Correct Dual Battery Switch setup

[foilled]

minus the shore power on board battery charger that has a wire going to the positive and negative of each battery it appears my battery’s are hooked up on there own separate grounds to engine and also have 1 separate positive wire going to the 1 and 2 on the dial battery switch. How am I supposed to keep both batteries charged. Your not supposed to run on “BOTH” right? Am I missing part or the wiring setup? I normally run boat and start on battery 1 and for all power when boat is off I use battery 2. After killing battery two I’m wondering how to set this up correctly ? Thanks

 

[alldodge]

You can use an ACR so don't have to switch, but then you would also need to move accessories to bat 2. So long as the stereo, fish finder and others are not separated you will always need to move the bat switch to save the start bat

 

[foilled]

You can use an ACR so don't have to switch, but then you would also need to move accessories to bat 2. So long as the stereo, fish finder and others are not separated you will always need to move the bat switch to save the start bat

What’s is the correct way to operate the system I have to maintain full batteries for both starter and deep cycle without acr?

 

[alldodge]

What’s is the correct way to operate the system I have to maintain full batteries for both starter and deep cycle without acr?

Your bat switch should be a make before brake switch, so start on 1, and once running, switch to both.

Now if you have an OB then it might be a waste of time because most OB do not have a alternator large enough to recharge both bats. Also if your not draining the deep cycle below 80% during a normal boating day, then it can just be recharged upon return

 

[foilled]

Your bat switch should be a make before brake switch, so start on 1, and once running, switch to both.

Now if you have an OB then it might be a waste of time because most OB do not have a alternator large enough to recharge both bats. Also if your not draining the deep cycle below 80% during a normal boating day, then it can just be recharged upon return

I am running a I/O. And yea I do drain deep cycle down really far. To low to even start boat on some days. So it’s safe to run on BOTH , start it on 1 and use 2 for all electronics when boats off?

 

[alldodge]

Yes, that's correct

 

[alldodge]

Now if your deep cycle shorts out (normally doesn't) it can drain the start bat.
This is why the ACR is best for both worlds. It protects both bats and you would no longer need to move the switch.

 

[sam am I]

If you're draining the #2 battery really low, even an I/O's depending on alt, can struggle to bring up the super dead battery....That said and if you've gone through two batts (other than simply wearing them out) using the/your method of "starting one #1" and switching to "both", then perhaps a change is needed/suggested?

If it were me and I have drained the #2 battery down to ANY level, I always start on my #1 starting batt like you have done, then let the #1 batt voltage come back up and stabilize for a few while running a bit, then switch to #2.......Allow the alt's full current to charge solely the battery that needs the charge...#2!!

Skip the "both" setting if at all possible, parallel charging a dead'ish batts with your/a reserved fresh #1batt makes no sense. If the alt is dropping out (voltage sagging), back charging is occurring. I suspect this is occurring to some extent with your system and each individual batt's SOC is masking the needs of the other by "both"ing.

Hence multi bank/tap chargers were invented and are greatly valued/used (industry and marine use), not only can they prevent back charging when charging multi batts (2,3,4) because each batt usually can have various SOC's and demands can vary greatly, multi banked chargers also allows each individual battery to draw its OWN required current and not mask ones needs over/under another others needs by paralleling. This is what you'll simulate by staying away from the "both" setting while charging.

 

[foilled]

If you're draining the #2 battery really low, even an I/O's depending on alt, can struggle to bring up the super dead battery....That said and if you've gone through two batts (other than simply wearing them out) using the/your method of "starting one #1" and switching to "both", then perhaps a change is needed/suggested?

If it were me and I have drained the #2 battery down to ANY level, I always start on my #1 starting batt like you have done, then let the #1 batt voltage come back up and stabilize for a few while running a bit, then switch to #2.......Allow the alt's full current to charge solely the battery that needs the charge...#2!!

Skip the "both" setting if at all possible, parallel charging a dead'ish batts with your/a reserved fresh #1batt makes no sense. If the alt is dropping out (voltage sagging), back charging is occurring. I suspect this is occurring to some extent with your system and each individual batt's SOC is masking the needs of the other by "both"ing.

Hence multi bank/tap chargers were invented and are greatly valued/used (industry and marine use), not only can they prevent back charging when charging multi batts (2,3,4) because each batt usually can have various SOC's and demands can vary greatly, multi banked chargers also allows each individual battery to draw its OWN required current and not mask ones needs over/under another others needs by paralleling. This is what you'll simulate by staying away from the "both" setting while charging.

