Boat Re-Wire

[Lovey80]

Hi all.

I’ve bought at newer Webster Twinfisher that I’ve decided to re-wire myself. That could turn out to be a mistake but I really want to know the ins and outs of the whole wiring system so that I can fault find any issues when I’m away camping as it has got me unstuck with the old boat in the past. I’m hoping the resident electrical gurus can guide me along as I go.

first step is getting the two batteries wired up correctly.

I have a BEP VSR that will be located close to the start battery under the gunwhale. From the VSR to the house battery (163Ah Calb Lithium) I have a 4m run. From where the bus bars under the console will be located to where the Anderson plug for the 12v Minnkota will be mounted is a 3.5m run.

There will only be approximately 11.5amps from the outboard available once the start battery hits 13.7v. I’ll be keeping the house topped up before fishing trips with a separate charger.

Start Battery will have the outboard, Minnkota Heading Sensor, and maybe one or two small LED lights running off it.

House Battery will run the rest of the electrics including the MinnKota, 10in Garmin Combo, VHF/Radio, 12v lighter socket outlets, 2 small bilge pumps, Nav lights, LED lights, a big deck wash pump (that will also run the live bait tanks) and a Furuno FCV 620

First question: What gauge tinned wire is sufficient for the 4 and 3.5m runs?

Second Question: What bus bars are recommended for under the console to run the Minnkota and the rest of the electrics.

Third Question: I want to run the Furuno off the same power lines as the MinnKota. If I put a say 75amp fuse before the Anderson plug on the positive line. Wire the Furuno power plug to the same Anderson plug terminals with the appropriate sized fuse for the Furuno. Will that be safe?

Basically the Furuno will have its tranny clamped to the TM so will only be used when the TM is running I have the option of putting a second switch up the front for the Furuno if I don’t want it running at the same time as the TM.

as always. Any help is greatly appreciated.

[baitable]

Search Victron toolkit in the App Store . Will answer all your questions

[baitable]

And don’t run Furuno off minn kota power feed. Keep a clean power run to minimize noise. Furuno will also wig out with power drops when mk switches on

[552Evo]

Hi Lovely80

What style start battery do you have ?

Do you have any particular setup for charging the calb lithium house battery ?


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[Lovey80]

Hi Lovely80

What style start battery do you have ?

Do you have any particular setup for charging the calb lithium house battery ?


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The Start battery is a 40Ah Winston lithium. As I couldn’t get any real advice on using this set up and one piece of advice concerning the low output of the outboard suggested that the 13.7 cut-off in the VSR should provide some protection for the batteries (looking for BMS options also). Along with keeping the batteries near full before going out should provide some measure of keeping the charging draw lower I am going to go with this and test it.

[Lovey80]

Search Victron toolkit in the App Store . Will answer all your questions

thanks for that. Will come in handy.

one thing I can’t get my head around with VSR’s. I’m hoping someone can answer.

if my outboard alternator/stator/regulator is putting out 11.5 amps into the start battery and the VSR is set to 13.7volts. When the start battery hits 13.7volts and the VSR combines both batteries. Is the extra 11.5 amps from the alternator all going to the house battery only?

Or if the house battery is say 12.4 volts and the start battery gets to 13.7volts that triggers the relay. Is both the outboard pumping in 11.5amps PLUS the start battery throwing huge amounts of power towards the house battery as they level out? If so, how many amps can I expect the house battery to draw from the start battery until it cuts out at 12.8volts?

If the latter is the case, and the start is lithium which can discharge large amounts of power, I could be looking at large amounts of power transfer down the 4m cable. Even more so if the house gets very low? How can I calculate that?

edit: I suppose if that number can be potentially very large I can put in a DC/DC charger in the line to the house to regulate the amps the house draws?

[552Evo]

What outboard are you running?


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[baitable]

thanks for that. Will come in handy.

one thing I can’t get my head around with VSR’s. I’m hoping someone can answer.

if my outboard alternator/stator/regulator is putting out 11.5 amps into the start battery and the VSR is set to 13.7volts. When the start battery hits 13.7volts and the VSR combines both batteries. Is the extra 11.5 amps from the alternator all going to the house battery only?

Or if the house battery is say 12.4 volts and the start battery gets to 13.7volts that triggers the relay. Is both the outboard pumping in 11.5amps PLUS the start battery throwing huge amounts of power towards the house battery as they level out? If so, how many amps can I expect the house battery to draw from the start battery until it cuts out at 12.8volts?

If the latter is the case, and the start is lithium which can discharge large amounts of power, I could be looking at large amounts of power transfer down the 4m cable. Even more so if the house gets very low? How can I calculate that?

edit: I suppose if that number can be potentially very large I can put in a DC/DC charger in the line to the house to regulate the amps the house draws?

you wont need a VSR if you run DC2DC

[Lovey80]

What outboard are you running?


