Battery switches
- Thread starter Cjdport
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My B393 has two on-off switches for the positive terminal of the starter battery and the house bank, respectively. It also has one negative switch for both banks. I assume that is what you have too.
I find it easy to use. To parallel the starter and house bank, simply put both positive switches on. To isolate the starter battery while sailing or one the hook/mooring, turn off that switch. No problem, except when I forget.
The negative on-off is there if you need to shut down the entire system for long-term storage, or an electrical fire, etc. I never turn it off, but I could if needed.
negative disconnect
The negative disconnect greatly decreases battery discharge while the boat is layed up. More importantly, the negative disconnect takes all the ship's grounding (engine/transmission, batts) off-line while working on the batteries. Simple, safer procedure for working on these big amperage energy storage devices. In an emergency the negative disconnect is your sure way to de-energize the ship's DC electrical system with the flip of a switch.
The negative disconnect greatly decreases battery discharge while the boat is layed up. More importantly, the negative disconnect takes all the ship's grounding (engine/transmission, batts) off-line while working on the batteries. Simple, safer procedure for working on these big amperage energy storage devices. In an emergency the negative disconnect is your sure way to de-energize the ship's DC electrical system with the flip of a switch.
Thanks for feedback. I've drawn this out, and seen it on several Ben's & Jen's recently. By closing (switching on) both start and house bank switches, both banks are still isolated. Granted, with the negative switch closed, now you have a common ground (as suggested by ABYC standards), but then only if you install a fourth switch and cable to both bank hot posts on their switches and close that switch, then you can finally parallel your banks, in the event you start batt dies. And what is simpler than a common negative ground system, and one positive battery switch with a 1, 2, and BOTH and OFF positions?
I've got to call Ben & Jen and get to their logic.
I've got to call Ben & Jen and get to their logic.
And to add fun to it, on a Ben 49 today, found situation where a third positive switch was placed for second house, but accomplished nothing because a strap was placed that tied both house banks together, despite the switch. A diagram is worth a lot of time in the wiring world.
I’m not sure why you think Beneteau is “wrong”, compared to ABYC. I, and most other owners, agree that our “one switch per battery positive” system is the best way to have it. I make these replies based on the assumption that all recent Beneteaus are wired the same manner as my 2006 323. I have done major rewiring on my 323, so am very familiar with it.
Post #1… As my dealer told me, the neg switch is to totally remove the ground from the system to prevent accidental operation of the components of the system- particularly the starter if the engine is being worked on. As was already pointed out, there are “always-on” circuits such as the radio memory and bilge pumps. Operating the neg switch turns off everything in the boat, like if it’s hauled out, and prevents draining the battery(s). It’s cheap insurance. I would think that all battery negs go to one side of the switch, all the loads to the other side. This comes in to play if you install a Victron battery monitor, which wires into the neg buss. A lesser possibility is if someone tries to stel the boat and the neg is off, they couldn’t start the engine.
Post #1… The way to parallel banks is to turn on any combination of pos switches. I added a third battery and a third switch. Installed that way, I can parallel any batteries I want, or take off line any defective or undercharged battery at the flip of the wrist.
Replies # 2& 4… Ditto
Post 3#... If the boat was designed with a switch, I can’t see taking it out “just because”. There IS a function for it, so maybe you’ll put it back in?
Post # 5… Perhaps your wording did not convey what you meant, but “closing” the switches (ON) both batteries ARE paralleled- bridged together. As said above, the batteries would be paralleled by the “buss” cable that links the switches. You don’t need that “fourth” switch- you already have a way to parallel batteries. Besides, if your “start” battery dies, you DO NOT want to parallel them, as that would probably only draw down the good battery.
And THAT is what is simpler than a 1/2/both/off switch, and in addition if the 1-2 dies, you have to break out the tools. On the Benny, you just flip a different switch. I think if you knew how your boat is wired, you’d uinderstand the beauty of the system. Sure, there are those who like the 1-2-B-Off switch, but why trash a perfectly good system you already have?
The batteries’ pos lug SHOULD be wired to the same side (for simplicity) of each red battery switch. The lugs on the other side of the switches should be linked between all red battery switches, keeping in mind the amp load this could carry, and size the cable appropriately. This link is, in reality, the “POSITIVE BUSS”. Granted, depending on your needs/desires, maybe all batteries are not part of the 12v+ buss. From this buss you’d go thrugh a mega fuse and on to the 12 circuit breaker panel, starter, and maybe the alternator.