I haven’t been running on “Both”. Ive been starting and running the boat on battery 1, when boat is off and using accessories I leave it on 2. Was wondering how to keep both batteries charged on a long trip. Previous poster said to run on both but I haven’t yet

 

[Silvertip]

In this particular case, one needs to look at current consumption which obviously greatly exceeds the available battery and charging capability. First, lets talk about killing the house battery. What on earth are you running that routinely kills this battery? What size is it. The partial solution here would be a) a much larger deep cycle house battery, b) two of what you currently have, c) think about more conservative use of available power and/or d) install an alternator with a much higher output

Next, a properly tuned engine and an operator that knows how to quickly start the engine should never have to rely on the HOUSE battery for starting the engine. Yes -- weird stuff happens but the start battery does not need as much help as one thinks it does (of course a battery on its way to battery heaven is beyond help). As was pointed out earlier, there is no single way to properly use the battery switch. It is a device that lets you, the operator, send starting, charging and discharge current to/from whatever battery you select. Since an engine will start many dozens of times on a battery that is not recharged immediately there is no urgency in getting it topped off "immediately" since it initially just came off the on-board charger (did it not?)

Next, running on BOTH is generally not necessary nor advantageous. One battery will always be charged to a different level than the other so pick the one that needs the most help. That comes with one caveat in that if the start battery and house batteries are both down, send the charge to one or the other since the selected battery will receive the full available charge current from the alternator. If both batteries are down just a bit, run on BOTH. The alternator can handle that Diesel powered vehicles can have two, four, or even six batteries and the alternator handles them just fine.

But the main issue here is too much current consumption for the available battery and charging system. No automatic management system is going to fix that. And by the way, better quality multi-output on-board chargers can and do share outputs. If output 1 senses the battery is charged, it can switch to battery 2 to help out. That switch is done internal to the charger -- not at the batteries. Lastly -- if one is "switch challenged" then some automatic system may be a partial solution.

 

[foilled]

In this particular case, one needs to look at current consumption which obviously greatly exceeds the available battery and charging capability. First, lets talk about killing the house battery. What on earth are you running that routinely kills this battery? What size is it. The partial solution here would be a) a much larger deep cycle house battery, b) two of what you currently have, c) think about more conservative use of available power and/or d) install an alternator with a much higher output

Next, a properly tuned engine and an operator that knows how to quickly start the engine should never have to rely on the HOUSE battery for starting the engine. Yes -- weird stuff happens but the start battery does not need as much help as one thinks it does (of course a battery on its way to battery heaven is beyond help). As was pointed out earlier, there is no single way to properly use the battery switch. It is a device that lets you, the operator, send starting, charging and discharge current to/from whatever battery you select. Since an engine will start many dozens of times on a battery that is not recharged immediately there is no urgency in getting it topped off "immediately" since it initially just came off the on-board charger (did it not?)

Next, running on BOTH is generally not necessary nor advantageous. One battery will always be charged to a different level than the other so pick the one that needs the most help. That comes with one caveat in that if the start battery and house batteries are both down, send the charge to one or the other since the selected battery will receive the full available charge current from the alternator. If both batteries are down just a bit, run on BOTH. The alternator can handle that Diesel powered vehicles can have two, four, or even six batteries and the alternator handles them just fine.

But the main issue here is too much current consumption for the available battery and charging system. No automatic management system is going to fix that. And by the way, better quality multi-output on-board chargers can and do share outputs. If output 1 senses the battery is charged, it can switch to battery 2 to help out. That switch is done internal to the charger -- not at the batteries. Lastly -- if one is "switch challenged" then some automatic system may be a partial solution.

What killed the battery was a multiple day trip where the house battery was used and the boat never being ran on “2” to recharge and one night were the key stayed turned on in the access position killing it. After that died had to use battery 1 for everything. My trips include a decent haul there and back but within a bunch of restarts where the boat is turned on and off without a lot of driving to just reset while drift fishing. Battery 1 ended up dieing as well. Thankfully for a back upto continue I recharged 1 with alt and everything was fine. But now I’m making sure I’m operating correctly. I do understand you with charging a single battery that isolate maximum charging to which ever needs it more. So without a lot of driving and often quick restarts I’m trying to keep batteries with most battery possible.

Running the volt gauge on dash reads about 14 while underway but on a fully charged battery with key on accessories it should 10 to 11 but voltmeter reads over 13 when I freshly take it off charger. Where do I begin to fix gauge reading so I know which battery to switch and charge to while running. Also no matter what battery level while boat is underway gauge reads 14 so while running would I be able to tell when the battery is topped off so I can switch and charge the other?

 

[sam am I]

What killed the battery was a multiple day trip where the house battery was used and the boat never being ran on “2”

So get an automatic method if you're (anyone is using the boat) forgetting to manually go to #2

Use an ACR as dodge suggested (the "both'ing/paralleling" technique)........

However, I prefer (non-paralleling as I explained above) and use one of these. which singles out low batt and charges them individually.........No messing with Off, 1,Both 2 switches (or Off, On, Both) per-se, optimizes ANY alt output capacity , (i.e., doesn't need to parallel to charge but, does automatically when all are topped off), automatically prevents back charging in the event of a sagging alt due to highly dis-charged batts coming online.

Running the volt gauge on dash reads about 14 while underway but on a fully charged battery with key on accessories it should 10 to 11 but voltmeter reads over 13 when I freshly take it off charger.

14'ish while charging is correct, "it should 10 to 11 but voltmeter reads over 13 when I freshly take it off charger."? This sounds about right. It's a "surface charge", wait a day with no load, it'll burn off and should drop to around 12.8'ish.

