Fuses

[BaitDropper]

Question...

I have dual batteries, wired in parallel, down back, going to a blue seas standard switch, 1 2 & both.

From there cables run up to a positive and negative buzz bar behind the dash, then from there go to the various fused switch panels.

Now I did this wiring job myself, was checked over by an auto electrician, then by the marine shop when I fitted up the new 4 stroke 18 months back, both said it was good to go.

I use battery 1 for starting and running, if I'm anchored up, running sounder, bait pump etc I'll switch over to battery 2. 

So, to the question, Was I suppose to put a fuse, in the main positive cable from the battery, either before the battery switch, or just after ???

I never did !!   So in investigating this, the literature states not to put an inline fuse on the positive battery cable, that starts the engine ??      A bit confused about this issue.

Anyone have an answer on this please.....  what is best practice here ?   I'm getting some conflicting opinions.

Edited December 14, 2023 by BaitDropper
spelling

[noelm]

The starter draws huge current (amps) any fuse will blow when you start the engine. As long as the devices are adequately fused, you will be right. The theory of a fuse in the main feed is if somehow it shorts to earth along the way, the battery cable being thick, and the battery can supply lots of current, a short “might” create an “issue”

[BaitDropper]

Thanks Noel,  Yeah, I was a bit confused when I was told I should have one, Well, a breaker not a fuse, and I couldn't get my head around this blokes reasoning.

In fact the bloke telling me was adamant that I install one for my safety. I discussed it with him on how I had wired the batteries in series/parallel, showed him the fuse panels up front etc etc, but he was adamant !!  I told him that it was my belief that you shouldn't do so if it was direct feed to the starter, which all positions on my blue seas switch will start the engine, I have just dedicated pos 1  as my starting battery.

I have fused every accessory well, and even gone up in cable size on most accessories, so I'm comfortable there, this bloke just made me second guess myself.

The internet is very wishy washy about the facts on this as well, So I just wanted to confirm what I had done was fine.

Thankyou Sir, I shall continue on as normal 😁 appreciated..

[XD351]

The way I would have wired it is to use a cable set from the starter battery to the starter motor with no fuse, no breaker and no switch as I want this connection to be as reliable as possible . A dual battery set up like many 4wd use supplies a charge to the aux battery when the motor is running and once the starter battery is full - starting the motor is always the prime consideration. A high current link cable and switch links the two batteries ( +terminal) so the aux battery can be switched in to start the motor if needed - or you could use a set of jumper leads . The aux battery feeds everything else on the boat and I would have a fuse or breaker at the battery terminal that is rated no higher than what the cable you have used to feed power from the battery to your bus bar is rated for ( constant current rating ) I would have used 8awg which is rated 50amps but the thicker wire does have another benefit - it has less voltage drop over a comparable length of cable than what a thinner wire like 10 or 12awg will have - the more current you draw the greater the voltage drop will be over a given length of cable because of its inherent resistance . Also the batteries you use for each will be different - starter batteries and deep cycle have different ratings -CCA rating ( cold cranking amps ) - can be many hundreds of amps for a  starter battery and usually the rating of maximum current draw for deep cycle - might be 100amps or so . I think there may be a sort of hybrid that is a deep cycle battery that has the same cca rating as a starter - not 100 sure though . 

[BaitDropper]

9 hours ago, XD351 said:

The way I would have wired it is to use a cable set from the starter battery to the starter motor with no fuse, no breaker and no switch as I want this connection to be as reliable as possible . A dual battery set up like many 4wd use supplies a charge to the aux battery when the motor is running and once the starter battery is full - starting the motor is always the prime consideration. A high current link cable and switch links the two batteries ( +terminal) so the aux battery can be switched in to start the motor if needed - or you could use a set of jumper leads . The aux battery feeds everything else on the boat and I would have a fuse or breaker at the battery terminal that is rated no higher than what the cable you have used to feed power from the battery to your bus bar is rated for ( constant current rating ) I would have used 8awg which is rated 50amps but the thicker wire does have another benefit - it has less voltage drop over a comparable length of cable than what a thinner wire like 10 or 12awg will have - the more current you draw the greater the voltage drop will be over a given length of cable because of its inherent resistance . Also the batteries you use for each will be different - starter batteries and deep cycle have different ratings -CCA rating ( cold cranking amps ) - can be many hundreds of amps for a  starter battery and usually the rating of maximum current draw for deep cycle - might be 100amps or so . I think there may be a sort of hybrid that is a deep cycle battery that has the same cca rating as a starter - not 100 sure though . 

