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Boiling Batteries


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#1 Fish

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Posted 28 December 2017 - 06:18 PM

Flooded lead acid batteries have boiled dry over 1 month flat. What does that mean?

 

They are 275 AH deep cycle Crown batteries, they are old but we don't know exactly how old (5-7 yrs), and we have been getting suspicious of them for a while. Fully topped up the water almost exactly one month ago, and all cells were dry today. Recently we have put 180 watts of solar on with an MPPT controller, so they are getting way more ergs than they've had for a while.

 

We've had the odd dry cell before, and generally they don't hold charge that well.

 

Could we have set a setting wrong on the controller?

Are they just stuffed?

Is there a risk of them getting too hot and causing damage in the current state?

 

(I have disconnected the solar array, and topped the water up on all cells)

 

We also have a 'de-sulphinator' that clips to the +ve and -ve terminals and apparently puts a pulse of electricity through the batteries. I'm not a fan of it but my father reckons its good for the batteries. Could this screw up the MPPT controller causing it to over-charge the batteries?

 

My main question is - is there any risk of overheating / fire if I keep using these batteries? I've already been sussing new batteries but don't really want to be rushing out to buy new ones just on the New Year holiday period.

 

As a note, Crown don't do 275 AH now, the closest match is 260 AH, has anyone got any comments on how good Crown deep cycle batteries are? They were supposed to be good, but they are cheaper than a few of the more recognised brands, and the fact these ones are discontinued makes me suspicious.


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#2 Island Time

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Posted 28 December 2017 - 07:13 PM

Hmm, that's bad! Are the batts really dry, or just low in electolye?
If theyhave really boiled dry the voltage was too high, and the batts are stuffed. Sorry.
Chuck out the pulse unit. Not required.
Kiss principle. Check the charging specs on whatever batts you are using, and set all your charging sources to comply with those specs - on the product data sheet for the specific make and model of your batts. Don't believe anything anyone tells you., including me! The battery manufacturer knows best!!
Make certain that all charging sources comply with these charging parameters, wind,solar,alternator, genset. Check the settings in each one, and verify with a meter. Batteries don't die prematurely, they are murdered!
If any of your charge controllers can't be set to the correct voltages, change them for ones that can.
If your in Auckland, I can help after 19 Jan...
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#3 wheels

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Posted 29 December 2017 - 05:14 AM

What IT said and I second the getting rid of the "desulphonator". Waste of time and money. They do not work. Plus it may well be that the combination of the two units connected has done something. Although it could also be that one battery had a bad cell and that set the ball rolling into a cascade of events.
Now that the bank has been boiled dry, you need to replace the Bank. They will never come back to full life and the likely chance of bad cells causing the issue only increases.

What happens is that a bad cell causes the Regulator to "see"the bank as low in Voltage. So it piles in full current charge all the time. But the good cells are fully charged and the excess current simply boils the electrolyte. Once the plate surface has been exposed to air, the surface sulphates up dramatically and insulates the plate, thus it fails to work once the levels have been restored.
Shorted Cells are caused by age and the gap between the bottom of the plates and the Battery case. Crud, being Sulphate builds up till it reaches the plates and then this crud shorts the cell out. This unbalances the battery in relation to Voltage. A similar situation happens with an older battery and a new one being put together, The Old one does not draw quite as much current as the new one and this can cause the new one to accept more charge current that is needed and the brand new battery boils and destroys itself. You always replace all batteries in a bank, not just one.
 


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#4 harrytom

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Posted 29 December 2017 - 06:26 PM

have a 120ah  650?? battery,4 yrs old ,after a week of no use shows 20%,is it stuffed? going to bring it home and put on charger,sealed can I still check fluid level? and would home charging bring it back to life?


