BATTERIES

[mitzimad]

Can someone describe how to do the drop test on my leisure batteries ive got two varta ld 90s one came with the van and the other is 4 years old added when we bought the van.I understand the principle of putting a test light on each to see if the voltage drops if i do both the batteries simultaneously but singly i would assume if one is failing the voltage will drop faster? alternately what voltage drop am i expecting in what time scale i intend to use 21watt bulbs am i right that amps will be 21 divided by 12 giving me 1.75 amps would i be better using larger bulbs? worried about heat with larger bulbs?

 

[Lenny HB]

What you mean is a slow discharge test.

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.

 

[autorouter]

Batteries are usually tested at the '20 Hour' rate, which is the load that will completely discharge it in 20 hours. To find the amps load for this test, divide the Ah capacity by 20. So, as Lenny HB says, for a 100Ah battery that's 5 amps.

 

[mitzimad]

so for a ninety amphour battery i need a 4.5 amp load so the 21watt bulbs i have will not be big enough?
could i daisy chain three bulbs to gether to get 5.25?

 

[Gizmouk]

so for a ninety amphour battery i need a 4.5 amp load so the 21watt bulbs i have will not be big enough?
could i daisy chain three bulbs to gether to get 5.25?

Yes, 3 QTY 21W bulbs in parallel will be close enough load

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[autorouter]

25% of 90Ah is 22.5Ah. If the load is 5.25A, it should take 22.5/5.25 = 4.29 hours, ie 4 hr 17 min.

Stop after this time, let it settle, and measure the voltage. A new battery would be at the 75% level. If it's degraded it will be lower, so you can see how much worse it is.

 

[mitzimad]

thank you all

 

[mitzimad]

Made my test lamp rig went to garage turned of the ehu and left the batteries to settle for an hour. Went back to van to disconnect and put on test and realised the solar was still charging so now to wait another hour

 

[mitzimad]

ok they are on test but out of curiosity i put the amp meter on the test leads one is showing 10 one is showing 9 amps i was only expecting 5.25 now i don't know what the true load is
amazing how bright 6 bulbs are neighbours will think im growing weed in there

 

[ManTheVan]

A techie once came out to the boat and load tested a battery for me with a meter. Interest piqued by your question and the great replies, I looked up a possible meter which might be worth adding to Santa's list? £17.24 buys you a Silverline load tester on Amazon.

For some reason the insert link function results in a blank, sorry.

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[mitzimad]

A techie once came out to the boat and load tested a battery for me with a meter. Interest piqued by your question and the great replies, I looked up a possible meter which might be worth adding to Santa's list? £17.24 buys you a Silverline load tester on Amazon.

For some reason the insert link function results in a blank, sorry.

View attachment 448876

acording to our electrical specialist these are not the right test for leisure batteries

 

[jezport]

A techie once came out to the boat and load tested a battery for me with a meter. Interest piqued by your question and the great replies, I looked up a possible meter which might be worth adding to Santa's list? £17.24 buys you a Silverline load tester on Amazon.

For some reason the insert link function results in a blank, sorry.

View attachment 448876

Thats a low price, If I buy that and post it out there would be £2.00 left for me and the tax man to share.

 

[mitzimad]

just over 4 hours on test and one battery is at 12.2 and the other at 12 assuming my ammeter is correct the 12,2 seems about right being approx 40 amps drawn roughly half the capacity and the 12.0 is failing strangely its the unknown age battery thats holding and the 4 year one failing. Of to find some way to check my ampmeter WHAT DOES EVERYONE ELSE THINK?
#

 

[Lenny HB]

just over 4 hours on test and one battery is at 12.2 and the other at 12 assuming my ammeter is correct the 12,2 seems about right being approx 40 amps drawn roughly half the capacity and the 12.0 is failing strangely its the unknown age battery thats holding and the 4 year one failing. Of to find some way to check my ampmeter WHAT DOES EVERYONE ELSE THINK?
#

Have you let them settle for half an hour without a load before measuring voltage?

 

[Lenny HB]

A techie once came out to the boat and load tested a battery for me with a meter. Interest piqued by your question and the great replies, I looked up a possible meter which might be worth adding to Santa's list? £17.24 buys you a Silverline load tester on Amazon.

For some reason the insert link function results in a blank, sorry.

View attachment 448876

Those are useless for testing a leisure battery they test CCA which is a starter battery test. There isn't anything you can buy of the shelf for testing leisure batteries.

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[ManTheVan]

That explains that then. Thanks Lenny HB. To be fair, the techie was testing a starter battery for me. Shame there isn't something that will give a quick idea of the battery longevity and state, although it wouldn't be as accurate as the one you have detailed above.

 

[mitzimad]

Have you let them settle for half an hour without a load before measuring voltage?

no will pop out now and test again

 

[mitzimad]

12.3 and 12.17 after resting my real problem is whether i trust the ampmeter or use the expected ampage from the 3 bulbs

 

[Lenny HB]

I think you a meter is very suspect and if you had 3 bulbs as a load I would work on 5 amps so it looks like your batteries are shot.

 

[Lenny HB]

If want a decent meter that can read up to 100 amps these are good. I always keep one in the van.

Pardon our interruption...

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[mitzimad]

whats the deal with gels len if i can run them down further do i need less capacity ?ive been looking at exide https://www.tayna.co.uk/leisure-batteries/exide/es1600/

 

[mitzimad]

or this
Amazon product ASIN B07NPMZK91

 

[Lenny HB]

You can take Gels down to 20% and still get a long life they also last a lot longer 6 to 10 years plus.

Only disadvantage is they take longer to charge as they need an absorbstion phase of several hours to reach a full charge.
You do need a charger with a proper Gel profile and for best performance your solar regulator needs to have a Gel profile.

Exide and Sonnenschine are the most popular, Sonnenschine make the Exide Gels and tend to be a bit cheaper.
I have 3 x Sonnenschine GF12065Y 78a/h Gel's, 2 are 5 years old & 1 is 3½ years old still performing like new batteries.

Not come across the Photonic Universe one before but they are a reliable company and you get 10% discount if a member of the C&CC. Very cheap for the size but I don't think I would want to fit it, weighs 61.5 kg.

I would rather have 2 or 3 smaller batteries so if one does fail you are not left without power.

 

[68c]

If want a decent meter that can read up to 100 amps these are good. I always keep one in the van.

Pardon our interruption...

I am considering buying a clamp on meter. One thing that worries me is how good they are at reading low DC Amps, less than 10A, which is a common requirement with automobiles. Some folk talk about wrapping several coils around rhe clamp which rather takes away any advantage in using a clamp on rather than series connected meter.

 

[Lenny HB]

I am considering buying a clamp on meter. One thing that worries me is how good they are at reading low DC Amps, less than 10A, which is a common requirement with automobiles. Some folk talk about wrapping several coils around rhe clamp which rather takes away any advantage in using a clamp on rather than series connected meter.

It will measure down to milliamps, I found readings vary a bit below 100ma.

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