Are my Leasure Batteries done for (1 Viewer)

[DerryW]

Please see my other thread “Another Battery Query” post yesterday evening.

as mentioned the batteries are reading 13.6v this morning. If I turn on the lights it’s showing a draw of 1.5amps on the control panel, the draw increases to 3.4amps if I also turn on the TV. After 10 minutes the batteries are now reading 13.0v. I have just put the fridge on battery the draw instantly increased to 9.8 and the batteries to 8.3v

I have a EP Solar controller, it has a picture of 2 batteries on the front. Battery 1 is flashing green, battery 2 is stationary green light.
would really appreciate any advice. I don’t want to replace the batteries (2 x 110ah gel batteries) at only 5 years old.
Thanks once again.

 

[Richard n Ann]

Is it a compressor fridge?

How much solar have you got?

You need to switch everything off for the rest of the day (at least) and let the batteries charge up.

 

[Jev88]

The only worthwhile battery reading (IMHO) is when everything turned off, including EHU and Solar, and leave battery for an hour - that number I can understand.
Reading anything above 13 volts just tells me charge is coming in from somewhere and so I am not measuring the battery itself but whatever is being fed in (EHU or Solar for example).

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[bigtwin]

have just put the fridge on battery the draw instantly increased to 9.8 and the batteries to 8.3v

That statement there has just consigned your batteries to the bin. Time for new batteries.

Ian

 

[cmcardle75]

Please see my other thread “Another Battery Query” post yesterday evening.

as mentioned the batteries are reading 13.6v this morning. If I turn on the lights it’s showing a draw of 1.5amps on the control panel, the draw increases to 3.4amps if I also turn on the TV. After 10 minutes the batteries are now reading 13.0v. I have just put the fridge on battery the draw instantly increased to 9.8 and the batteries to 8.3v

I have a EP Solar controller, it has a picture of 2 batteries on the front. Battery 1 is flashing green, battery 2 is stationary green light.
would really appreciate any advice. I don’t want to replace the batteries (2 x 110ah gel batteries) at only 5 years old.
Thanks once again.

Yes, your batteries are knackered. Whatever type of fridge you have (only compressor types should be used on battery without the engine running), a drop to 8.3V when drawing 10A when the battery should have been just about fully charged shows they are toasted. I guess a really poor connection at the battery terminal could also cause this, but I strongly suspect this isn't the case here.

Next you need to work out why they're toasted, as if you just replace them, the new ones will go the same way if there is an underlying condition that needs addressing, such as a broken charger, usage way in excess of supply, or inappropriate usage of a 3 way fridge on battery power.

 

[Richard n Ann]

Yes, your batteries are knackered. Whatever type of fridge you have (only compressor types should be used on battery without the engine running), a drop to 8.3V when drawing 10A when the battery should have been just about fully charged shows they are toasted. I guess a really poor connection at the battery terminal could also cause this, but I strongly suspect this isn't the case here.

Next you need to work out why they're toasted, as if you just replace them, the new ones will go the same way if there is an underlying condition that needs addressing, such as a broken charger, usage way in excess of supply, or inappropriate usage of a 3 way fridge on battery power.

They were flat last night and are reading 13.6 this morning because solar has started charging them, they're still flat.

Gels can tolerate discharge better than standard lead acid so the first thing to do is put them on charge for 24 hours and see if they will still hold a charge.

Next job is buy a decent battery monitor like the NASA BM1 so you know what's happening in future.

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[EML]

I agree with the last post - I wouldn't throw anything away yet. 8.3V is consistent with a final discharge voltage for AGM, and I think gel is probably similar (I don't have the numbers). So, basically, you're probably in deep discharge, but a proper charge may (or may not) get things back with only a minor loss of capacity.

 

[steveh57]

I been reading online about recovering Gel batteries and the suggestion is to do it as slowly as possible i.e trickle charge I guess. Whether this is correct/ beneficial or plain wrong I've no idea.

