Two parts to this thread. 1) My 2006 Beneteau 343 has a maze of electronics, rectifiers, relays, and what not, in the battery compartment. My engine battery is not isolated from the house batteries when it is switched on (common problem with Beneteaus, in fact, the engine battery will run the house when it is switched on). I wish to isolate my engine battery so that it is only connected to the engine, via the engine battery switch, and perhaps have the alternator charging only the engine battery when engine is running. When plugged in to shore line, the engine battery already has its own charger. In view of all the electronics, is there a bad or down side to making this change? 2) One fellow stated that he eliminated his Ground/Neg. switch entirely, it being unnecessary, and all grounds or neg's were then connected to a common bus. Is there any reason that this is not a good idea? Many thanks, y'all.
Battery system changes
- Thread starter jmkinsfbay
- Start date
There should be a few threads on mods like this in the archives. The consensus is that replacing the negative switch with a bus is the right thing to do. It is also often suggested to use the negative switch as an emergency cross over between house and engine banks, and removing the jumper connecting them. The only part of your plan that doesn't sound conventional is to have the engine charge only the engine battery. The best thing to do would be to have the engine charge the house bank, and use something like an ACR to keep the engine battery charged.
Our 2014 Beneteau came without the jumper between the banks, so the engine bank only runs the starter and the house bank only runs the house. The alternator is connected to an isolator that charges both banks without otherwise interconnecting them.
Our 2014 Beneteau came without the jumper between the banks, so the engine bank only runs the starter and the house bank only runs the house. The alternator is connected to an isolator that charges both banks without otherwise interconnecting them.
Let's unpack this quesion.
Start batteries use a lot of current for a very short time. For this reason they do not become deeply discharged and subsequently recharge quickly. House batteries tend to use a little current for a long time and tend to discharge deeply requiring longer recharging times. Again go to the Musings with MaineSail and search the forum. Or go to MarineHowTo.com for more information.
This is both good and bad. You don't want your start battery to run the house electronics except when you do. When do you want the start battery to run stuff? When the house battery fails.
You are sort of on the right track here. You do want the start battery to be separate from the house battery, but you also want the house battery to be able to start the engine if the start battery fails. This can be done with a combining switch such as the Blue Sea 5511e and separate on/off switches on the house and start batteries. This arrangement will allow you to start the engine off of the house battery, the start battery, or both batteries in parallel. MaineSail has a great post on this on his forum on this website. Take a look at the Musing with MaineSail forum.
Start batteries use a lot of current for a very short time. For this reason they do not become deeply discharged and subsequently recharge quickly. House batteries tend to use a little current for a long time and tend to discharge deeply requiring longer recharging times. Again go to the Musings with MaineSail and search the forum. Or go to MarineHowTo.com for more information.
It is best to give charging priority to the house battery. Use an Automatic Combing Relay (ACR) to charge 2 separate battery banks (house and start) from one source. Here's one from Blue Sea. SI-ACR Automatic Charging Relay - 12/24V DC 120A - Blue Sea Systems
So thanks to all. It seems that what I want to do is basically what Beneteau has finally done with its newer battery systems. I wish my engine battery to be isolated because it is essential (to me!), the house batteries (I have two house batteries on separate chargers) are much less important, and, if mandatory, I can jumper a house battery to engine battery. Really, the critical thing on my house batteries, while underway, is the GPS, and I keep a loaded iPhone with me for backup. And this begs the question: are boaters keeping one of the new, small, battery boosters on board for a battery emergency?
As far as sailboats are concerned, this is not a good solution.
From Maine Sail, here's why:
AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm
I believe the concept should be to have a robust electrical system without the need for jumper cables or battery packs.
Read some of these to find out how to:
Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html
Because of your inherent Beneteau wiring silliness, you'll have to work around the issues. With proper and minimal wiring changes, you can do it, too. A search here on "Beneteau wiring" will uncover lots of prior discussions.
Good luck.
Thanks, Stu, your replies are always appreciated. I suppose that I can perhaps find an online lesson that will reasonably explain all the electrical and electronic boxes in the house-battery compartment of my Beneteau. I have schematics, but it's been many years since I could read those. I'd still like to know if anybody has experience using the new, small, lightweight battery booster/charger/starter units. My suspicion is that they will sit somewhere in the boat for so long they will not function if and when needed. The forum-provided links were somewhat useful, but I'm really believing that I just want to have my engine battery completely separate from the house system.
Spend some time reading the links. Reading 12V schematics is just a road map with no high tech detours..Your desire of isolating the start (emergency) battery from the house bank is good. A well designed system will do that and also be able to switch any battery to any desired function should it be necessary..With a correctly designed system, there is no need to carry any portable battery/starter units. If you get lost, ask specific questions here.. If you get totally lost, I would suggest hiring a competent marine electrician..We're here to help, but you have to put some time into understanding what needs to be done....
Wired with 2 simple On-Off switches and 1 2 circuit switch (like the Blue Sea) the house batteries and the start batteries are isolated until they need to be combined. The 2 Circuit switch has 3 positions, off, on, emergency on. In the on position both circuits are on and are isolated. In the emergency position, both circuits are on and power both the starter and the house circuit. These are different from the 1-2 Both switch, which is a selector switch allowing you to choose which battery to supply power.
