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Author Topic: Tester for 12v batteries  (Read 5962 times)

PipKelpy

  • Joined Mar 2019
  • North Shropshire
  • Dreamer with Mary, (cow) and sheep.
Tester for 12v batteries
« on: October 22, 2023, 08:36:35 pm »
I have several 12v batteries for the fencers. They all say charged, even with a UV light, the green float is high.

Can anyone recommend a tester for 12v please? I see many which are like the fence line tester, lights only, though I have seen some with have numbers on a led display, which I would prefer, but there are several available so am wondering which would be best.
Halter train the cattle to keep them quiet but watch your back when they come a'bulling! Give them all names even those you plan to eat. Always be calm. Most importantly, invest in wellies with steel toe caps and be prepared for the clever cow who knows where the toe caps end!!

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Tester for 12v batteries
« Reply #1 on: October 23, 2023, 12:42:41 pm »
Do you just want to know the voltage across the terminals?

If so, a cheap multimeter will give you that, for example https://www.ebay.co.uk/itm/145317214178? at a cost of 6.50.

Set the dial to DC Volts 20 (the setting at about 10 o'clock on the dial), put the black lead to the -ve terminal on the battery and the red lead to the +ve, then read off the result in volts. A lead-acid battery will give a bit more than 12V; usually 12.6 for a charged car battery.

Does that help?
« Last Edit: October 23, 2023, 12:44:47 pm by Womble »
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

chrismahon

  • Joined Dec 2011
  • Gascony, France
Re: Tester for 12v batteries
« Reply #2 on: October 23, 2023, 01:47:29 pm »
I had a mower battery fail this year which was only 2 years old. Nice bright green light, but measured 11.5V and there wasn't enough power in it to operate the starter solenoid. The green 'light' (floating indicator) is only on one cell, so if one of the others fails it won't show.


As Womble says, a simple voltmeter will suffice. There are two test to do. First is the no load voltage and the second with a load. You expect the voltage to drop slightly under load, but not that much. Connect a headlight bulb across the terminals- it shouldn't be dim or drop the voltage below 12V.

PipKelpy

  • Joined Mar 2019
  • North Shropshire
  • Dreamer with Mary, (cow) and sheep.
Re: Tester for 12v batteries
« Reply #3 on: October 23, 2023, 09:36:57 pm »
Do you just want to know the voltage across the terminals?

If so, a cheap multimeter will give you that, for example https://www.ebay.co.uk/itm/145317214178? at a cost of 6.50.

Set the dial to DC Volts 20 (the setting at about 10 o'clock on the dial), put the black lead to the -ve terminal on the battery and the red lead to the +ve, then read off the result in volts. A lead-acid battery will give a bit more than 12V; usually 12.6 for a charged car battery.

Does that help?

To be honest I don't know. My batteries all float but Mary is currently stripping the front field on a fencer flashing red, though the line testers say 8000v (I have 2 different testers). I also get a shock when I touch the wire and I trust Mary. The sheep are also wire trained and they come and nose too.

It's the calf I don't trust, Mary due 8th November and my experience of calves and electric fences is that they test them! I can stick a head collar on it, it'll learn faster! However, I have 5 or 6 12v batteries and varying energisers all flashing red on good wire, which makes me think my batteries, as per usual, are all wanting to die at the same bloody time!
Halter train the cattle to keep them quiet but watch your back when they come a'bulling! Give them all names even those you plan to eat. Always be calm. Most importantly, invest in wellies with steel toe caps and be prepared for the clever cow who knows where the toe caps end!!

PipKelpy

  • Joined Mar 2019
  • North Shropshire
  • Dreamer with Mary, (cow) and sheep.
Re: Tester for 12v batteries
« Reply #4 on: October 24, 2023, 08:20:29 pm »
I had a mower battery fail this year which was only 2 years old. Nice bright green light, but measured 11.5V and there wasn't enough power in it to operate the starter solenoid. The green 'light' (floating indicator) is only on one cell, so if one of the others fails it won't show.


As Womble says, a simple voltmeter will suffice. There are two test to do. First is the no load voltage and the second with a load. You expect the voltage to drop slightly under load, but not that much. Connect a headlight bulb across the terminals- it shouldn't be dim or drop the voltage below 12V.

Right, update:

Today, someone lent me a konnwei car battery tester (you'll be fine, read instructions.....).

I tested 4 batteries, 3 leisure, 1 car (my old Kia battery, not only was it salvage written off, just when I needed to get dog to vet, she wouldn't start, wouldn't jump, was really at the end of my tether! Mechanic came out "sounds like cam belt love" not what you want to hear when you've taken salvage price over full write off price! Few days later, my usual mechanic come out, do full test, "you need a new battery".) Old battery taken to Shippon, charged once (this was late last year).

Meter today states car battery at 50%.

65A CCA 480 (I think, I know it's little)

3 leisure batteries ALL with green floats,

85A MCA(is it?) 780

2 at 10.3v 10.3A,
1 at 10v 9A

Which I'm assuming is not good?

All were tested as out of car and the top 2 options regarding type of battery which I think (off memory) is regular flooded and agm flat plate.

However, each had CHARGE-RETEST on the display and according to to instructions means I need to recharge, then retest and if the same results appear, battery knackered, this could be very expensive!

So, do i go by this new tester OR do I buy a multimeter and check that way, or do I consider praying as batteries haven't gone down in price?
Halter train the cattle to keep them quiet but watch your back when they come a'bulling! Give them all names even those you plan to eat. Always be calm. Most importantly, invest in wellies with steel toe caps and be prepared for the clever cow who knows where the toe caps end!!

