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Old 13-02-2018, 03:22   #136
rom
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Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by a64pilot View Post
Any good charger will be temperature compensated and will adjust charge voltage to battery temp.
Which means limiting current right ? So by expressing temp compensation figures the manufacturer somewhat implies limiting current. So what's the point in having a very high charge capacity (for the only purpose of charging admitted here) if it's ouput is to be limited ? Wouldn't it be better (cost effective) to keep current & temp lower ?

From Victron: "The charge current should preferably not exceed 0,2 C (20A for a 100Ah battery).The temperature of a battery will increase by more than 10įC if the charge current exceeds 0,2C. Therefore temperature compensation is required if the charge current exceeds 0,2C."

From Victron again, effect of temp on service life (for AGMs):
7 to 10 years @ 20įC / 68įF
4 years @ 30įC / 86įF

Rolls:
"The initial charge current is recommended to be set at I1= 0.25 X C20 (Imax= 0.35 X C20)"

MK:
"Bulk Stage I1 Maintain Current <= 30 A per 100 Ah C20"

I am reporting that stuff (again, I am not giving any advice) because it seems to me you may be doing a little too much charging your batt @ 100%, forcing absorption for longer time, to a point that it may actually decrease battery life.

Lifeline, on recommended absorption time:
"Less than 30% DoD - 2 hours"
(From there to say one might get his batt fully charged by lunch time on solar ...


But this is all off topic, and I was actually interested in the debugging process at the beginning of this thread. Many have suggested a loose connection. I have been thinking about it, and I cannot imagine a scenario where a loose connection would report a low voltage measure but at the same time would allow 30amps consumption. If anyone cares to explain, I am interested. I am looking forward to reading the conclusions of IP485's investigation here.
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Old 13-02-2018, 04:58   #137
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Re: Battery problem thoughts much appreciated!

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Originally Posted by Ip485 View Post
I dont see how the bank could possibly have been murdered. Since new if it has run off grid at most it is for a few nights, and not that many days when I would expect supplemented with the 850W of solar they would not have been significantly discharged.
You've not given us any information about the charge voltage settings of your chargers or your solar controllers? Rolls has very clear guidance for the absorption and float voltages of 14.7V Absorption and 13.8V Float @ 77F, but it needs to be temp compensated at other temps... If the chargers and solar don't match up to this, or damn close, then it is really pretty easy to destroy any battery.

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I have learnt a lesson about relying on the current gauge without guaranteeing that the batteries are brought up to full charge and recalibrating, but even so I have never allowed them to drop below 60% and as I say that maybe on half a dozen occasions at most.
Far too many boat owners put way too much faith into their battery monitors and its % SOC read out. The link below explains the inner workings of an typical Ah counter.

Making Your Battery Monitor More Accurate


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Originally Posted by Ip485 View Post
I shall be interested to see what Rolls say and will decide then the route to take. In theory they are fully covered by their guarantee. If they are not for any reason I may consider going back to Lifeline or Lipo if the current chargers are compatible. I am not bothered about the cost, I am very bothered about as bullet proof a system as achievable, and rather hoped that was what I had with the new Rolls!
If you think managing lead acid is tough LiFePO4 will be 10X worse and most likely result in a massive hole in the wallet.

At least with the new found knowledge the bank will not been abused when cruising, albeit perhaps more by luck it most certainly has not been in the past more due to lack of cruising!

All batteries need to be charged properly using manufacturer suggested voltages as well as temp compensated. Hitting a "dip switch" that says AGM without first confirming the charging voltages are accurate is simply going to result in poor battery health.? Are there temp sensors on these batteries.

How was this bank physically wired?
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Old 13-02-2018, 05:28   #138
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Battery problem thoughts much appreciated!

Quote:
Originally Posted by rom View Post
Which means limiting current right ? So by expressing temp compensation figures the manufacturer somewhat implies limiting current.


No, your incorrect, they are NOT current limiting, the voltage is adjusted to meet the batteries requirement based on temperature, there is no current limiting, the battery will accept lower current at lower voltages, and higher at higher voltages but the charger is not limiting current.