As the saying goes, an ounce of prevention is worth a pound of cure. It is much easier to simply turn 2 switches to isolate the start battery and run everything (starter included) off of the house battery, or vice-versa. No jump packs (which are of questionable reliability and utility) or running jumper cables from one place to another. If you have have to change the power source to your starter, it probably won't be at the dock and will be in some dicey situation.
Another part of the equation is an accurate and reliable way to monitor the health and state of charge of your batteries. A Balmar Smartguage and/or a Victron Battery Monitor (Balmar Smartgauge | Compass Marine)
I have both, the Smartgauge is easier to set up and use and is a more accurate at measuring SOC while the Victron provides accurate measurement of the amps used and replaced and offers redundancy with SOC monitoring.
They also may not have the energy to start a diesel. They are made for car engines which usually much easier to turn over.
Ken
Which should never be required. UNLESS charging is present. Discussed in detail in the link in my reply #5. Written by our trusted friend and guru, Maine Sail.
This is only the tip of the iceberg, please, read the entire link which has great explanatory material and much more detail and reasoning.
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Dual Circuit Plus Battery Switch Rant:
This is also a rant or vent about the Blue Seas Dual Circuit Plus battery switch. This owner installed one, and when his house bank failed internally last week, he had no way to switch to only his starting bank, in an isolated manner. They key here is; "in an isolated manner".
to get any sort of VHF, instruments etc. without combining a good battery with a completely failed, internally shorted battery/bank.
The start battery still likely had a little life in it, about 110 cranking amps (Midtronics) before I tried to start the motor, vs. the 1000+ it should have, but due to the Blue Seas DCP switch he was unable to take any advantage of his second bank, in an isolated manner, as a safety back up because the failure in the house bank bled it down to the point where he could not start his motor at all after using the "COMBINE" position of the DCP switch.
The owner did not realize the house bank had failed internally so when he got to his destination, and could not make a VHF call or turn on any of his electronics, he did what he thought he should do, he turned the battery switch to COMBINE.....
When he did combine the start battery with the house bank it was apparently into an internally shorted house bank. He left it in combine/parallel long enough, while using the VHF radio & trying to figure stuff out, that it sucked the remaining useful life out of his starting battery and he was left dead in the water and needed a tow to get home
- If buying a Blue Seas Dual Circuit Plus Switch please do your home work and make sure it is the right fit for you.
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Stu, with all due respect to your knowledge, you may want to re-read my posts.
emphasis added.
The Dual Circuit plus is not a good solution unless there is a simple way to completely isolate the house and starter batteries from each other. Need to isolate the start battery, turn it off and then turn the dual circuit to emergency or parallel. See this follow up post.
The goal is to be able to supply power to either house or start circuit quickly and safely without the use of jump packs or jumper cables. The simple 3 switch solution works.
When the time comes to isolate a bank, it is never a good time, like being in a double set of busy locks with a dead start battery and strangely configured battery system that defies simple description while riding up and down a lock with a bevy of watchful eyes on the bridge above the lock. Just saying. (To the best of my knowledge there is no evidence on You Tube that any event like might have occurred.)
Stu you really should have read what Dave wrote before jumping on his post about the DCP. What he described is a great way of installing a DCP switch. In the diagram below the only switch visable to vessel occupants is the DCP. The emergency isolation switches are in the battery compartment or "out of sight, out of mind" to guests.. Simple and ticks all the boxes....
What he described is this:
The same situation happens on other boats only backwards from the way Beneteau often buses the banks together. This was an essentially brand new Hanse. It had an engine circuit and house circuit from the factory. The two battery factory switches are not even adequately rated to handle the installed loads on the boat because this boat has a large inverter and bow thruster. The new switches can handle 300A continuously.
The owner experienced a dead start battery, due to a stuck bilge switch, and due to an incorrectly wired bilge pump pulling off the start bank. Once he could not stat the motor, he quickly realized he had no way to use the adequately charged house bank, to start the motor with, because he had no emergency parallel switch or cross connecting switch. He was pretty angry at the poor factory switch configuration and brought me in..
We discussed numerous options and installed a Blue Sea three ON/OFF switch panel, ACR, Solar etc.. He now has complete bank isolation, emergency cross connecting & automatic charging of both banks etc. etc....
Before:
After:
The owner experienced a dead start battery, due to a stuck bilge switch, and due to an incorrectly wired bilge pump pulling off the start bank. Once he could not stat the motor, he quickly realized he had no way to use the adequately charged house bank, to start the motor with, because he had no emergency parallel switch or cross connecting switch. He was pretty angry at the poor factory switch configuration and brought me in..
We discussed numerous options and installed a Blue Sea three ON/OFF switch panel, ACR, Solar etc.. He now has complete bank isolation, emergency cross connecting & automatic charging of both banks etc. etc....
