Boat Re-Wire

[baitable]

Exactly why you use lead acid to accept charge from your outboard then use a dc2dc to send charge to house batteries. It’s safe a idiot proof.

[Lovey80]

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.

I’ve thought about this a lot. The Winston lithium’s can take huge amounts of charge before they start to go nuts. I figure I’ll set the Winston BMS to only open circuit at around 14.8volts. 14.6 is considered fully charged and I’d probably run out of fuel before both banks are above 14.6 anyway with such a small output from the outboard. If the outboard is running the sounder is, almost all the time. I’ll have a battery monitor on both batteries so if I see them get anything close to 14.6 volts I’ll just throw some lights or something on.

my biggest worry is the opposite. The banks being too low and cooking the stator.

[Lovey80]

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.

thanks Scottar- Bloody legend.

I have one of these that I’m hopefully putting in tomorrow. https://chsmith.com.au/Products/BEP-...hoCImQQAvD_BwE

the VSR. Does it parallel both batteries when it charges the house? I’m just thinking of a likely scenario where I take a fairly long run to the fishing spots then long hours of spot locking or casting lures with hardly any outboard use. If I’ve used say 80 of the available 160 amps in the house and I start up for the run home with an essentially full starter battery how many amps can I expect the house to draw initially?

edit: will running two leads from the house battery, 1 to the bus bar and one to the TM through a breaker help with noise issues?

[scottar]

my biggest worry is the opposite. The banks being too low and cooking the stator.

A legitimate concern - contact Suzuki and see if they have a duty cycle rating for full output use.

thanks Scottar- Bloody legend.

I have one of these that I’m hopefully putting in tomorrow. https://chsmith.com.au/Products/BEP-...hoCImQQAvD_BwE

the VSR. Does it parallel both batteries when it charges the house? I’m just thinking of a likely scenario where I take a fairly long run to the fishing spots then long hours of spot locking or casting lures with hardly any outboard use. If I’ve used say 80 of the available 160 amps in the house and I start up for the run home with an essentially full starter battery how many amps can I expect the house to draw initially?

edit: will running two leads from the house battery, 1 to the bus bar and one to the TM through a breaker help with noise issues?

Yes, the VSR will parallel the batteries. They are essentially an automatic paralleling switch.

High current between the batteries - also a legitimate concern. Pretty much everything I can find on lithium charging mentions the first stage of a lithium charging profile being "constant current" to avoid the batteries overheating. Your scenario of paralleling a half charged unit with a fully charged one could see significant current flowing between the batteries. This is something that a DC-DC charger is a solution for as it will limit the current to it's maximum output. This could actually upset the BMS in your starting battery with an extended high current output - causing an open circuit situation. I'm only "internet educated" on lithium's - I would strongly recommend running your plan past your battery supplier before proceeding.

[Lovey80]

Ok so I’ve learned a few things so far with the re-wire. BTW big thanks to everyone so far that have contributed.

1. Even with some thought behind it, getting the cart before the horse is extremely difficult when you’re trying to push wires around rod holders etc and trying to make the best use of space available.

2. Calb lithium cells don’t all have the same terminals. On my house battery the terminal 6mm threaded ally plate is spot welded to a base plate on the top of the battery. On the earth side, I had too thick a set of earth leads for the 6mm SS bolt that is supplied to easily secure them all. Not thinking it through properly I went to a slightly longer bolt. Too long. The base plate isn’t threaded/drilled out and the pressure of the bolt separated the base plate and the terminal plate. That left me very depressed last night as it was the last thing before a tidy up and it all had to come out today so I could get the terminal welded back onto the base plate.

3. The BEP Digital VSR is constantly paralleling both batteries if the volts are above 12.8. I thought the VSR would only parallel them if the start battery was above 13.4v AND there was power coming from the engine. That is not the case as the engine hasn’t been started and the VSR’s led has been on since I connected all the wires.

4. The Victron 712 Smart Shunt is supplied with a very long Cat 5E cable that has RJ12 terminals (the smaller telephone cable type plugs not the larger Ethernet type that typically comes with Cat 5E cable) on both ends. Already with space at a premium under the console I didn’t want another mass of bundled up and zip tied wires under there. So I went back to Jay car for the 10th time since I started this thread, and bought a 1m RJ12 cable. Upon connecting it up to the Victron gauge the low voltage alarm went off and it was showing 7v on both batteries. Today I took it back to Jaycar and the very helpful dude there put both cables into a little tester thingy he had. Turns out the RJ12 cable will work perfectly fine with the shunt, it just needs one of the plug ends reversed 180. Tip for those going through this process.

