1,2 Both Switch - When on Both do the 2 batteries even out on charge?

[shaunksb]

A taxi is unlikely to be parked for more than a couple of days for its abused battery to self-discharge.

.

It's obvious a taxi needs a 1-2-both switch so that after initial starting and a short charge it can swap over to its more abused battery and keep the starter one in peak condition.

Bugger me if I know what my boat needs though...

_______________________

 

[RichardS]

Sorry, can you repeat the question? I got distracted by the rugby!

Ahh ... welcome back! It's post #83.

Thanks.

Richard

 

[Ceirwan]

Most new AWBs have two on/off switches (one for engine, one for domestics) and a charge isolator (usually a low-loss device). It's interesting that they have gone this route rather than using VSRs, especially as VSRs are much cheaper (£40 or so vs £160 or so).

I work for a large workboat company and I was actually asking the electrician from our technical department about this last week.

In his opinion VSRs have no place on a boat unless they're current limiting, and even then he would always use a different type of splitter. This came up because he was onboard to diagnose an issue that was caused by a failed VSR on one of the vessels.

He's been doing it around 10 years so I'll take him at his word. Fortunately for me its not an issue as my alternator has dual outputs.

 

[sailinglegend420]

Very entertaining read, i also enjoyed The Chronicles of Narnia. Whilst an alternative World in the back of my wardrobe might be fun, i don't think any of us would enjoy your alternative World of battery/charging technology.

May I suggest a more hard core adult read: Energy Unlimited by Victron @ https://www.victronenergy.com/upload/documents/Book-EN-EnergyUnlimited.pdf

This 72 page brochure will tell you everything you need to know if you are going to post on a technical forum like this. Battery gassing is a misunderstood problem and is especially important with todays sealed 'maintenance free" batteries.

Many other battery manufacturers also say the same things about "overcharging" batteries, which is why they all recommend Multi-Stage Smart Chargers.

I knew my post would generate this familiar question:

How come it isn't it a problem for millions of cars with alternator regulator set to 14 plus volts?...

....but BabaYaga has the key to the answer:

Y.... If I am not mistaken alternators often have thermistors in them, reducing voltage as they run hot....

This a very complex subject so let me offer another reference as some readers here don't believe my posts. This link explains battery gassing and why control of the absorption voltage is so important as the battery temperature rises. At 25ºC batteries start to gas at 14.4v, at 40ºC they gas at 14v so any charger or regulator should reduce the charging voltage automatically to compensate for this.

http://docplayer.net/21620754-Temperature-compensated-charging-of-lead-acid-batteries.html

Gassing
Batteries need to reach their correct "absorption Voltage" to start to gas very slightly and to charge properly by stirring up the electrolyte. (FLA only). When the battery is 100% fully charged the extra energy going into a fully charged battery rapidly causes excessive gassing. This "gas" is Hydrogen and Oxygen - water - which cannot be replaced in a sealed battery and will lead to them eventually drying out. When they drop down to a lower Float voltage the gassing stops.

With a modern automobile alternator that charges at 14.4v or over they do all have temperature compensation of their charging voltage. As the temperature of the car engine rises the alternator output voltage reduces to keep the battery voltage below the gassing voltage. So the car battery never gets "overcharged".

The same alternator in a boat will do the same thing, but it will lead to "Undercharging" of both banks.

I did say in my post - "It is possible with all these automated systems that the starter battery can be overcharged".

If the alternator on your boat does have an external regulator or a shore power charger or generator driving the shore power - without any external battery temperature sensors - then this is the situation where the starter battery would be overcharged if your boat charging systems are set up to maintain 14.4v under all temperatures - especially if the batteries are in the battery compartment!

 

[pvb]

You should apply for a job writing the long-winded alarmist guff which Sterling put in their instructions.

 

[GHA]

May
The same alternator in a boat will do the same thing, but it will lead to "Undercharging" of both banks.
!

Except it doesn't.

From the real world, iskra aak will put out 14.5ish. Hour after hour.

Barely enough to get a bubble from a t105.

 

[pvb]

Except it doesn't.

Exactly. If the dire warnings were true, we'd all be replacing our starter batteries every year!

