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Old 06-21-2013, 12:08 AM   #1
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Power for electronics during engine start

Well I've discussed this before with some folks here on TF and at Blue Seas and even tried installing a DC-DC converter that didn't work. With my new electronics I don't want the stuff going off line every time I start the engines.

Blue Seas makes a "Add a Battery" kit that is a battery selector switch that works in combination with a ACR (automatic charging relay). If you install the start isolation wire it will keep the house battery bank and engine start battery bank isolated until both engines are started thus accomplishing what I want. However there is a big draw back to this setup. After the engines are started you cannot select the charging current to the lowest bank, the ACR sends the charge equally to both banks. After being on the hook overnight I want all the charging amps from the alternators going to the house bank. Currently to do this I simply select the house bank on the battery selector switch after the engines are started and all the current goes to the house bank.

So back to square one. How bout I install a small wet cell battery at the helm that powers all the electronics and through a diode is charged by the alternators. Thus when I start the engines, the electronics are unaffected because they are powered by their own battery.

Below is a diagram.

Question; will the battery charge from the alternators through the ships battery? I put the diode in to prevent the electronics battery from back flowing into the ships battery. Is this correct and necessary?
Any other comments?

Thanks guys.
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Old 06-21-2013, 12:13 AM   #2
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Why not go direct from 12V panel to instruments? I have about 6 12V breakers to handle all instruments with no problems
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Old 06-21-2013, 12:21 AM   #3
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Why not go direct from 12V panel to instruments? I have about 6 12V breakers to handle all instruments with no problems
On my boat I can isolate the house and start battery banks but I cannot isolate the engine start load and the house loads where the electronics are connected. Thus regardless of which position I place the battery switch in, the electronics will be powered by the same bank that's starting the engines. Voltage will go below the electronics threshold when the engines start and the electronics will turn off.
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Old 06-21-2013, 12:29 AM   #4
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Capt. Tim, are you running your house and starting banks in parallel? I have the electronics powered by the house bank that is isolated from the starting bank. No issues with voltage draw down. The 500 hp diesels take a lot of cranking power, but that recovers very quickly. The house bank is not affected. They can be paralleled in an emergency, but I have never had to do it. Can you separate those circuits or even run them from a sub-panel? It shouldn't be that complicated.
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Old 06-21-2013, 12:41 AM   #5
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I have the electronics powered by the house bank that is isolated from the starting bank. No issues with voltage draw down.
Don, I can't isolate the loads only the battery banks. Everything is powered by the battery bank that is selected on the battery selector switch. I cannot have the start bank start the engines and have the remaining house loads including the electronics on the house bank.
The 500 hp diesels take a lot of cranking power, but that recovers very quickly. The house bank is not affected.
Since I cannot isolate loads the house bank is affected when I start engines.
They can be paralleled in an emergency, but I have never had to do it. Can you separate those circuits or even run them from a sub-panel? It shouldn't be that complicated.
Yes I think so but that would be far more complicated than the setup I devised above. I think you may have an ACR which will isolated the loads but I get back to the problem of not being able to charge the house bank quickly when needed. We anchor out a lot so re-charging the house bank quickly is important.

I think there is probably a way of directing the charging current to the lowest charged bank, and that with an ACR would solve the problem of quickly charging the lowest bank and isolating the loads during start. Probably a lot more cabling and devices needed to do this though.
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Old 06-21-2013, 12:54 AM   #6
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Or wait until the engines are started to turn on electronics. I do that quite often to avoid the potential of what you describe.
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Old 06-21-2013, 12:55 AM   #7
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Capt. Tim, take a look at this

Promariner Proisocharge Battery Isolator 130amp 2-Alt 4-Bat - 12v

It will combine your alternators as well as isolate your battery banks. It will direct the charge to the bank that needs it most.

I think that Hodges Marine is located not too far from you. Maybe you could run up and take a look.
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Old 06-21-2013, 01:48 AM   #8
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Take a look at the Newmar StartGuard.
DC Power Onboard with Newmar’s DC Power Conditioners. Newmar’s power array of dc conditioners provide stabilizing voltage during engine crank, voltage stabilizers with Isolated DC-DC converters, electronic noise filters and automatic powe

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Old 06-21-2013, 01:48 AM   #9
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Many boats come with the loads routed through the start cables to provide simultaneous selection of load and charge through the battery switch(es). In this setup, your loads are automatically tied to the charge preference you have selected. It sounds to me like your boat is set up in this manner.

