Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 13-02-2018, 10:12   #151
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Location: Bellingham
Boat: Outbound 44
Posts: 5,535
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by a64pilot View Post
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.
....
You could compromise by calling it a voltage source that is current limited.
__________________

Paul L is offline   Reply With Quote
Old 13-02-2018, 11:07   #152
rom
Registered User

Join Date: Mar 2016
Boat: Lagoon 440
Posts: 480
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by Paul L View Post
You could compromise by calling it a voltage source that is current limited.
Which seems to better fit the description of a "power supply".

A basic voltage regulator is a simple voltmeter that measures the battery voltage, and increases or decreases current to the rotor (field), which directly increases or decreases current at the ouput of the alternator (whatever voltage there is there).

It is by limiting the ouput current that an alternator can keep a battery at a specified voltage. Explaining it the other way round is nonsense IMHO.
__________________

rom is offline   Reply With Quote
Old 13-02-2018, 13:14   #153
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 20,459
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by rom View Post

It is by limiting the ouput current that an alternator can keep a battery at a specified voltage. Explaining it the other way round is nonsense IMHO.

Yes that is how it works, but itís adjusting to voltage, voltage, not amperage is itís set point. It varies current to maintain a constant voltage.
Adjusting to amperage is when I adjust one of my chargers to be limited to 20 amps, which I can do, they then hold a steady 20 amps by allowing voltage to vary.
There are constant current chargers, go to Walmart and buy a cheap battery charger, hook it up to a battery and leave it, it will eventually kill the battery, reason is itís supplying a constant current and allowing voltage to rise above the batteries ability to absorb it, just hopefully there are very few of us that charge our banks with such a primitive charger.
I think the original charger in my boat was such a charger though, I donít think it was a three stage. Just on and off
That is why early in I said they were interrelated, one changes the other.
I have yet though to see a battery charger or an alternator controller where you set Absorption and Float amperage though, you set voltage.
Look at it this way, you can hook a huge 6 V charger up to a 12 V battery and there will be no current flow, even if itís a huge charger. In order for there to be current flow, the charger has to have a higher voltage than the battery, the higher the voltage differential, the more current that can flow, too high of a voltage will have too much current flowing and will cook your battery, that is why Float is a lower voltage, not a lower current.
If I have not convinced you by now, then Iím not going to, no point in beating a dead horse, we are actually saying similar things.
a64pilot is offline   Reply With Quote
Old 13-02-2018, 17:49   #154
Registered User

Join Date: Jan 2017
Posts: 5,588
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by a64pilot View Post
I believe that an alternator and a battery charger controls voltage, not amperage.
Internally voltage is controlled by adjusting **field current**, hundreds of times per second.

From an outside "black box" POV, the charge to the battery is being voltage regulated only.

It is the battery that controls the actual **charging** current.

So you're "more right" if that matters, but he scored a technicality 8-)
john61ct is offline   Reply With Quote
Old 15-02-2018, 03:03   #155
Registered User

Join Date: Dec 2014
Location: the Med
Boat: Nauta 54' by Scott Kaufman/S&S - 1989
Posts: 1,164
Images: 3
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by a64pilot View Post
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.
...
Of course it can, it just requires more equipment than a charger.

Hi Pilot!

Do you mean it in order to charge each and every battery on its negative, other than through the bank (that which affects individual voltage), or for any other reason?

Thanks
TheThunderbird is offline   Reply With Quote
Old 15-02-2018, 03:12   #156
Registered User

Join Date: Dec 2014
Location: the Med
Boat: Nauta 54' by Scott Kaufman/S&S - 1989
Posts: 1,164
Images: 3
Re: Battery problem thoughts much appreciated!

Voltage is a pressure, a height of water (V)
Current is a flow, quantity over time (l)
As far as battery is charged, its internal resistance gets higher. As V = RxI then l goes down.

Think of water, it flows down, I.e. From higher to lower Voltage
TheThunderbird is offline   Reply With Quote
Old 15-02-2018, 05:07   #157
Registered User

Join Date: Jan 2017
Posts: 5,588
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by TheThunderbird View Post
Hi Pilot!

Do you mean it in order to charge each and every battery on its negative, other than through the bank (that which affects individual voltage), or for any other reason?

Thanks
I don't understand that question, but nothing to do with the charge process.

Think of the shunt as a flow meter. For a BM, all return negative current must route throught it to get measured, let some circuit bypass it then that flow is missed.

If you put it on just one source or one consumer, that's all it measures.
john61ct is offline   Reply With Quote
Old 19-02-2018, 12:25   #158
Registered User

Join Date: Mar 2014
Posts: 115
Re: Battery problem thoughts much appreciated!

