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Looking after a L36-EFB
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useraandncaravan
Posted: 8 September 2018 10:27 AM
Subject: RE: Looking after a L36-EFB
 
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Stuwsmith - 2018-09-02 8:37 AM

Thanks for the charging info.  I think that Yuasa's technical sheet that you link to is strange though.  It really only gives the physical spec for the battery.  There is a "recommended charge rate" with an A and a tick next to it but no mention as to what that means!  I've had a look at Yuasas site and unless i have missed something I cant find anything that documents the recommended charging regime for their various batteries.  Given what I have read on this forum correct battery charging seems to be pretty important.


Sorry sent you the wrong Tech page link : https://www.alpha-batteries.co.uk/12v-yuasa-100ah-efb-leisure-battery-l36-efb/ See Technical Specifications.

I think I said somewhere in the above that the Yuasa L36-EFB was an exceptionally low gassing battery, almost as low as an AGM, but Yuasa still recommend a vent tube to the outside is always used.




Edited by aandncaravan 2018-09-08 10:31 AM
userStuwsmith
Posted: 8 September 2018 7:35 PM
Subject: RE: Looking after a L36-EFB
 
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Thanks for that, yes I have connected a vent tube to it just in case.  Ive tried the battery and new regulator in anger this last three days and the set up seems to be holding up alright.  One of the useful bits of information available from the Victron regular is a daily record of max and min battery voltages. I did notice that on one day where it was dull and wet in the afternoon the minimum voltage recorded was 12.45 but this was with the fridge on and drawing around 3.6 amps.  When the fridge switched off the battery volts returned to 12.6 or 7 volts so I assume that was ok and not draining the battery beyond 50%.
useraandncaravan
Posted: 8 September 2018 8:48 PM
Subject: RE: Looking after a L36-EFB
 
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Stuwsmith - 2018-09-08 7:35 PM

Thanks for that, yes I have connected a vent tube to it just in case.  I've tried the battery and new regulator in anger this last three days and the set up seems to be holding up alright.  One of the useful bits of information available from the Victron regular is a daily record of max and min battery voltages. I did notice that on one day where it was dull and wet in the afternoon the minimum voltage recorded was 12.45 but this was with the fridge on and drawing around 3.6 amps.  When the fridge switched off the battery volts returned to 12.6 or 7 volts so I assume that was ok and not draining the battery beyond 50%.



Two points on your comments, which you probably already know but adding them on here for readers that may not :

1. The State Of Charge (SOC) voltage should be taken under zero load, even a low 3 amp current can have an impact and show an artificially low voltage.
However, conversely, if it was early afternoon and the Solar charger still putting power into the battery, then the Solar charger would be doing the reverse of the Fridge and trying to raise the voltage to 14v.
So when the Fridge stopped some of that 12.7v could have been 'artificially' high from the Victron Solar charger trying to get the battery 'up to 14v'.
So I would guess, that the 'real' battery voltage was somewhere between the 12.45v 'Load' and the 12.7v 'charge'? But obviously depends on the sun/cloud.



2. Don't forget that what you are seeing on the volt meter is the voltage at the battery, not the actual battery voltage.
Just as shown above the 'real' battery voltage could be 12.55v, yet the voltage on the meter, because it's under load, show 12.45v.
Similarly, if the battery is being charged by any type of charger, the charger will be trying to raise the battery voltage to 14v'ish. The battery may still only be 12.55v, but the display will show the Solar chargers 14v it is trying to put into the battery.

Just as you see the voltmeter show a 12.3v battery rise up to 14v when the Alternator starts charging it, the actual battery is still only 12.3v. No matter what you do, the voltmeter will only ever show the highest voltage at the battery, not the battery voltage. Unless it has been off charge and off load for a few hours.


So to get a 'fairly' true SOC voltage you need to be, ideally, off 'load' for an hour or two and about 2 hours after sunset when the Solar charger has been 'asleep' for a couple of hours.

That is one of the reasons that I don't like the Victron's daily Min/Max, because it can be really misleading, particularly when the van is being used when it is the least accurate.



Edited by aandncaravan 2018-09-08 8:57 PM
userStuwsmith
Posted: 8 September 2018 9:34 PM
Subject: RE: Looking after a L36-EFB
 
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Thanks verymuch for that explanation. I must admit the voltage readings i was seeing on the dull day werent as high as i had hoped but in the evening the battery voltage seemed to return to a far more optimistic level.  I think i might be getting a wee bit paranoid about trying to be kind to my new battery by not letting the voltage appear to get too low.  Perhaps i would be better just to check it in the evening as you say, when things have settled down.
userspirou
Posted: 9 September 2018 5:39 AM
Subject: RE: Looking after a L36-EFB
 


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If the fridge and other loads are OFF then the min/max are still useful indicators. As are other recorded parameters if you know what they are telling you.

Consider a scenario where the max V is below 14.4 (or whatever you have it set) and the "time in absorption" & "time in float" are 0 but "time in bulk" is some high number. That tells you the load from the fridge was too big the entire solar day and the panel couldn't produce enough to meet demand. Which could well be something you see later in the year.

I presume the fridge isn't ON all day&night so check the voltage after sunset when the fridge was OFF a few hours. If you can't wait that long, 30min after no load is being applied should be close enough to within 0.05V or so.
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