What is the life of gel batteries?

[Revolvor]

The D250S is a dual charger, with MPPT solar and a 20A B2B, charging from the alternator/starter battery. The lower left input is from the alternator/starter battery, the lower right output is to the leisure battery.

I have a. CTEK D250S on my van, but without the Smartpass. It seems to do a good job of charging my 2x 110Ah LA batteries. You cannot change the battery profile, and it is NOT suitable for Lithium. There is a newer version (D250SE) that caters for various batteries, including Lithium.

 

[ChrisL]

I had three lead carbon gel batteries from Alpha Batteries that lasted less then three years, they started to go down hill after being on hookup for two winters according to the shunt they'd never been lower then 50%, I've now gone to lithium.

 

[TheLifeofBrian]

I had three lead carbon gel batteries from Alpha Batteries that lasted less then three years, they started to go down hill after being on hookup for two winters according to the shunt they'd never been lower then 50%, I've now gone to lithium.

Did they replace them under warranty as they have a 5 year guarantee?

 

[ChrisL]

Did they replace them under warranty as they have a 5 year guarantee?

No, if you look at the guarantee sheet it's not worth the paper it's printed on.

 

[TheLifeofBrian]

No, if you look at the guarantee sheet it's not worth the paper it's printed on.

That doesn't look good. I haven't even got a shunt !
Did you try to get them replaced or not bother?

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[ChrisL]

That doesn't look good. I haven't even got a shunt !
Did you try to get them replaced or not bother?

I didn't bother as it would have cost £60 to ship the three batteries back and they would most likely have refused the claim anyway. I chalked it down to experience and Offgrid recycled them for me when they installed the Fogstar Drift.

 

[TheLifeofBrian]

OK next update!
I got home after driving 4 hours & left the tv & all the lights on & everything was fine for 2 hours!
Next day I plugged into the mains & charged them all day & that night left everything on for 4 hours & still ok!
They were just flat I thought but today I tried my lads MK capacity tester on them (after a full charge) one after the other and the one gave 15% and the other 14% so both obviously knackered
I'm just trying a pulse charger to see if it makes any difference but I doubt it

just realised there was audio - luckily I didn't swear!

 

[Ducatian]

OK next update!
I got home after driving 4 hours & left the tv & all the lights on & everything was fine for 2 hours!
Next day I plugged into the mains & charged them all day & that night left everything on for 4 hours & still ok!
They were just flat I thought but today I tried my lads MK capacity tester on them (after a full charge) one after the other and the one gave 15% and the other 14% so both obviously knackered
I'm just trying a pulse charger to see if it makes any difference but I doubt it

View attachment 956388
just realised there was audio - luckily I didn't swear!

View attachment 956389

Those voltage readings of 10.6 and 9.6 volts are rather consistent with dead batteries.

 

[Langtoftlad]

Presumably you've followed standard advice about separating the pair of batteries - just in case only one is goosed and is dragging the other one down?

Having just had 2 gels fitted, I'm rather hoping they'll last a bit longer than 2 years

 

[TheLifeofBrian]

Those voltage readings of 10.6 and 9.6 volts are rather consistent with dead batteries.

Those are the readings as the tester has finished testing them

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[TheLifeofBrian]

Presumably you've followed standard advice about separating the pair of batteries - just in case only one is goosed and is dragging the other one down?

Having just had 2 gels fitted, I'm rather hoping they'll last a bit longer than 2 years

Yes they were both charged & tested separately.

 

[headlight]

I'm still trying to find the cause.....
Could it just be I've taken too much power out of them? I don't really see how, even if I had the satellite & TV on, plus stereo & various chargers for several hours I don't think that would have been more than 15 amps, so even for 5 hours that's only 75 amps (or has my maths failed after 40+ years since school ) & there are 2 x 110 ah batteries!! Couple that with overcast weather so not much solar power....
I think I'll speak to the battery supplier tomorrow (alpha batteries) & see what they suggest. We're booked into Malvern in 2 weeks so need to get it sorted asap!
Also I'll try testing them individually & see what the results are

If they have died & get replaced I might sell them & bite the bullet & get a lithium - partly to save weight!

Thank you all for your help - excellent Funster advice as usual

If you use your inverter the problem isn't the total amps drawn but the speed at which they are drawn especially with other electrical items being used at the same time.

 

[TheLifeofBrian]

The CTEK D250S charges the leisure battery from the alternator at 20A, and the CTEK Smartpass boosts this by another 80A to make 100A total. I don't know what size your two Gel batteries are, but I suspect that might be too much for them. For the best long-term battery life, the charging amps should be limited to C/5, where C is the battery capacity. So for two 100Ah gels, that would be 200/5 = 40A. A bit extra might be OK, but I think 20 + 80 = 100A might be too much.

