Run electronics only from auxiliary battery

[ranmar850]

What Scottar said ^^^^ if you are running everything off a house battery, you are effectively isolated from the start the moment you hit the ignition key, if you weren't already. Typically, they switch off at 12.4v, effectively isolating House from Start, so if you have been running electronics /whatever for a while , it will be at/below the 12.4v. They will close and start charging the house battery at 12.7, which is effectively as soon as the engine is running. Moment you hit the key, they will switch off., as start battery voltage drops. Modern electronics are rather more sensitive than the old stuff, and need some caring for--cost of how much better they are. Fit a battery switch in parallel to it, set to Off for normal operation. If the VSR fails, which will manifest itself by the house batterry voltage slowly dropping, because it is not being charged, just turn that paralleing switch to On, and you are now running both batteries as Start. Are you now back to where you started? Not really, because you are starting with two batteries, and the voltage will not drop as much. But, best to replace it fairly soon.

[Dignity]

Electronics is just too testicle for me. I run a Start battery which is purely for starting, the trim tabs and the anchor winch. The house battery runs all of the rest and is charged from the motors auxiliary charging circuit which basically from my understanding splits the charging rate. The original dual switch (1, 2 or both) is still in play for emergency use and labelled accordingly. I modified it slightly so that you needed to pull a pin out to turn it from switch 1 so that no one accidentally switched it over.
Based on this scenario would I get away with a power conditioner on only the house battery. All my electronics are getting on and planning on what to do if replacements are in order.

[Moonlighter]

Duplicate post

[Moonlighter]

Does the VSR have a power conditioner or is that still needed to be added to the system.

No, but when the engine is turned off, within a few seconds the VSR disconnects the start battery from the house battery.

So when the engine is started, the items like sounders etc that run off the house battery cannot be affected by spikes thru the starting battery caused when the engine is started.

Simples.

[Dignity]

No, but when the engine is turned off, within a few seconds the VSR disconnects the start battery from the house battery.

So when the engine is started, the items like sounders etc that run off the house battery cannot be affected by spikes thru the starting battery caused when the engine is started.

Simples.

In my case I don't have a VSR as each battery is independently charged which then means I need a power conditioner on each circuit although the only thing that I can see being an issue would be the trim tab circuitry.

[seastrength]

Hi Guys
Just to clarify previous expert advice regarding voltage protection. In my case, I run a Lowrance HDS7 plotter / sounder from a main start battery (Seamaster Gold) with in line fuse for protection against voltage surge. I always start the main motor before turning on the sounder to avoid any voltage drop in the system. However, there are times during a session that I turn off the motor and switch to spotlock or track a route with my electric motor on a separate AGM battery (120 AH AmpTech). When I return to start the main motor, should I turn off the sounder before starting the main motor to avoid voltage drop and potential damage to the sounder? I have kept it on previously, but have not noted any alarm or error message to date. Thanks in advance. Cheers SS

[Fed]

Voltage drop won't hurt your sounder.

A ~25Kg battery is good at absorbing spikes and any high voltage.

[Dignity]

Voltage drop won't hurt your sounder.

A ~25Kg battery is good at absorbing spikes and any high voltage.

That is generally my what I thought might happen as there are a number of things running when the motor has been switched off. I think that is what Moonlighter was maybe also saying. My initial start of the sounder and GPS is after launch and in the water, in the meantime I've called the Coast Guard and the motor is running so no spikes there, but as Seastrength says it's once at at sea that things change. But as as I've mentioned before, electrikery is far to testical for me to understand. If I ever have to replace gear I might change the setup I have but in the meantime I'll stick with what is currently working.

[scottar]

Hi Guys
Just to clarify previous expert advice regarding voltage protection. In my case, I run a Lowrance HDS7 plotter / sounder from a main start battery (Seamaster Gold) with in line fuse for protection against voltage surge. I always start the main motor before turning on the sounder to avoid any voltage drop in the system. However, there are times during a session that I turn off the motor and switch to spotlock or track a route with my electric motor on a separate AGM battery (120 AH AmpTech). When I return to start the main motor, should I turn off the sounder before starting the main motor to avoid voltage drop and potential damage to the sounder? I have kept it on previously, but have not noted any alarm or error message to date. Thanks in advance. Cheers SS

One point of clarification. Fuses offer absolutely no protection against a primary failure when it comes to electronics. They do protect against a secondary failure (any further damage caused by high current draw created by the primary failure) which is basically a burnt out PCB in a lot of cases if the fuse protection is not present or too big. The fuses main job is fire prevention - it stops excess current heating the wiring to the point it catches fire. The reason a fuse usually blows is because the device has failed for whatever reason and is drawing excess current.

Should you turn the unit off........it's a grey area basically. Many people run electronics off a start battery ( me included for a lot of years) and have no issues. There are a few potential reasons for this - good batteries, good wiring, low current required for the starter, voltage tolerant electronics or a combination of the same. Others suffer the usual issue - equipment rebooting every time they start the engine - which can be caused by basically any of the opposites of the above factors. Potentially it can cause failures and in the later generation products that are "software heavy" it can cause obscure lock up faults or even failures. Shutting the unit down will prevent software lock up type situations but the time taken for modern equipment to reboot can be a real PITA.