As far as which I chose to believe, the manufacturer of the battery, or a battery charger manufacturer? Iíll chose to believe the company that actually manufacturers the battery on how their battery should be charged.
Also I have quite a bit of history with Concorde aircraft batteries, and can tell you they have done more testing and design improvements than all other manufacturers combined, in aircraft batteries anyway, and a Lifeline battery from what I can tell is essentially a Concorde aircraft battery.
Download and read Lifelines technical manual for their batteries, you can tell immediately that these people have done extensive testing, have accumulated a wealth of knowledge from doing so, and are distributing that knowledge.
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Old 13-02-2018, 05:33   #139
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Re: Battery problem thoughts much appreciated!

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Long story short, I was VP of an aircraft manufacturing facility, Concorde batteries are far and away the best lead acid aircraft battery there is, so I had an inside if you will with Concorde. Concorde is Lifeline, they are a family owned US business that manufactures in the US. If you look at their phone directory, almost everyone up top has the last name of Goodbar I think, or Good something.
The last name is Godber..

What a lot of folks don't realize is that one side of the family is Trojan Battery and the other side is Concorde/Lifeline. Trojan and Concorde/Lifeline however are 100% separate entities not intertwined at all other than by last name. A Godber still heads each company...
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Old 13-02-2018, 05:46   #140
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Battery problem thoughts much appreciated!

I didnít know that, I just knew about Concorde.
There are two major aircraft battery manufacturers. Gill which is a flooded battery and a piece of junk, you are lucky to get two years out of one, and Concorde, which if you donít get five years out of a Concorde, you killed it somehow.
Gill essentially gives batteries away to manufacturers knowing the most people will ask for the battery the airplane came with as a replacement, all their ads say the original equipment battery, and for that reason I never could get our factory to switch over as the owner was only looking at price.


On edit, itís been almost three years and Iím terrible with names, but I think it may have been Justin Godber I spoke with.
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Old 13-02-2018, 06:09   #141
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Re: Battery problem thoughts much appreciated!

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On edit, it’s been almost three years and I’m terrible with names, but I think it may have been Justin Godber I spoke with.
I believe Justin is now the GM of Concorde/Lifeline group. There is also Dave Godber that you may talk with for tech support too. However I don't believe they get too hung up on titles as some days Justin will answer or Dave etc... Lifeline just has really good support... They keel Dave V., their lead engineer & VP, pretty well hidden from day to day tech stuff..
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Old 13-02-2018, 07:34   #142
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Re: Battery problem thoughts much appreciated!

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No, your incorrect, they are NOT current limiting, the voltage is adjusted to meet the batteries requirement based on temperature, there is no current limiting, the battery will accept lower current at lower voltages, and higher at higher voltages but the charger is not limiting current.
ok, please allow me to rephrase: the charger (if battery temp compensation available) will start limiting current (absorption phase) sooner if the battery gets hot.

So, Victron's (and other batt manufacturers) recommendations, plus the article from mainsail you made a reference to and where it took him pretty much the same time to recharge a 100Ah battery from 50 to 100% SOC with a 40A and 20A charge, that leads me to think it is both not cost effective and possibly bad for the battery to use a "big" charger. IMHO of course.
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Old 13-02-2018, 07:38   #143
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Re: Battery problem thoughts much appreciated!

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Originally Posted by rom View Post
Which means limiting current right ? So by expressing temp compensation figures the manufacturer somewhat implies limiting current. So what's the point in having a very high charge capacity (for the only purpose of charging admitted here) if it's ouput is to be limited ? Wouldn't it be better (cost effective) to keep current & temp lower ?
There are a (very) few chargers that have any current limiting beyond a static maximum, and its purpose is protecting the upstream power source. None do so dynamically during the charge cycle, only voltage is regulated.

Quote:
Originally Posted by rom View Post
"The charge current should preferably not exceed 0,2 C (20A for a 100Ah battery).The temperature of a battery will increase by more than 10įC if the charge current exceeds 0,2C. Therefore temperature compensation is required if the charge current exceeds 0,2C."
Definitely overstated, unless ambient temps are already very high a 10į rise does not "require" anything. Temp compensation is an optimization, separate from monitoring temps for safety.