 

[Gaston aires]

In my experience of gel batteries they have all lasted 10 years or more and are not knackered after five years.
Ask an auto electrician or you could be could be wasting perfectly good batteries.
Phil

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[Raul]

I would throw them to scrapie man. A empty discharged lead of any kind, being ( flooded, vrla, agm or gel) they are all lead, the terminal discharged voltage is 1,75v per cell; 10,5v for a 12v block. Every manufacturer when declares the capacity at 20h rate, specifies: end voltage 1,75vpc. Like a 100ah battery discharged with 5a for 20hrs and end voltage will be 10,5v.

 

[EML]

Ok, not an expert, and don't really want to get into an argument about it, but the generic lead-acid figure of 1.75V/cell is a cutoff voltage, which is achieved at a low discharge rate. If the OP discharged at a higher rate, then the cutoff will be lower, and could easily get down to 1.37V (that number is in the Power-Sonic technical manual, for a 3C discharge). Besides, the cutoff is the voluntary cut-off point: you can go below this, into deep discharge, and recover. The more interesting number is actually the Final Discharge Voltage, which (for AGM, at least) is in the region of 8V (ie. ~1.4V/cell).

A Broken Link Removed gives a quote from one book which states that "Gel batteries can be deep discharged, i.e., discharged below the specified cutoff voltage in extreme cases or down to zero volt, which will lead to a small capacity loss only after recharge".

Besides, we don't really know anything DerryW's battery without a no-load voltage, which could take 12 to 24 hours to stabilise. Given all this, surely the only sensible advice is to charge properly, and find out if the battery's still Ok.

 

[Raul]

It’s normal to have voltage sag under load. Many cranking batteries go down to 8v under load but recover within the second. If I remember right, the op has 2x110ah. When fridge was on at 9,8a, for 10 mins, the voltage dived below what is considered a empty battery. That, with a load of less than 20hr rate for his capacity. This concludes the batteries does not hold much charge, if anything.
As bigtwin pointed, the op has already done a test without realising.

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[cmcardle75]

It’s normal to have voltage sag under load. Many cranking batteries go down to 8v under load but recover within the second. If I remember right, the op has 2x110ah. When fridge was on at 9,8a, for 10 mins, the voltage dived below what is considered a empty battery. That, with a load of less than 20hr rate for his capacity. This concludes the batteries does not hold much charge, if anything.
As bigtwin pointed, the op has already done a test without realising.

The only question is whether the battery was charged before the test. I interpreted it as yes, other as no. I think I may have been wrong. I mean, the battery has definitely been through the mill, but we can't know for sure its state until it is genuinely fully charged and tested from there.

 

[Raul]

Even on partial state of charge, for such a low load, voltage should not dive. We are talking a mare 9,8a draw out of 220ah.
But yes I agree with you, I assumed the batteries had some charge. And reading the other tread behaviour leads to weak batteries.

 

[DerryW]

Yes, your batteries are knackered. Whatever type of fridge you have (only compressor types should be used on battery without the engine running), a drop to 8.3V when drawing 10A when the battery should have been just about fully charged shows they are toasted. I guess a really poor connection at the battery terminal could also cause this, but I strongly suspect this isn't the case here.

Next you need to work out why they're toasted, as if you just replace them, the new ones will go the same way if there is an underlying condition that needs addressing, such as a broken charger, usage way in excess of supply, or inappropriate usage of a 3 way fridge on battery power.

Thanks CMcardie. It’s go to be the fridge running purely on battery, I’m a bugger for forgetting to switch over to gas when we park up. I’m currently in the process of charging both batteries for 48hours then will disconnect everything including solar, letting the batteries rest for a couple of hours and then test with a meter. The above process has been recommended by fellow gunstet ChrisL

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[Richard n Ann]

Thanks CMcardie. It’s go to be the fridge running purely on battery, I’m a bugger for forgetting to switch over to gas when we park up. I’m currently in the process of charging both batteries for 48hours then will disconnect everything including solar, letting the batteries rest for a couple of hours and then test with a meter. The above process has been recommended by fellow gunstet ChrisL

If working correctly the fridge should just go off when the engine stops.

 

[PhilandMena]

You have nothing to loose by fully charging your batteries, disconnecting them and then seeing how well they hold there charge. You could then do a drop test if all is well after 24 hrs. To get them fully charged I would use a good charger and charge them for at least 36 hrs. You have nothing to loose.

