Battery question

Robmac said:
Unfortunately I don't have an inverter David.

I did disconnect all chargers (Mains and Solar) about 2 hours ago and it seems to be holding a constant 12.6 - 12.7 at the moment.

All that is switched on is the 'fridge which consumes 40W at about 3.3A at 12V.
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Batteries will sit at 12.7 or a tad lower, but still can be fooked when under a load, my car battery was at 12.6 but would not turn the starter, splash out on l carbon and give the pub a mis for a day or two LOL.
 
trevskoda said:
Should charge the same as 12v when wired in series, problem with them is low cycles and plates fussing up, lead carbon will be better.
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The smart charger is supposed to Desulphate the batteries if required Trev, but I've no idea how well this works although I did recover a 12v battery for my daughters van once using the reconditioning step and it lasted a further 6 months.
 
trevskoda said:
Batteries will sit at 12.7 or a tad lower, but still can be fooked when under a load, my car battery was at 12.6 but would not turn the starter, splash out on l carbon and give the pub a mis for a day or two LOL.
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Still not convinced to get lead/carbon Trev.

The Trojans have lasted 6 years and been abused quite a bit so they haven't done bad. Still looking into it.
 
Robmac said:
That's the thing though Barry. Whilst on EHU in Cornwall they were only showing 12.6 and falling - same when driving back as well.

I think they are kerfooked!
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But you think they charged ok off your clever controller and solar but not off the cheap charger or driving the van. Could it be a charging problem?

The only way you will know is as suggested run a load on them when you think they are fully charged. I would think if your fridge pulls 40w that would be significant over 24/48 hrs to know they are knackered or not. Just make sure the solar isn't topping them up during the test.
 
barryd said:
But you think they charged ok off your clever controller and solar but not off the cheap charger or driving the van. Could it be a charging problem?

The only way you will know is as suggested run a load on them when you think they are fully charged. I would think if your fridge pulls 40w that would be significant over 24/48 hrs to know they are knackered or not. Just make sure the solar isn't topping them up during the test.
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Yes I'll leave the fridge on overnight and see how cold it is in the morning. All lights switching on nice and bright but they are LED's so don't really use anything.

The alternator thing is baffling me now (not hard) but I suspect that now the batteries have been up to full charge that it may bump it right up if I turn the engine on. I'll leave that until tomorrow though.
 
Robmac said:
Yes I'll leave the fridge on overnight and see how cold it is in the morning. All lights switching on nice and bright but they are LED's so don't really use anything.

The alternator thing is baffling me now (not hard) but I suspect that now the batteries have been up to full charge that it may bump it right up if I turn the engine on. I'll leave that until tomorrow though.
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Actually sod it, I just gave it a try.

Started the engine and within seconds both the engine and leisure batteries were showing 14.3V so the alternator is doing it's job.
 
Nabsim said:
You don’t need an inverter, remove all charge sources and put know wattage 12v bulb on hab bank.
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Would if I had one Neil.

Anyhoo, I thought I'd try an experiment with the smart charger and put it back on charge to see if it still behaved the way it did this morning ie. whip quickly through to the trickle stage. Strangely enough, it didn't. This time it stopped in the absorption stage (this is the stage where de-sulphurisation happens NOT in the recon stage which I said earlier). It has been in this stage for about half an hour now, so I will let it finish all 7 stages, see if it detects any faults this time and resume in the morning. 🤔
 
Rob, a batteries voltage will only give you reliable info IF you know that the battery is in good condition, if the battery is knackered then it's voltage won't count for much.
You could take some specific gravity readings from all of the cells with a hydrometer, this would tell you a lot but to be honest it'll probably only confirm what you already suspect, that at least one cell is knackered. Time for a new battery I suspect considering the age and usage.
Don't discount lead carbon, they are well worth the little extra expense.
If you wanted to you can get 6V lead carbons but if you can get the 12v version in then (in any format) then go for that option, it'll be cheaper, don't know where you got the 6v charge quicker than 12 but it's complete bowlox mate. A 12v battery is simply 2 X 6v batteries in the same case. The Ah rating will determine the charge time for any given charger.
 