A major reason AGM has a lower lifespan is that any fluid lost to offgassing can't be replaced. That is perhaps one reason some mfg are so overly conservative, but marketing and legal ones dominate IMO.

Lifeline sets .2C, or 80A for a 400AH bank as the **minimum** charge rate, and .85C as a maximum continuous rate, but up to 5C (2000A) as acceptable for a short time.

Odyssey's minimum is .4C, or 160A per 400AH.


Quote:
Originally Posted by rom View Post
From Victron again, effect of temp on service life (for AGMs):
7 to 10 years @ 20įC / 68įF
4 years @ 30įC / 86įF
That's about ambient temps.


Quote:
Originally Posted by rom View Post
it seems to me you may be doing a little too much charging your batt @ 100%, forcing absorption for longer time, to a point that it may actually decrease battery life.

Lifeline, on recommended absorption time:
"Less than 30% DoD - 2 hours"
(From there to say one might get his batt fully charged by lunch time on solar ...
Whoa Nelly! Very strongly disagree with you there.

The most common bank murder problem out there is people not charging up to Full, some "often enough" many (as here) "ever".

The actual spec for dropping from Absorb is current dropping to the endAmps setpoint of .005C, or 2A for a 400AH bank.

What you state may be an **estimate** of time to get there, and likely based on a slow charge rate, and added to a couple of hours before the CC/CV transition.

In any case egg-timer is a very poor way to spec Hold Absorb time, any time based algorithm will be inherently rough, endAmps is the way to go.

Not to say leave it going forever, an older bank will change the picture, so "trailing amps current stops dropping, no change for over an hour" is a useful fallback.

But on no case should anyone think **shortening** Hold Absorb time is a good idea for longevity, nor believe any gear saying the bank is full unless it's been calibrated with predictable usage patterns against a trusted endAmps measurement.
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Old 13-02-2018, 08:21   #144
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Re: Battery problem thoughts much appreciated!

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Originally Posted by rom View Post
ok, please allow me to rephrase: the charger (if battery temp compensation available) will start limiting current (absorption phase) sooner if the battery gets hot.

So, Victron's (and other batt manufacturers) recommendations, plus the article from mainsail you made a reference to and where it took him pretty much the same time to recharge a 100Ah battery from 50 to 100% SOC with a 40A and 20A charge, that leads me to think it is both not cost effective and possibly bad for the battery to use a "big" charger. IMHO of course.


No, the charger does NOT start limiting current, it reduces voltage. At reduced voltages the battery will accept less current. You still have a fire hose hooked to a water fountain if you will, you do not reduce the size of the hose, but you do reduce the pressure.
You may be thinking, well thats the same thing, but itís not. Voltage and amperage do interrelate, but they are different things.

This morning, we are making water, so the generator is on for hours. I started at 75% SOC and threw all 185 amps of charger at the bank, it was only accepting about 150 though due to the SOC being so high. The whole time all 185 amps are available, but the battery acceptance has fallen to 17.2 amps in two hours and five minutes.
Battery temp at the start of charging was 84F and is now 86F.
I am now at 96 % SOC and that last 4% is going to take hours.
So I have gone from 75% SOC with what amounts to an unlimited charger size, cause the bank has never drawn the full capacity of the chargers to 96% SOC with a 2 degree rise in temp.
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Old 13-02-2018, 08:35   #145
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Re: Battery problem thoughts much appreciated!

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I am now at 96 % SOC and that last 4% is going to take hours.
bingo, there's the bit that 98% of bank owners never realize.

Their non-adjusted "smart" charge sources would likely have dropped to Float a long time ago, pretty blinky lights and voltmeter reassuringly cooing all is well, bank is 'full'.

Badly installed or miscalibrated ones maybe stop at 5% DoD or more.

Murdered bank.
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Old 13-02-2018, 08:46   #146
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Battery problem thoughts much appreciated!