Before:
After:
The photos and drawings via Maine Sail are very explanatory and clear. Nonetheless, I'm going to draw a schematic and offer it up for comments, only because the Combiner & ACR mechanisms seem unnecessary. Gunni, I'm not sure what you mean when you say that my boat, by OEM, has an isolated starter battery. If you mean that it is isolated when switched off, well, of course. But when it is switched on, it is common with my house battery circuitry. Like other Beneteau owners, I learned the hard way when I left the boat for bottom coating last Fall - having left starter and house switches on, both sets were completely dead, 5 days later.
I hope this thread continues, as bit by bit, it is becoming clearer about what people are doing that seems to work for them.
I hope this thread continues, as bit by bit, it is becoming clearer about what people are doing that seems to work for them.
Yes, which means that in addition to being your starter battery you have an emergency power supply for the house. Just make sure you switch off the house disconnect to prevent current draining to a dead house battery, and cut loads down to match your reduced supply.
That is user error, SOP is to throw the disconnect when leaving the boat. And in any case there is NO reason to leave the start disconnect in the on position. Like I said, always have your starter battery in disconnect waiting for an emergency start and treat your boat like it has one battery, the house.
Like I said, I learned the hard way!
See drawing link, below.
1) Grounding system is left out for simplicity.
2) I have three batteries, two house and one engine, and separate charging to each. There is obviously a problem with House battery charging, in that the charger(s) can cross-charge if both House batteries are switched on while charging at dock. Any cross-charging via engine-alternator charging, with engine running, is not considered significant, as that time is minimal.
3) There was a good Maine Sail (?) article on the non-reality of supposed deep-cycle marine batteries, and it has been suggested that twin 6v golf-cart type batteries be used. With a lot of new technology, is/are there now any good recommendation(s) for real 12v deep-cycle batteries. My sense is that even with twin 6v batteries, they will slowly diverge in their quality and capacity, and therefore become a charging mismatch.
4) Okay, tear this up, and tell me why my setup otherwise is not a good one. Many thanks.
See drawing link, below.
1) Grounding system is left out for simplicity.
2) I have three batteries, two house and one engine, and separate charging to each. There is obviously a problem with House battery charging, in that the charger(s) can cross-charge if both House batteries are switched on while charging at dock. Any cross-charging via engine-alternator charging, with engine running, is not considered significant, as that time is minimal.
3) There was a good Maine Sail (?) article on the non-reality of supposed deep-cycle marine batteries, and it has been suggested that twin 6v golf-cart type batteries be used. With a lot of new technology, is/are there now any good recommendation(s) for real 12v deep-cycle batteries. My sense is that even with twin 6v batteries, they will slowly diverge in their quality and capacity, and therefore become a charging mismatch.
4) Okay, tear this up, and tell me why my setup otherwise is not a good one. Many thanks.
Attachments
If your house battery is dead and can't start your engine you also need power for your VHF, instruments, and perhaps nav lights so I see no utility in putting another disconnect in the starter battery circuit. If you are worried about other loads turn them off at your breaker panel. The people who get in trouble with the Beneteau electrical system are those who neglect to disconnect a dead house battery when going to emergency power...and kill their starter battery trying to equalize to the dead battery.
Odd that you have separate chargers for all batteries, I know there are some reasons for doing so but I believe there are better ways to address those reasons and treat your house battery like a single battery. I have 4, 12vdc AGM batteries but they are paralleled and treated as a single 500Ah battery. They are co-located midships, outside the engine bay and charged by a big temp-compensated single charger.
Odd that you have separate chargers for all batteries, I know there are some reasons for doing so but I believe there are better ways to address those reasons and treat your house battery like a single battery. I have 4, 12vdc AGM batteries but they are paralleled and treated as a single 500Ah battery. They are co-located midships, outside the engine bay and charged by a big temp-compensated single charger.
I have three batteries in my B323, with a switch for each. Shore charger wired to batts. I don't understand why you want an off switch on your starter battery. Why not just wire the starter to the battery side of a switch and leave the switch open? If that battery dies, you can just move the cable to the load side to make use of the house batteries. Yes, you're using the switch as a buss, but it's already there, so why not? But this is still all the hard way.
Just several weeks ago someone posted a dead start battery, and that started a whole thread that about duplicates this one. I have a strap across the three load sides of the switches. Anything that makes or uses electricity is wired to this "12-volt buss wire". I can use any or all batteries by just turning it/them on. I rotate shutting off a battery when docked or anchored. This means each battery is used and can be monitored as being up to snuff at least once a month. No more switching to a start battery only to find it is dead. Once the engine is started, you can turn on the off battery to charge it under way. No need to do a major rewire of an already good Beneteau system.
Just several weeks ago someone posted a dead start battery, and that started a whole thread that about duplicates this one. I have a strap across the three load sides of the switches. Anything that makes or uses electricity is wired to this "12-volt buss wire". I can use any or all batteries by just turning it/them on. I rotate shutting off a battery when docked or anchored. This means each battery is used and can be monitored as being up to snuff at least once a month. No more switching to a start battery only to find it is dead. Once the engine is started, you can turn on the off battery to charge it under way. No need to do a major rewire of an already good Beneteau system.