AGM OR LEAD BATTERY (1 Viewer)

[PhilandMena]

First charge the battery fully and leave it to settle for an hour then:-

For example if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged.

Always best to test each battery individually if in any doubt.

View attachment 531381

Thanks for this ! I have read that a leisure battery subject to a drop test should be disconnected for at least two weeks before starting the test as a good battery will hold its charge for weeks if not months, yet a battery with limited capacity will still hold a full charge for quite a while after being fully charged and doing a drop test within a short time after charging will give a false result. Do you agree with that premise ?

 

[PhilandMena]

There are also lead carbon gel batteries available, i have recently installed three 110 ahs, time will tell how well they perform.

I think you will find that Lead Acid, AGM & Gel are all lead based batteries. I've not heard of lead carbon Gel batteries and wonder if they could be Pure lead Carbon sold at a higher price ????? The leisure battery market place is in such a mess with so much mis selling and utter crap out there !

 

[PhilandMena]

First charge the battery fully and leave it to settle for an hour then:-

For example if it's a 100a/h battery load it with a 5 amp load and run for 5 hours, this will represent a 25% discharge. (adjust load/time to suit the size of the battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeat the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged.

Always best to test each battery individually if in any doubt.

View attachment 531381

I have another question for you (Sorry to be a pain in the rear mate!). What's the purpose of measuring the voltage after letting the battery stand for 30 minutes after removing the load and what do you do with the result (what result should you see and what if its lower than expected ? what then ?)

^{_{Subscribers  do not see these advertisements}}

 

[ChrisL]

I think you will find that Lead Acid, AGM & Gel are all lead based batteries. I've not heard of lead carbon Gel batteries and wonder if they could be Pure lead Carbon sold at a higher price ????? The leisure battery market place is in such a mess with so much mis selling and utter crap out there !

99% pure lead plus carbon similar to the agm variants, 5 year guarantee, 1500 cycles at 50% dod, 15 year design life. The advantage over agm is they can be charged from -20 C the agm ones say charge from 0 C, the disadvantage from agm is they can't be charged as quickly, but still quicker than regular lead acid or gel. I bought mine from alpha batteries £169.98 each. I thought them worth a try as I have sisters who live in the alps where it regularly gets down to -16C in the winter.

 

[Lenny HB]

Thanks for this ! I have read that a leisure battery subject to a drop test should be disconnected for at least two weeks before starting the test as a good battery will hold its charge for weeks if not months, yet a battery with limited capacity will still hold a full charge for quite a while after being fully charged and doing a drop test within a short time after charging will give a false result. Do you agree with that premise ?

The problem lem with a drop /CCA test is it is designed to measure short term high current capability which is the opposite of what you want for leisure use.
Batteries will often pass this test but on a slow discharge only give a few amp hours.
The AGM's that failed on me a few years ago gave a CCA test pass of 80% but with a 5 amp load they lasted 2 hours.

 

[Lenny HB]

I have another question for you (Sorry to be a pain in the rear mate!). What's the purpose of measuring the voltage after letting the battery stand for 30 minutes after removing the load and what do you do with the result (what result should you see and what if its lower than expected ? what then ?)

You are always a pain Phil unless you are buying me €1 beers or talking to 'er indoors about birding.
If testing that way and the voltage is lower that expected, the battery no longer has its full capacity and from the results you should be able to guesstimate how much capacity it has lost.

^{_{Subscribers  do not see these advertisements}}

 

[PhilandMena]

You are always a pain Phil unless you are buying me €1 beers or talking to 'er indoors about birding.
If testing that way and the voltage is lower that expected, the battery no longer has its full capacity and from the results you should be able to guesstimate how much capacity it has lost.

I agree with that ! I'm not sure of the math though so will seek advice elsewhere.

The problem lem with a drop /CCA test is it is designed to measure short term high current capability which is the opposite of what you want for leisure use.
Batteries will often pass this test but on a slow discharge only give a few amp hours.
The AGM's that failed on me a few years ago gave a CCA test pass of 80% but with a 5 amp load they lasted 2 hours.

I understand this Lenny but that's not what I asked you ! I will seek confirmation or otherwise from elsewhere. Thanks for responding.

 

[PhilandMena]

Reply from anandncaravans.