Well the saga continues.

Please can I ask a couple of supplementary questions.

So they removed all the batteries and individually tested. The results were as follows;

Battery observations
Battery headline capacity. SERVICE 690ah
Capacity at 70% DOD approx.. 483ah
Estimated duration time given a medial standing load (24h) of <> 12a 40 Hours max
As above at 18a duration = 26 hours Max
Battery voltage at float 13.2v
Rising to 13.9v with 28 amp load
Battery temperature with ambient 15deg 18 deg on charge


The batteries have gone off to the suppliers for cyclic testing (is that some form of load testing). All fine and good, but it would seem from start to finish this process will take 2 weeks, which was not mentioned at the outset. The explanation is each battery takes 7 to 8 hours to cyclic test and I assume they are doing one at a time, and there are 7 batteries. To be fair I assume there are a few days lost each way with transport. I just would have thought a supplier would be able to do more than one battery at a time?


More to the point given their age is it reasonable to expect them to swap them regardless assuming (as would seem to be the case) there are no other issues.


I have asked the electrical engineeres to a pop a wire in for me so I can fit a Smartgauge - their reaction is what is the point given I have a BMV-501. My logic from the experience you have all shared is this is a good combination because each works in a different way. The 501 is very good at indicating amps in and out, and also the momentary voltage of the house bank BUT it is very bad at indicating the charge level. Although it indicates 100% charge this is not reliable. On the other hand it would seem most people agree the Smartgauge probably gives the best running indication of actual charge. I fully appreciate this would still be in combination with resetting the charger to ensure the indications from them and the BMV-501 in terms of amps accepted also suggests the batteries are coming back up to 100%, or as close as. I now appreciate as time progresses 100% will gradually fall off, down to 80% at which point it may be time to replace the bank again.


Finally, I am still struggling to understand if a battery / more than one battery proves faulty, it could be any fault of mine. As I said at the outset if they have been off manins charging for more than a few nights in their complete life, that is about it. 95% of the time they have gone from weekend to weekend on mains charger WITH the solar charger running as well, and no use at all during the week other than the draw from fridge and freezer. It seems to me you would not expect a new battery bank to fail in those circumstances. Am I missing something?
Ip485 is offline   Reply With Quote
Old 19-02-2018, 14:03   #159
Registered User

Join Date: Jan 2017
Posts: 5,588
Re: Battery problem thoughts much appreciated!

Over a year any bank will be damaged if the charging infrastructure is not doing its job properly.

It takes a knowledgeable owner with decent tools to verify that it is.

Which one would think should happen with an expensive setup being installed by so-called professionals, but alas is rarely the case.

A scenario that results in only some of the batts being damaged or worn much faster than the others IMO would be faulty wiring if not faulty batteries.

I hope you're not just relying on the one outfit, get a second opinion for sure, ideally a sparkie recommended here.
john61ct is offline   Reply With Quote
Old 19-02-2018, 14:14   #160
Registered User

Join Date: Mar 2014
Posts: 115
Re: Battery problem thoughts much appreciated!

Quote:
Over a year any bank will be damaged if the charging infrastructure is not doing its job properly.

It takes a knowledgeable owner with decent tools to verify that it is.
Thank you. I know this has been said a few times and I accept that I was not as knowledgeable as I should be. Notwithstanding I am nto sure on the evidence i follow your point. We have both checked the output of the charger and it is as it should be. I cant see why the BMV-501 would not accurately reflect the amps being put into the house bank? I suppose it is possible the charger was well off bring the bank to full charge, but this still seems to me odd given even if it went to float early, in a full week of charging at least the bank wasnt being brought up to nearly a full charge. In terms of the wiring etc while I appreciate things can go wrong the previous batteries worked fine for getting on for ten years, they were the same battery type and nothing has been changed in that time.

A full audit (depending on the final findings) may well be warranted but sadly you try and find people around me that really know these systems and it is a huge struggle - not impossible but certainly asking them to come with a days travel in total involved.
Ip485 is offline   Reply With Quote
Old 19-02-2018, 14:26   #161
Registered User

Join Date: Jan 2017
Posts: 5,588
Re: Battery problem thoughts much appreciated!

> We have both checked the output of the charger and it is as it should be.

If you could post the logged data over a full charge cycle, then others could confirm.


> I cant see why the BMV-501 would not accurately reflect the amps being put into the house bank

I was not aware of anyone saying it didn't.