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#5 Island Time

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Posted 29 December 2017 - 07:24 PM

Shows 20% how? Voltage, on a battery monitor, with a capacity test or what?
To properly test the capacity, it must be fully charged, left to settle for 10 hours or more, then have a voltage check, followed ideally by a 20 hour discharge test.
This is ONLY for a deep cycle battery. A starting battery can be easily tested using a load tester.
I have a load tester and a discharge tester, free testing for crew.org.nz members if you bring me the battery (at Gulf Harbour).
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#6 harrytom

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Posted 29 December 2017 - 07:56 PM

Deep cycle,sitting for a week  metre onboard shows 20%,run for an hour and shows 100%,but drops quickly to 50% when I plug fridge in +3 waeco,slow crank if lucky,start battery is fine.

 

start on crank and run 30 minutes then turn off and put deep cycle on for 1hr. deep cycle when new ran fridge easy for 10hrs,dvd through converter and 12v tv + lights,2 hrs of movies a night,and if I forgot to swap to crank in morning would fire up motor .Now Haha. might just bite the bullet and replace.


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#7 Island Time

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Posted 29 December 2017 - 08:25 PM

You have killed the current battery. You will kill the new one in the same way if it's not fixed.
Sounds like the battery computer is not set up right, or is wired incorrectly.
There is no way an hour can charge a battery from 20% to 100 percent, unless it's a lithium. To charge to 100 percent will take 10 hours or more, and it's not close until current at recommended charging voltage is less than 1% of battery capacity.
So. Charge the battery properly, with a decent 3 stage charger, preferably with an equalisation mode. Once done, leave the battery disconnected completely for 10 hours, then measure voltage with a good meter. Report back what the voltage is.
From what you said so far, I suspect that the battery has never/rarely fully recharged, and/or there is a load on it when everything is switched off for the week. It almost certainly does not have 120amp hours capacity now.
A good battery, suitably sized, and looked after, should give 10 years plus of good service.
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#8 Fish

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Posted 29 December 2017 - 08:28 PM

My battery cells weren't bone dry, but all the plates were out and I couldn't see the fluid. We have had a couple of cells (2) going below the plates previously, so I believe we've had one bad cell, then another, and now they are all stuffed...

 

Collected two new 6v deep cycle batteries today. Always fun shopping for boat stuff in the holidays instead of boating.

And yes, now i have new batteries the de-sulphinator can go in the bin.

 

Just a note IT, how do I check the charge sources are giving the correct charge? is it just a volt meter across the battery terminals at the appropriate stages of charge? Or would it be more accurate to put the volt meter across the output terminals of the charge controller?


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#9 wheels

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Posted 30 December 2017 - 06:05 AM

Fish, You measure the Voltage at the Battery terminals.
Immediate Voltage measurement is next to useless in understanding the charge state of the battery. Voltage only tells you the state of the battery after it has rested for at the least 10hrs, and Voltage only must always be read when there is no load on the battery.
The only thing you can check with charge sources and Voltage measurement, is that the charge source is raising the voltage level from the batteries resting state, to the correct charge voltage, which for the alternator, if it is basic, will be 13.8V.
All regulators should be bulk charging the bank between14.4V-14.8V.( Assuming a Lead Acid battery), Float voltage will be 13.3V. Please note that Lead acid battery types have different charge voltages and the manufacturer will state what voltage should be used.
So the best and only real way of knowing what state the battery is at is to use a Charge computer, that monitors discharge and charge levels and computes the state of the battery using a complex formulae.


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#10 Island Time

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Posted 30 December 2017 - 09:23 AM

I'd like to add that the battery computer needs to be correctly installed -, the shunt being the first connection on the negative lead - NO other wires direct to battery negative. Then it needs to be correctly programmed - battery type and capacity, reset current (circa 1% of capacity), proper purkets factor for that battery etc.
The purkets factor for that battery and the correct charging voltages will be given on the product data sheet, and sometimes on the side of the battery.
Not to do all this means the battery computer will not be accurate, possibly by so much its useless. In my experience 90 odd percent of them are not set up correctly.
Personally I use VRSLA batts (sealed) so I don't have to worry about electolye levels.
Remember, never discharge below 50%,recharge asap to full, use float charge systems, and you'll get 10years or more from your batts. 😀.
Don't do this and you'll kill them early.
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