Like in an airplane, I'd split the loads and power sources so either alternator can supply power to each battery separately or both batteries (if desired) and house and start loads are either split or combined as you deem necessary. It's relatively easy to do and allows you total control over your electron flow. When house and start loads are isolated, the electronics won't see a voltage sag or spike during engine start.

Don's suggestion for the Promariner Proisocharge Isolator looks like a great product to automatically manage the charge side of the equation.

Isolating power distribution to the house buss and start feeds can be done by recabling the heavy cables through battery switches (outside of the ER) to the buss(es). With properly routed power distribution and controls, you'll have as much authority over loads and charges as you would in any transport category airplane you'd fly.

That was my goal in recabling my boat and I am very satisfied with the results.

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Old 06-21-2013, 02:54 AM   #10
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Electricity befuddles me. So far I've kept out of trouble by keeping the engine's starter battery unconnected to the house batteries. Think it's wise to have a battery monitor.

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Old 06-21-2013, 05:39 AM   #11
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One advantage of having a small engine is the low power requirement for starting. I get very little voltage drop to start the 36hp volvo, and the electronics don't notice it.
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Old 06-21-2013, 06:57 AM   #12
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Quote:
Originally Posted by timjet View Post
Well I've discussed this before with some folks here on TF and at Blue Seas and even tried installing a DC-DC converter that didn't work. With my new electronics I don't want the stuff going off line every time I start the engines.

Blue Seas makes a "Add a Battery" kit that is a battery selector switch that works in combination with a ACR (automatic charging relay). If you install the start isolation wire it will keep the house battery bank and engine start battery bank isolated until both engines are started thus accomplishing what I want. However there is a big draw back to this setup. After the engines are started you cannot select the charging current to the lowest bank, the ACR sends the charge equally to both banks. After being on the hook overnight I want all the charging amps from the alternators going to the house bank. Currently to do this I simply select the house bank on the battery selector switch after the engines are started and all the current goes to the house bank.

So back to square one. How bout I install a small wet cell battery at the helm that powers all the electronics and through a diode is charged by the alternators. Thus when I start the engines, the electronics are unaffected because they are powered by their own battery.

Below is a diagram.

Question; will the battery charge from the alternators through the ships battery? I put the diode in to prevent the electronics battery from back flowing into the ships battery. Is this correct and necessary?
Any other comments?

Thanks guys.
Simple and inexpensive.

What I did on my sportfish to keep the electronics from shutting down on starts.

What we did to hundreds of others when I worked for a marine electronics company.

What many comm fishermen do as the USCG requires a separate pilothouse power source for safety/emergency communications radio.

What I would do to any vessel that running a large size 12V feed to the flybridge area would be a problem.

A small lawn tractor battery would be sufficient...maybe even a sealed "home security system sized battery"...I just used an old car battery that kept a charge but had lost a lot of it's cranking amps...worked great for 3 years till I sold the boat.
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Old 06-21-2013, 07:51 AM   #13
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This is an interesting post since the PO of our boat had a log book with info passed on to him and one item in it says "turn off all electronics before starting boat". The boat has a single starting battery and 4 golf cart house batteries. I have never had to turn off things on any other boat I have had so I decided to try it out. Tried with the selector on House and then on Start and in neither case with the Stereo and the Chartplotter running did it shut anything off. May not be good for them?? I normally don't have anything on until I start the boat anyway.
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Old 06-21-2013, 10:02 AM   #14
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Or wait until the engines are started to turn on electronics. I do that quite often to avoid the potential of what you describe.
Yes the KISS principal which in the end is always best. I'm considering adding "Turn off Electronics" on my before start check list.

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Originally Posted by Moonstruck View Post
Capt. Tim, take a look at this

Promariner Proisocharge Battery Isolator 130amp 2-Alt 4-Bat - 12v

It will combine your alternators as well as isolate your battery banks. It will direct the charge to the bank that needs it most.

I think that Hodges Marine is located not too far from you. Maybe you could run up and take a look.
Yup that should do it. It just seems like a lot of work to simply protect the electronics.

That pretty much is what I diagrammed above at 3X the cost.

Quote:
Originally Posted by AusCan View Post
One advantage of having a small engine is the low power requirement for starting. I get very little voltage drop to start the 36hp volvo, and the electronics don't notice it.
But your 36 HP volvo won't move my 2BR 2BA floating condo at 20 kts.
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Old 06-21-2013, 10:21 AM   #15
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Many boats come with the loads routed through the start cables to provide simultaneous selection of load and charge through the battery switch(es). In this setup, your loads are automatically tied to the charge preference you have selected. It sounds to me like your boat is set up in this manner.