Dear Philip,



Thank you for your enquiry via our contact page.



You should NEVER drop test a habitation/leisure technology battery it will be damaged and shorten its usable life.

A drop test is for Cold Cranking batteries only like Wet Lead or AGM where you are measuring the ability for a battery to turn over an engine.



Here is our suggested way to DIY test a habitation battery for capacity or you need to invest in a good battery analyser.



+++++++++++++++++



Never use a “drop” tester to test a leisure type battery. It will do physical damage to the plates and reduce its useful working life. If you want to DIY test your habitation battery to see if it has reduced capacity you should charge the battery to full capacity, minimum of 6 hours and maximum of 16 hours at 14.2 volts. Leave it to stand for a minimum of 24 hours and measure the voltage. The “standing” voltage should be above 12.5 volts for a wet or gel lead battery. Then you need to discharge the battery at a known current. The easiest way is to use a 21-watt car stop light bulb as this draws 1.75 Amps. (we’re not talking supper accurate here). With the load connected, monitor the battery voltage and note the time it takes to drop to 12.1 volts. Disconnect the load so as not to discharge it below this figure. If the battery was, for instance, rated at 70 Ah and it takes 20 hours to discharge to 12.1 the remaining usable capacity has dropped to (20 x 1.75 = 35) 35 Ah which is 50% of the original rating. Anything below 80% is considered to be exhausted and should be replaced. If you continue to use the battery with only 50% of its capacity available, it will discharge in approximately one quarter of the original time and may do damage to the charging system.



+++++++++++++++++



With best regards



Martin Bushnell

Senior Engineer



URL: http://www.aandncaravanservices.co.uk

email: service@aandncaravanservices.co.uk

Tel: +44 (0) 7434641685

Fax: +44 (0) 1745822169

If you have found the website useful please click this link http://www.aandncaravanservices.co.uk/scholarship-fund.php

 

[PhilandMena]

I've started to test my 3 year old batteries and will publish results in a few days !

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

Reply from anandncaravans.

Dear Philip,



Thank you for your enquiry via our contact page.



You should NEVER drop test a habitation/leisure technology battery it will be damaged and shorten its usable life.

A drop test is for Cold Cranking batteries only like Wet Lead or AGM where you are measuring the ability for a battery to turn over an engine.



Here is our suggested way to DIY test a habitation battery for capacity or you need to invest in a good battery analyser.



+++++++++++++++++



Never use a “drop” tester to test a leisure type battery. It will do physical damage to the plates and reduce its useful working life. If you want to DIY test your habitation battery to see if it has reduced capacity you should charge the battery to full capacity, minimum of 6 hours and maximum of 16 hours at 14.2 volts. Leave it to stand for a minimum of 24 hours and measure the voltage. The “standing” voltage should be above 12.5 volts for a wet or gel lead battery. Then you need to discharge the battery at a known current. The easiest way is to use a 21-watt car stop light bulb as this draws 1.75 Amps. (we’re not talking supper accurate here). With the load connected, monitor the battery voltage and note the time it takes to drop to 12.1 volts. Disconnect the load so as not to discharge it below this figure. If the battery was, for instance, rated at 70 Ah and it takes 20 hours to discharge to 12.1 the remaining usable capacity has dropped to (20 x 1.75 = 35) 35 Ah which is 50% of the original rating. Anything below 80% is considered to be exhausted and should be replaced. If you continue to use the battery with only 50% of its capacity available, it will discharge in approximately one quarter of the original time and may do damage to the charging system.



+++++++++++++++++



With best regards



Martin Bushnell

Senior Engineer



URL: http://www.aandncaravanservices.co.uk

email: service@aandncaravanservices.co.uk

Tel: +44 (0) 7434641685

Fax: +44 (0) 1745822169

If you have found the website useful please click this link http://www.aandncaravanservices.co.uk/scholarship-fund.php

Virtually what I said.

 

[Lenny HB]

I've started to test my 3 year old batteries and will publish results in a few days !

What A&N suggest is a too lower load for a real live test you need to test them with a load that draws 5 to 10 amps as that is more typical of the real life use. in. Also you will get a better idea of there condition if you do it in 25% stages like I suggested eairler.

