Solar Watts : Daily AH Consumption

[Jon Hacking]

Yes, it's very important for ANY charging device to measure the AMPS INTO THE BATTERY. That's the only way it can know the State of Charge (SoC) of the battery, & to then know when to drop from Acceptance to Float. Time based "solutions" are very poor. Much better to directly read the amps into the battery. Our Blue-Sky SB-50 & my alternator regulators do this. Our AC charger doesn't, but we never plug into AC ('cause then we'd have to charge THEM! )

[a64pilot]

I understand and agree with the voltage issue, up to a point.
As I have said over and over the Concorde aircraft AGM batteries that are the same as a Lifeline battery, and indeed even Lifeline batteries live for years, running around in vehicles that maintain a constant voltage that is within tolerance of Lifelines accepted absorption criteria, and are not temp regulated, so the ones in engine compartments that are held at a steady temp of above 100f are certainly “overcharged”.
Yet they don’t die? They are not dried out in a single year?

Excessive voltage and or excessive time at high voltage will absolutely kill a battery, just I don’t think an hour so, every now and again at absorption is going to do it, and as how you cannot make a timer based charger hit the full charge set point most of the time, your either going to slightly over or slightly under charge, often.
It’s my belief that a slight overcharge is less damaging over time than a slight undercharge, however neither is really all that harmful, assuming You equalize as needed.

However I have not yet seen a factory default setting that wasn’t overly conservative, dropping the bank into float way prematurely. My Sterling Pro Charge Ultra is an excellent charger, but to get to fully charged, I have to turn it off and on about three times, each time you cycle the power it starts over in absorption and runs a timer.

So we agree to a point, excessive anything is bad for a bank, the definition of excessive may be where we disagree?

[a64pilot]

Originally Posted by sailinglegend

I have just installed two new Victron SmartSolar charge controllers and the 'Drop to Float' feature at 1 amp is fantastic and will stop overcharging over winter.

Sounds good, but they will never trip to float in any average cruising Boat, cause something that draws more than 1 amp is always on, phone charger, laptop, or me it’s the fridge drawing 6 amps continuously, every afternoon. If it cycles off, it does so in the middle of the night when no one has opened it and added food etc.

Now in storage they will trip to float most probably, but if so leave the boat I set my outback to hold float voltage, I don’t let it get any higher.

[sailinglegend]

Originally Posted by a64pilot

Sounds good, but they will never trip to float in any average cruising Boat, cause something that draws more than 1 amp is always on, phone charger, laptop.....

I did say this was a very useful feature over the winter months to stop batteries being held at absorption for too long. If you've got 4 solar controllers then 1 amp per controller is more than possible.

Originally Posted by a64pilot

.....even Lifeline batteries live for years, running around in vehicles that maintain a constant voltage that is within tolerance of Lifelines accepted absorption criteria, and are not temp regulated, so the ones in engine compartments that are held at a steady temp of above 100f are certainly “overcharged”....

All detractors of gassing and overcharging theories always quote car batteries and simple alternator regulators as not being a problem. A car battery is happy sitting there for hours without overcharging!

This is because many car alternators regulate at 14-14.2 volts, or less, well below the gassing voltage. Modern alternators may go as high as 14.6v, but they also have built in temperature compensation that will fairly quickly reduces the voltage below 14v - well below the gassing voltage, this makes them like very simple multi stage chargers. Modern cars with smart alternators are ECU controlled to drop the voltage down to a float level when the batteries are charged.

So the bottom line is car batteries never get overcharged - just check the voltage after half an hour of motoring. Most boats are supplied with car alternators that will very quickly overheat and drop their voltage because they are being asked to work too hard. The modern alternators with built-in temperature compensation will also drop the voltage down quickly to below 14 volts. I have an expensive Balmar hot rated alternator with built in regulator that can be switched on when or if the external regulator fails. This falls to below 14v very quickly which means a service battery on a boat that needs to sit at 14.4 volts for several hours is always being undercharged without a proper external regulator.

[Stu Jackson]

Originally Posted by sailinglegend

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This is because many car alternators regulate at 14-14.2 volts, or less, well below the gassing voltage. Modern alternators may go as high as 14.6v, but they also have built in temperature compensation that will fairly quickly reduces the voltage below 14v - well below the gassing voltage, this makes them like very simple multi stage chargers. >>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>

Temperature compensation on alternators is to stop the alternator itself from overheating, and has absolutely nothing to do with charging voltages. When temp compen kicks in, the field current is affected, reducing the amperage output, i.e., the load on the alternator, without changing the voltage. The only change to the voltage is made between the Cv (calculated voltage) and Bv (battery voltage) based on the programming of the regulator. Temp compen is simply automatic Small Engine Mode on a Balmar MC-series regulator.

[john61ct]

Originally Posted by Stu Jackson

Temperature compensation on alternators is to stop the alternator itself from overheating, and has absolutely nothing to do with charging voltages. When temp compen kicks in, the field current is affected, reducing the amperage output, i.e., the load on the alternator, without changing the voltage. The only change to the voltage is made between the Cv (calculated voltage) and Bv (battery voltage) based on the programming of the regulator. Temp compen is simply automatic Small Engine Mode on a Balmar MC-series regulator.

Sorry, but the most advanced VR's do include proper temperature compensation

which has **everything** to do with automatically adjusting the voltage setpoints according to ambient temperature, as per batt maker specs.