merl said:
Rob, a batteries voltage will only give you reliable info IF you know that the battery is in good condition, if the battery is knackered then it's voltage won't count for much.
You could take some specific gravity readings from all of the cells with a hydrometer, this would tell you a lot but to be honest it'll probably only confirm what you already suspect, that at least one cell is knackered. Time for a new battery I suspect considering the age and usage.
Don't discount lead carbon, they are well worth the little extra expense.
If you wanted to you can get 6V lead carbons but if you can get the 12v version in then (in any format) then go for that option, it'll be cheaper, don't know where you got the 6v charge quicker than 12 but it's complete bowlox mate. A 12v battery is simply 2 X 6v batteries in the same case. The Ah rating will determine the charge time for any given charger.
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I will look into the Lead/Carbon but I am governed by size so will have to take some measurements. Maybe 1 large AH 12v is the way to go. One thing though, if one cell is kaput would that not take that battery out meaning that my reading should be 6V max. (or even 10V from 5 cells?)

No, I don't know where I got the 6V quicker charging from, but I think it was an old thread here.
 
Robmac said:
I will look into the Lead/Carbon but I am governed by size so will have to take some measurements. Maybe 1 large AH 12v is the way to go. One thing though, if one cell is kaput would that not take that battery out meaning that my reading should be 6V max. (or even 10V from 5 cells?)

No, I don't know where I got the 6V quicker charging from, but I think it was an old thread here.
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IF one cell went open circuit then you'd have zero output, it's a bit like putting a lot of switches all in a line, all the switches have to be closed to make a circuit, open just one and you've broken the line so to speak.
Your dodgy cell will be still conductive but not producing very much so it will affect the charge/discharge voltage more than any other cell, think about it like you or me taking the place of one of the members of the 4X400m relay team, yep we'd still finish but in a really crap time!
 
Robmac said:
Not sure what I could do to put such a load on the battery without an inverter. (I may buy one though). :)

I'll see how it gets on for the rest of the day, the fridge is doing it's job (very cold!). I have an upcoming trip to Norfolk in a couple of weeks and as long as I get through that with no problems I will have a re-think. I will be on EHU so I don't think I will really know until I'm next off grid.

I'm still a bit puzzled why the alternator didn't put the voltage right up though on a 7 hour trip back from Cornwall? The deeper points of leccy are a complete mystery to me though!
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While you're using the van and have the option to use ehu is the perfect time to test the batteries. Assume you're off grid and then switch to ehu when you finally come to the conclusion that your batteries are shagged!
 
merl said:
While you're using the van and have the option to use ehu is the perfect time to test the batteries. Assume you're off grid and then switch to ehu when you finally come to the conclusion that your batteries are shagged!
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That's the plan. :)
 
Make sure all your connections are good. They may look good but may not necessarily be so.
 
Well, it's now completed the full charging sequence and is sitting at a constant 14.1 at the moment! (12V system now switched off).

I'll check it again in half an hour and then leave it until morning.
 
Robmac said:
Well, it's now completed the full charging sequence and is sitting at a constant 14.1 at the moment! (12V system now switched off).

I'll check it again in half an hour and then leave it until morning.
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Bin them or sell the good one on, lead carbon is miles ahead in tec to the old trogs and will cycle longer, just buy one and stop farting about.
 
Robmac said:
I ain't gonna bin them until I'm sure they're done Trev.

Last time I looked they were showing 13V so I'll give them a blast in the morning.
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Think you will find a cell down with one battery, lookin to see if one is white or fizziling heavey on charge, may also be dead with no movement when the others are bubbling,get the money out of the lumpy matress and have a better nights sleep.
 
trevskoda said:
Think you will find a cell down with one battery, lookin to see if one is white or fizziling heavey on charge, may also be dead with no movement when the others are bubbling,get the money out of the lumpy matress and have a better nights sleep.
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12.9 this morning but as others have said that may not mean too much. I will stick it on charge and inspect each cell though for fizzing differences though.

I guess I won't know for sure until we use the batteries in earnest on our upcoming trip to Norfolk, but I'm in no rush.
 
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