Power for electronics during engine start

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timjet

timjet

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Apr 9, 2009
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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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Why not go direct from 12V panel to instruments? I have about 6 12V breakers to handle all instruments with no problems
 
sunchaser said:
Why not go direct from 12V panel to instruments? I have about 6 12V breakers to handle all instruments with no problems
Click to expand...

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.
 
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.
 
Moonstruck said:
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.
Click to expand...
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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Or wait until the engines are started to turn on electronics. I do that quite often to avoid the potential of what you describe.
 
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.

img_164132_0_90812851ade0b2b1b59f52641c05b5e1.jpg
 
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.

img_164142_0_2d9be0da8f7c6c157f2e9be77d9b4da3.jpg
 
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.
 
timjet said:
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.
Click to expand...

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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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.
 
sunchaser said:
Or wait until the engines are started to turn on electronics. I do that quite often to avoid the potential of what you describe.
Click to expand...

Yes the KISS principal which in the end is always best. I'm considering adding "Turn off Electronics" on my before start check list.

Moonstruck said:
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.
Click to expand...

Yup that should do it. It just seems like a lot of work to simply protect the electronics.

HopCar said:
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

sg.jpg
Click to expand...

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

AusCan said:
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.
Click to expand...

But your 36 HP volvo won't move my 2BR 2BA floating condo at 20 kts.
 
FlyWright said:
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.
Click to expand...

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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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.
 
psneeld said:
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.
Click to expand...

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.
 
timjet said:
Yup that should do it. It just seems like a lot of work to simply protect the electronics.
Click to expand...

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.
 
timjet said:
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.
Click to expand...

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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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
 
Well I've decided to keep it as simple as I can and in the process try and improve my memory. I'm going to leave my electrical system as is and REMEMBER to turn off the electronics before engine starting.

Paul was very helpful in designing an electronics battery setup for me and that's the way I'll go if my memory fails me.
 
I guess I do not really understand the issue here. Our chartplotter has sometimes gone off line if we start with it operating. We no longer do this on the basis that it probably does no good to the electronics and we do not need the electronics activated until the engine has been started. So our usual routine is to start the main engine and let it idle for e few minutes while we get the rest of the boat finally ready to move, and that includes turning on electronics.
 
There are reasons that your electronics would be on and you need to start your engine...

They shouldn't drop offline, especially if you needed them quickly after starting say at anchor in the fog/night and you needed to move quickly. Not many times...but they could arise.

There are many fixes; some very simple, inexpensive and as I always recommend...a bridge/pilothouse electronics battery is a good idea and mandatory as a safety item by the USCG on commercial fishing vessels.
 
psneeld said:
There are reasons that your electronics would be on and you need to start your engine...

They shouldn't drop offline, especially if you needed them quickly after starting say at anchor in the fog/night and you needed to move quickly. Not many times...but they could arise.

There are many fixes; some very simple, inexpensive and as I always recommend...a bridge/pilothouse electronics battery is a good idea and mandatory as a safety item by the USCG on commercial fishing vessels.
Click to expand...


While my electronics are unaffected by starting our engines (we have always run a separate house bank) I have often thought about a separate electronics battery in case of emergency.

For example if you were experiencing a flooding event, many battery banks are low in the hull (for good reason) making house power one of the first things that goes out in an emergency.

I've always thought that a small 12 volt battery that just powers the VHF would be invaluable as a guaranteed way to call for help.
 
ksanders said:
While my electronics are unaffected by starting our engines (we have always run a separate house bank) I have often thought about a separate electronics battery in case of emergency.

For example if you were experiencing a flooding event, many battery banks are low in the hull (for good reason) making house power one of the first things that goes out in an emergency.

I've always thought that a small 12 volt battery that just powers the VHF would be invaluable as a guaranteed way to call for help.[/QUOTE]

Smart man...as I said..after 35 years of assisting boaters...both I and the USCG think so too.
Click to expand...
 
If safety is the concern the 35mm parachute flair set might be a better deal than hand held.
 
DC-DC converters | Mastervolt Marine

When I put several ten grand of electronics on an ocean-going sailboat, with a smallish diesel engine and smaller generator, the electronics manufacturer could not solve the problem of electronics dropping out when engines were started. The manufacturer provided a DC DC converter free of charge in lieu of having to deal with a significant produict return. All agreed the electrical system was well designed and installed.

On a sailboat where engines are not necessarily running you don't want to have to shut things down to start an engine, or a generator.
 
"On a sailboat where engines are not necessarily running you don't want to have to shut things down to start an engine, or a generator."

That's why there is a set of house batts and a different battery to start the engine.

NO problem if they are not joined during engine start.

If they are joined during start its an operator problem , or a rotten electric system that was not thought out properly during the boats construction..

This is a non existiant "problem" for 99% of boats.
 
FF said:
"On a sailboat where engines are not necessarily running you don't want to have to shut things down to start an engine, or a generator."

That's why there is a set of house batts and a different battery to start the engine.

NO problem if they are not joined during engine start.

If they are joined during start its an operator problem , or a rotten electric system that was not thought out properly during the boats construction..

This is a non existiant "problem" for 99% of boats.
Click to expand...

FF while I agree it SHOULD be a non problem...I bet there's a lot more than 1% of boats out there with 2 engines and 2 batteries (sometimes a second attached to another to make a third and the 2 batts together is called the house bank.

My old Silverton with twin cat 3208s had one 8D per engine and one was assigned as the "house" batt. I've worked on hundreds of boats that were set up similar...and as I said in one post or another...most boaters are pretty clueless about electrical systems...especially the care and feeding of batteries.
 
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