 

 

Now, I have to digest this a tad.🙃.........I have used, two similar type marine batteries, to a single battery switch, 1-2 & both. wired in series.  Now, I understand the principle of having different batteries, one dedicated to starting, the other dedicated for everything else, which they use a deep cycle type battery. When I arrived up here and ordered the new 4 stroke, they told me 3 months, which I figured would be a heap of time to get the wiring finished, batteries in etc, Well, the new 4 stroke turned up in 3 weeks, I basically had a day to get the wiring finished and dropped off for the new motor to be fitted.  So, fast forward, They wired the feed to the starter from battery 1 to the motor, all good, I use position one for starting and running etc, if I'm ever drifting, anchored up, not motoring, I switch over to battery 2.  But here's the thing XD, battery 1 will run all my electronics and pumps as does battery 2, both positions will start the motor, so if I dedicated battery 2 for my house and fused it as per above, using battery 2 to start in an emergency would potentially pop the fuse, Yes ??  Because both position 1 and position 2 can both start and run all the accessories, surely the batteries would have to be wired differently to how I have it now, a fuse at battery 2 could/would potentially blow if I started on battery 2 ?   In my way of thinking, the only way that would/could work, is if a fuse/breaker, was fitted AFTER the battery switch itself, on the main cable going forward, away from the parallelled wired batteries ??        I probably haven't explained myself well here XD 😁,  sometimes I'm like a computer, I need the information punched into me 🤪...  So, surely, an inline fuse/breaker after the switch forward, away from the batteries, protects all cables forward of the switch ? to try and protect the battery cables, should a battery cell cause major issues or an earth situation, kind of defeats the purpose of being able to use both batteries to start ??

[XD351]

I'm not a fan of being able to connect two batteries together because if one has dropped a plate and the other is fully charged there will be a massive current dump and you can fry the wiring or switch . The way I have wired it in the drawing is so you can use the aux battery to start the motor in an emergency via the high current  battery switch. The only time there is any current flow from the main battery to the aux battery is when the engine is running and this is fed through the dual battery controller. There is no fuse between any of the batteries and the switch which is mounted as close to the batteries as possible . The fuse is on the feed wire to the switch panel and as close to the battery as possible so it protects all of the wiring running around the boat .

The dotted line running to the alternator may or may not be present on your motor as it may use the negative cable for the starter motor 

[JustJames]

I was wondering if this would turn into the house vs. starting battery discussion.  And it has.

 

I too have been around this, and have opted for simplicity.  Or, doing nothing.  My boat doesn't have anything very current hungry, and I always have the voltage showing on the fish finder screen, and a very conservative low voltage alarm.  I have 2 batteries, and take it in turns to use them.  I have a reminder on the boat on which battery I used last time out.  When I park the boat up, I switch the batteries to off.  When I get ready to go out, I select that battery that I didn't use last time, and click my reminder over so that next time I will know which battery I used.

[BaitDropper]

28 minutes ago, JustJames said:

I was wondering if this would turn into the house vs. starting battery discussion.  And it has.

 

I too have been around this, and have opted for simplicity.  Or, doing nothing.  My boat doesn't have anything very current hungry, and I always have the voltage showing on the fish finder screen, and a very conservative low voltage alarm.  I have 2 batteries, and take it in turns to use them.  I have a reminder on the boat on which battery I used last time out.  When I park the boat up, I switch the batteries to off.  When I get ready to go out, I select that battery that I didn't use last time, and click my reminder over so that next time I will know which battery I used.

