Moving from 1,2,Both switch to VSR

[BabaYaga]

See my reply above on the A2B charger. My mains charger is then only connected to the house bank.

No doubt that's a good solution, with many additional features. At a price, though.
There are many ways to avoid the risks highlighted in posts #30 and 37.
I use a heavy duty non-voltage sensing relay, controlled by alternator D+, to parallel the batteries. So split charging only takes place during the limited time (in my case) when the engine is running. Others, I believe, achieve the same by using a VSR, but putting an additional small head lamp relay in its negative connection. Same effect, the VSR only closes when the engine is running, not because of solar or mains charging of the house bank.

 

[PaulRainbow]

The Ops question was how to change from a 1-2-B switch and fit a VSR, so that's what i thought it best to answer. There are, of course, many ways to skin the charging cat. Some might not suit a particular installation, but it's often the case that you could choose from several alternatives and each would work perfectly OK, it then becomes a matter of choice. There are also some installations that are just plain unsuitable, dangerous or just half baked, best avoid those

There are also some old wives tales and myths. One of those being the harm done to the starter battery if it's connected to the domestic bank via a VSR and it's subjected to the charging regime from the domestic batteries. If this was anything else, an anchor thread, for instance, there would be demands for some evidence, i see no such evidence. What we do often see is a theory, that might, on the surface, look valid. But, it's usually just an opinion, no evidence.

My batteries, 3 x 130ah domestic and 1 x car starter battery, all sealed, are connected to a Victron VSR. During the Summer the batteries are charged by solar power, i'm onboard, so they are getting cycled. During the Winter, i leave the mains charger on and the solar connected. My engine battery is four years old, sealed and in good order. I have countless customers and friends who leave the batteries on mains charge all of the time and several who live aboard and have substantial solar arrays, that power the whole boat. It is very rare that i'm asked to fit a new engine battery and i cannot remember the last time i fitted one due to premature failure.

Of course, if you have a large deep cycle bank that you charge at high voltages or regularly de-sulphate, it might be a different story. In either case, if you want to fit a system that doesn't automatically charge the engine battery, that's your choice. Doesn't mean it was essential though.

 

[ghostlymoron]

It's true that the start or engine battery should have an easy life as it's recharged by the alternator in a few minutes after every start so should last almost indefinitely. (The battery in my Audi is ten years old).
Getting back to battery isolation, I'd always avoid 12B0 switches as they rely on the operator remembering to switch over at the appropriate time. At least two of my friends have been caught out by this and accidentally flattened both battery banks and been unable to start the engine. (Neither had an alternate charging source). One had to row ashore, remove his car battery and use this to start.
I'd had a discussion with him prior to this incident and he assured me that after 20 years experience, he wouldn't forget and anyway he liked to have manual control over his battery charging regime. He still hasn't changed from manual switching and has now installed a second rotary switch, the function of which is a mystery to anyone but him.

 

[PaulRainbow]

No doubt that's a good solution, with many additional features. At a price, though.
There are many ways to avoid the risks highlighted in posts #30 and 37.
I use a heavy duty non-voltage sensing relay, controlled by alternator D+, to parallel the batteries. So split charging only takes place during the limited time (in my case) when the engine is running. Others, I believe, achieve the same by using a VSR, but putting an additional small head lamp relay in its negative connection. Same effect, the VSR only closes when the engine is running, not because of solar or mains charging of the house bank.

I think we've had this discussion before......

Whilst your relay works if there are no problems, it's the same as having a 1-2-B switch set to both, while the engine is running. A failed battery could easily leave you with no power. The VSR with a realy in the negative give the usual VSR benefits/safeguards while the engine is running, leaving the engine battery standing alone with the engine off, so is a better solution. But it's almost always a solution to a problem that doesn't exist.

 

[fredrussell]

OP here. Funnily enough, the first of Paul Rainbow’s circuit suggestions is pretty much what I had come up with sitting on the boat yesterday - so I’ll go with that for starters and see if it suits my M.O.

 

[Beneteau381]

1,2, both works fine for us for reasons you've given in #30. We don't have crew to worry about getting things wrong and the switch is less likely to fail than anything containing relays and/or software. I don't understand worries about engine battery charging and wonder if people put their car on charge if not used for a few days.

Both my Benes had/have 2 positive switches, one for each bank, and a common negative. There is a link on the switched sides of the positives. Both banks will start the engine separately. Engine bank off conserves it. The mains charging system charges both banks whether switched on or off. Whichever bank is switched on gets the alternator charge. The solar goes only to the house bank. In practice I switch both on at all tines, Ive never had a flat starter bank.