 

[autorouter]

I have no idea how to conduct an accurate capacity test, I assume this is a ‘bench test’ exercise running a known Ah demand on the battery for a defined period or until failure?

You're going to be sorry you said that Here's how to do it.

1. Fully charge the battery, leave it to settle for a couple of hours.
2. Attach a load that draws an amps value of Capacity/20. (for example for a 100Ah battery, 100/20 = 5A.
3. Run the load for 5 hours. The amp-hours taken from the battery is Amps x 5 hours. (for the same example, 5 x 5 = 25Ah. For a brand new battery this would be 25% of the capacity, so it should be down to the 75% level.
4. Let the battery settle for a couple of hours
5. Measure the voltage.
6. Use this voltage, referring to the battery charge/voltage scale (In Lenny HB's post #32) to estimate what percentage charge is left in the battery. For this example, let's suppose it is 12.28V. If it's a Sealed Lead-acid type, that represents a level of 60%. Since you drew 25% of the label capacity, you would expect the voltage to be at the 75% level on the charge/voltage scale. However because the battery has aged, it is now at the lower level of 60%.

7. If the battery is actually at 60% when you expect it to be 75%, its capacity when full is
(60 / 75) x 100 = 80% of the original capacity.

So the battery capacity has reduced due to aging, and is now only 80% of its original capacity

^{_{Subscribers  do not see these advertisements}}

 

[PhilandMena]

What A&N suggest is a too lower load for a real live test you need to test them with a load that draws 5 to 10 amps as that is more typical of the real life use. in. Also you will get a better idea of there condition if you do it in 25% stages like I suggested eairler.

Agreed, I have a 55 W bulb and will use that. (4.6 Amps)

 

[PhilandMena]

From aandncaravns if you fancy a read ! its a long one too!

How Does A Lead Acid Battery Work?

Why do Lead Acid Batteries fail? The most common causes of battery failure by battery technology. How a battery works and how to get the best from your purchase. Myths busted : Gel and AGM batteries do Gas fluid. Lead Antimony battery

www.aandncaravanservices.co.uk

 

[PhilandMena]

So! 3 hrs after disconnecting batteries they are reading 13.3V ! I will start test tomorrow.

^{_{Subscribers  do not see these advertisements}}

 

[LostinWales]

Your going to get a lot of different advice on here ! A lot of it good, some of it bad and whilst I generally agree with Lenny HB about AGM leisure batteries, there is a new type of AGM leisure battery that IMO is worth considering. Pure Lead Carbon batteries. These are cheaper than Gel batteries. (Gel batteries would last longer though !), They have a much longer life than your standard AGM batterie and can be safety discharged to a much lower lever than a standard AGM battery without any long term damage. There are quite a few manufacturers producing them now and I'll attach a link for one as to give you some idea what there all about.
As Lenny says if your on hook up all the time any old knackered 12 Volt lead Acid battery will do.

Leoch Pure Lead Carbon AGM 12V 100Ah Battery (PLH+C 100)

The Leoch PLH+C 100 AGM Battery. Designed for solar, golf, lighting, industrial, leisure applications and much more. More power than your lead WET acid batteries and has faster charging abilities. 12V 100Ah power output. Dimensions - 341.5L x 175W x 213H

www.tayna.co.uk

Tayna is local to me, good company. I note from their website they are not selling these on the leisure batteries page, but have at least equivalent cost batteries on that page. Any guess as to why they would not be selling these as suitable?

 

[PhilandMena]

Tayna is local to me, good company. I note from their website they are not selling these on the leisure batteries page, but have at least equivalent cost batteries on that page. Any guess as to why they would not be selling these as suitable?

Nope! However, if your interested in these types of batteries I would suggest you have a look at the Victron Pure Lead Carbon Battery. https://www.batterymegastore.co.uk/...d-carbon-battery-12v-106ah-mate-bat612110081/

 

[ChrisL]

Tayna is local to me, good company. I note from their website they are not selling these on the leisure batteries page, but have at least equivalent cost batteries on that page. Any guess as to why they would not be selling these as suitable?

I had a look at the Tayna website and it seems to me that they have no stock of lead carbon leisure batteries, all the ones they do have, have cold cranking amps defined in the tech specs, all the ones that have no cca defined are out of stock.