Where do I begin to fix gauge reading so I know which battery to switch and charge to while running.

Can wire up a switch so you can single toggle between the two battery's to dual monitor each batt or install dual meters.

Also no matter what battery level while boat is underway gauge reads 14 so while running would I be able to tell when the battery is topped off so I can switch and charge the other?

Yes, see above dual meters suggestion or single toggle switch dual monitor and/or install a automatic system such as ACR or my fav

 

[foilled]

So get an automatic method if you're forgetting to manually go to #

No messing with Off, 1,Both 2 switches (or Off, On, Both) per-se, optimizes ANY alt output capacity , (i.e., doesn't need to parallel to charge but, does automatically when all are topped off), automatically prevents back charging



14'ish while charging is correct, "it should 10 to 11 but voltmeter reads over 13 when I freshly take it off charger."? This sounds about right. It's a "surface charge", wait a day with no load, it'll burn off and should drop to around 12.8'ish.



Can wire up a switch so you can single toggle between the two battery's to dual monitor each batt or install dual meters.



Yes, see above dual meters suggestion or single toggle switch dual monitor and/or install a automatic system such as ACR or my fav

I didn’t really forget i just didn’t know that i had to run alternatively between 1 and 2 batteries but I now will.

Off charger I measured 12.8 voltage or so at the the battery. On the two posts on back of gauge im getting 11.7 volts. From back on gauge with just fridge on I get 10.5. Still testing behind gauge with just nav lights on I’m getting .5 volts. Now with the meter testing straight off battery I get the 12.8 but with the nav on it only drops to 12.6 and just the fridge on drops to 12.5 when testing from battery. With all accessories on boat on at once. Testing from battery it goes down to 12.3 Why the variation at the gauge and between battery??

 

[Silvertip]

Ahhhhh. "just the fridge on!!!!" Do you realize how much current that fridge draws? Therein lies the real problem. You do not have enough battery capacity for that. If your voltmeter registers 10 - 11 volts then 1) the gauge is incorrect, 2) wiring is bad, or 3) the battery is not capable of holding a charge (it is in need of replacement). Charge it and then have any auto store do a load test.

 

[foilled]

Ahhhhh. "just the fridge on!!!!" Do you realize how much current that fridge draws? Therein lies the real problem. You do not have enough battery capacity for that. If your voltmeter registers 10 - 11 volts then 1) the gauge is incorrect, 2) wiring is bad, or 3) the battery is not capable of holding a charge (it is in need of replacement). Charge it and then have any auto store do a load test.

I only run fridge when boat is on to prevent drainage. I said I get 12.6 volts testing from battery with fridge on. But testing voltage of wires behind voltameter gauge on dash with accessories like the fridge on when testing from wires at gauge read 10.5. The nav lights make reading .5 volts at wires behind gauge. Keep in mind testing right at battery during same scenario reads over 12 volts. So I don’t no believe that’s my issue

 

[foilled]

The gauge is reading what multimeter reads off the nuts on back of gauge. The problem is the gauge reads different from the battery

 

[sam am I]

The gauge is reading what multimeter reads off the nuts on back of gauge. The problem is the gauge reads different from the battery

Bad gauge then eh?

Else if the gauge and meter both match (not your case sounds now unless both meter and gauge match BUT, are lower then the batt)..............Poor connections/inline resistance in-between the batt and where the voltmeter itself taps off its ground and positive sources. The more of a load (fridge) the higher the drop V= IR where V = the drop, I = the load current and R = is a somewhat constant resistance IF its normal resistance (copper wire) verse flaky changing resistance if it's crap/corrosion in the connections.

 

[foilled]

Bad gauge then eh?

Else if the gauge and meter both match (not your case sounds now)..............Poor connections/inline resistance in-between the batt and where the voltmeter itself taps off its ground and positive sources. The more of a load (fridge) the higher the drop V= IR where V = the drop, I = the load current and R = is a somewhat constant resistance IF its normal resistance (copper wire) verse flaky changing resistance if it's crap/corrosion in the connections.

The gauge and the multimeter testing from the wires going to gauge( on the gauge side) match voltage. The volts from the gauge and multimeter tested from battery are different..Were should I begin testing resistance and what should it be?

 

[sam am I]

Were should I begin testing resistance and what should it be?

Test for and find voltage drop (non-normal, which sounds like you have)........

Turn on load/s

Run a meter lead from battery + to gauge +

Note reading...

Run a meter lead from battery - to gauge -

Note reading...

These (voltage measurements) will tell you which side the problem drop is on and will break the problem in half. Go from there cleaning/tightening connection/s on the side that measured that largest/problem voltage drop.

 

[foilled]

Test for and find voltage drop (non-normal, which sounds like you have)........

Turn on load/s

Run a meter lead from battery + to gauge +

Note reading...

Run a meter lead from battery - to gauge -

Note reading...

These (voltage measurements) will tell you which side the problem drop is on and will break the problem in half. Go from there cleaning connection on the side that measured that largest/problem voltage drop.

I’d never be able to reach my multimeter from gauge to battery. ANy ideas?