Help me find this electrical device . . .

[Bleemus]

I have a Blue Seas battery switch. The one that only has Off-On-Combine. I have an ACR to facilitate start bank charging.

If one bank completely fails due to a shorted cell or if the bank is so low that it would drag the other down so much in Combine I could have both banks fail.

Is there a device that is settable to a cutoff voltage that I could wire into the positive line at each battery to automatically disconnect that bank if I chose Combine without realizing one bank was compromised?

I think if I put an On-Off switch on each battery I could easily do it manually but was wondering if there was a solution that would protect me or my wife if we stupidly didnt check bank voltages before combining the two banks.

If this piece of gear exists can someone point me in the right direction?

[john61ct]

Jumper cables with a reminder note

[Bleemus]

Originally Posted by john61ct

Jumper cables with a reminder note

I think you missed my point. Trying to automate the prevention of worse case scenario. Jumper cables would require us to have determined one bank is compromised manually. Trying to find a way to avoid that.

[john61ct]

Sorry to be flip. If everything is set up properly you may go years without ever needing to jump start off House.

No need to use Combine in any case, just switch the starter to House alone instead.

And to me keeping track of State of Health, State of Charge accurately, knowing the voltages of each bank at any time should be completely routine if not automatic right there at a glance.

But OK, all that aside, two ACR/VSRs, with single sense only, one directed at each bank, only if both are above voltage will Combine work.

[S/V Illusion]

The short answer is yes. There are battery cut-off units specifically made which you can set minimum voltage at which point the batteries are disconnected.

I don't have the manufacturer(s) name(s) handy but they advertise in QST which is a ham radio magazine. If you search HRO or other ham store catalogs or someone else here has a citing, you can find exactly what you are looking for.

I'm amazed all boaters don't have them as standard equipment.

[Bleemus]

Originally Posted by S/V Illusion

The short answer is yes. There are battery cut-off units specifically made which you can set minimum voltage at which point the batteries are disconnected.

I don't have the manufacturer(s) name(s) handy but they advertise in QST which is a ham radio magazine. If you search HRO or other ham store catalogs or someone else here has a citing, you can find exactly what you are looking for.

I'm amazed all boaters don't have them as standard equipment.

So it does exist! Thank you. I will try to hunt them down. I have friends that borrow my boat on occasion and want to make it as dummy proof as possible. They are competent sailors but we all make mistakes.

[barnakiel]

The banks can be kept disconnected at all times EXCEPT when being charged. This is very simple. A relay will do.

Then use only a 1 or 2 switch for the starting battery.

This is very minimalistic, but very reliable too.

b.

[skipmac]

Originally Posted by barnakiel

The banks can be kept disconnected at all times EXCEPT when being charged. This is very simple. A relay will do.

Then use only a 1 or 2 switch for the starting battery.

This is very minimalistic, but very reliable too.

b.

My setup. House and start batteries go to a 1-2-Both-OFF switch that feeds the starter directly (through a high amp fuse).

Always set to 1 (start battery) unless there's a problem, then switched to 2. Relay to keep both banks charged.

[FionaJC]

I have a 85Ah Start, 2 x 110Ah domestic and a 110Ah auxiliary spare.
There is a device that joins the start and domestic for charging if the engine is running, when the starter is fully charged, it then switches in the domestic. The auxiliary is kept separate as an emergency.

There are separate switches for domestic, start and auxiliary so I can switch anything to anything manually if I need it.

[sailalibi]

We use Balmars DUO CHARGE regulator. We have 1 house bank and 1 start battery wired to a 1/2/both switch. Bat 1 goes to the house bank as a way to start from the house, Bat 2 goes to the start battery for normal starting. The start battery is charged via the house bank thru the DUO when the house bank reaches 13v as it is charged via solar,alternator, or shore power. We leave this switch on bat 1 always. The DUO can be programmed for all major battery types and can charge at 20 amps.
Simple.

[leftbrainstuff]

Our freedom inverter / charger will shutoff the inverter function when house voltage drops below 10.5V. The freedom drives an echo charger which charges our starting bank and is limited to 15A output.

Our house bank is 3 sets of 2 6V Trojans. We can have 0, 1, 2 or all 3 banks connected.

Our start bank is two Optimas which can be 0, 1 or both.

We also have a jump start battery pack. If all are flat we can manually start our generator.

There are controllers which have the logic you mention but I prefer manual switching and the ability to check voltage and current draw. You could also build your own with a RaspberryPi.

We also have checklists we use to start, stop and change configurations. They are mandatory and alleviate the problem of an idiot blindly pushing buttons.

Our heart interface and dc voltage gauge show our house and start battery voltage. Easily visible. Getting in the habit of always glancing when passing works well.

[fdr14127]

We have installed a new Blue Sea's product that addresses your requirements, in conjunction with the now famous Blue Sea's ACR to handle the battery isolation. Switching is reduced to Off, On, and Emergency. Four circuits nominally are alway on to handle the fridge, bilge pump, intrusion alarm, and Fire alarm. The system is simple and easily installed to replace the OEM arrangement that came with the boat. This plus the ELI is the way of the future.

https://www.bluesea.com/products/868...nagement_Panel

[hamburking]

Originally Posted by Bleemus

So it does exist! Thank you. I will try to hunt them down. I have friends that borrow my boat on occasion and want to make it as dummy proof as possible. They are competent sailors but we all make mistakes.

LOL...so true. I sold my Pearson 30 last year, and the new owner went out for an evening sail. He put the powerful spreader lights on, like car headlights, for the whole trip. As you already guessed, when he went to start the engine to get home, no volts left. So he phoned me, angry, cause the engine would not start.

You can try to make some systems dummy proof, but I have found that the dummies will do something you would never expect!

For example, I would sometimes ask a guest to turn the battery switch (saving me a trip below). To my surprise, many people think BOTH and 2 are the same thing...(btw, they are not, especially on a battery switch).

I used a simple, cheap, digital voltmeter that plugs into any 12V socket. Like $3 on ebay. That way I always know the battery voltage, and so will everyone aboard.

http://www.ebay.ca/itm/12V-24V-Digit...dYCdbk&vxp=mtr

[Ivansgarage]

Here is a slick battery monitor with alarm.
Used one in my big truck for years so I wouldn't wake up
with dead batteries. 44 bucks

Digital Voltmeter | VoltMinder.com

[mitiempo]

Originally Posted by Bleemus

I think you missed my point. Trying to automate the prevention of worse case scenario. Jumper cables would require us to have determined one bank is compromised manually. Trying to find a way to avoid that.

The only reason to ever use the combine position on the switch is if the start battery is dead and you cannot start the engine or the house bank is dead and you need to use the start battery for house loads. Both these circumstances are extremely rare.

A simple on/off switch in the start battery wire (Blue Seas 6006) between the battery and the dual circuit switch would solve the non-starting problem. If you really think it is necessary a similar switch in the house bank wiring could be installed. These switches would not have to be visible so could be less accessible than the main switch.

The dual circuit switch is best used in small boats where each bank is composed of a single battery - typically small fishing boats and the like. That is what it was designed for.

My preference is for a single on/off switch for each bank with a switch less accessible to allow using each bank individually for either load.