John, if left alone and allowed to run in full automatic, My Sterling Pro Charge Ultra will drop into float as early as 85% SOC. Now usually it wonít until 90% or so, but that is still way premature, and I think itís a very good charger, itís not junk.
In order to have a charger that can be programmed to drop to float at a certain battery acceptance rate, that requires a shunt at the bank, and requires ALL negative grounds to be connected to this shunt, which usually means a bus bar of course. That is beyond what most people are willing to do, realizing of course that full time cruisers are at most a small percentage of Boat owners, so to market to them isnít likely as profitable as the base is so small.
Plus most people want something that is fully automatic, they donít understand why their cell phone can be charged fully automatically, then why canít their boat?
Of course it can, it just requires more equipment than a charger.
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Old 13-02-2018, 09:03   #147
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Re: Battery problem thoughts much appreciated!

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No, the charger does NOT start limiting current, it reduces voltage. At reduced voltages the battery will accept less current. You still have a fire hose hooked to a water fountain if you will, you do not reduce the size of the hose, but you do reduce the pressure.
You may be thinking, well thats the same thing, but itís not. Voltage and amperage do interrelate, but they are different things.
Thank you for the water analogy, but really, a charger is a current source, not a voltage source. e.g the regulator of an alternator senses battery voltage and will limit its current output in order to keep the battery at/below a specified voltage. If it kept on providing "illimited" current the battery voltage would rise till death.

Quote:
Originally Posted by a64pilot
This morning, we are making water, so the generator is on for hours. I started at 75% SOC and threw all 185 amps of charger at the bank, it was only accepting about 150 though due to the SOC being so high. The whole time all 185 amps are available, but the battery acceptance has fallen to 17.2 amps in two hours and five minutes.
Battery temp at the start of charging was 84F and is now 86F.
I am now at 96 % SOC and that last 4% is going to take hours.
So I have gone from 75% SOC with what amounts to an unlimited charger size, cause the bank has never drawn the full capacity of the chargers to 96% SOC with a 2 degree rise in temp.
Well, if everyone here agrees that this is how you properly recharge a battery then I have to agree with you that there are probably not many of us doing it well !
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Old 13-02-2018, 09:09   #148
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Re: Battery problem thoughts much appreciated!

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In order to have a charger that can be programmed to drop to float at a certain battery acceptance rate, that requires a shunt at the bank, and requires ALL negative grounds to be connected to this shunt, which usually means a bus bar of course. That is beyond what most people are willing to do,
Ö
Plus most people want something that is fully automatic
Exactly, why most banks are PSOC abused.

The solution's not hard, nor expensive, but does take knowledge and motivation.

Full automation takes greater knowledge and spending a bit more.

Or one shrugs and accepts replacing the bank more often.
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Old 13-02-2018, 09:11   #149
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there are probably not many of us doing it well
Absolutely true.
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Old 13-02-2018, 10:03   #150
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Re: Battery problem thoughts much appreciated!

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Thank you for the water analogy, but really, a charger is a current source, not a voltage source. e.g the regulator of an alternator senses battery voltage and will limit its current output in order to keep the battery at/below a specified voltage. If it kept on providing "illimited" current the battery voltage would rise till death !

See, this is exactly the gist of what a I am saying, and where you and I disagree, and one of us is wrong.
I believe that an alternator and a battery charger controls voltage, not amperage. Amperage or current fluctuates as a function of voltage.
See I am saying that bulk charge is where the charge source does not have enough amperage to reach absorption voltage, itís maxed out at all it can produce, but canít make the voltage
Once absorption voltage is reached, that voltage is maintained and current begins to drop as the battery acceptance rate drops, turn on DC powered anything or your inverter and amperage will increase as a function of the charge source maintaining voltage.
Voltage is sensed and maintained, not current.
The device that controls and alternator is called a voltage regulator, not a current regulator, because it controls voltage, not current.

Right now my bank is down to accepting 8 amps at 14.20 volts. It would accept 8 amps with a 10 amp charger connected to it, or a 1000 amp charger.
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