[scottar]

In my case I don't have a VSR as each battery is independently charged which then means I need a power conditioner on each circuit although the only thing that I can see being an issue would be the trim tab circuitry.

Do you "need" to do it. In reality probably not Sam. Very few boats actually have a problem these days. Some people do fit them after having been told that there electronics failed due to "spiking" but in reality, it's near on impossible to tell. Running an individual house battery so the units aren't subject to voltage drop at each motor start and maintaining your wiring in good order will in reality stop 99.99 percent of issues IMO. Provided your charge output never exceeds the limits for a "normal" 12 volt circuit, I doubt you will have any issues. It doesn't guarantee stuff won't fail, but if it does, it's highly improbable the power supply was the issue.

[seastrength]

One point of clarification. Fuses offer absolutely no protection against a primary failure when it comes to electronics. They do protect against a secondary failure (any further damage caused by high current draw created by the primary failure) which is basically a burnt out PCB in a lot of cases if the fuse protection is not present or too big. The fuses main job is fire prevention - it stops excess current heating the wiring to the point it catches fire. The reason a fuse usually blows is because the device has failed for whatever reason and is drawing excess current.

Should you turn the unit off........it's a grey area basically. Many people run electronics off a start battery ( me included for a lot of years) and have no issues. There are a few potential reasons for this - good batteries, good wiring, low current required for the starter, voltage tolerant electronics or a combination of the same. Others suffer the usual issue - equipment rebooting every time they start the engine - which can be caused by basically any of the opposites of the above factors. Potentially it can cause failures and in the later generation products that are "software heavy" it can cause obscure lock up faults or even failures. Shutting the unit down will prevent software lock up type situations but the time taken for modern equipment to reboot can be a real PITA.

Scottar, would you recommend the VSR device for added protection of the sounder circuit. I rarely have to charge the start battery as I tend to troll, only the electric motor battery after each session, which I disconnect with the circuit breaker before charging. Thanks in advance. Cheers SS

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[scottar]

Scottar, would you recommend the VSR device for added protection of the sounder circuit. I rarely have to charge the start battery as I tend to troll, only the electric motor battery after each session, which I disconnect with the circuit breaker before charging. Thanks in advance. Cheers SS

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If I understood your initial post correctly Seastrength, you don't run a separate house battery to power your electronics. A VSR is purely a charging mechanism for a house battery that eliminates the house battery being subjected to any starting loads as it automatically disconnects as the voltage drops. As such - no - a VSR will not help you at all.

If you are wanting to protect your electronics, a power conditioner would be your best option if you want to remain running off the start battery - they aren't necessarily cheap though. It would be far cheaper to add another battery simply to run your sounder and charge it at the end of the day. All depends on whether you have the room or can be bothered messing around maintaining another battery. As I posted, boats all over the world run electronics off a starting battery without issue provided the necessary parameters are met. There would be just as many that run a house battery set up. I have had my own boats done either way. I have fitted power conditioners to clients boats but generally only in cases where equipment was known to be extremely voltage sensitive - usually happy to run on 12 volts but not necessarily at 14 (charging voltage). Would I bother with "normal " electronics though - probably not. If you are concerned about spiking and happy to spend the money though, they are an option.

[seastrength]

If I understood your initial post correctly Seastrength, you don't run a separate house battery to power your electronics. A VSR is purely a charging mechanism for a house battery that eliminates the house battery being subjected to any starting loads as it automatically disconnects as the voltage drops. As such - no - a VSR will not help you at all.

If you are wanting to protect your electronics, a power conditioner would be your best option if you want to remain running off the start battery - they aren't necessarily cheap though. It would be far cheaper to add another battery simply to run your sounder and charge it at the end of the day. All depends on whether you have the room or can be bothered messing around maintaining another battery. As I posted, boats all over the world run electronics off a starting battery without issue provided the necessary parameters are met. There would be just as many that run a house battery set up. I have had my own boats done either way. I have fitted power conditioners to clients boats but generally only in cases where equipment was known to be extremely voltage sensitive - usually happy to run on 12 volts but not necessarily at 14 (charging voltage). Would I bother with "normal " electronics though - probably not. If you are concerned about spiking and happy to spend the money though, they are an option.

Thank you for explaining the two options and relative benefits/risks. Yes, you understood my setup correctly, the sounder is connected to the start battery and the electric motor has a separate power supply from an AGM battery. I had thought of changing the sounder to the electric motor circuit, if it would reduce risk of sounder damage due to voltage drop when starting the outboard motor. However, this option does not seem to provide any additional protection so best to leave the setup unchanged. Thanks again for helpful advice. SS

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[scottar]

Thank you for explaining the two options and relative benefits/risks. Yes, you understood my setup correctly, the sounder is connected to the start battery and the electric motor has a separate power supply from an AGM battery. I had thought of changing the sounder to the electric motor circuit, if it would reduce risk of sounder damage due to voltage drop when starting the outboard motor. However, this option does not seem to provide any additional protection so best to leave the setup unchanged. Thanks again for helpful advice. SS

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Normally you would avoid running sounders off an electric motor bank. It's pretty common these days for electric motors to cause noise issues on sounders. It would stop any issues with spikes from your main engine but could create other headaches. Minn Kota make specific mention of it in their installation literature.

[gazza2006au]

Thanks for that Scott i was planning on running one battery in my boat for a little bit

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