 

[PhilandMena]

You may find the following informative.

StuartO - 2017-01-18 11:04 AM I'm still not much wiser about how these different sorts of battery tester work. Load testers (ie testers which apply a calibrated load and use the voltage response to extrapolate to the big picture) are simple enough to relate to schoolboy physics but how do these more expensive testers "simulate a full 20 hour discharge" in a few seconds? Stuart, You and me both. Derek Uzzell recently posted that he had to replace the Starter battery on his Skoda because at 6 years it was showing sign of losing charge after standing a few days. He replaced it and all was well. He fully charged the old battery and then let it stand. It reached full charge in an acceptable manner, but after standing a short while had lost a lot of capacity. If he had taken that 'rubbish' battery to a shop for testing after charging, it would have almost certainly passed an old fashioned load test where they just check if the battery will deliver x amps for x seconds. Just as it would start his car engine when fully charged. Clearly a battery that is rapidly losing charge, regardless of any test result, is fit only for scrap and why the usual Car battery test has always been flawed. I have not come across the testers that "simulate a full 20 hour discharge" in a few seconds so don't know how they work, but it sounds to me like marketing 'talk'. We have used the 'Resistance meters' costing up to £360. Ours was a Sealey, I think £160?? On these you type in the claimed 'capacity' from the label and then it estimates how many amps the tested battery MIGHT be able to deliver. There are variations on this where the software can use Amp hours as the base. Because the functioning of the tester is based around changing resistance it is limited in it's accuracy. While quite good on Starter batteries we have seen such varying readings for habitation batteries, especially those not of conventional construction, that we found they couldn't be trusted. One G80 Gel battery that 'passed' with 75Ah capability, would last less than 30 minutes on a couple of Halogen bulbs after being fully charged. We charged/discharged it 3 times because we trusted the Meter more than our own eyes. When our meter was dropped, I didn't get another. I think the easy, reliable way to test a battery is remove it from the vehicle. Charge it up for 48 hours, leave it 2 weeks then do a standard discharge test to around 50%. Leaving it 2 weeks after charging before beginning the test is important. As noted above in Dereks case, if he had carried out a discharge test straight after charging he would have most likely got a good result? A good modern battery will stay close to full charge for 3 months (note that Banner and most budget batteries have a higher self discharge rate and can be down to 'Sulphation' voltage inside 2 months). Our favourite Varta LFD's/Bosch L5's will still be close to full after 6 months. So all new batteries, even those with the highest self discharge, should survive being left 2 weeks with almost no voltage drop or change in capacity. Any drop in voltage at all is a dying battery, but the standard discharge test will show how bad/good.

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[DerryW]

If working correctly the fridge should just go off when the engine stops.

Thanks Richard n Ann
I don't like having the gas turned on when driving, therefore I don't set the fridge to Auto, but leave it on battery.

 

[Richard n Ann]

Thanks Richard n Ann
I don't like having the gas turned on when driving, therefore I don't set the fridge to Auto, but leave it on battery.

Should still go off.
Ours isn't auto and when we forget to switch to gas when stopped everything defrosts.

 

[cmcardle75]

Thanks Richard n Ann
I don't like having the gas turned on when driving, therefore I don't set the fridge to Auto, but leave it on battery.

Isn't that the whole purpose of auto? Turn off the gas and run the engine and it will switch to battery? I've never had an auto 3 way, so don't actually know, but assumed this was the purpose. I.e. take mains in preference, then gas, then battery (hopefully with some sort of engine run detection).

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[DerryW]

Isn't that the whole purpose of auto? Turn off the gas and run the engine and it will switch to battery? I've never had an auto 3 way, so don't actually know, but assumed this was the purpose. I.e. take mains in preference, then gas, then battery (hopefully with some sort of engine run detection).

You're quite right, that's the idea of 3-way., but like I say, we're not keen on driving with the gas turned on. Call me old fashion.

 

[cmcardle75]

You're quite right, that's the idea of 3-way., but like I say, we're not keen on driving with the gas turned on. Call me old fashion.

What I mean is, you are supposed to turn the gas off when travelling. The fridge will then switch to battery when the little amount of gas in the pipework is exhausted.