Like in an airplane, I'd split the loads and power sources so either alternator can supply power to each battery separately or both batteries (if desired) and house and start loads are either split or combined as you deem necessary. It's relatively easy to do and allows you total control over your electron flow. When house and start loads are isolated, the electronics won't see a voltage sag or spike during engine start.

Don's suggestion for the Promariner Proisocharge Isolator looks like a great product to automatically manage the charge side of the equation.

Isolating power distribution to the house buss and start feeds can be done by recabling the heavy cables through battery switches (outside of the ER) to the buss(es). With properly routed power distribution and controls, you'll have as much authority over loads and charges as you would in any transport category airplane you'd fly.

That was my goal in recabling my boat and I am very satisfied with the results.
Art, that's a well thought out system. I'm headed down to SJO and back to CLT today so I'll have some time to study it.

The aircraft enginneers don't always get it right either.
Our airbuses have a Arinc phone that when activated provides a direct radio link to Arinc and then if necessary to MedLink and our dispatch. A nice system and relieves the necessity of trying to contact Ainc on the radio which I find sometimes very difficult especially in the Caribbean.
Last month I had to accomplish a fume evacuation procedure because the F/A were complaining about an odor in the cabin of which we could smell too. The procedure is to remove galley power first to eliminate the possibility of the odor coming from galley use items. Well guess where the Arinc phone is connected to. Yup, the galley bus.

We were headed to LAX and had to divert to MSY and trying to contact the company while following the fume evacuation procedure, working with ATC about the re-route and notifying the company of our situation became a handful that would have been made much easier with that phone.

Well the airbus manta certainly applies: Unintended consequences and Loss of situational awareness.

But not to be undone, below is a schematic of my electronics setup with the proposed electronics battery.
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Old 06-21-2013, 10:22 AM   #16
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I'm not one for gadgets but I am very happy with my BlueSeas ACR-SI @$80. Combines banks automatically if either bank is charging, isolates automatically when starting or when not charging.
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Old 06-21-2013, 10:25 AM   #17
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Simple and inexpensive.

What I did on my sportfish to keep the electronics from shutting down on starts.

A small lawn tractor battery would be sufficient...maybe even a sealed "home security system sized battery"...I just used an old car battery that kept a charge but had lost a lot of it's cranking amps...worked great for 3 years till I sold the boat.
Exactly what I diagrammed above. How did you keep the battery charged?
With Radar I estimate I will draw about 15 amps. The battery won't last long at that rate without being recharged.
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Old 06-21-2013, 10:35 AM   #18
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Yup that should do it. It just seems like a lot of work to simply protect the electronics.
Tim, that is just one advantage of the IsoCharge. The big advantage is that it will combine the outputs of your two alternators to charge the bank in most need of charging. After topping up the start batteries which should only take a few minutes, it will pack a double amount of charge into your house bank. You should have near a 100% charge in your house bank when anchoring after a run.
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Old 06-21-2013, 10:38 AM   #19
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Exactly what I diagrammed above. How did you keep the battery charged?
With Radar I estimate I will draw about 15 amps. The battery won't last long at that rate without being recharged.
Just hook it up to an engine start batt (assuming it gets fully charged pretty quick thus even with the diode loss it will still fully charge after several hours of the start batt being fully charged.

Of course use a fuse/cb on the beginning and end of run.

Throw a littlw solar charger or tiny batt charger when plugged in on it if it doesn't stay charged the way you are using it. I had a direct run between the 2 batts so it stayed as charged as my start batts...even while docked on the charger....not through an accessory switch (hook it to the hot side of the acc switch.
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Old 06-22-2013, 01:21 PM   #20
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The reason it is best practice to not have electrical items on line with the start battery is the chance of a hung starter.

The starter is geared to the flywheel at a huge ratio, so if the Bendex does not drop out quickly enough that huge gearing spins the starter. The gearing is such that 100+V DC can easily be tossed into whats on.

Just a dozen LED , never mind all new electric toys makes the practice worthwhile.

On our boat we have 2 rotary switches , one to select the battery for start , the other to select the battery for the electric toys.

With (2) truck batts 8D as power it is simple to manage.

The drill is to start on the batt that has been supplying house power overnight .

This checks that our DC loads are within reason without a SOC meter.

Both rotaries to BOTH underway , and reselect for overnight , with the engine start rotary going to off.

We check the oil and fluids after shutdown , then select that nights batt.

KISS
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