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2013 Suzuki DF60

[Lovey80]

you wont need a VSR if you run DC2DC

VSR bought and going in tomorrow. Are you able to answer the current draw between the two?

[scottar]

Current question - no and yes - depends on whether the start battery is fully charged. If it still wants to draw current at the voltage being put out by the alternator it will. If it is fully charged, all excess available current will flow to the house battery.

Are you using a battery switch? Is your house battery capable of being used as a secondary starting battery? This will in part determine your cable requirements as it will be the highest current draw. 2B&S should be ample for anything starting related over those distances for that engine. If you are using a battery switch and don't yet have one and your house battery is starting capable, the Blue Seas 5511E is a good option - one switch switches both banks on - the second position parallels. Your VSR simply goes between the output terminals of both banks.

Minn Kota off the same bank as your sounders could be problematic. The speed controllers of these use pulse width modulation at a guess - inherently noisy and reports of interference issues do seem to be pretty common. MK do make a point of saying the battery bank should run the motor and basically nothing else. In my small rig, I run a stand alone small lead acid purely for the sounder. Problematic if doing extended trips and with bigger displays due to current draw though.

Bus bars - big fan of these style of things these days - compact and keeps all the fuses for accessories in one area. No good for the MK though. It really should have it's own dedicated circuit breaker.12 Way Fuse Block with Bus Bar | Jaycar Electronics If you do want to split supplies they do a smaller one as well - might need a couple.

[552Evo]

Hi all.

I’ve bought at newer Webster Twinfisher that I’ve decided to re-wire myself. That could turn out to be a mistake but I really want to know the ins and outs of the whole wiring system so that I can fault find any issues when I’m away camping as it has got me unstuck with the old boat in the past. I’m hoping the resident electrical gurus can guide me along as I go.

first step is getting the two batteries wired up correctly.

I have a BEP VSR that will be located close to the start battery under the gunwhale. From the VSR to the house battery (163Ah Calb Lithium) I have a 4m run. From where the bus bars under the console will be located to where the Anderson plug for the 12v Minnkota will be mounted is a 3.5m run.

There will only be approximately 11.5amps from the outboard available once the start battery hits 13.7v. I’ll be keeping the house topped up before fishing trips with a separate charger.

Start Battery will have the outboard, Minnkota Heading Sensor, and maybe one or two small LED lights running off it.

House Battery will run the rest of the electrics including the MinnKota, 10in Garmin Combo, VHF/Radio, 12v lighter socket outlets, 2 small bilge pumps, Nav lights, LED lights, a big deck wash pump (that will also run the live bait tanks) and a Furuno FCV 620

First question: What gauge tinned wire is sufficient for the 4 and 3.5m runs?

Second Question: What bus bars are recommended for under the console to run the Minnkota and the rest of the electrics.

Third Question: I want to run the Furuno off the same power lines as the MinnKota. If I put a say 75amp fuse before the Anderson plug on the positive line. Wire the Furuno power plug to the same Anderson plug terminals with the appropriate sized fuse for the Furuno. Will that be safe?

Basically the Furuno will have its tranny clamped to the TM so will only be used when the TM is running I have the option of putting a second switch up the front for the Furuno if I don’t want it running at the same time as the TM.

as always. Any help is greatly appreciated.

Sorry I started to reply and deleted the lot by mistake then I saw Scottars post. [emoji106]Fantastic advice as always
Nothing to see here,,,,,

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[tunaticer]

Your biggest power user outside of your engine is the minn kota. run the earth direct to the battery terminal and the positive direct from the battery through a circuit breaker...keep these cables as short as possible.

Electric motors can interfere with clean power supply for the sounder so better off running the sounder off a 3rd battery alone, Charge it with a VSD. Wire the sounder directly to the battery terminals, not through a bus bar and switch.

A lot will depend on how long you drive the boat to a destination, short runs may not keep the crank battery charged fully and may not let the VSD make the switch to the house battery.

[scottar]

Wire the sounder directly to the battery terminals, not through a bus bar and switch.

.

Not necessary if the rest of your wiring is up to speed. I've seen more problems caused by this over the years than it has fixed - usually as a result of having small diameter cables and fuse holders in an area of the boat that if not cared for properly is inherently prone to water damage and the resulting corrosion.

[Dignity]

The other question I'd raise is what happens when both lithium batteries are fully charged. Recent posts here indicate that the BMS of the batteries shut down and refuse further charge and start blowing electronic components on the motor. Is this the case, I don't know but is a definite possibility on older motors but with newer motors one would hope that this wasn't the case.