Is this the end ? Battery

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Hymercedes

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Hymer MLT620
Is this the end ?
Touring and the Leisure Battery has suddenly started crashing in a matter of hours, even with the panel switched off.
Shows being fully charged after just a couple of minutes with engine running, but then drains overnight with everything switched off.
Is this the end ?
Hymer ML620 2018.
 
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Yes. When faulty inside you can see and measure 12.8V (full) but under any load it collapses or shorts out internally.
Time to replace.
But always check charging system voltages weren't at fault and caused it to die (don't want to ruin your new one) (y)
 
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Sounds like heavy sulphation to me. A bit like scale building up in a tank of water. The area that isn’t sulphated works ok and charges up quickly but the battery capacity is much reduced. A 100Ah battery might have only 10Ah left working properly.

Sulphation is usually caused by undercharging or leaving the battery less than fully charged for long periods. AGM batteries are particularly fussy in this respect. If you get a new battery it will be worth checking that it is getting properly charged.

What type of battery do you have at present and how old is your MLT? Mercedes have been fitting smart alternators for a long time and split charge relays don’t work with smart alternators. I had a 2015 Hymer Mercedes that had a smart alternator and only a split charge relay. I cured the problem by fitting a B2B. By 2018 they might have been fitting a B2B/booster.
 
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Hymercedes said:
Shows being fully charged after just a couple of minutes with engine running, but then drains overnight with everything switched off.
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I think you are being misled by the voltage level. It is true that if a battery is not being charged, and has no load on it, then the voltage will be an indication of the state of charge. But when anything is charging it, the voltage just shows the charging voltage imposed by the charger, and is no indication of state of charge. Those panel LEDs are only anything like true when nothing is charging the battery. That means when the engine is not running, and when it's dark if you have solar panels.

Charging a battery is a chemical reaction, which takes several hours to complete. There's no way a battery can go from flat to fully charged in a couple of minutes. If the battery capacity is 90Ah (amp-hours) and it's charging at 18A (amps), then it's going to take a minimum of 90 / 18 = 5 hours. More like 8 hours in reality because charging slows down as the battery becomes full.
 
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autorouter said:
Charging a battery is a chemical reaction, which takes several hours to complete. There's no way a battery can go from flat to fully charged in a couple of minutes. If the battery capacity is 90Ah (amp-hours) and it's charging at 18A (amps), then it's going to take a minimum of 90 / 18 = 5 hours. More like 8 hours in reality because charging slows down as the battery becomes full.
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I believe it can happen with sulphation. If there is only say 10Ah capacity left the whole 18A charge is applied to the small area left working and quickly charges it up.
 
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Pausim said:
I believe it can happen with sulphation. If there is only say 10Ah capacity left the whole 18A charge is applied to the small area left working and quickly charges it up.
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Even if it's 9Ah, that will take 9 / 18 = 0.5 hours to charge, which is a lot more than a couple of minutes. The other possibility is that there's a shorted cell, which is the kind of fault that happens suddenly rather than gradually like sulfation. In that case the voltage will drop to 10.5V very rapidly, and go back up rapidly when charging starts. Either way it's not looking good for the battery.

But it's important to make sure that the battery problem was not caused by something else, like a faulty charger or a device taking a load when it's supposed to be switched off.
 
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Thank you all with helpful advice.

It may have been drained when the Satnav was inadvertently left on overnight and a phone was left charging on a 12v socket with no EHU.
Now 3 days in without a EHU so could it come back to life with some proper 240 stuff, or am I dreaming ?
Chris
 
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Hymercedes said:
Now 3 days in without a EHU so could it come back to life with some proper 240 stuff, or am I dreaming ?
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Worth a try if you can get on EHU for 24 hours or so, it might be your lucky day, but don't be surprised if it's failed. Keep an eye on it and watch for it overheating or any bad smells from it, and disconnect immediately if that happens.
 
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Hymercedes said:
Thank you all with helpful advice.

It may have been drained when the Satnav was inadvertently left on overnight and a phone was left charging on a 12v socket with no EHU.
Now 3 days in without a EHU so could it come back to life with some proper 240 stuff, or am I dreaming ?
Chris
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No. You need a new battery.

Lithium is more expensive but well worth the extra.

For fun/info…

I’ve been an engineer for decades and understand lots about physics and chemistry and have always enjoyed messing around practically as well. I’ve built my own fuel stills and powered a camper for a year off home made fuel a few years back.

It’s long been ‘said’ that it is possible to recover a heavily sulphated (dead) lead acid battery using an arc welder. The idea is to drive extremely heavy current into the battery and reverse the sulphation reaction to clean the plates. It literally redissolves and boils off the plate deposits to recover the battery. It’s quite dangerous, you need all the plugs out, lots of ventilation and to monitor the boiling acid, keeping each cell topped off with distilled water. You can use battery test equipment to determine the improvement, the test equipment works by subjecting the battery to a heavy load and measuring peak deliverable CCA, and post load voltage recovery to determine capacity.

I tried it on 3 dead batteries, one it didn’t really work on, the other I recovered 40% of capacity (making the battery somewhat useful again) and on the last I got back to 70% capacity, effectively turning it back into a new battery. It took days of messing around, and multiple runs each time. Heaven knows how much electricity I used, and how much poison gas I created. These days I would just buy a new battery :)

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Hymercedes said:
Is this the end ?
Touring and the Leisure Battery has suddenly started crashing in a matter of hours, even with the panel switched off.
Shows being fully charged after just a couple of minutes with engine running, but then drains overnight with everything switched off.
Is this the end ?
Hymer ML620 2018.
Click to expand...
Yes
 
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dawsey said:
No. You need a new battery.
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99.9% agree with that. But I think, based on the limited history given, there's a small chance it's not sulfated, just been run flat for a few days. So worth trying to recharge it by a normal mains charger. Probably won't work, but might be lucky.
 
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nicholsong said:
Why not?

They come with new batteries. don't they? :LOL:
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Exactly and you could have lithium ones specced that would save changing the van for maybe 10 years

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Hymercedes said:
Is this the end ?
Touring and the Leisure Battery has suddenly started crashing in a matter of hours, even with the panel switched off.
Shows being fully charged after just a couple of minutes with engine running, but then drains overnight with everything switched off.
Is this the end ?
Hymer ML620 2018.
Click to expand...
Stuffed , not worth flogging a dead horse imo.
 
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