Dual battery set up.

[Rhys Rowlo]

Hi all, 

just after info about setting up a dual battery system in my boat which is powered by a 4stroke 60hp yammy. 

Wandering if using a VSR is the way to go out just switching between the starting battery and Aux battery. 

Many diagrams would be helpful. 

Cheers Rowlo. 

[dmck]

THis was in another thread.  It is perfect for your use... compliments to Zoran.

Whether you use a VSR or manually switch is really up to you and will depend upon how long you travel over the water.

I use this wiring with out a VSR, but I 'float' both batteries (battery switch to OFF) on separate C-Tec chargers  when the boat is in the shed.    In lieu of PORT and STarboard batteries, think Main and Aux

Edited August 8, 2019 by dmck

[zmk1962]

Hey @Rhys Rowlo and @dmck, 

You'll probably find this post from 2017 of interest - please read start to end - a few of us covered just about everything there was to discuss regarding dual batteries and VSRs ....

Cheers Zoran

[Formosan]

VSR is the way to go just install and forget. You will find lotsa diagrams for it on the net. 

Look for Blueseas or BEP versions .

[zmk1962]

13 hours ago, Formosan said:

VSR is the way to go just install and forget. You will find lotsa diagrams for it on the net. 

Look for Blueseas or BEP versions .

Fully appreciate what your saying @Formosan especially if the main objective is to keep both batteries fully charged with minimum manual intervention.

But there are several types of VSRs out there, some just manage keeping both batteries charged, others also allow you to isolate your circuits so the electronics and motor run off different batteries. 

Also VSRs can be installed with or without isolation switches and you may actually need to add isolation switches in your VSR set up to protect your self from certain failures.  So I don't feel comfortable to say the answer is VSR  without fully understanding what the problem is.

In the end it all comes down to requirements -

• what electrical devices you plan to run, when and for how long, and
• what redundancy you need (ie. from what failures you are trying to protect your self). 

Your power requirements will help determine the optimum choice of battery type and quantity: Start or Deepcycle or Hybrid battery. So list all the devices you plan to run and when they will be running (motors, radio, lights, sounder, anchor winch, bilge, bait pump, deck wash, minn kota etc)

Your redundancy requirements will help determine the optimum wiring configuration (with or without VSR). So list out the key electrical issues you are trying to protect yourself from (flat battery, dead battery, etc) and how quickly you need to recover from that issue. 

Your understanding of the limitations of your wiring set up will drive you to decide if you are comfortable with a manual set up  or want to invest in an automated set up. I can see @dmck  is happy with a manual set up as I am - it meets all our requirements.

All these considerations  were discussed in the previous post I mentioned.

Cheers Zoran

[dmck]

16 hours ago, zmk1962 said:

Hey @Rhys Rowlo and @dmck, 

You'll probably find this post from 2017 of interest - please read start to end - a few of us covered just about everything there was to discuss regarding dual batteries and VSRs ....

Cheers Zoran

Thanks Zoran, interesting reading.

THe latest vehicles, especially relevant in 4WD, actually reduce the charge voltage as the vehicle electronics sense the battery is nearly charged.  Reduction can be to the point where the VSR will not activate to charge the second battery.

I dont know if the new outboards have adopted this yet... if they have it will cause a problem for very many dual battery configurations.

DC/DC chargers seem to be the only safe way to overcome the issue.

[antonywardle]

+1 to what @zmk1962 said.

 

I have a VSR between the two batteries and my 1-2-both-off switch is always on 1 (my starter battery)

If I ever find one of these at a good price, I'll replace my current setup with it.

 

 

[dmck]

53 minutes ago, antonywardle said:

+1 to what @zmk1962 said.

 

I have a VSR between the two batteries and my 1-2-both-off switch is always on 1 (my starter battery)

If I ever find one of these at a good price, I'll replace my current setup with it.

 

 

Get a competent boat/auto sparky to fit it for you !!

 

I'd have to go back through old posts to find the brand, but one of the manufacturers recommends a wiring install that is downright dangerous.

It their 'preferred' wiring it is impossible to totally isolate a faulty battery and run the electronics + motor on the remaining one.  Its only a simple reconfig to make it safe.

 

I emailed the manufacturer with my concern and they replied saying my wiring was OK but they preferred theirs....  I reckon they are too frightened to admit their setup could cause serious trouble.

 

btw... that setup can be easily simulated with 3 simple battery isolator switches and a VSR, you just dont get the pretty colours and labels.

 

this style of switch.... https://www.a shop.com.au/p/bep-battery-switch-275a/116409.html

Edited August 9, 2019 by dmck

[antonywardle]

presumably, you use the third switch to join the two batteries together to do the both switch on a single battery?

 

 

[dmck]

Correct.