 

[BabaYaga]

There are also some old wives tales and myths. One of those being the harm done to the starter battery if it's connected to the domestic bank via a VSR and it's subjected to the charging regime from the domestic batteries. If this was anything else, an anchor thread, for instance, there would be demands for some evidence, i see no such evidence. What we do often see is a theory, that might, on the surface, look valid. But, it's usually just an opinion, no evidence.

My engine battery is four years old, sealed and in good order.

It is very rare that i'm asked to fit a new engine battery and i cannot remember the last time i fitted one due to premature failure.

The fact that a theory, or opinion if you like, is not backed up by evidence, does not automatically make it a myth or worse.
Setting up a scientific test of how different usage patterns affect battery life in leisure boats would be a major undertaking and probably quite difficult too, as there are many factors involved. Who would pay and who would even be interested? Lead acid is old technology and boaters are niche battery users.
So in lack of hard evidence one way or the other we must use reason. For instance: There is a reason for the existence of float voltage in mains chargers and solar controllers. They are there to minimize the time the battery spends at absorption voltage. If this was just old wives tales, why do we have float voltage?
Perhaps it all boils down to how we define words like 'harm' and 'premature'. In that context it might be telling that you back up your statement by referring to you four years old, healthy starter battery. Well, my Red Flash starter battery is 11 years old and healthy, but of course neither of our batteries are evidence of anything – apart possibly from different perspectives.
But I hope we might agree that the OP of this recent thread
What to expect from my batteries
who had his new AGM starter battery die in less than 20 months, was victim to a premature failure?

 

[PaulRainbow]

The fact that a theory, or opinion if you like, is not backed up by evidence, does not automatically make it a myth or worse.
Setting up a scientific test of how different usage patterns affect battery life in leisure boats would be a major undertaking and probably quite difficult too, as there are many factors involved. Who would pay and who would even be interested? Lead acid is old technology and boaters are niche battery users.
So in lack of hard evidence one way or the other we must use reason. For instance: There is a reason for the existence of float voltage in mains chargers and solar controllers. They are there to minimize the time the battery spends at absorption voltage. If this was just old wives tales, why do we have float voltage?
Perhaps it all boils down to how we define words like 'harm' and 'premature'. In that context it might be telling that you back up your statement by referring to you four years old, healthy starter battery. Well, my Red Flash starter battery is 11 years old and healthy, but of course neither of our batteries are evidence of anything – apart possibly from different perspectives.
But I hope we might agree that the OP of this recent thread
What to expect from my batteries
who had his new AGM starter battery die in less than 20 months, was victim to a premature failure?

When i start to get called out by lots of people with failed starter batteries, i'll look into the possible reasons. The fact is, in the real World, it isn't happening, despite huge numbers of boats being on charge all of the time.

One person with a failed AGM battery, the cause of which is unknown tells us absolutely nothing at all.

 

[pvb]

When i start to get called out by lots of people with failed starter batteries, i'll look into the possible reasons. The fact is, in the real World, it isn't happening, despite huge numbers of boats being on charge all of the time.

And, also in the real world, even larger numbers of cars and vans running around all day at alternator voltage, without problems.

 

[geem]

Wh

And, also in the real world, even larger numbers of cars and vans running around all day at alternator voltage, without problems.

which brings us back to the very well made point, why do we have float on our solar and mains chargers if running the batteries at absorption voltage all day is such a great idea?

 

[PCUK]

Further proof, if proof is needed, of the folly of having a 1-2-Both switch!

But if this only selects the domestic batteries then I still think they are the best solution for keeping a domestic battery in reserve for when the first runs down at 11 0'clock at night just as the party is getting under way!.

 

[pvb]

But if this only selects the domestic batteries then I still think they are the best solution for keeping a domestic battery in reserve for when the first runs down at 11 0'clock at night just as the party is getting under way!.

Domestic batteries are best wired in parallel as a single bank. In this way, the batteries will deliver more Ah. Say you have 2 house batteries, each 100Ah, and that you have a 10A load on them from lights, radio, fridge, instruments, etc. If you wire them in parallel as a 200Ah bank, they'll run for 10 hours until they reach 50% depth-of-discharge, and will therefore have delivered 100Ah. But if you have only have one of the batteries in circuit, it will only last about 4.3 hours, and therefore deliver 43Ah. Switch over to the second battery and the same thing will happen, so in total you'll only have 86Ah effective capacity by using the batteries separately, or 100Ah effective capacity if you run them together.

 

[halcyon]

Wh

which brings us back to the very well made point, why do we have float on our solar and mains chargers if running the batteries at absorption voltage all day is such a great idea?