 

[sailinglegend420]

.....From the real world, iskra aak will put out 14.5ish. Hour after hour.....

From my real world my Balmar hot rated alternator switched to use the internal regulator will be below 14v after an hour. The two cars at home do the same thing.

 

[GHA]

From my real world my Balmar hot rated alternator switched to use the internal regulator will be below 14v after an hour. The two cars at home do the same thing.

Yo in won't find a balmar on a car.
Data link for the cars, please? What alternator, voltage against temperature graph .

No data, how can you know what's going on?

 

[PaulRainbow]

May I suggest a more hard core adult read

This 72 page brochure will tell you everything you need to know if you are going to post on a technical forum like this. Battery gassing is a misunderstood problem and is especially important with todays sealed 'maintenance free" batteries.

No need, i work with these things everyday. I see more real World battery/charging situations in an average week than most people will see in a lifetime, unless they are seriously unlucky.

Many other battery manufacturers also say the same things about "overcharging" batteries, which is why they all recommend Multi-Stage Smart Chargers.

How are these smart chargers fitted to car/van/lorries etc ?

With a modern automobile alternator that charges at 14.4v or over they do all have temperature compensation of their charging voltage. As the temperature of the car engine rises the alternator output voltage reduces to keep the battery voltage below the gassing voltage. So the car battery never gets "overcharged".

The same alternator in a boat will do the same thing, but it will lead to "Undercharging" of both banks.

Where do you get this stuff from ?

Sorry to say, that's utter nonsense.

 

[sailorman]

Is the 1 Both 2 the new anchor debate

 

[PaulRainbow]

Is the 1 Both 2 the new anchor debate

Don't be ridiculous, who ever heard of anyone using a switch as an anchor ?

On the other hand, that may be a better use for these old dinosaurs

 

[sailinglegend420]

.......Where do you get this stuff from ?

Sorry to say, that's utter nonsense.

Read my links and then try this site - a highly respected US marine electrical engineer:

pbase.com: "A deep cycle battery assassin"

If we assume 145F with a typical Yanmar / Hitachi alternator, based on the thermistor temp gradient built into the regulation circuit, we can see that at 68F it should produce 14.4V +/- 0.3V (BTW +/- 0.3V is horribly SLOPPY). However, for every degree rise above 20C/68F, it reduces the regulation voltage limit by -.01V per degree Celsius. An engine bay temp of 145F is 63C. This 63C is an ambient temp increase of 43 degrees Celsius beyond the thermistors baseline of 20C / 68F.


43 X .01V = -.43V


With just an engine room temp of 145F the highest regulation voltage we can attain is 13.97V. Keep in mind I have not even included for any heat generated by the alternator itself here, just the engine room temp.

 

[lw395]

Y

So why aren't car/van starter batteries dying consistently and why would a boat starter battery be any different with the same treatment?

"If leaving the battery at 14 point something volts long term was a good idea, we would not be using 3 stage battery chargers.
Ask a battery manufacturer"
so why aren't the battery manufacturers screaming and shouting about modern alternators putting out ~14.4v

Car batteries generally get 18 to 20 hours rest every day.
Car batteries get a relatively easy life, rarely called upon to do more than crank an easy to start engine for a few seconds, having been charged a few days before.
But it's not unknown for car batteries to fail within the warranty period.
"Starter batteries in vehicles have also become failure-prone. In 2008, ADAC (Allgemeiner Deutscher Automobil-Club e.V.) stated that 40 percent of all roadside automotive failures are battery-related. A 2013 ADAC report says that battery problems have quadrupled between 1996 and 2010."
Maybe the modern higher voltage alternators are part of that?

Motorbike batteries, which tend to have to deliver a higher % of their rated CCA in normal use, and get left for longer before charging, frequently have very short lives.

I guess a lot of boats don't see a problem because they are only stared a few dozen times a year, and only run for a few hours?

 

[GHA]

If we assume 145F with a typical Yanmar / Hitachi alternator, based on the thermistor temp gradient built into the regulation circuit,

Hitachi's are well known for their regulator temperature behaviour. That's just one alternator make which is known to be excessive.

What about all the other millions out there which don't behave like that still putting out high voltages?