 

You could use any single pole battery switch (single pole = 1 wire, simple on/off)

[Formosan]

On 8/9/2019 at 12:03 PM, zmk1962 said:

Fully appreciate what your saying @Formosan especially if the main objective is to keep both batteries fully charged with minimum manual intervention.

But there are several types of VSRs out there, some just manage keeping both batteries charged, others also allow you to isolate your circuits so the electronics and motor run off different batteries. 

Also VSRs can be installed with or without isolation switches and you may actually need to add isolation switches in your VSR set up to protect your self from certain failures.  So I don't feel comfortable to say the answer is VSR  without fully understanding what the problem is.

In the end it all comes down to requirements -

• what electrical devices you plan to run, when and for how long, and
• what redundancy you need (ie. from what failures you are trying to protect your self). 

Your power requirements will help determine the optimum choice of battery type and quantity: Start or Deepcycle or Hybrid battery. So list all the devices you plan to run and when they will be running (motors, radio, lights, sounder, anchor winch, bilge, bait pump, deck wash, minn kota etc)

Your redundancy requirements will help determine the optimum wiring configuration (with or without VSR). So list out the key electrical issues you are trying to protect yourself from (flat battery, dead battery, etc) and how quickly you need to recover from that issue. 

Your understanding of the limitations of your wiring set up will drive you to decide if you are comfortable with a manual set up  or want to invest in an automated set up. I can see @dmck  is happy with a manual set up as I am - it meets all our requirements.

All these considerations  were discussed in the previous post I mentioned.

Cheers Zoran

 

Zoran,  You may be over thinking this but good points there to help justify consideration for a manual switch.

@Rhys Rowlo

You have a 60 Hp engine, so not a huge boat. Are you a bait fisho or a offshore fisho? Trolling cover some distant? Downrigging?

Can you calculate and measure your power requirements (what electrical devices. what it consumes, how long run for?) every day on the water could be different typically sounder ,lights, livie pump goes on all day and possibilty electric reels. If you are a bait fisher anchor up and engine off. Manual switch will be fine but I would still get an auto charge.

If you are an offshore fisho cover alot of distance , have electronics running all the time and not sure what everything uses and past age 40 (memory loss which battery did i use last time?). Then definitely get a VSR kit.

For peace of mine ..grab an add a 2nd battery kit. When you add a 2nd battery in a boat or a 4wd it is best pratice is to put in a  VSR (Relay) and it comes with the kit with a switch, to close the circuit to charge the 2nd battery. With a 4wd you could always walk home.

A VSR it is just a relay that closes the circuit .  VSR , a Voltage sensitive relay it will closes when it senses 13.6V.It isnt that hard. When you get the boat with single battery, it is all wired into one circuit to one battery.Just leave the engine and bilge pump 's circuit on the first battery.  Add a 2nd battery and put all the accessories onto a new circuit that connects to 2nd battery so now you have isolation. Add the VSR to bridge the two for charging.

BEP and Blueseas makes kits for Marine.

Check them out, the Blueseas  i think is better as it has one switch that does it all unlike the BEPs multiple switches.

 

 

 

 

 

 

[JonD]

For years I've had dual systems but for the last three I've done away with them. Simple reason was that in all the years of having dual ive never needed them. It's more to maintain, purchase and more weight and room taken up on a small boat. If I was to go back to night broadbill fishing then yes I would have dual setup. 

These days the tiny jumper starters will crank over the biggest of motors and can be carried almost anywhere, in fact my daughter has pinched mine to carry in her car when she heads out remote in the bush. Our local 4x4 centre actually recommends these battery's over dual setups in off-road vehicles.

You also have a small outboard which are actually quite easy to start with a pull cord. I had an issue last year where my engine wouldn't start off the battery or jumper due to a fault in the battery lead itself, pull starting wasn't a problem.

There has been heaps of great advice above, I'm just suggesting an alternative if you haven't already got dual setup which will save you an easy $1000 and further costs down the track.

Edited August 18, 2019 by JonD

[zmk1962]

Not sure if I am overthinking this. I'm just sharing based on my experiences and requirements.

On 8/17/2019 at 11:55 PM, Formosan said:

Just leave the engine and bilge pump 's circuit on the first battery.  Add a 2nd battery and put all the accessories onto a new circuit that connects to 2nd battery so now you have isolation. Add the VSR to bridge the two for charging.

As you describe it @Formosan the VSR set up simplifies keeping both batteries charged. Also if its wired up as per your diagram, then you also have isolation of the circuits so essentially you are less likely to drain your start motor - another positive.

However, as @dmck and I have highlighted the problem with this set up is that the switch provides:

1. Off (both batteries switched out of their respective circuits),
2. On (Start battery online to motor and House battery online to other electronics) and
3. Combined (both batteries are online to the motor and other electronics.)  Note: There is no built in way to isolate a bad battery.