Basically how mine is set up and how I operate mine as well James....

And I'm sure, as Noel pointed out, if accessories are well fused, there shouldn't  ( touch wood ) ever be an issue. The only time there would be, if there was ever a battery plate dump, as XD mentioned, there's not a lot of protection there for that occurrence.  I'm picking that most out there are set up like yours and mine and have no issue. But it's definitely food for thought all the same.  I have a method, I always start the outing on battery 1, but switch over to Battery 2 before heading back. Those ACR units, supposedly do all the thinking for you, with regard to charging the idle battery, but I didn't have enough time to consider that when I set mine up...

Edited December 15, 2023 by BaitDropper

[BaitDropper]

35 minutes ago, XD351 said:

I'm not a fan of being able to connect two batteries together because if one has dropped a plate and the other is fully charged there will be a massive current dump and you can fry the wiring or switch . The way I have wired it in the drawing is so you can use the aux battery to start the motor in an emergency via the high current  battery switch. The only time there is any current flow from the main battery to the aux battery is when the engine is running and this is fed through the dual battery controller. There is no fuse between any of the batteries and the switch which is mounted as close to the batteries as possible . The fuse is on the feed wire to the switch panel and as close to the battery as possible so it protects all of the wiring running around the boat .

The dotted line running to the alternator may or may not be present on your motor as it may use the negative cable for the starter motor 

Thankyou for your time an effort to draw this up for me XD..

I'm kinda seeing what you mean now, I need to have a good look and see exactly how the shop wired the outboard in now, then reference your above drawing again.

I can, or rather I try to put my hand to most things, but  I need to physically see something to relate to it, so thanks...

I couldn't for the life of me get it to sink in, the different set up, which could allow the aux battery to be fused. I'm picking that most would have it set up, like JustJames mentioned and how mine is currently, but I do see now, how it could be wired up.  In all honesty, before I re did the wiring on my boat, if something had of gone wrong while out, I would have been dead on the water !! So by forcing myself to re wire the boat myself, I learned so much and I'm fairly confident if something went wrong while out wide, I could at least identify the problem and more than likely rectify it. I was lucky I helped out an auto electrix shop 2 doors down when I was doing it, so one of the workers there was popping in giving me help and advice, soldering was the hardest part of the process, but I got reasonably efficient at it by the end. But as mentioned, the main cabling was done after I moved up and in a rush to boot.

Once again XD, thanks for that, once I get some free time again, I'm going to check out, how the engine was wired and go from there...

Cheers

[Billmack]

Just James has nailed it. The second battery is a reserve. Note to baitdropper, your batteries are never in series and only in parallel when the selector is set to “both”. You can set to “both” when motoring home to top up the charge on both batteries. 

[JustJames]

20 minutes ago, Billmack said:

Just James has nailed it. The second battery is a reserve. Note to baitdropper, your batteries are never in series and only in parallel when the selector is set to “both”. You can set to “both” when motoring home to top up the charge on both batteries. 

Thanks Billmack

 

Just to expand/clarify...

 

Although the second battery is reserve, my batteries take turns to be the reserve battery.  By using them alternately, I keep them both charged, and I know what state they are in.

 

And NEVER touch the battery selector switch while the motor is running, or you risk fying the alternator (regulator).  I believe that better switches are "make before break" contact, but I wouldn't be gambling on that being what I have, nor on it working as advertised.

[BaitDropper]

Yes, wired in series is how I wired up my old 6 volt Bonneville's coils, wired parallel is the correct term.

Just James, I never switch between while the motor is running either, out of habit I guess, But I did notice, that the Blue Seas battery selector, sais that you actually can do this with there battery switches, it states it can be done between all positions without damage being caused.  BUT, I have to say, old habits die hard, I haven't and wont put this into practice.

