Best way to test battery (suspect it's on it's way out) (1 Viewer)

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Ridgeway

LIFE MEMBER
Mar 10, 2012
3,709
6,315
Lausanne
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20,102
MH
NiBi Arto 85E
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Since 2012
Twice now my Project 2000 step didn't lower, this was in both cases after the van had been left for several days (it's also now pretty cold here). Having had a quick look at the steps they seem fine and it's not that there's some movement or straining (as usually can happen with these steps) but that there's nothing happening at all. I am right in thinking that the motors draws quite a bit of juice at start up and hence the issue maybe my 6yr old leisure battery ?

What's the best way to check my battery for "end of life" ?

Current battery is a Banner 92Ah glass matt type (ref 59201), i'm guessing there's some better options out there, will search on here.
 
Oct 29, 2016
4,560
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Carthago C Tourer
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Motor Homing 5 years, caravan previously
First you will need a battery meter or a simple multimeter,check voltage across terminals, before charging, then charge and recheck the terminal voltage having switched of the charger for an hour or so.
See link on charts below, select your battery type, and the figures for all states of charge are there.
Hope that helps
Les
https://www.altestore.com/howto/batteries-measuring-state-of-charge-a81/
 

SandraL

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Jan 24, 2012
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Also check battery voltage as step is energised. If it starts over 12.5 and falls below 12 then probably knackered.
 
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Ridgeway

Ridgeway

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Mar 10, 2012
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Also check battery voltage as step is energised. If it starts over 12.5 and falls below 12 then probably knackered.

Will try that, i think that's going to show it is...
 
Apr 27, 2016
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Since the 80s
Also check battery voltage as step is energised. If it starts over 12.5 and falls below 12 then probably knackered.
If it doesn't fall but the steps still doesn't work, check the wiring connections, including the negative/earth connections. It's possible there's a bad connection in the step wiring circuit, or maybe the fuse is corroded slightly.

Is there any problem with all the other circuits, or is it just the step?

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Ridgeway

Ridgeway

LIFE MEMBER
Mar 10, 2012
3,709
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Lausanne
Funster No
20,102
MH
NiBi Arto 85E
Exp
Since 2012
If it doesn't fall but the steps still doesn't work, check the wiring connections, including the negative/earth connections. It's possible there's a bad connection in the step wiring circuit, or maybe the fuse is corroded slightly.

Is there any problem with all the other circuits, or is it just the step?


All OK only the step and that's dead but only after leaving it for a few days hence my thoughts about the battery.
 

Lenny HB

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Oct 18, 2007
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Since 2008 & many years tugging
Amazing you got 6 years out of a Banner AGM ,12 to 18 months is the norm with Banner rubbish.
At that age not worth testing them but if you want to.

Best way to test is to do a controlled discharge like this:-

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 battery)
Disconnect the load and leave to stand for at least 30 min then measure the voltage.
Repeate the the test and you will have discharged the battery to 50%.
You can repeat again then it will be 75% discharged but not recomended for wet cell batteries.

upload_2017-10-17_12-14-31.png
 
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Ridgeway

Ridgeway

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Cheers Lenny, what replacement would you suggest ?
 

Lenny HB

LIFE MEMBER
Oct 18, 2007
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On the coast in West Sussex
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Since 2008 & many years tugging
Cheers Lenny, what replacement would you suggest ?
Sonnenschein Gel if your charger can support gel.
Got rid of the AGM that came in my van and fitted 3 X Gel. Last van had Banner AGM's they lasted 18 months and wouldn't honor the warranty because they passed a starter battery test.
 
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Ridgeway

Ridgeway

LIFE MEMBER
Mar 10, 2012
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OK tested the battery today:

12.8v was the best i got and when the step energised it dropped to 12.60. After about 20 step cycles it dropped about 0.2v (12.6 - 12.40 respectively)

Funny that this time the stepped worked first time and many times, no obvious mechanical issues and the connections underneath all looked fine so i guess it's probably the old/crap battery.

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Apr 27, 2016
7,020
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Since the 80s
As a battery ages and deteriorates, it ability to take a charge reduces. For example, a new fully charged 100 amp-hour battery can in theory supply 5 amps for 20 hours, giving a total charge capacity of 5 x 20 = 100 amp-hours. When it's a few years old, or if it's been abused, it might only be able to supply 5 amps for 16 hours, so its capacity is now 5 x 16 = 80 amp-hours, even when fully charged. Its charge capacity has reduced. Eventually it will reduce to such an extent that the user will decide it is no longer any good.

Here's how to test your battery to see how much the charge capacity has degraded from the value when the battery was new.

Charge the battery until it is fully charged.

Disconnect the charger, and any loads, solar panels or anything else.

Set up a suitable load for the test. Choose a load (in amps) that is about 1/20 of the battery capacity in amp-hours. For example, for a 100Ah battery, load it with 100/20 = 5 amps; for an 80Ah battery, load it with 80/20 = 4 amps. As an example, a single 55 watt halogen headlamp will draw 55/12 = 4.6 amps.

Apply the load for 5 hours.

Disconnect the load and let the battery stand for at least an hour.

Work out how much charge the load has taken from the battery. For the examples above, 5 amps for 5 hours is 25 amp-hours; 4 amps for 5 hours is 20 amp-hours. For the 4.6 amp headlamp load, it's 4.6 x 5 = 23 amp-hours.

Measure the battery voltage.

Next, looking at the voltage table for your battery type, estimate what the discharge level is. For example, if the voltage is 12.30 volts, the discharge level is between 35% and 40%, so let's call it 37%.

With the charge taken by the load that you just measured, we now have enough information to work out the total charge capacity of the battery.

For example, if 25 Ah is 40% of capacity, then full capacity is 25 / 40 x 100 = 62.5 Ah
For the headlamp example, 23 Ah is 37% of capacity, so the full capacity is 23/37 x 100 = 62.2 Ah

This figure is the true charge capacity, which has deteriorated from the charge capacity of the battery when brand-new.

Finally you can work out the percentage degradation. For example, if a battery that was 80 Ah when new now has a capacity of 62.5 Ah, then the percentage degradation is 62.5/80 x 100 = 78.125%

Manufacturers usually say that a battery has reached the end of its life when the charge capacity has reduced to below 80% of its original value. MH owners on a tight budget might continue to use batteries down to 60% or even 50% of its original value. It's your choice. But at least, now it is an informed choice instead of a guess.

Here's a table of battery voltages at different charge levels. I've taken @Lenny HB's table, and filled in extra values in 5% steps, to make things easier. Also I added a column showing Discharge Level % as well as Charge Level %

BatteryChargeLevelVoltage.png
 
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