo]

Problem with system chimo if the main battery being charged never reaches the pre-determined level the other battery nwill never receive a charge.. the auto battery coupler is good muntil this scenario occurs but then its too late:'(
Garry

The ABC I use is connected to the motor battery at all times except
1 When the key is turned to start the motor and the voltage drops in the motor battery below a specified figure ( cannot remember what it is but could look it up; I think 11.5 ?)
2 the motor battery for any other reason drops below the magic no?

If either of my motor batteries dies I can start the affected motor with the other battery by switching the third individual isolator to "ON" For usual operations it is never used.

The individual switches, that I have 3 of, cost very little cf to some of the other things out there and ther is no doubt about whats on and whats not. If 1 and 2 are not then the motors cannot be started 3 is only used if one of the motor bateries fails. The Auto battery Coupler is always there and stays connected unless situations as described above occur. All radios, GPS the sounders are all off the house battery with no spikes possible from motors when they are turned on which is nice as Lowrance replaced the GlobalMap when it lost pixcels due to spikes before the boat was rewired.;)

http://www.whitworths.com.au/main_itemdetail.asp?item=84384&search123=battery+isolator&intAbsolutePage=4

Cheers
Chimo

[dnej]

Garry,
I have a socket on the dash,one for each battery,and trickle charge,with a float charger.The sockets by pass the switches.

Just changed the batteries,they were 7 years old.

Were you able to follow the process,of re routing power,from one point to another.
If you needed to use the start battery,say for an emergency radio call,and the house battery were flat for some reason,moving the switch to " Both",redirects the power.

Work both ways.
Regards David

[Spaniard_King]

David,

yes I followed the diagram for using the second battery, I was just wondering if you ever charged it using the engine and if so what position you had the switches in?

[dnej]

I can charge the house battery,by using the method of re routing.Just got to think about it sometimes.
David

[krazyfisher]

I check the volts and I would think some thing was wrong if they always read the same number???

[Spaniard_King]

I check the volts and I would think some thing was wrong if they always read the same number???

Krazy, that wouldn't mhave helped in my case???????

[Smithy]

Thanks for the heads up Garry. Checked mine and different voltage readings between isolating #1 and #2 on my gps. Hope that is right!

[polky]

Gary , My mate has duel battery set up in his 4b, he has duel voltage gauges set up to read each battery. Cost about $50 bucks for gauges and he installed it himself his a sparky, going to get him to wire mine up gauges are 15mm dial will set them on stainless bracket and put them beside the isolator, I think Smithy has nailed the problem to. It is a good point, as you say I have never checked for this problem and don,t know if other people would. Thanks for highlighting it. Polky.

[Spaniard_King]

Thanks for the heads up Garry. Checked mine and different voltage readings between isolating #1 and #2 on my gps. Hope that is right!


Smithy, the only true way is to read the voltage when battery 1 is isolated and battery 2 is on supply (or vice versa). You cannot determin this is happening until you can acheive this. By switching batteries and reading from the same peice of electronic equiptment (GPS) will not tell you if you have correct Isolation.

Takes a bit to get your head around but thats it.

I placed signifiacnt load on the switch (ie spotties on) then took a digital volt reading or each battery using a multi meter, then switch over batteries and took another set of readings of each battery. I actually wanted to observe the load switch between batteries when I installed the new switch.

Also I need to add, I could not fault the battery switch when it was removed and tested using a multi meter::) but it sure was faulty when isntalled again.. had switches in and out .. started pullin me hair out at one stage:-X

[Bashir]

I have the same problem, my batteries even work when its switched to off. Getting it all re done soon.

[Grand_Marlin]

G'day Garry,

Just read the thread - very interesting and a very annoying situation.

You just dont expect new equipment (especially BEP) to give trouble.

A laymans way of double checking would be to turn the switch to battery 1.
Disconnect both + and - cables from battery 2.
Touch the + & - from battery 2 together.
In the unlikely event there is power bridged through the switch, it will ark straight away.
... just make sure you know which is battery 1 and which is battery 2 ;D


Bashir,

I see a number of these switches that are hooked up incorrectly, so dont be disheartened.
Actually, some of the wiring I see you would not believe ... and this is own relatively new boats worth hundreds of thousands of dollars :-/

Cheers

Pete

[Spaniard_King]

Yeh Pete,

verry annoying and hard to detect unless your actually looking for it:P