I just got back from giving the boat a run on the ShoalHaven river and getting rid of some old fuel, it always blows me away how much of a fantastic waterway it is,,, took the O'l fella next door out, he's 78, lived in Nowra for all but 4 years of that and hadn't been out in a boat since he had a bad experience in a tinny in about 1968 😁. He's a funny bloke and he decided that he would accept an offer for a run in the river, it was like being in a tour guided bus, he knew just about all there was to know about the history of the river etc, interestingly, both him and his wife, have streets named after both of their families !!! a bit of history there..

Anyways, back on topic, I left from the Nowra bridge, went right up to Green Well point ( battery 1), tied up and got the O'l bloke a coffee at Green well point, then we headed back on Battery 2. So I think we use the same system of battery usage. It works for me and has done on most of the boats and batteries I've had over the years.

But I will add, XD definitely has something with his explanation on why the " reserve battery is fused, as per his explanation and diagram, I'm yet to check out exactly how my motor was wired, but I am going to look further into that.

Apart from taking the boat out and burning some fuel, with the influx of tourists arriving now and up until Xmas, I won't get back out and fish again till end of Jan, when the rush is over. But I was quite happy with my new live bait tank's performance, the drainage hole in the tank kept the level in the live bait tank at the perfect level the whole time I was motoring, so that was a win..  All ready to drop a bait or a lure again after the tourists leave 🤪

Edited December 18, 2023 by BaitDropper

[eitai2001]

Hey All. Just to kick on this discussion, I'm new to boating with a electric start motors and what not. My boat currently has a dual battery setup, 1 starter, 1 deep cycle. My understanding is turn on using switch 1 (the starter battery), and leave on switch 1 while boating around. When stopped and engine off, change over to battery 2 for gadgets (fish finder / VHF / lights). That's all good and well. I've learnt about not switching while motor is runnings, even if switch allows, just to form a good habit of not cooking the alternator.

My question is, if you shouldn't be starting the motor on battery 2 as it's a deep cycle, and you shouldn't be switching after engine is on, then how do you charge up battery 2? My understanding of the position 1+2 on the switch was for emergency situations where battery 1 is lacking charge and you need to jump start battery 1 with battery 2 effectively. 

Also, somewhat related, I need to replace the deep cycle battery as it's beyond dead (couldn't even power on the battery tester!) ... anyone have any experience with the Kings 115AH battery? On their site says can be used for boats too.

I know some people use the CCA + Semi Cycle batteries as their second, but I have some pretty strong front and rear spots for night fishing, so imagine they can draw a decent amount coupled with the sounder, cabin light, etc. Hence wanting to keep to deep cycle for the second.

(I know there are relays and what not that can be used to automate this, but let's ignore those for this question to help better my understanding).

Thanks

Itai

[xerotao]

3 minutes ago, eitai2001 said:

My question is, if you shouldn't be starting the motor on battery 2 as it's a deep cycle, and you shouldn't be switching after engine is on, then how do you charge up battery 2? My understanding of the position 1+2 on the switch was for emergency situations where battery 1 is lacking charge and you need to jump start battery 1 with battery 2 effectively. 

switch to 1 + 2 while motor is running to charge both batteries.

 

4 minutes ago, eitai2001 said:

Also, somewhat related, I need to replace the deep cycle battery as it's beyond dead (couldn't even power on the battery tester!) ... anyone have any experience with the Kings 115AH battery? On their site says can be used for boats too.

No experience with kings batteries, But im sure it will work. In 4x4 land AGM for cranking was a no no, but on an outboard, im not too sure.