I will regret this, simple answer,

Why regulate at 14.4 ? above this battery starts to gas heavily and the gain in recharge level starts to fall, sinusoidal curve. But transformer chargers have a sinusoidal output curve which is higher than the 14.4 volt you see on your meter, But only pulses, so limits high water lose while providing high recharge level, as no further gain can be achieved float voltage, or maintenance cycle, is selected. When they bought out switch mode chargers they had a straight line voltage output, so to achieve the high recharge they had to introduce absorption voltage and increased water lose. Running at absorption would gain nothing bar boiling the battery, hense float level. The alternator on your car has a sinusoidal curve so less gassing, most loads on the alternator are resistive loads, these reduce peak and running voltage, most car journeys are not 24/7 like mains chargers and solar panels, most now controlled by your ECU, or a number of ECU's, for voltage and current, ventilation tends to be better on cars so not a problem. For interest float voltage comes from the old fixed back-up battery banks ( telephone exchanges) run 24/7 on charge, around 13.6 volt gave no water lose. but needed a periodic full charge to maintain battery life.

Brian

 

[geem]

I will regret this, simple answer,

Why regulate at 14.4 ? above this battery starts to gas heavily and the gain in recharge level starts to fall, sinusoidal curve. But transformer chargers have a sinusoidal output curve which is higher than the 14.4 volt you see on your meter, But only pulses, so limits high water lose while providing high recharge level, as no further gain can be achieved float voltage, or maintenance cycle, is selected. When they bought out switch mode chargers they had a straight line voltage output, so to achieve the high recharge they had to introduce absorption voltage and increased water lose. Running at absorption would gain nothing bar boiling the battery, hense float level. The alternator on your car has a sinusoidal curve so less gassing, most loads on the alternator are resistive loads, these reduce peak and running voltage, most car journeys are not 24/7 like mains chargers and solar panels, most now controlled by your ECU, or a number of ECU's, for voltage and current, ventilation tends to be better on cars so not a problem. For interest float voltage comes from the old fixed back-up battery banks ( telephone exchanges) run 24/7 on charge, around 13.6 volt gave no water lose. but needed a periodic full charge to maintain battery life.

Brian

So, an aggressive solar charge of the engine batteries every day because they are linked via the VSR (even though they are fully charged) to the domestic battery (that needs the charge cycle to obtain full charge status) will eventually boil the engine battery dry?

 

[halcyon]

Assuming you are using a bi-directional VSR, though no more damage than your service battery bank gets, assuming common spec.

If you use a VSR sensed from engine battery only, you have no problem with solar charge to service bank.

Or a VSR with high voltage protection, which can produce a maintenance cycle for the engine battery.

Brian

 

[PaulRainbow]

So, an aggressive solar charge of the engine batteries every day because they are linked via the VSR (even though they are fully charged) to the domestic battery (that needs the charge cycle to obtain full charge status) will eventually boil the engine battery dry?

Define aggressive ?

 

[geem]

Define aggressive ?

Manufacturers recommendations, so in my case 14.8v for my domestic bank

 

[PCUK]

Domestic batteries are best wired in parallel as a single bank. In this way, the batteries will deliver more Ah. Say you have 2 house batteries, each 100Ah, and that you have a 10A load on them from lights, radio, fridge, instruments, etc. If you wire them in parallel as a 200Ah bank, they'll run for 10 hours until they reach 50% depth-of-discharge, and will therefore have delivered 100Ah. But if you have only have one of the batteries in circuit, it will only last about 4.3 hours, and therefore deliver 43Ah. Switch over to the second battery and the same thing will happen, so in total you'll only have 86Ah effective capacity by using the batteries separately, or 100Ah effective capacity if you run them together.

I'll stick with the selectable domestic batteries as long experience has taught me that it is always better to have something in reserve.

 

[geem]

I'll stick with the selectable domestic batteries as long experience has taught me that it is always better to have something in reserve.

Except PVB is correct. Your reserve is your isolated engine battery

 

[[176172]]

I fail to see how you're going to use a 1-2-Both switch as well as a VSR. The 1-2-Both switch concept is way outdated, and there are much better solutions today. A VSR to link the batteries when charging, plus two simple on/off switches, will control your batteries easily without any of the risks associated with 1-2-Both switches (primarily flattening the starter battery!).

Perfectly logical, but outdated? not so sure. Personall used the the manual system for some 30 years, it becomes automatic to select 2, in my case starter, then switch to both as soon as on course or otherwise settled. Its just a routine I am used to. If solo I select both to start, and leave it there until the opportunity presents itself to revert to 1.
That is not a strict pattern, but a conscious procedure automatically operating from habit. I am not alone I feel sure, no, I know I am not from conversations we social creatures have with our fellow addicts. Those who prefer an electronic system are welcome to it, you pays your money and takes your choice.