I have just spoken to CTEK & they say:
The CTEK chargers only put in what is required so unless the batteries were discharged all the time then yes but then the voltage and current does drop off and when fully charged the charger switches off.
So that shouldn't have damaged the batteries - the EBL is also set to GEL so I still have no idea what could have caused them to fail???

 

[Coolcats]

Hi all,
Anyone any idea what could kill my gel batteries in only 18 months?
April last year I changed both batteries as the old AGMs had died - we got 110ah gel batteries from Alpha & they have been absolutely great all year but got to the Lincoln show Thursday (no ehu) & by Friday night they had both dropped to 11v
When the sun comes out they read up to 14v but turn a tap on & they drop like a brick to 12v
I've tried disconnecting one of them to see if it's just one dragging the other down but last night (Saturday) it dropped so low it turned the control panel off & the sun had been shining all day & the only thing plugged in was our 2 phones.

This is virtually the same thing that happened to the last pair of AGM batteries!
The only thing I can think is I tried the inverter (that is wired in) with a coffee machine but it wasn't big enough so turned it off.
It's a 600w pure sine inverter with a remote switch:
View attachment 953502

Other than that the Lincoln show is great

Any ideas anyone please?
Cheers Chris

Mine are now 7 years old and still fine 2x95Ah

 

[autorouter]

The CTEK chargers only put in what is required

So, did CTEK give you a number for the amps that will go into a pair of gel batteries discharged to say 50%? I think it will be 20A + 80A = 100A. What amps do they say?

Have you measured the charging amps yourself with a clamp meter? I would imagine the lad who services wheelchairs has one. If not, you know what to buy him for Christmas.

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[CAB96]

Autorouter has basically said this twice:

Your batteries should be charged at no more than 40a for the pair (20a each).

Your setup has been charging them at 100a.

QED.

 

[TheLifeofBrian]

So, did CTEK give you a number for the amps that will go into a pair of gel batteries discharged to say 50%? I think it will be 20A + 80A = 100A. What amps do they say?

Have you measured the charging amps yourself with a clamp meter? I would imagine the lad who services wheelchairs has one. If not, you know what to buy him for Christmas.

Thanks for pointing that out but I don't think they would have been discharged anywhere near that amount. They have always been charged via the solar which is permanently connected and occasionally EHU but nothing has been used that would take that sort of current to flatten them?
As CTEK say - that is their job to control how much current is diverted to them and I can't see why anyone would fit the extra smartpass if it could overcharge them?
I haven't got a clamp meter but was looking at a smart shunt to monitor them but I think I'm going with lithium which has a smart BMS so I wouldn't need it.

 

[Flairy]

Mine are 23 years old original still working well.

 

[ChrisL]

I think I'm going with lithium which has a smart BMS so I wouldn't need it.

A smart shunt will be much more accurate then the BMS which won't record small discharge/charges.

 

[TheLifeofBrian]

Autorouter has basically said this twice:

Your batteries should be charged at no more than 40a for the pair (20a each).

Your setup has been charging them at 100a.

QED.

I can't see why any company would sell a dedicated charger that would overcharge the batteries it was trying to control?
There wouldn't be a need to sell the extra smartpass controller if it could damage them?
If this was the case CTEK would have stopped selling them & no one would install them!

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[TheLifeofBrian]

A smart shunt will be much more accurate then the BMS which won't record small discharge/charge

Their selling point is that the battery is the main component & that is what needs monitoring. Their BMS does that - I'm not sure all of them do.

 

[autorouter]

The first stage of charging is called 'bulk'. The charger is in 'Constant Current' mode. This is not the same as the more usual 'Constant Voltage' mode. In Constant Current mode, the charger pushes out the full amps output that it is capable of. The voltage is whatever results from this. The Constant Current mode continues until the voltage rises to the 'Absorption voltage'. Normally this happens when the battery is about 80% full.

So when the charger is first switched on, if the batteries are at say 50%, they will be charged at the full amps output of the charger.

Don't take my word for it, if you look at Page 23 of the DS250S manual, you can see that happening. After a short desulphation stage, the Bulk stage starts. The current (amps) is constant, and the voltage slowly rises, typical of Constant Current mode. The current (amps) is the maximum the charger can deliver. As far as I know, there is no way to reduce this number of amps.

Some chargers, like the new Victron Orion XS B2B charger, can be set from 1A to 50A in steps of 1A. The Sterling B2B has a half power mode, where a 60A B2B can be set to only give 30A. The small CTEK charger I have can be set to either 5A for a car battery, or 2A for a motorcycle battery.

The DS250S is not adjustable, and neither is the SmartPass. That means the output amps is as I said, 20A + 80A =100A.
For two 100Ah gel batteries I think that is too much. The maximum recommended amps for two 100Ah gel batteries is 40A. @AdrienChen described what is likely to happen in that situation.