Im in a similar situation where im looking at upgrading my house batter (century marine pro 680) as it doesnt have enough juice when i take my family out (charging devives, lights, etc.). Also i do not sure an isolator switch to swap between batteries, mainly because im very forgetful. I use a VSR. With motor running, once starter hits a 13.3V (i think) it would then also charge house battery. A lot better than switch isolators

[dunc333]

hi eitai start on battery 1 .then half way through your trip when engine is off switch to battery 2 .start engine on battery 2 for the rest of the day so battery 2 gets charged up as well .as xerotao just  said vsr (voltage sensitive relay) is the way to go i have one but its still sitting on my bench but will hook it up when i get a chance cheers dunc333

Edited January 19 by dunc333

[eitai2001]

3 minutes ago, dunc333 said:

hi eitai start on battery 1 .then half way through your trip when engine is off switch to battery 2 .start engine on battery 2 for the rest of the day so battery 2 gets charged up as well

Thanks mate. Only thing is it's my understanding a standard deep cycle battery shouldn't really be used for starting except in emergency as they're not designed for quick discharge.

[eitai2001]

7 minutes ago, xerotao said:

switch to 1 + 2 while motor is running to charge both batteries.

 

No experience with kings batteries, But im sure it will work. In 4x4 land AGM for cranking was a no no, but on an outboard, im not too sure.

Im in a similar situation where im looking at upgrading my house batter (century marine pro 680) as it doesnt have enough juice when i take my family out (charging devives, lights, etc.). Also i do not sure an isolator switch to swap between batteries, mainly because im very forgetful. I use a VSR. With motor running, once starter hits a 13.3V (i think) it would then also charge house battery. A lot better than switch isolators

Yeah, I've read not great for cranking either but ok to be used as a jump start battery to the primary cranking battery (I also have the marine pro 680).

I agree, and intend to get one of those automatic ones at some point. But not for now.

[BaitDropper]

I run 2 standard batteries, not deep cycle. As Dunc sais above, swap over during the day, or you should have a " both " alternative as well.

I run a blue seas Battery switch, There quality products, after the above chat, I rang the blue Seas supplier ( a Marine electrical shop ) and he confirmed that their Battery switches CAN be switched between Batteries while the engine is going. I haven't really done this as yet, but the technology allows for this. As far as deep cycle batteries go, I understand the general reasons behind this, but as a day boater, my engine basically is never turned off, I don't really anchor much at all ( I have an anchor winch ) So basically, I felt I have no need for one battery to be a deep cycle. I did have the set up in my bigger boat, years back, but we would spend 3-4 days away, different scenario. So if it were me, a day tripper, I don't see the need ( I'll probably get shot down for that 😁), But, that's how I roll..

[eitai2001]

I'm thinking to get the 120AH / 800CCA battery here as the house battery (friend of mine can get it very cheap through his car shop):
https://www.lionbatteries.com.au/product/marine-dual-purpose-batteries-starting-and-deep-cycling/

It's a dual purpose, but considering all I might be running engine off is Lights at night (forward spots probably only when under way), Fish Finder, VHF in emergency, ipad plugged in, phone charger, maybe a bait tank one day, then I think this should be enough. Doubt I will ever put a Sound System in the boat as bluetooth speakers are enough. 

And at least it gives me starting ability in emergency. Or can be operated in the 'ol switcheroo method of 1 on Day A and 2 on Day B.

The primary battery I have is the Century 680CCA which has light cycle ... so for both, assume a month of sitting off if I'm not out boating is no worries. It's parked on the street, so I can't plug in a trickle charger.

[noelm]

Just a tip….you do NOT need “headlights” when under way,  better to have minimal required legal  lighting only, when close to a dock/jetty maybe, but, that’s it, people with light bars mounted on their boats are creating a dangerous situation.

Edited January 22 by noelm

[BaitDropper]

1 hour ago, noelm said:

Just a tip….you do NOT need “headlights” when under way,  better to have minimal required legal  lighting only, when close to a dock/jetty maybe, but, that’s it, people with light bars mounted on their boats are creating a dangerous situation.

It's a debatable topic, front spots,  I definitely have experience from absolute idiots using them full time while motoring at night, nothing worse than those who feel the need to have them blaring, you actually see better with out any lighting.  I actually bought a decent spotty for the rebuild and have it already wired ready to install mine if/once I get a bracket made. But in all honesty, I don't think I need it now.  In Melbourne, I had numerous close calls, with idiots in tinnies, a couple of KM's out, anchored, with no anchor lights, it was fair frightening when coming back in at night and a tinnie appears right in front of you !!

