Twin motors and battery set up

Update- I have wired as per suggested in diagram  andhave  attached pics 

i haven’t started the boat yet just  turned the  gnition on to get power 

I can only get power to port from port  battery and starboard from starboard battery  and only get power to both motors if isolator is on 1&2 and both batteries are still on 

Just to confirm wired like this I should be able to start from either  or both batteries ?  

 

Image Upload: 

Rob H's picture

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Ok, your isolator set looks

Fri, 2019-05-31 23:01

Ok, your isolator set looks exactly the same as mine but may not be wired the same. 

Mine is set up so the centre isolator runs all the accessories and electronics.

In the both position I can run both outboards (and charge 1 battery) thru both outboards. 

An AGM battery can cope with much bigger charge amperage 

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Thanks Rob think I might have

Sat, 2019-06-01 05:40

Thanks Rob think I might have to have a closer look to see what is exactly going on. 

So you start  on both batteries? And might be a silly question but how do you charge 1 battery ? do you switch To bat 1 or 2 after start up ? 

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Date Joined: 07/03/19

Be careful with your battery wiring...

Sat, 2019-06-01 13:41


The reccomended wiring from one of the battery isolation switch manufactures is, I belive, dangerous. (I wont mention the manufacturer).


A simple test to determine your wiring safety/security is...


1  turn all isolaters OFF


2  Test your electronics etc to see if any work.  If they do, their wiring needs checking- All isolaters off should mean no instruments/electronics will work.  A possible exception is an automatic bilge pump which may be wired directly to a battery.


3 Turn the middle switch to '1' and test.  No electronics etc should work.


4  Turn the middle switch to '2' and test.  No electronics etc should work.


If the electronics do work at '1' and/or '2', then that/those batteries CANNOT be fully isolated. This means that a battery may fail and cause the other to malfunction (ie it may fail too)


Wired correctly, a faulty battery can be totally disconnected from everything else, and your 2 motors can be started and run from the remaining good battery.


To fix the wiring is generally a simple matter of moving 2 wires/links that connect the middle switch to the outside switches ,   1 from each of the PORT and STARBOARD switches.


In the suspect wiring these links will be connected to the BATTERY side of the PORT/Starboard swich.   IN the 'safe' wiring they will be connected to the MOTOR side.


I did produce  2 wiring diagrams but could not copy them in to the post... and I'm not stuffing around trying to make them a URL...


If you want them... PM me an email address and I'll send them.



Now... other comments.


You have 2 totally separate battery starting/charging systems which operate independantly.  If necessary they can be connected together (if 1 battery fails) to start both motors.


THIS IS COMBINATION OFFERS A VERY HIGH DEGREE OF SECURITY, both batteries would need to fail for you to get in to trouble.


On top of that, your 'house' systems can be switched to run off either motor. THere is really no need for a separate 'house battery'.


You should only switch the middle switch to 'both' if one of the batteries has failed.


THere are some specific operating issues with your setup, regardless of the wiring and I'll gladly expound on that once you have decided what wiring connections you are going to use.


 

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Great info mate, makes Sense

Sat, 2019-06-01 18:18

Great info mate, makes Sense to me. cheers for taking the time out to post that  

Rob H's picture

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 DMCK has it exactly right,

Sun, 2019-06-02 23:53

 DMCK has it exactly right, and this is how I have wired mine.

I have AGM batteries which can cope with a relatively high charge rate.
I generally only run my fridge lights and electronics etc off the stb battery.
Then when we go for a fish I put the centre isolator on both, and turn port one off.
I can start off that and then both outboards charge the stb battery much quicker.

Note that this may not be wise if using conventional lead acid batteries.
I have run this way on my present boat for about 5 yrs and still on the same AGM

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 Just inspecting the wiring

Mon, 2019-06-03 10:08

 

Just inspecting the wiring on the boat,  it seems the two batteries are hooked up together  as in parallel this would mean I can’t isolate the batteries unless I remove the connection  and run it to the other isolator ? 

You can see in the pics the port isolator has 1 wire and the others have 2.

i assume this is correct.

yep makes total sense to me Rob. these motors have a high output charge so will have to check the details more thoroughly 

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Date Joined: 07/03/19

ITs just where the wires are connected.

Mon, 2019-06-03 14:15

 I enlareged the photo and lightened it up.

 

There is:

1 cable to the port switch

2 cables to the starboard switch

2 cables to the centre switch.

 

There arelinks between the switches behind the covers, that you cannot see.

 

One of the PORT cables is connected to the middle switch, probably for convenience when installing it all (easier to get to.)