Womble

  • Joined Mar 2009
  • Stirlingshire, Central Scotland
Re: Tester for 12v batteries
« Reply #5 on: October 24, 2023, 08:54:33 pm »
A multimeter isn't going to tell you anything that the battery tester (more advanced) hasn't already.

Did you test the leisure batteries after they had been charged? If not, I'd recharge and retest.
"All fungi are edible. Some fungi are only edible once." -Terry Pratchett

PipKelpy

  • Joined Mar 2019
  • North Shropshire
  • Dreamer with Mary, (cow) and sheep.
Re: Tester for 12v batteries
« Reply #6 on: October 25, 2023, 03:58:43 pm »
A multimeter isn't going to tell you anything that the battery tester (more advanced) hasn't already.

Did you test the leisure batteries after they had been charged? If not, I'd recharge and retest.

Well, you've saved me around 7 for the multimeter, but i think I am going to fork out for a tester similar to one I borrowed. I admit I'm a dunce re stuff like this so assumed 1 of each gadget necessary (I did actually read about multimeters and like the idea of testing household batteries with one as last year we bought some 9v (smoke alarm type) for the controllers of mum's stair lift and when we come to use them they don't work yet they expire around 2030, Duracell industrial.)

The 12v, 1 is currently charging, 3 are waiting their turn and then they will be charged.

I wired up another field today for Mary and sheep, used the same fencer, put the Kia battery on it after a quick 15 min charge on fast charge (whilst wiring up the grass) and the fencer flashes green!

Then came in and ordered a fit 1 charge 1 kit with charger off Tanya batterys via ebay, but the 50amp battery. Normally i swear by the heavy dudes (85 amp, 25kg (wheel barrow job)) but considering they are supposed to go at least 200 cycles etc and 85 each...... I would rather have a lower amp and recharge more regularly.

Halter train the cattle to keep them quiet but watch your back when they come a'bulling! Give them all names even those you plan to eat. Always be calm. Most importantly, invest in wellies with steel toe caps and be prepared for the clever cow who knows where the toe caps end!!

chrismahon

  • Joined Dec 2011
  • Gascony, France
Re: Tester for 12v batteries
« Reply #7 on: October 25, 2023, 06:48:49 pm »
Two of our 100Ah leisure batteries were 140 each ten years ago (the other was 85 but is 20 years old), so that's really cheap [member=194324]PipKelpy[/member] . Perhaps that's the problem? Of course a smaller battery being charged more frequently is going to fail more quickly. Worth noting that, whilst a car battery will take a fast charge, a leisure battery needs a much slower charge but is supposed to have a much longer life. From when the green light goes out to fully recharged is taking 48 hours on our batteries.


As mentioned before, the green light is only on one cell and therefore represents the state of charge of a battery in good condition. It won't indicate failure of one of the other cells, only a meter will do that.

Kiran

  • Joined Apr 2019
Re: Tester for 12v batteries
« Reply #8 on: October 26, 2023, 02:15:34 am »
So we use leisure batteries on our fences, every 6 months or so I put them on a recovery cycle on the battery charger. It desulphates the plates in the batteries and their capacity to hold charge increases. Its a good way to keep them healthy if they are ever allowed to run down to minimum power. Measuring the voltage is fine for the state of the battery but it doesn't help if that battery drops instantly/overnight. I use the Noco Genius chargers as they always seem to work well but there are loads that have recovery modes

PipKelpy

  • Joined Mar 2019
  • North Shropshire
  • Dreamer with Mary, (cow) and sheep.
Re: Tester for 12v batteries
« Reply #9 on: December 17, 2023, 03:46:30 pm »
So we use leisure batteries on our fences, every 6 months or so I put them on a recovery cycle on the battery charger. It desulphates the plates in the batteries and their capacity to hold charge increases. Its a good way to keep them healthy if they are ever allowed to run down to minimum power. Measuring the voltage is fine for the state of the battery but it doesn't help if that battery drops instantly/overnight. I use the Noco Genius chargers as they always seem to work well but there are loads that have recovery modes

THANKYOU very much for introducing me to these fancy chargers!!

Blimey, what a lot there are, brother in law who lives next door, "yeah, I got one" never told me about them though!

I read about the Noco Genius and eyed up the 5, but couldn't get one, however, didn't want to wait for Black Friday (when they reduced the bloody price by 10) and bought myself a Ctek MXS 5, EVERY 12V battery on the place has been descaled etc.

Out of all 5, 3 couldn't get past stage 4 (on the Ctek) apparently too knackered or too far gone, each registering 11.5v but I have a couple of 12v bulbs incase of power cuts, they'll do for that.

2 will hold a charge (not for long), one of which the meter read it as being at 3v, charger got it to 12.2v and it has powered 250m of wire for the sheep for about 4 days, before it started to send the fencer red, but I'll use it as a floater, one to cover just in case. The other being the old car battery, that goes for about a week before it starts to die.

I have also splashed on on a new dual terminal 70ah leisure battery to keep my 2 new 50ah batteries company. Hannah (calf) has learnt NOT to touch the wire and fortunately a couple of the sheep have also given her the evil eye, (others run for their lives!)

Love my charger.

Halter train the cattle to keep them quiet but watch your back when they come a'bulling! Give them all names even those you plan to eat. Always be calm. Most importantly, invest in wellies with steel toe caps and be prepared for the clever cow who knows where the toe caps end!!

 

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