Marine Electronics Forum - Running electronics off house batteries

Last year I had swapped out my my house and motor batteries as preventive maintence. Before I made the swap I had no issues with the voltage drop when the electronics where hooked up to the motor batteries. After the swap, electronics shut off at start up. Still had the original batteries and swapped them back, same issue (year latter). Talking to people they are surprised that I didn't have this issue previously.

To resolve this I am thinking of moving the electronics to the house bank (currently 2 group 29's). These charge via the "extra" power lead off the F225's. Is this a reasonable solution? Or should I spend the time focusing on what changed previously? Or is there something else I am not thinking about?

Fwiw GW 265 F225's one group 29 to each motor and 2 in the bow for house power. Should also mention windlass is off the house as well.

A voltage conditioner (http://www.davesmarineelectronics.com/PowerVoltageConditioner.aspx) will buffer the electronics from the expected voltage droop when cranking the engine.

It may be that the problem could be improved by using larger positive and negative cables from the battery to the electronics.

The "easy" way to determine if larger cables would help would be to use a multimeter w/ peak hold. Attach that meter to the battery, turn on peak hold, then crank the engine.

If the droop voltage is too low to keep the electronics happy (per the electronics specs), then larger positive and negative supply cables won't help. If the droop voltage is within the specified range for the electronics, then larger cables will help.

Another option is a contactor to shunt the two banks together. A momentary action contactor (high-current relay) could be energized prior to cranking the engine, to help decrease the expected droop.

It may be that the problem could be improved by using larger positive and negative cables from the battery to the electronics.

It's unlikely that on a small load, increasing the cables to the electronics will help substantially. It's far more likely if you try and solve this by larger cables, that they go to the starter (+) and from the engine to the negative terminal.

Last year I had swapped out my my house and motor batteries as preventive maintence. Before I made the swap I had no issues with the voltage drop when the electronics where hooked up to the motor batteries. After the swap, electronics shut off at start up. Still had the original batteries and swapped them back, same issue (year latter). Talking to people they are surprised that I didn't have this issue previously.

To resolve this I am thinking of moving the electronics to the house bank (currently 2 group 29's). These charge via the "extra" power lead off the F225's. Is this a reasonable solution? Or should I spend the time focusing on what changed previously? Or is there something else I am not thinking about?

Fwiw GW 265 F225's one group 29 to each motor and 2 in the bow for house power. Should also mention windlass is off the house as well.

Yes... IMO that's the purpose of the house battery, and the electronics already be on it.

The ONLY thing on my engine battery is the engine. I want it always at 100% and used only to start the engine. Electronics, blower, etc. all run off the house battery. I do not want the chance to anchor up and accidentally run the engine battery down. The battery chemistries are also different - the start battery is a marine cranking battery (high CCA), the house batteries are deep cycles.

I do have a "hidden" double-pole switch where I can swap them over to the engine battery if the need persists. This way, if there is an issue with the house electrical feed or anything for any reason, it would then be fed off the ignition circuit feed which is the engine battery.

Last year I had swapped out my my house and motor batteries as preventive maintence. Before I made the swap I had no issues with the voltage drop when the electronics where hooked up to the motor batteries. After the swap, electronics shut off at start up. Still had the original batteries and swapped them back, same issue (year latter). Talking to people they are surprised that I didn't have this issue previously.

To resolve this I am thinking of moving the electronics to the house bank (currently 2 group 29's). These charge via the "extra" power lead off the F225's. Is this a reasonable solution? Or should I spend the time focusing on what changed previously? Or is there something else I am not thinking about?

Fwiw GW 265 F225's one group 29 to each motor and 2 in the bow for house power. Should also mention windlass is off the house as well.

Sure. That's how I re-wired mine. Why would you not want your electronics on the house bank? I would.

I apprecate the feedback. I will be putting together the parts list to do that tomorrow. It really makes much more sense. Hopefully the draw from the windlass will not be enough to do the same.

May want to put the windlass on the start battery. Make sure the engine is running before using the windlass.