Simple Battery Isolator Diagram ?

[hellosailor]

"trying to make tone battery not be drawn by anything but the starter and be charged whenever the other is." That's what a combiner solves.

Dave-
The ordinary civilian looking for diode isolators, has no idea what a Schottky is much less where to find or read the specs on one. And usually no no remote voltage sense lead on the alternator, so also no way of overcoming it. Isolators are infamous for solving a problem (isolation) at the cost of having both batteries continually undercharged, or the alternator continually overworked. For the average boater who is not an electronics technician, they're no answer.

[btrayfors]

Originally Posted by goboatingnow

But of your battery sensing that's over cones the voltage drop , or use Schottky or even ideal MOSFET diode isolators , which essentially removes the voltage drop.

Very little energy is wasted in the voltage drop anyway.

I certainly prefer mosfet ideal diodes over mechanical relays.

Dave

You don't have to use them. The EchoCharge and DuoCharge are solid-state devices which are essentially voltage-followers. They don't do anything until charging voltages are sensed on the house batteries, then they bleed off some charging current to top off the start battery (up to 15A for the EchoCharge and 30A for the DuoCharge).

These devices are not combiners, they allow (limited) current flow in only one direction, don't involve a voltage drop, and don't have mechanical contacts...four reasons why I much prefer them over combiners. They are also very reliable in 24/7 operation.

Bill

[Cheechako]

Originally Posted by Maine Sail

I would not suggest using a diode isolator. A voltage sensitive relay/automatic combining relay/Yandina Combiner) (VSR or ACR) or a battery to battery charger (B2B) such as an Echo Charger or Duo Charger would be fine for the second aux battery bank. The Echo Charger is the most simple to install

These are very easy to wire in... With an Echo Charger one wire goes to the house positive (the red one) one wire goes to Start/Reserve positive (the red with white stripe) and one wire to the house neg post or the loads side of a shunt. When installing an ACR/VSR or Echo charger you simply run the alt output to the house bank as well as the voltage sensing for the regulator. The VSR or Echo/B2B charger do the rest.... Now your 1/2/BOTH is a simple on/off use switch and charging both banks is done seamlessly and behind the scenes..

So here's the stiuation, this is a summer boat, used maybe 8-10 times during the fair weather months. It's a powerboat, so undercharging the batteries is probably not a concern, even if charging .6 volts low due to an isolator I doubt they'll know the difference, as they will normally live their lives at a much higher level of charge than your average sailboat. Just trying to do something cheap and easy.... to avoid all the switching... it "aint no world cruiser"! My cost for an isolator is $55.
What do yo think I should do? I could move the battery switch requiring longer new cables. Strangely, the alternator charge cable goes to the + starter post which is then tied to the Batt selector switch. (common for these small powerboats and part of the wiring loom)

[hellosailor]

cheechako-
Chrysler is no more. The mark is now owned by Fiat, as I undertand it, and while the product exceeds anything either one of them used to make...I'm just not sure it is "Chrysler" anymore.
GM...how they dumped Pontiac, found a market in China to justify keeping Buick, and managed to lose money on Saturn for 30 years while earning nothing but acclaim and loyalty from the owners...I'm stumped there too.
I'd almost say Ford has got the right idea, but I took an Escape for a test ride this spring and the engine and gas pedal had to negotiate and discuss what my foot was doing anytime I stepped down. Throttle lag doesn't impress me, neither did the odd dash options.
There's an awful lot of modern cars that just don't impress me. I wonder how many of their engineers went to the same school as that plant manager?

I like the concrete strips in parking lots so you can't pull too far forward. In some places they are actually mandatory in parking lots. While an OSHA inspector in a factory yard would call them "tripping hazards" and order them removed while writing up the citations for them.

Decisions, decisions. How about just one big battery, and a low voltage cut-off on it? I think they're about $60, including a keychain remote to bypass them.

[Cheechako]

Originally Posted by DotDun

I've had good luck with Victron's Cyrix, fairly cheap and easy. It has a 'emergency' mode.

Cyrix-i 120A/ 225A /425A - Victron Energy

Kinda liking that solution.... just put that in line on the pos cable to the starting battery and it charges when the house batt is near full and disconnects when voltage starts to go down..... if I've got that right....

[Andina Marie]

In over 20 years of selling Combiner100 and over 50,000 in the field, all on unconditional warranty, we have NEVER had a warranty return where the relay contact failed. Keep it simple, solid state doesn't necessarily equate to "better".

Our Combiners can stand voltage spikes over 1,000 volts that will destroy a diode isolator in less than 1/1000 second. They can stand short circuit currents to 500% of rating and can operate in an engine compartment at 150F without any cooling problems like solid state switches.

The installation is just as easy as the echo charger, one positive lead to each battery and a negative connection. For less than 1/2 the price they can handle the output of a 100 amp alternator instead of the 15 amp limit for solid state echo combiners.

[DotDun]

Originally Posted by Cheechako

Kinda liking that solution.... just put that in line on the pos cable to the starting battery and it charges when the house batt is near full and disconnects when voltage starts to go down..... if I've got that right....

Some like it, some don't.

I put a switch on the cyrix at the 12v panel so I can 'control' it. The switch is on-off-on and wired: operate normally-off-emergency mode (even with a 2-color led).

My generator shares a start battery with my port engine, so when I'm running the generator and charging the house bank with the 60a shorepower charger, I engage the cyrix and utilize the 12v alternator (35a) in the generator during bulk charge, then shut it down as the batteries charge (under 60a).