The only issue with Gels that I have heard of (and a few years back so may not apply to new stuff like carbon gels....) is that they can "boil" if they are charged too fast at too high voltage, ie bubbles form in the gel electrolyte, that then don't move and are present for evermore, if against the battery plates the capacity is reduced, so it's important to charge, within the battery's specification

To me it seems from your description that is exactly what has happened, the batteries are no good after less than a couple of years, when they should be giving many years of good service.

 

[peterc10]

Their selling point is that the battery is the main component & that is what needs monitoring. Their BMS does that - I'm not sure all of them do.

All do. The problem is that with low current they cannot do it very accurately. And those errors accumulate. Only a shunt will give you accurate figures.

 

[TheLifeofBrian]

The first stage of charging is called 'bulk'. The charger is in 'Constant Current' mode. This is not the same as the more usual 'Constant Voltage' mode. In Constant Current mode, the charger pushes out the full amps output that it is capable of. The voltage is whatever results from this. The Constant Current mode continues until the voltage rises to the 'Absorption voltage'. Normally this happens when the battery is about 80% full.

So when the charger is first switched on, if the batteries are at say 50%, they will be charged at the full amps output of the charger.

Don't take my word for it, if you look at Page 23 of the DS250S manual, you can see that happening. After a short desulphation stage, the Bulk stage starts. The current (amps) is constant, and the voltage slowly rises, typical of Constant Current mode. The current (amps) is the maximum the charger can deliver. As far as I know, there is no way to reduce this number of amps.

Some chargers, like the new Victron Orion XS B2B charger, can be set from 1A to 50A in steps of 1A. The Sterling B2B has a half power mode, where a 60A B2B can be set to only give 30A. The small CTEK charger I have can be set to either 5A for a car battery, or 2A for a motorcycle battery.

The DS250S is not adjustable, and neither is the SmartPass. That means the output amps is as I said, 20A + 80A =100A.
For two 100Ah gel batteries I think that is too much. The maximum recommended amps for two 100Ah gel batteries is 40A. @AdrienChen described what is likely to happen in that situation.


To me it seems from your description that is exactly what has happened, the batteries are no good after less than a couple of years, when they should be giving many years of good service.

Thanks for all your comments autorouter - I have emailed CTEK to ask for their comments!

 

[TheMachMan]

You're probably seeing the solar charging voltage the batteries will be flat.

You can't test a leisure battery with a starter battery tester as it won't show you the capacity which is the important bit.

This is the clamp meter most of us use:

Pardon our interruption...

Bit of a dark art to me, so how do you use one of these to check if your leisure batteries are ok? Got suspicions about ours.

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[Richard n Ann]

how do you use one of these to check if your leisure batteries are ok?

You can't you have to do a discharge test with a known amperage and after a few hours see what the charge level is by measuring the voltage.
I always think it's a bit like using them, you know if they're getting tired, actually your suspicions will probably be correct

 

[ChrisL]

You need one of these to do a discharge test, available on ebay, set a cut off voltage so you don't damage the battery perhaps 50% (12 volts?) set a current load and run the test, it will stop when it gets to the cut off voltage and you will be able to see how many amps were consumed, that will give you an idea of capacity. In this test, the battery dropped immediately to 8.84 volts with a 2 amp load indicating the battery was beyond saving.

 

[autorouter]

You need one of these to do a discharge test, available on ebay, set a cut off voltage so you don't damage the battery perhaps 50% (12 volts?) set a current load and run the test, it will stop when it gets to the cut off voltage and you will be able to see how many amps were consumed, that will give you an idea of capacity. In this test, the battery dropped immediately to 8.84 volts with a 2 amp load indicating the battery was beyond saving.

If you want to test the battery just like the manufacturers do, then set the amps load to be 1/20 of the amp-hour capacity. So for example for a 100Ah battery set the amps load to 5A. The manufacturers run the test for 20 hours, until the battery is completely flat, but you don't want to do that. Maybe run for 10 hours, and use the voltage chart to see what percentage level it has dropped to. For a new battery that would be 50%, for an older battery maybe it will go down to 40% or even lower, giving you some idea of how much it has deteriorated.

 

[headlight]

Thanks for all your comments autorouter - I have emailed CTEK to ask for their comments!

I'm having trouble understanding this.
You have drained your batteries quicker than they are rated at, you have charged your batteries quicker than they are rated at which has resulted in goosed batteries.
Why are you emailing CTEK, what are you expecting them to say ?

 

[TheLifeofBrian]

I'm having trouble understanding this.
You have drained your batteries quicker than they are rated at, you have charged your batteries quicker than they are rated at which has resulted in goosed batteries.
Why are you emailing CTEK, what are you expecting them to say ?

I'm having trouble following you as well?
How have I drained my batteries too quickly - unless you are referring to trying an inverter which turned on and instantly off and I am not doing anything to charge the batteries other than using the CTEK equipment as it was designed and professionally installed?
I am asking them for their opinion on the fact that it has been suggested to me that they can output too much current for the job they are designed for and could therefore have overcharged my batteries.

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