Post #6… Like you mentioned, I too have added a second “house” battery with a red switch added. I assume you are sure the cable you mention was actually wired across the batteries, but might have been on the switch- like the battery side of the switches, or the 12-volt buss side of the switches? If your statement is correct, then, indeed it seems the third switch was of no purpose.
I agree, any boat owner should have the owner’s manual which includes all wiring, or plumbing schematics. Lacking a manual, a schematic should be made from hands-on inspection.
Post #1… As my dealer told me, the neg switch is to totally remove the ground from the system to prevent accidental operation of the components of the system- particularly the starter if the engine is being worked on. As was already pointed out, there are “always-on” circuits such as the radio memory and bilge pumps. Operating the neg switch turns off everything in the boat, like if it’s hauled out, and prevents draining the battery(s). It’s cheap insurance. I would think that all battery negs go to one side of the switch, all the loads to the other side. This comes in to play if you install a Victron battery monitor, which wires into the neg buss. A lesser possibility is if someone tries to stel the boat and the neg is off, they couldn’t start the engine.
Post #1… The way to parallel banks is to turn on any combination of pos switches. I added a third battery and a third switch. Installed that way, I can parallel any batteries I want, or take off line any defective or undercharged battery at the flip of the wrist.
Replies # 2& 4… Ditto
Post 3#... If the boat was designed with a switch, I can’t see taking it out “just because”. There IS a function for it, so maybe you’ll put it back in?
Post # 5… Perhaps your wording did not convey what you meant, but “closing” the switches (ON) both batteries ARE paralleled- bridged together. As said above, the batteries would be paralleled by the “buss” cable that links the switches. You don’t need that “fourth” switch- you already have a way to parallel batteries. Besides, if your “start” battery dies, you DO NOT want to parallel them, as that would probably only draw down the good battery.
And THAT is what is simpler than a 1/2/both/off switch, and in addition if the 1-2 dies, you have to break out the tools. On the Benny, you just flip a different switch. I think if you knew how your boat is wired, you’d uinderstand the beauty of the system. Sure, there are those who like the 1-2-B-Off switch, but why trash a perfectly good system you already have?
The batteries’ pos lug SHOULD be wired to the same side (for simplicity) of each red battery switch. The lugs on the other side of the switches should be linked between all red battery switches, keeping in mind the amp load this could carry, and size the cable appropriately. This link is, in reality, the “POSITIVE BUSS”. Granted, depending on your needs/desires, maybe all batteries are not part of the 12v+ buss. From this buss you’d go thrugh a mega fuse and on to the 12 circuit breaker panel, starter, and maybe the alternator.
Post #6… Like you mentioned, I too have added a second “house” battery with a red switch added. I assume you are sure the cable you mention was actually wired across the batteries, but might have been on the switch- like the battery side of the switches, or the 12-volt buss side of the switches? If your statement is correct, then, indeed it seems the third switch was of no purpose.
I agree, any boat owner should have the owner’s manual which includes all wiring, or plumbing schematics. Lacking a manual, a schematic should be made from hands-on inspection.
Hi, I agree with Ron that the Beneteau switch are a very nice set-up but I still have a problem with them. I think there is a major draw back to the set-up when you start looking at the alternator side. Suppose you have been at anchor for a while and the house battery is now discharge and you have use 20% of the capacity. The start battery is still at 100%. To charge the start and house batteries from the alternator the switches must be ON, as soon as you do this you put the batteries in parallel and that is when yoou get in trouble I think.
The alternator regulator only sees one battery pack. I think that the start battery will influence the regulator in the alternator. I don't know how the alternator will control the charging. Ewhen batteries are combined the one with the higher charge will discharge in the other bank. The alternator does not see two different voltages for the batteries but a combined voltage and I think that will lower the alternator ouput, thus taking more time to charge the batteires and eventually undercharging them.
I am currently looking at battery isolators from Sterling Power or Victron to solve this problem. Both claim near 0 voltage drop.
Comments, suggestions will be greatly appreciated.
Thanks
Georges
The alternator regulator only sees one battery pack. I think that the start battery will influence the regulator in the alternator. I don't know how the alternator will control the charging. Ewhen batteries are combined the one with the higher charge will discharge in the other bank. The alternator does not see two different voltages for the batteries but a combined voltage and I think that will lower the alternator ouput, thus taking more time to charge the batteires and eventually undercharging them.
I am currently looking at battery isolators from Sterling Power or Victron to solve this problem. Both claim near 0 voltage drop.
Comments, suggestions will be greatly appreciated.