^{_{Subscribers  do not see these advertisements}}

 

[busby]

Although my agm’s lasted 7yrs I did replace them with gels… only because of the chances that I got lucky with the agm’s….

incidentally, I can’t see all the posts on this thread I think someone has me on ignore…

It's not me,,I am not that rude BUSBY.

 

[Lenny HB]

From aandncaravns if you fancy a read ! its a long one too!

How Does A Lead Acid Battery Work?

Why do Lead Acid Batteries fail? The most common causes of battery failure by battery technology. How a battery works and how to get the best from your purchase. Myths busted : Gel and AGM batteries do Gas fluid. Lead Antimony battery

www.aandncaravanservices.co.uk

Nope I'm on holiday.

 

[Lenny HB]

Although my agm’s lasted 7yrs I did replace them with gels… only because of the chances that I got lucky with the agm’s….

incidentally, I can’t see all the posts on this thread I think someone has me on ignore…

It's not me, if I ignored you there would be no fun in taking the piss out of you for that terrible wine you gave me.

^{_{Subscribers  do not see these advertisements}}

 

[PaulandChrissy]

I have found AGMs to be rubbish for off grid motorhoming. They only last 2 years at best for me. I’ve found Trojan 6volt golf cart batteries to be excellent. I’ve had 2 sets of them now, each lasting 9years. My next battery change when the current set of Trojans give up will definitely be Lithium. No contest. They charge much quicker and you have a much larger discharge window. Plus the voltage drop in use is minimal. Only downside is cost, but for off grid use, they are by far the best. For people who are always hooked up to the grid, save your money and by the cheapest.

PaulandChrissy

 

[Lenny HB]

I have found AGMs to be rubbish for off grid motorhoming. They only last 2 years at best for me.

A lot longer than they did for me, totally unsuitable as a leisure battery.

 

[PhilandMena]

OK! I have now started my test. At 09.00 this morning both batteries were found to be 12.96 V. They were disconnected at 14.00 hrs yesterday and both at 13.66 V.
I have put a 4.6 Amp load on to one of the batteries at 09.00 and it dropped immediately to 12.33 V (which is meaningless information !) I'll leave the load on for 5 hours then remove load allow to settle and calculate remaining capacity. I'm only going to do this one on one of thee batteries as they have both been linked as a pair from new and the readings up to the point where a load has been applied have been identical. Watch this space.

^{_{Subscribers  do not see these advertisements}}

 

[Lenny HB]

For only a 4.6amp load that's a hell of a drop, doesn't look to promising for your test.

 

[PhilandMena]

For only a 4.6amp load that's a hell of a drop, doesn't look to promising for your test.

I thought you were on holiday LOL!. It's my understanding that you can not accurately measure a battery when you have a load on it ! We shall see how well and by how much it recovers when I remove the load at 2.pm. The batteries have been in use since 2018 and subject to a fair bit of wilding and hook up and with 245 W of solar panel. I too am looking forward to the end result. Fingers crossed.

 

[pappajohn]

Just put an old lead acid on charge.
8.7v showing and the charger reverted to 6v.
After a few minutes it changed to 12v and began charging at the 2amp setting.
I'll see what it does.

^{_{Subscribers  do not see these advertisements}}

 

[pappajohn]

Sorry for ignorance, but are AGM batteries good for engine battery use? Our battery failed today and RAC recommended AGM.

Only if the failed one is AGM otherwise the alternator may not charge it properly as it will built for lead acid charge voltage

 

[PhilandMena]

There are loads of members on here who state AGM batteries are crap and I think they may be referring to AGM batteries used as Leisure batteries and from quite a while back too.
I think there has been some improvements in AGM batteries recently and in particular the stop-start type used in modern cars. Googling this subject the advice I read was if your starter batter has had it, you should replace it like for like as it will be the correct battery for the configuration of your cars charging system.

 

[PhilandMena]

So First update. Test is now completed. I measured the voltage with the load of 4.6 Amps still applied and after 5 hours the voltage reading dropped from 12.33 to 12.25 a drop of 0.08 of an Amp what does this mean. I don't have an effing clue
I will measure battery in an hour to see where its at. A picture of the battery at the the end of the test.

^{_{Subscribers  do not see these advertisements}}