 

[lw395]

It's obvious a taxi needs a 1-2-both switch so that after initial starting and a short charge it can swap over to its more abused battery and keep the starter one in peak condition.

Bugger me if I know what my boat needs though...

_______________________

Taxis should have jump leads. That's a bit like 1-2 both, but more manual. When I worked in Germany, my flat mate's car would not start, he thought it was entirely reasonable to phone a taxi and get a jump start!

 

[GHA]

Car batteries generally get 18 to 20 hours rest every day.
Car batteries get a relatively easy life, rarely called upon to do more than crank an easy to start engine for a few seconds, having been charged a few days before.
But it's not unknown for car batteries to fail within the warranty period.
"Starter batteries in vehicles have also become failure-prone. In 2008, ADAC (Allgemeiner Deutscher Automobil-Club e.V.) stated that 40 percent of all roadside automotive failures are battery-related. A 2013 ADAC report says that battery problems have quadrupled between 1996 and 2010."
Maybe the modern higher voltage alternators are part of that?

Or after a bit of time on google, battery death seems to be also connected with the increase in current sucking electronics with led screen displays etc. No mention of high voltage came up in a quick 10 minute google.

 

[PaulRainbow]

Read my links and then try this site - a highly respected US marine electrical engineer:

pbase.com: "A deep cycle battery assassin"

If we assume 145F with a typical Yanmar / Hitachi alternator, based on the thermistor temp gradient built into the regulation circuit, we can see that at 68F it should produce 14.4V +/- 0.3V (BTW +/- 0.3V is horribly SLOPPY). However, for every degree rise above 20C/68F, it reduces the regulation voltage limit by -.01V per degree Celsius. An engine bay temp of 145F is 63C. This 63C is an ambient temp increase of 43 degrees Celsius beyond the thermistors baseline of 20C / 68F.


43 X .01V = -.43V


With just an engine room temp of 145F the highest regulation voltage we can attain is 13.97V. Keep in mind I have not even included for any heat generated by the alternator itself here, just the engine room temp.

More nonsense. Not all batteries are in the engine bay. Those that are, are increasingly insulated. Even so, that doesn't explain how engine temperature is controlling alternator output. Simple fact is, it isn't. The reason for that is because it's not truly relevant, if automotive manufacturers were really worried they would fit battery temp sensors. They don't.

 

[PaulRainbow]

Car batteries generally get 18 to 20 hours rest every day.
Car batteries get a relatively easy life, rarely called upon to do more than crank an easy to start engine for a few seconds, having been charged a few days before.

My van often runs for 10-12 hours a day. It gets a hard life. It is fitted with lots of flashing lights and a heavy duty winch. Sometimes it sits for 4 or 5 days without being used. It (and the batteries) are coming up to 4 years old and have covered 88,000 miles. The batteries are in excellent shape. That doesn't mean to say that all they have to do is start the engine. There are times when they are not being charged but are powering the lights, flashing lights and operating the winch, all of which they do without complaint.

But it's not unknown for car batteries to fail within the warranty period.

Not unknown, but rare.

"Starter batteries in vehicles have also become failure-prone.

Untrue.

In 2008, ADAC (Allgemeiner Deutscher Automobil-Club e.V.) stated that 40 percent of all roadside automotive failures are battery-related. A 2013 ADAC report says that battery problems have quadrupled between 1996 and 2010."
Maybe the modern higher voltage alternators are part of that?

Those figures are about right. The underlying cause is not that battery problems have quadrupled. The reason behind the spike in roadside failure figures is the relatively recent acceptance by breakdown organisation that a battery failure constitutes a breakdown, within the terms of their cover. Added to by the fact that more and more people now have breakdown cover.

Motorbike batteries, which tend to have to deliver a higher % of their rated CCA in normal use, and get left for longer before charging, frequently have very short lives.

Shorter lives because they are all to often allowed to self discharge to unacceptable levels. Connected to a decent smart charger when not i use they last for years.

 

[sailinglegend420]

?...i work with these things everyday. I see more real World battery/charging situations in an average week than most people will see in a lifetime.......

Iif you work in the industry then you are the reason that I post so much to try and educate poor boat owners who are getting fleeced by ignorant experts like you.