4. I hope someone can help me with this because it doesn’t make sense. I bought the bus bar that Scottar recommended. I wired in a breaker between the house battery and the bus bar. All went well. The bus bar is currently receiving about 13.4v. Yet with no fuses in any of the positive outlets. The positive terminals of the bus bar are still receiving 11.54v.

Why would this be? To still give power to the little led indicators that a fuse is blown? In my mind, if I have a short somewhere, say on the 25A Salt water pump and the fuse blows, I want zero power going through that circuit not 11.54 volts. Is this normal and should I be as concerned as I am?

[scottar]

Most VSR's these days have a small loop of wire that can be cut and wired to a 12 volt "ignition" so that the VSR is only active when the engine ignition is on. The instructions for your VSR will cover this.

The voltage reading is caused by the indicator circuit for the blown fuse LED. Nothing to worry about.

[Lovey80]

Thanks Scottar. After posting I went and ran a wire to a low draw led light. Not a thing without the fuse in but the multimeter still reads 11.52 volts. Got me buggered.

[tjotter]

In my limited experience:

A volt meter (or meters) to monitor battery can be handy, especially if you are out on the water and the outboard is turned off. Some plug into a cigarette lighter or usb slot.

Bus bars are great, especially if you are going to tweak or fine tune things later.

I added a Anderson plug to my batteries, can disconnect batteries from boat circuit and plug in 240v charger without having to disconnect terminals and box covers etc, handy through winter.

Batteries with threaded, and or double posts, are easier to work with.



Sent from my SM-T820 using Ausfish mobile app

[scottar]

Thanks Scottar. After posting I went and ran a wire to a low draw led light. Not a thing without the fuse in but the multimeter still reads 11.52 volts. Got me buggered.

Bit of info on the sort of basic "blown fuse" indication usually found in these.

Blown Fuse Indicator (theorycircuit.com)

The reason the meter will show a voltage is because it draws so little current that the resistor doesn't drop an appreciable amount of voltage. The test light on the other hand does so the voltage drops to ground or thereabouts and there isn't sufficient to light the globe.

[scottar]

I added a Anderson plug to my batteries, can disconnect batteries from boat circuit and plug in 240v charger without having to disconnect terminals and box covers etc, handy through winter.

Just be mindful of making sure that the Anderson always has good clean contacts and can never be disconnected with the engine running. If this happens it can result in irreparable damage to electric modules in your outboard as well as damaging anything electrical connected at the time. Without the load imposed by the battery on the charging circuit, some outboard charging systems outputs can jump to in excess of 100 volts DC. Nothing electrical on your boat likes this happening - light bulbs blow and most electronic devices will also fail.

[Lovey80]

Bit of info on the sort of basic "blown fuse" indication usually found in these.

Blown Fuse Indicator (theorycircuit.com)

The reason the meter will show a voltage is because it draws so little current that the resistor doesn't drop an appreciable amount of voltage. The test light on the other hand does so the voltage drops to ground or thereabouts and there isn't sufficient to light the globe.

That’s really interesting Scottar. The blow Fuse light lights up with a touch of a finger. Like it thinks my fingers is a load.

[Lovey80]

Fingers crossed tomorrow I’ll finish off this re-wire. One thing that’s annoying me is that with both breakers isolated so that I’m drawing no power other than the Victron BMV 712 shunt and gauge. It’s showing 0.07Amp draw when I have everything isolated. The shunt is supposed to only draw 0.01Amps.

[Jarrad stevenson]

Who would have thought 12v circuitry would be so complex.

My new boat runs a very simple twin battery setup with everything running from a single battery and an isolation switch allowing you to switch to the 2nd battery in need. I don’t run an electric of course and Have a 175HP Evinrude G2 which has a high charging output. I’d considered changing the setup to have a dedicated house battery but after reading the above I think my simple setup would actually be best for my use. I needed to replace my 2nd battery so going a semi deep cycle high CCA option to cover both grounds. If I have a long run in the boat I’ll switch the isolator to Both to run batteries in parallel and charge both batteries - then switch back to single battery on isolator when I arrive.

Does the above sound reasonable?

[Lovey80]

Who would have thought 12v circuitry would be so complex.

My new boat runs a very simple twin battery setup with everything running from a single battery and an isolation switch allowing you to switch to the 2nd battery in need. I don’t run an electric of course and Have a 175HP Evinrude G2 which has a high charging output. I’d considered changing the setup to have a dedicated house battery but after reading the above I think my simple setup would actually be best for my use. I needed to replace my 2nd battery so going a semi deep cycle high CCA option to cover both grounds. If I have a long run in the boat I’ll switch the isolator to Both to run batteries in parallel and charge both batteries - then switch back to single battery on isolator when I arrive.

Does the above sound reasonable?

for your use that’s more than reasonable.

[tunaticer]

rewired my boat last weekend....now schmicko....