Just like the better solar controllers, mains chargers etc.

Temperature **protection** features are completely separate conceptually, and although implemented even in many stock factory alternator setups, only the high-end aftermarket VRs afaik do so properly, keeping voltage high but reducing current output.

That does include the Balmar MC line.

[a64pilot]

I agree, automobile alternators will run voltages as high as 14.2 V, and do so continuously, least the older ones that the ECU doesn’t control the voltage anyway.
Lifeline absorption voltage is 14.3 plus or minus .1 V, so 14.2 is within Lifeline absorption limits.
Then add in what is the under hood temp in Summer of a car in traffic, where the battery is located? That throws 14.2 above Lifeline absorption voltage, cause as you correctly state, it does vary with temp, basically the hotter the temp, the lower the voltage.

I’m not abdicating setting your chargers to maintain absorption continuously, just wondering how much damage does absorption voltages do, if only held for an hour or two, occasionally.
My belief is it doesn’t do any damage.

I know higher voltages do of course.

[sailinglegend]

Originally Posted by Stu Jackson

Temperature compensation on alternators is to stop the alternator itself from overheating, and has absolutely nothing to do with charging voltages.......

Sorry Stu I think you are wrong here on internally regulated alternators - that is why I explained about my Balmar hot rated alternator falling to less than 14v very quickly. I failed to add that this is at around 65C when the alternator hot rated design temperature is 105C. Above that yes the Balmar regulator cuts the amps delivered to protect the alternator but maintains the voltage.

[john61ct]

Originally Posted by Jon Hacking

Yes, it's very important for ANY charging device to measure the AMPS INTO THE BATTERY. That's the only way it can know the State of Charge (SoC) of the battery, & to then know when to drop from Acceptance to Float.

Yes but there is not a single OTS commercial VR that does that for alt charging.

I only know of very few mains chargers that do, most cost thousands.

And maybe a handful of solar controllers that do, costs hundreds more to implement the required BM or remote add-ons required.

> Time based "solutions" are very poor.

Yes but 99.99% of even the top well-engineered solutions work that way.

Very few customers are even aware of the issue, and many even here that are aware don't think it's important.

[a64pilot]

He is correct on internally regulated Hitachi alternators that come with most Yanmar Marine Diesels, they are internally protected against overheating and do in fact derate themselves pretty quickly.
It’s likely one reason why the darn things can last for decades.

[john61ct]

Originally Posted by sailinglegend

Well Im afraid I have to disagree with both of you.

I saw nothing in what you wrote that is in disagreement with what I know to be true.

[a64pilot]

Current and voltage are interrelated, you can’t keep one high and reduce the other. Remember these are voltage, not current regulators, there is no shunt to measure current output.
VR does control field current of course, that is how it regulates voltage of the output, but it can’t keep output voltage high and reduce output current, current is controlled by output voltage, it will reduce current by reducing voltage.
Unless of course I don’t understand the thing.

[john61ct]

Originally Posted by a64pilot

I understand and agree with the voltage issue, up to a point.
As I have said over and over the Concorde aircraft AGM batteries that are the same as a Lifeline battery, and indeed even Lifeline batteries live for years, running around in vehicles that maintain a constant voltage that is within tolerance of Lifelines accepted absorption criteria, and are not temp regulated, so the ones in engine compartments that are held at a steady temp of above 100f are certainly “overcharged”.
Yet they don’t die? They are not dried out in a single year?

Excessive voltage and or excessive time at high voltage will absolutely kill a battery, just I don’t think an hour so, every now and again at absorption is going to do it, and as how you cannot make a timer based charger hit the full charge set point most of the time, your either going to slightly over or slightly under charge, often.
It’s my belief that a slight overcharge is less damaging over time than a slight undercharge, however neither is really all that harmful, assuming You equalize as needed.

However I have not yet seen a factory default setting that wasn’t overly conservative, dropping the bank into float way prematurely. My Sterling Pro Charge Ultra is an excellent charger, but to get to fully charged, I have to turn it off and on about three times, each time you cycle the power it starts over in absorption and runs a timer.

I also see no point of disagreement in what you wrote.

GEL and AGM will have their lifetime shortened by extreme long-term overcharging.

Say your Lifeline bank would last a decade if perfectly coddled. Most people would say 5-7 years shows there is no problem, consider that a nice long life.

Did the bank get "damaged" by "abuse"? No.

Was it cared for optimally? No.

Whether you care or not enough to invest time effort money into the optimal infrastructure, is of course a personal choice

[john61ct]

Originally Posted by a64pilot

I’m not abdicating setting your chargers to maintain absorption continuously, just wondering how much damage does absorption voltages do, if only held for an hour or two, occasionally.
My belief is it doesn’t do any damage.

I don't think anyone lately has expressed that it does, right-thinking members are in consensus on that by now.

With FLA, even more frequently and much longer times will do no harm, long as the water level is maintained.

GEL are very susceptible, AGM a bit less so, but **much** more than FLA.

[john61ct]

Originally Posted by a64pilot

Current and voltage are interrelated, you can’t keep one high and reduce the other.

Of course you can!

Just that stock VRs - which are the ones you're talking about, usually don't do a good job at allowing for finely adjusted profiles.

Really dumb ones just drop voltage when the alt gets too hot, in effect stop all charging.

Good ones like 614MC- are much smarter, can regulate current while maintaining voltage setpoint. Not battery shunt-based transitions though, no OTS VR does that.