Thanks
Georges
Georges,
This is not an issue. Any batteries in parallel will become on contiguous voltage and "bank" during charging and you will have the same Ah's you had in both banks prior to charging minus some slight loss in charge efficiency.
You can not over or undercharge either bank as they become one and will "equalize" or find "equilibrium" and then be charged as one bank.
Alternator regulators, smart or dumb, only know voltage and the current will flow as the batteries accept it. When you combine the banks there will be a breif in-rush of current from the full battery to the lesser charged bank but as the voltages get closer together less and less current flows between banks because voltage is pressure.
When you fire up the alt, solar, wind or shore charger the banks accept or take what they take or the charging device is up against it "limit".. If the combination of the two banks is below the charge devices "acceptance voltage" the alternator or charge source will be in bulk mode. Bulk means it is simply ON and supplying all it can or what ever the batteries will take. When the banks terminal voltage come up to absorption voltage set point the alternator or charge source simply begins to limit the voltage to that setting.
Personally, I do not like the Sterling unit as it is "claimed" to first charge the start bank, which it does not really do. This is nothing more than a marketing scare tactic used by Charles Sterling to sell his products. The start bank is usually at 98-100% SOC anyway so a simple Echo Charger or ACR/VSR will suffice.
A standard "voltage sensitive relay" often referred to as an ACR will be better than an "isolator", even a FET isolator.
The Victron Cyrix, Blue Sea ACR or the Yandina combiners, all VSR's, are all excellent products. There is also the Echo Charger from Xantrex which bleeds off up to 15A of charge current for a start battery. I prefer the Blue Seas ACR's or the Echo Charger's or a true 12V DC to DC battery to battery charger and Sterling makes excellent ones..
This biggest problem with manually "combining banks" is "HEF" or the human error factor and forgetting to un-combine them when they are not being charged. This is where an automated system like a VSR or Echo Charger really shines.
Originally on my 2003 B331 the two red handles were connected by a short piece of 2/0 wire which automatically places them in parallel (if both switches are on). There was no means of operating with House and Start isolated from one another... except for switching one battery on at a time, then remembering to switch the switches. The original alternator (Westerbeke 30B engine) wiring was to a post on the starter solenoid shared with the 2/0 wire from the "Start" battery. I now have the system separated so the alternator charges a house bank of two batteries, then through an Xantrex Echo-charger the Start battery is charged. I can leave both red handles on and be assured of only using the Start battery to start.
To assume you meant you took out that wire between the 2 switches, otherwise, both switches on and you've over-ridden the Echo. Why not just wire the starter to the start battery side of the switch, the alt to the 12-volt buss side? Left off, it is still isolated from the house battery.
This is something I've still not got clear in my mind. My B331 is set up in the same way as described previously. My concern is a partially discharged house battery (@ 20%) dragging down a previously isolated starter battery when you close the isolator to start the engine - leading to a combined capacity of less than that needed to fire up the donkey! Also I did read that repeated large in-rushes of current can damage the battery prematurely?
One final thought - I was hoping to fit a 'smart' monitor to the house battery, however when the banks are combined apparently this can mess with it's calculations and leave the % remaining / hours remaining calculations wrong?
That's the beauty of our switch-system. You COULD try to start the battery on the house if you wanted to- nothing wrong with that- then it would recharge. Otherwise, just shut OFF the house switch and turn ON the engine switch, and they are not bridged. Once started, you can turn the house on, and THEN the engine one off.
My "new" DC system uses one red handle to switch the House Bank and one to switch the Start Battery. The hardwired connection (parallel) between the two red handles is now switched using the third handle (painted it blue to differentiate). I have no black "common" switch. The start battery EchoCharger draws its power from the house bank only if the house bank is being charged (determined by sensed voltage). The engine alternator now charges only the house bank. The two battery systems are normally totally separate and can be left switched on without fear of depleting the start battery. The house battery can be used to start if the parallel handle is switched on.
I thought you were not suppose to turn a new battery switch on once you start charging with the alternator. I may just be misunderstanding the "once started, you can turn the house on, and Then the engine one off" part.
You wouldn't turn one OFF before turning the other one ON, as it may blow a diode in the alt. You wouldn't do it if one battery was severly drained, but if they are close in charge state, not a problem and you can have both on to charge both. I usually start the engine in the slip with the start battery to make sure it works, then by the time i get to the sailing grounds it has replaced the used amps. After raising sails and shutting off the engine i turn on the house then off the start batt so the house charges when returning. This way i know all batts function as they should.
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