The Cyrix seems to be very reliable, I know of several in service for 2-3 years with no issues.

[Andina Marie]

Originally Posted by Cheechako

So here's the stiuation, this is a summer boat, used maybe 8-10 times during the fair weather months. It's a powerboat, so undercharging the batteries is probably not a concern, even if charging .6 volts low due to an isolator I doubt they'll know the difference, as they will normally live their lives at a much higher level of charge than your average sailboat. Just trying to do something cheap and easy.... to avoid all the switching... it "aint no world cruiser"! My cost for an isolator is $55.
What do yo think I should do? I could move the battery switch requiring longer new cables. Strangely, the alternator charge cable goes to the + starter post which is then tied to the Batt selector switch. (common for these small powerboats and part of the wiring loom)

For the same price you could install a Combiner100. No voltage drop. Charge up to 100 amps. No messing with existing wiring. No messing with the alternator circuit. One battery will always be charged even if it fails. Can stand voltage spikes to 1000 volts that will kill an isolator in 1/1000 second. Unlimited warranty, not available with isolators. No cooling fins needed. Bi-directional so if you have shore or solar charging on the house battery, the starting battery will also be charged without having to install an additional isolator.

[Cheechako]

I'll check it out!

[hellosailor]

Andina-
"Bi-directional " This is an improvement over the original combiners, which only kicked in based on the voltage at Battery #1, yes? Or can the old ones be wired up to work this way as well?

[pbiJim]

Originally Posted by Cheechako

using a simple battery isolator... 2 batteries, one alternator. want to isolate one battery so it wont discharge in reserve for starting. I would like the option to be able to combine batteries in case of emergency so would like to use my existing battery selector (#1/both/#2) switch for that. I find diagrams on line but without the combining option.
Yeah, I can figure it out, but I imagine someone has this done.
and yes I know the pitfall is the alternator only senses one battery for charging.

I see that a lot of people have posted about the system that they think is best. I'm not reading a lot of options that conform to the original request of something simple that uses the existing 1-2-both switch. I'll try to honor the original request, as asked.

Wire the alternator directly to one battery. Attach that battery to the bat 1 post on the 1-2-b switch.

Wire the other battery to the bat 2 post on the 1-2-b switch

Wire all your stuff to the other post (often "C") on the 1-2-b switch.

Run with the switch on bat 1 for normal use. Run with the switch on both while the motor is running to charge both batteries. Switch to bat 2 or both for emergency starting, depending on how dead bat 1 is.

This is not my fantasy "wish I had it" system. This is a simple set up that uses the 1-2-b switch & keeps 1 battery in reserve for emergency use as asked for, but unfortunately relies on the operator to use it correctly. If you leave the switch set to both while the alternator is not running & the bank runs down, that's just tough cookies for you.

One nice thing about this set up, is that if you make the common mistake of switching to off while the alternator is running, you don't blow out the alternator because the alternator is permanently hard wired to a battery.

[Uncle Bob]

Originally Posted by Guy

Or you can operate the regular switch correctly. and not add anymore "stuff". I find the idea that there is always going to be human error in something this simple, unfounded. You develope procedures and stick to them.
And then have a back up plan

+1 I took it a step further and installed two 3 way switches, load connection from one switch to house load, load connection from the other to engine start and windlass with both switches connected to both banks.
This gives me the option of sourcing the load requirements from either battery bank if required. When motoring just switch the start switch to both and the house bank charges. (Have to remember to switch back when not running engine) This works really well for me, and of course the solar panels keep both banks charged via a sunsaver duo charge controller.

[Stu Jackson]

Maine Sail & I have been "promoting" this concept for the past 15 years. Glad others have picked up on it.

We have a combiner, in my boat since 1998, no problems at all.

And, if you do what Jim suggests, as I have been saying for years, B on the switch is for Both and for Backup, if, just if, your combiner, echo charger (or duo charger, not really needed, more expensive, needed for different battery types) ever fails.

Originally Posted by pbiJim

I see that a lot of people have posted about the system that they think is best. I'm not reading a lot of options that conform to the original request of something simple that uses the existing 1-2-both switch. I'll try to honor the original request, as asked.

Wire the alternator directly to one battery. Attach that battery to the bat 1 post on the 1-2-b switch.

Wire the other battery to the bat 2 post on the 1-2-b switch

Wire all your stuff to the other post (often "C") on the 1-2-b switch.

Run with the switch on bat 1 for normal use. Run with the switch on both while the motor is running to charge both batteries. Switch to bat 2 or both for emergency starting, depending on how dead bat 1 is.

This is not my fantasy "wish I had it" system. This is a simple set up that uses the 1-2-b switch & keeps 1 battery in reserve for emergency use as asked for, but unfortunately relies on the operator to use it correctly. If you leave the switch set to both while the alternator is not running & the bank runs down, that's just tough cookies for you.

One nice thing about this set up, is that if you make the common mistake of switching to off while the alternator is running, you don't blow out the alternator because the alternator is permanently hard wired to a battery.

[pbiJim]

Sorry, I'm new here. I haven't read all the previous posts from the last 10 years yet.

Give me some time. I'll catch up eventually.

[Stu Jackson]

Jim,

You already "GOT IT!" I had to figure it out back in 1998 before someone invented the Echo Charger. Our combiner works just great. The "trick" is for folks to understand the difference between the 1-2-B switch as a USE only vs Use and Charging switch.

It's pretty simple once you draw a wiring diagram.