I was adamant, as most of my friends did, was to fit one for pure collision prevention, when just out from the marina's or ramps, They actually sit there, and are completely blind to those coming back in after a night fish. One instance we were coming back, I missed one by mere inches, near ran right over the top of him, the swell was up and seeing them was at the last minute, a frightening experience. We always radio'd it in, but it changed nothing, they were always there, risking everybody's life.

Where I am now, I haven't had such an issue, but port phillip bay, is full of the night time idiots...

[eitai2001]

2 hours ago, noelm said:

Just a tip….you do NOT need “headlights” when under way,  better to have minimal required legal  lighting only, when close to a dock/jetty maybe, but, that’s it, people with light bars mounted on their boats are creating a dangerous situation.

Yeah, I only imagined using them to navigate in and out of port. My boat goes in by a river.

38 minutes ago, BaitDropper said:

It's a debatable topic, front spots,  I definitely have experience from absolute idiots using them full time while motoring at night, nothing worse than those who feel the need to have them blaring, you actually see better with out any lighting.  I actually bought a decent spotty for the rebuild and have it already wired ready to install mine if/once I get a bracket made. But in all honesty, I don't think I need it now.  In Melbourne, I had numerous close calls, with idiots in tinnies, a couple of KM's out, anchored, with no anchor lights, it was fair frightening when coming back in at night and a tinnie appears right in front of you !!

I was adamant, as most of my friends did, was to fit one for pure collision prevention, when just out from the marina's or ramps, They actually sit there, and are completely blind to those coming back in after a night fish. One instance we were coming back, I missed one by mere inches, near ran right over the top of him, the swell was up and seeing them was at the last minute, a frightening experience. We always radio'd it in, but it changed nothing, they were always there, risking everybody's life.

Where I am now, I haven't had such an issue, but port phillip bay, is full of the night time idiots...

But I never thought of this scenario.

I wonder how much use a spotlight would add though. They only see at best a couple hundred metres in front of you and at even 12kn, by the time you see a tinnie in front of you, it's probably a bit late.

[BaitDropper]

No, not the powerful ones, the same one I have, a mate fitted to his, its like an airport landing light !!

It reflects perfectly off ali boats.

I mainly went out on night fishes out of St Kilda, this is where all the " Illegal boat people "😁 used to go out from, they would sit right in the channel out, or straight out up to 1 or 2 Km from the marina entrance. And I'm talking small tinnies with 2 or 3 blokes fishing. They seem to clean it up for a while, but they would soon turn up again, it was dangerous, there was no way you saw them until you were right on top of them, I heard many a blokes chatting about near misses and from memory one larger boat went clean over one about a decade or so ago.

Spotties can have there uses, but like everything else, need to be used sparingly and for safety puposes. Even following another boat in with one of those LED strips on there rocket launcher basically blinds you, so in general, dont use driving lights !!  but for safety situations, spotties have there place.

Edited January 22 by BaitDropper

[JustJames]

On 1/19/2024 at 4:58 PM, BaitDropper said:

run a blue seas Battery switch, There quality products, after the above chat, I rang the blue Seas supplier ( a Marine electrical shop ) and he confirmed that their Battery switches CAN be switched between Batteries while the engine is going. I haven't really done this as yet, but the technology allows for this.

This known as 'make before break' or alternator field disconnect (two different approaches).  

 

But I can't think of a stuation where you would actually need to use it.  It's a sort of  Pascal's Wager for boaties.

[noelm]

1 hour ago, JustJames said:

This known as 'make before break' or alternator field disconnect (two different approaches).  

 

But I can't think of a stuation where you would actually need to use it.  It's a sort of  Pascal's Wager for boaties.

A really simple one, and common scenario, you have a flat battery, you get the motor started on the other one, then switch back to charge the flat battery.