 

I'm betting if you go through the test I outlined you will find the batteries are only in parallel when the middle switch is on '1&2"

(when I said 'turn all isolaters off' I mean the 2 outer AND the middle one...  I cant see the marking on the middle one but the OFF position has the black arrowhead pointing down)

 If I am wrong, then your wiring IS in serious need of correction.

Pity I live in Adelaide, I love working on peoples boats...

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Yeah I did the test. The

Wed, 2019-06-05 19:35

Yeah I did the test. The  starboard battery works on 1,2 and 1&2 

port has nothing.. I’ve got a feeling its been disconnected  from the port isolator and instead  hardwired to Starbord battery for what reason I don’t know 

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 May just have been

Fri, 2019-06-07 14:25

 May just have been inexperience. Wiring those switches can be daunting.

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Yeah who knows, seems like an

Mon, 2019-06-10 06:17

Yeah who knows, seems like an easy fix for me anyway... thanks for the info guys. Really helped me out

scubafish's picture

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Is this it ?

Mon, 2019-06-10 08:07

Alternate Dual Battery Configuration

http://continuouswave.com/whaler/reference/dualBattery.html

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Rob H's picture

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 Mine is different again to

Mon, 2019-06-10 12:33

 Mine is different again to those 3 examples.

Trying out Imgur.
As said, on my set up, you can

  • start off either or both batteries
  • Run house off either
  • Charge one battery from both outboards

The last one is the one to be careful of.

I use AGM's whjich will take a large charge rate (about 1/3 of the AH rating), but when close to fully charged your outboards charge system may not like it.
I havent had any such problem with my Suzukis, but only charge that way when they are fairly low.
I am on the same AGM for around 4-5 yrs and it is still holding ok though there is some reduced capacity.

This could also be attributed to the AGM requirement for a slightly higher voltage to fully charge.

https://imgur.com/SQledzz

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RobH has the correct wiring....

Mon, 2019-06-10 12:43

 For the following reasons.

1 both batteries can be totally isolated from the rest of the wiring.

2 either motor can be started from either or both batteries.

3 'house' electronics can be operated from either or both batteries, OR totally turned off.

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The only way I could get this

Sun, 2019-06-23 16:20

The only way I could get this working as explained ...... and don’t know if this is correct but seems to work. is if  i have both the motors positive cable  on the bottom selector along  with the house electronics ...that way I can select bat 1,2 or both  batteries  to start from....then the negatives  are on port and starboard but I put a negative cable between them because I wasn’t able to start one motor on bat 2   motor 2 on bat 1.... llnking those earths seemed to fix the problem and now I can isolate and start on  each and all the batteries... will this be ok and not overload the system? 

 

Rob H's picture

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 Not sure if this question is

Sun, 2019-06-23 17:23

 Not sure if this question is aimed at me or dmck?
But it would be easier if you did a drawing as Im not entirely sure what you mean?

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I'm not sure either....

Sun, 2019-06-23 18:58

 As Rob H requested... a drawing please....

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Hahah who ever will listen

Sun, 2019-06-23 19:44

Hahah who ever will listen and can help us out... I  have added a pic it’s not the best I just screen shot and marked it up

basically I’m hooking both  positive  motor cables to the central post (on the 1-2 and both isolation switch ) not to one or 2 as indicated on robs set up  I tried it this way and  couldn’t get it to work 

Rob H's picture

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 Still a little unclear, do

Sun, 2019-06-23 20:38

 Still a little unclear, do the 2 reds you have drawn go to the 1/2/both/off switch?
As, where I have written "off" is not actually a terminal but a switch position meaning no terminal is connected to another.

If the positive of the 2 outboards are linked permanently then you definitely have not got it set up right.

It sort of looks like the positive of the outboards are linked together, where they should go to the terminals I have drawn on the centre switch.

I think you should get it looked at by a marine or auto sparky, there is a hell of a lot of energy in an N70 battery and while you wont get electrocuted a fire or flash burns is a distinct possibility especially if its not fused.

EDIT-reading your description, I think you have both outboard positives connected to the centre where the house comes from. You cannot isolate your house supply while any outboard is running and both outboards must charge the same battery/batteries.
You cant run with stb on stb battery, port on port battery unless the switch is on both and batteries are linked through it.

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The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

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Date Joined: 25/05/12

Yes you are correct  with

Sun, 2019-06-23 20:56

Yes you are correct  with observation Rob . And that’s what I was worried about.

