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Random Quote: A home on land; You save up for one half of your life, only to find out once you get one that it's in the wrong neighborhood!
Trying to find out if running both batts are a good thing or a bad thing. Had this discussion with my friend this morning and we are trying to determine if running both batts does more harm then good to one or both. I have always run both but now I'm starting to wonder. I have never had a problem but don't want to end up with one.
seems to me the downside is that if you run both batteries at the same time, and something drains them both down, then you're dead in the water, whereas if you run one, and it dies you can switch over and get home.... just alternate back and forth, or run cranking off one, house off the other and wire it to charge both....
BaD BAD BAD to run both batteries. everytime i go out i go from one to another alternating them. this way here both stay freash and you always have a reserve. I think thats the point of having two batteries.
Interesting thing happened to me in my truck last month. THe alternator died and i got a dumb dumb light come on telling i had something going on. When your alternator dies your engine or at least in my case uses the batteries electricity to ignite the fuel so when my battery finnaly craped out a mear 100yards from the dealership i could of switched to the second battery and not have to ask the guy behind for a push into the dealership parking lot.
__________________ A quote by Zane Grey after Big Game Fishing.
"I am tired, my arms ache,my head boils, my feet are cold but I am not aware of any weakness"
Cabo 31
I always start off on my run out with both batteries on, but as soon as I come off plane at my first stop I switch to one battery and then alternate between the 2 the rest of the day. And if you have one battery weaker than the other that is the one I tend to use when I'm on the water that way I have my good battery to fall back on.
If you don't have any special way to charge the batteries, only the one that's switched on will be charged by the engine's alternator. In spite of all the warnings above not to run with both batteries switched on, that's exactly how battery combiners work and they have a proven track record.
Battery combiners sense the charging voltage from the alternator and connect the batteries together (an "automatic switch"). Once the engine is shut off, the batteries are disconnected from each other so heavy use of one (say a loud stereo or a trolling motor) will not discharge the other.
So - Start the engine on one battery, switch to both while the engine is running, then switch to a single battery when stopped (fishing, sandbar, etc.). Switch to the other battery to start the engine, then to both to recharge the other battery.
Or, install a combiner and seperate the wiring on the boat into "starting" and "house" loads.
Most motors these days have a battery isolater charging circuit built right in them (Yamahas do anyway). You should run a single cable from this provision to the battery designated as the backup. This allows the engines alternator to charge this battery, but the battery is not drawn from. Using this method many like to run all their electronics off this backup battery to isolate their electronics from surges when starting the engine off the main battery. If you ever have a issue with the main batt, you simply switch to the backup, that has been being charged up all along, to start the engine. Using the "both" is a last ditch effort to start your engine after trying the batteries one at atime and failing. It is highly unlikely to work. "Both" is asking for trouble in virtually all examples. If you have one weak battery and switch to "both", you are instantly feeding that weak battery with the good one. You would be much better off trying the other battery before switching to "both", which is drawing the backup down before even trying it by itself.
__________________ AKA, The SKIMMER! No way am I reading all that crap!
Does the accessory battery coupler come standard with all yamaha engines (specifically F250s) ? Also, is it better to use the accessory battery coupler to charge a house bank than it would be to use a separate battery combiner? Does the accessory battery coupler allow you to start the engine using the house (accessory) battery if your main engine battery dies? If not, I suppose it's just as easy to wire a parallel switch between the two...
I've got two '06 Yamaha High Power Four-Stroke F250s on my Edgewater 265 EX. Currently, I use a Wells Marine Batt Maxx Volt Seeker II Battery combiner to keep my battery banks charged or to allow me to start my engines using my house bank. I have one starting battery for each engine and a house bank consisting of two 12V batteries wired in parallel. All of my battery banks (Port/Stbd/House) have their own on/off switches. I'm not sure why, but whenever the house bank is switched on (even if the other banks are switched off), the combiner automatically combines the batteries. The combiner is only supposed to do that when one of the banks is putting out more than 13.5V. Since my two house batteries are wired in parallel, even at full charge, the entire bank should be putting out 12.6V, right? I've even tried wiring the combiner after the switches so that when a bank is switched off, the combiner is not connected to that bank, and the combiner still tries to combine the batteries.
"'So - Start the engine on one battery, switch to both while the engine is running, then switch to a single battery when stopped (fishing, sandbar, etc.). Switch to the other battery to start the engine, then to both to recharge the other battery"".
This is what I been doing for as long as I can remember with no problems,
in my current boat I have 4 batteries with twin engines.
Unless your electrical system is set up in the best fashion you should not operate the battery switch while the engine is running. The result can be that switching while running will destroy the alternator diodes thus rendering the alternator useless and resulting in discharged batteries.
Unless your electrical system is set up in the best fashion you should not operate the battery switch while the engine is running. The result can be that switching while running will destroy the alternator diodes thus rendering the alternator useless and resulting in discharged batteries.
The danger here is running the alternator with no load. Even for an instant. Most boat battery switches are "make before break", meaning that a connection is maintained to the first battery untill the second is connected. The only danger would be turning the switch to the "off" position while the engine is running. Switching between "1", "both", and "2" would not be an issue.
I must say great input guys! I bought a boat this fall that has dual batteries, which I haven't had before and assumed that I should always be running on two batteries.
I run my port motor on #1 and the starboard on #2, if you just use the both setting a bad battery will be masked by the good one. But I also have a house battery parallel to my starboard battery to run the TV, DVD, etc. I keep my boat on a mooring and have no shore power so I all so have a solar panel on the hardtop to help charge the house battery. The way I see it the battery switches are for a way to have backup if needed.
Excellent comments. I have always ran the boat to where I am going and after anchoring I switch to the house(party) battery, that way I have some juice to get back to dock.
So - Start the engine on one battery, switch to both while the engine is running, then switch to a single battery when stopped (fishing, sandbar, etc.). Switch to the other battery to start the engine, then to both to recharge the other battery.
Doing this landed me dead in the water 10 miles out a couple of seasons ago. The bad battery was bad enough that even with the alternator charging both 8D batteries for hours before I shut the engine off and switched to one, I was SOL when I went to start on either battery after drift fishing for an hour. Prior to this I had heard that this can happen, but in over 20 years it had never happened to me. Now I understand... one bad battery can suck more than the best alternator can put out, and what ever juice you have in your good battery, if the batteries are in parallel (both position).
Run on one. If you don't have a combiner you can develop a discipline to make sure you switch them enough that both stay charged. Most modern switches are "make before break" so you don't have to worry about frying your alternator when switching while the engine is running. If you are not sure about your battery switch find out before switching with the engine running. Combiners are cheap and easy to install if you don't trust yourself to remember.
__________________
Newburyport, MA
Eastern 35 FB
Door#3
Running both batteries-Yes or No? 