So if the house battery dies (eg drops a plate and has internal short circuit), you will be able to use the Start battery for the motor but will be running without radio, GPS, lights etc. If you Combine batteries then you are draining your good Start battery with the faulty House battery.  Similarly if the Start battery dies, if you Combine you are draining the House battery.  Combining batteries could be dangerous depending on the nature of the battery failure.

The only way out of this would be to manually isolate the bad battery (ie detach the battery terminal) and then put the switch into Combine so that everything runs off one battery.  OR as I said in my earlier post, install and isolation switch at each battery so that you have a built in way to isolate and don't have to do the manual isolation on the water.

People should be aware of this exposure - and hence that is why I said a VSR set us is not all "set and forget". .. otherwise without understanding this limitation, you may be lulled into a false sense of security without a fallback plan. 

From memory of the earlier posts I referenced, Dave ( @Sigma ) carries a third battery, ready to wire in if required as his fall back.

 

23 hours ago, JonD said:

For years I've had dual systems but for the last three I've done away with them. Simple reason was that in all the years of having dual ive never needed them. It's more to maintain, purchase and more weight and room taken up on a small boat. If I was to go back to night broadbill fishing then yes I would have dual setup. 

These days the tiny jumper starters will crank over the biggest of motors and can be carried almost anywhere,

Jon you have had a phenomenal amount of boating experience and I am sure in your bag of tricks you would have a way out of any situation. Personally, I've had one battery failure on the water in 20+yrs of boating. A battery dropped a plate, creating an internal short circuit - we were underway at 4000rpm, the engine stopped and all electronics died.  It turns out some motors cannot run without a working battery attached and even if you do get them started and run without a battery attached you a risking frying the charging circuit voltage regulators (VRs) or even the ECM. This was news to me - but confirmed by several Mercury mechs. So that's another thing to consider and check with your motor manufacturer if you plan to run with just one battery on board.

In my case, when we lost the battery I isolated the bad battery and switched to a good one and we were on our way in less then 30sec. We were in safe calm water so were never in danger but even if this had happened trolling next to the rocks we would have been out of there with minimal risk because I just had to flick two switches to get power online.  Jump starter packs are an alternative, but you need to factor the time it takes to undo battery boxes and connect the jump starter and whether that length of time meets your boating requirements (in addition to if your motor can run without a working battery).

BTW, when I inspected the damaged battery back at home, I found it had swelled like a puffer fish (we were lucky it did not explode). In the short time before the motor died, the charging circuit from the motor was basically boiling off hydrogen in the shorted battery. You would not want to connect a good battery to a damaged one like this one.

 

On 8/17/2019 at 11:55 PM, Formosan said:

Can you calculate and measure your power requirements (what electrical devices. what it consumes, how long run for?) every day on the water could be different typically sounder ,lights, livie pump goes on all day and possibilty electric reels. If you are a bait fisher anchor up and engine off. Manual switch will be fine but I would still get an auto charge.

If you are an offshore fisho cover alot of distance , have electronics running all the time and not sure what everything uses and past age 40 (memory loss which battery did i use last time?).

Well I'm definitely over 40 -- closer to 60.... and I fish mostly offshore, have all electronics running whether I'm trolling or anchored up.  Keeping track of the batteries comes down to routine. I have a digital Voltage readout on the dash. Motor off:  >12V all is good.  Motor cranking: voltage stays above 11V all is good. Motor running >14V all is good (batteries are being charged).

I have three batteries on board and the they are isolated "off" when at home.  Packing the boat, I have to tilt the motor up, so I switch any two online and run that way all day - a) because of what I had learnt about my motor always needing a working battery and, b) because the anchor winch manufacturer recommended to spread the winch load across two batteries.  So I have the third battery offline as backup.  When home, I plug in a charging cable that hooks up all three batteries to a trickle charger.

I could wire in a VSR to keep all my batteries topped up while underway but I can't justify it at present given the little additional benefit it would buy me.

If I was setting up a smaller boat, I'd pretty much do the same with just two batteries (everything runs off one or the other battery) with a switch that gave me: Off, 1,2, Both.....  I'd carry a jump pack as @JonD suggests in the unlikely case both batteries are run flat. 

Cheers Zoran

 

 

[dmck]

.... wish I was close to 60.... instead of long past it.........😢

[back cruncher]

Hi all...good reading fellas.ive had duel batteries in all my 4x4 vehicles for around 30 yrs.one thing I’ve found out is I have always been able to start my diesel vehicles with 2 flat batteries.or should I say 2 batteries beyond repair that won’t hold charge.

Edited August 19, 2019 by back cruncher