 When I had it hooked in the way in your illustration it wouldn’t work... I’ll have another gander over next few days... either switch is broken or I am missing something 

Rob H's picture

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 What wouldnt work, you dont

Sun, 2019-06-23 21:09

 What wouldnt work, you dont say what "it" is, house, either, both outboards?
Easy enough to check with a multimeter or even test light if switches are working?

I'll be a little blunt here, just due to the consequences of getting it wrong especially as I know how you need to squeeze and bend cables in place.
If it didnt work when connected up as per drawing, then it either wasnt, or a faulty switch (possible).
You do need to be able to know how to test a simple circuit/switch and read a drawing to be doing this as the consequences are severe of a dead short between 2 N70 batteries.
Also cooking ECU's and/or alternators on outboards.
I'd prefer that you get someone knowledgable on DC wiring to look at it, if you are in Gero Im happy to (home thurs) otherwise someone here may be able to?

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 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

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Date Joined: 25/05/12

Yep totally understand and

Sun, 2019-06-23 22:13

Yep totally understand and appreciate your concern.

I do understand the  consequences  and yes I have an ok knowledge of 12v systems  previously I’ve wired my  own dual and triple battery set ups  in my cruisers..Certainly no pro though so tread on the edge of caution.  And won’t be running anything until I get it correct. Especially with dual charging systems and touchy ems  like you mentioned 

Need to invest in a new my multi meter  had it stolen but yes that’s my next move. 

why it wouldn’t work.....:it was  the other day, but I’m pretty sure I could only start  port from port and starboard from starboard ... 

ill get it...just not as simple  as 1 motor but thanks for the offer. 

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Got it wired correctly and

Sun, 2019-06-30 08:20

Got it wired correctly and all working now... it was a mistake on my part wth how I was trying to start both outboards of the 1 battery 

you need one battery switched on and the isolators switched to both to start both motors  on the one battery.. I was switching it to 1 or 2 not both 

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Excellent !! thanks heaps for

Tue, 2019-06-11 18:48

Excellent !! thanks heaps for the information  and the diagrams..:I’ll definitely be hooking it up this way ..

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I wondered why it was  doing

Sat, 2019-06-22 13:05

I wondered why it was  doing my head in... I open it up swapping wires around  on the batteries doing little tests it seems they have wired it up using all negative instead of positive at the switches and running the house to 1 battery but then also had it ran in parallel in the battery bank... fun times ahead 

Posts: 685

Date Joined: 25/05/12

I wondered why it was  doing

Sat, 2019-06-22 13:05

I wondered why it was  doing my head in... I open it up swapping wires around  on the batteries doing little tests it seems they have wired it up using all negative instead of positive at the switches and running the house to 1 battery but then also had it ran in parallel in the battery bank... fun times ahead 

Posts: 61

Date Joined: 07/03/19

Now ya know.......

Sun, 2019-06-23 12:20

 why its called elec-trickery........

 

AT least when you are finished it will be wired to your standard  AND more importantly you will know how and why it is wired that way.  Imagine the 'fun' you would have had if you had been away on a trip and had an electrical problem....

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Date Joined: 25/05/12

Yes definitely  glad I’m

Sun, 2019-06-23 16:24

Yes definitely  glad I’m doing this now i will feel a lot more at ease when going offshore 

thanks for your help also, 

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Date Joined: 05/05/06

Glad you got it sorted.Just a

Sun, 2019-06-30 20:18

Glad you got it sorted.

Just a quick one on the battery set up for any gurus. If you have one battery that is not charged enough to start the motor and you switch to "Both" batteries...wont the dead battery suck the juice from the good battery pretty quickly??? rendering them both useless?

 

cheers

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Rob H's picture

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 The ONLY time you should

Sun, 2019-06-30 20:48

 The ONLY time you should EVER have it on "both" is to start an outboard if needed.
Never charge on both.

As you ave said "motor" Im assuming you are talking about a single outboard.

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 Give a man a mask, and he'll show you his true face...

 

 

The older you get the more you realize that no one has a f++king clue what they're doing.

Everyone's just winging it.

 

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Date Joined: 07/03/19

ANswer to Jim

Mon, 2019-07-01 07:52

 With the preferred wiring, the flat battery can be totally isolated using the dedicated (to that battery/motor) switch.

 

The 'Both' switch then connects the other battery to the motor to start it.

 

Once started, the skipper has the option to reconnect the flat battery then switch the 'select battery' switch to either 1 or 2 to drive the 'house electronics'

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Cheers fellas.

Mon, 2019-07-01 20:51

Cheers fellas.

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