> I suppose it is possible the charger was well off bring the bank to full charge, but this still seems to me odd given even if it went to float early, in a full week of charging at least the bank wasnt being brought up to nearly a full charge.

Float means no longer charging, usually at all, but certainly not enough to get to Full. Even if left running for months.

"Nearly full" is not Full, those last few hours at Absorb voltage (14.4?) make a huge difference.

I am confused, why are you still unclear as to what exactly the charger is/was doing?

Perhaps a new summary post is in order, put everything you **know** about the issues in one place, then a separate section with your conjecture, current understanding of possible causes.
john61ct is offline   Reply With Quote
Old 19-02-2018, 14:26   #162
Senior Cruiser

Cruisers Forum Supporter

Join Date: Jul 2005
Location: Bellingham
Boat: Outbound 44
Posts: 5,535
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by Ip485 View Post
Well the saga continues.

Please can I ask a couple of supplementary questions.

So they removed all the batteries and individually tested. The results were as follows;

Battery observations
Battery headline capacity. SERVICE 690ah
Capacity at 70% DOD approx.. 483ah
Estimated duration time given a medial standing load (24h) of <> 12a 40 Hours max
As above at 18a duration = 26 hours Max
Battery voltage at float 13.2v
Rising to 13.9v with 28 amp load
Battery temperature with ambient 15deg 18 deg on charge


.....
I m not understanding these specs. They sound like calculations not measurements.

I d wait to get back the actual battery tests before making any conclusions.
Paul L is offline   Reply With Quote
Old 19-02-2018, 14:35   #163
Registered User

Join Date: Mar 2014
Posts: 115
Re: Battery problem thoughts much appreciated!

Yes, i think they look a lot more like calculations to me as well.

I dont think I am confused what the charger was or wasnt doing, more I havent checked the data myself as the batteries are no longer there. I will have a much better understanding how to look after them now.

My point is I wasnt operating the previous AGM's any differently. The fact that these were run for many years longer and a lot more off grid leaves me puzzled that the "brand" new ones appear to have failed so quickly, while the "old" ones lasted so well. In fact they were still much better than these and I really only replaced them because after 10 years it seemed like they might be getting a bit tired.

BTW I am interested in views regarding the CYCLIC TESTING and whether the time to do this reasonable.
Ip485 is offline   Reply With Quote
Old 19-02-2018, 15:07   #164
rom
Registered User

Join Date: Mar 2016
Boat: Lagoon 440
Posts: 480
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by Paul L View Post
I m not understanding these specs. They sound like calculations not measurements.

I d wait to get back the actual battery tests before making any conclusions.
yes indeed. 0.7*690=483. Of course they meant 70% SOC btw, not DoD. But that is a detail.

I have a BMV-502. I have played quite a bit with it and have reasons to believe its algorithm to calculate SOC is broken. But you can still manage a not so bad approximation playing with its two important parameters: peukert & efficiency.

It is possible that the BMV does not show the correct amount of amps in & out .. if the shunt (the actual ammeter) is not properly installed. I have seen this. The shunt was installed (by a pro) on the path of two batteries out of a pack of 6. And therefore only showed 1/3 of the amps. This would not influence SOC calculation much though.

Your problem probably is somewhere else though, and I am among those suspecting a faulty battery.

Having a detailed diagram of your electrical system is critical when trying to debug it.
rom is offline   Reply With Quote
Old 19-02-2018, 15:11   #165
rom
Registered User

Join Date: Mar 2016
Boat: Lagoon 440
Posts: 480
Re: Battery problem thoughts much appreciated!

Quote:
Originally Posted by Ip485 View Post
I really only replaced them because after 10 years it seemed like they might be getting a bit tired.
You really got 10 years out of AGM ? you sure those were AGM ? I believe it is a first time I hear such a good report on those.
__________________

rom is offline   Reply With Quote
Reply

Tags
battery

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Feedback/Ideas welcome, in fact very much appreciated :) Captain Rob Roy Sailor Logs & Cruising Plans 10 16-05-2016 14:53
Xantrex Monitor Problem OR Battery bank problem? svstrider Electrical: Batteries, Generators & Solar 4 26-12-2011 20:08
Battery-Charging Regulator Problem ? MasterVolt Problem ? RJV Electrical: Batteries, Generators & Solar 18 06-11-2011 22:53
36' Endeavour G-Force Sport Cat - Comments and Thoughts Appreciated! Rolf the Rotten Multihull Sailboats 0 26-10-2010 11:21
Draft depth for Caribean Islands - how much is too much? theloneoux General Sailing Forum 11 07-08-2005 13:21



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:17.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.