Leisure battery problem, fridge not running but battery tests OK

[Nickg60]

Following on a bit from an earlier thread thinking I had goosed my LB and hunting for a replacement, spoke to the original suppliers who suggested a few things to test the LB first.
LB has a condition indicator, shows OK. Volts = 12.6v at rest. Suspect maybe not the battery at fault?

Problem i'm having is the fridge cutting out stopping, starting and giving the red light volt drop warning. This usually tells me LB is goosed. Current LB was the result of much research to get a good, powerful, semi traction battery that was perfect to start with, but now 3 1/2 years later and not much use thanks to covid and the fridge wont even do a full day. Everything else works fine (not much draw) and the battery shows well into the green on the van's in built battery monitor.

The battery has had 3/4 good 12 hour charges and wont run the fridge properly, but weirdly when used on the weekend, it played up in the day, seemed fine overnight and was still cold in the morning. Last weekend it played up all night so it got turned off as the stop/start cycle makes a racket.
It hasn't been charged since the weekend apart from a 2h drive home, and now 3 days later is still showing 12.6v. When it is cutting in/out it shows 12.6v perfectly fine on a tester but then when the compressor kicks in it drops down to 11.9v under load which I think triggers the battery protection on the fridge.
Pulled the fridge out tonight and reads 12.v at the terminals which indicates volt drop not an issue.
Any body with any ideas? I don't want to buy another battery and find my fault lies elsewhere...

Battery is an Exide 142ah ER650 semi traction deep cycle, good for 3-4 days happily running the frige when new. Fridge is the standard waeco cr 50.

Thanks!

 

[Pete C]

How is the leisure battery charged ? When driving and when on hookup ?

Pete

 

[Nickg60]

Both, has a split charge system and a 240v charger when on hookup.

 

[Pete C]

And does the fridge play up when the leisure battery is being charged ?

Pete

 

[Nickg60]

Not as far as I know but I haven’t sat in the van at home on charge to test properly.
What I have had is the rcd on the van cut out a couple of times while charging with the fridge on, which is what I thought had killed the LB. It seems fine for a few hours after driving though.

 

[Loz]

Look for loose or bad connections including earths etc. check all terminals are tight and fuses are tight.

 

[Nickg60]

Update, new AGM battery fitted as decided the LB was goosed.
Now it is charging on EHU with a muvonics 4 stage charger, which was originally set to float mode only, has 4 settings, float, flooded, gel, and agm.
I thought the float mode may have contributed to the early battery death as it won't fully charge it or equalize it. (little do I know).
Now set to AGM, all hooked back up but the new battery while on lookup is only reading 12.9v. it has climbed over the past couple of hours from 12.7v, but as soon as I hit the fridge on the load pulls it down to low voltage so I know it's not charged anywhere near fully.
Should the V not read approx 14.5 v? The charger should be putting out approx 14.5v as far as I am aware but it's not doing that. Or am I incorrect?
I've googled but nobody seems to actually give you a voltage at the battery while charging.
Of course if I read the voltage across the charger terminals I just get a no battery fault.
If I put the charger back into float mode it reads 13.5 v across the terminals which is exactly as i'd expect.
Anybody with an idea?
Cheers

 

[t0mb0]

Update, new AGM battery fitted as decided the LB was goosed.
Now it is charging on EHU with a muvonics 4 stage charger, which was originally set to float mode only, has 4 settings, float, flooded, gel, and agm.
I thought the float mode may have contributed to the early battery death as it won't fully charge it or equalize it. (little do I know).
Now set to AGM, all hooked back up but the new battery while on lookup is only reading 12.9v. it has climbed over the past couple of hours from 12.7v, but as soon as I hit the fridge on the load pulls it down to low voltage so I know it's not charged anywhere near fully.
Should the V not read approx 14.5 v? The charger should be putting out approx 14.5v as far as I am aware but it's not doing that. Or am I incorrect?
I've googled but nobody seems to actually give you a voltage at the battery while charging.
Of course if I read the voltage across the charger terminals I just get a no battery fault.
If I put the charger back into float mode it reads 13.5 v across the terminals which is exactly as i'd expect.
Anybody with an idea?
Cheers

A four stage charger should be following a similar profile to the one below - it happens to be a votronic unit but principle should be the same. The fact that it started at 12.7v and rose to 12.9v would indicate that it's in the early stage of charging (bulk) and that the voltage will rise until out of bulk phase - which may be around the 14.7v you mention. You should really leave it alone to complete its charging cycle before experimenting with any loads on it. If you do happen to have a clamp meter you could stick that on and it should register somewhere around the max current delivery of the charger whilst in bulk phase.

 

[Salty Spuds]

What’s the amp output of your charger?

 

[Nickg60]

18a max as far as i can tell.
back in float mode now and its running as before, the agm mode just didnt do a thing. Spoke to the converters who said likely the agm circuitry was dead as it had never been used which makes sense i suppose. They said just leave it in float, it would be fine with an agm battery with maybe a small reduction in life, but no major problems. Its running very hot and I've had the charger fan come in under load which I've never had before so im slightly concerned, but it is a gazillion degrees today.
hopefully when the solar gets installed that will do enough proper agm charging to negate any ill effects of the charger or split charge not putting the ideal charging currents in.

 

[FYPO]

What is the gauge and length of the wire between the battery and the fridge? I’ve heard the CR50 can struggle with voltage drop.

Charger will ramp up the voltage during the charging cycle so the voltage doesn’t seem irregular.

Wait for the charger to complete the charge cycle. Turn off all the loads and unplug the charger, then check what the voltage of the battery is.

 

[FYPO]

Spoke to the converters who said likely the agm circuitry was dead as it had never been used which makes sense i suppose.

This makes no sense in my opinion - having just looked at the manual Float only mode essentially turns it into a 13.8v power supply and not a 4 stage battery charger. You should really be using the AGM mode. The charger shouldn’t be dead just because it hasn’t been used!

Do you have a multimeter? Even just a really cheep multimeter would allow you to test to make sure the charger is working correctly.

 

[Nickg60]

Multimeter gives absolutely no change between charger on or off in agm mode. the mode lights sometimes flick on and off or stay on, either way nothing. Float gives a fixed output which has charged now. left the multimeter turned on though so need a new 9v battery to test

its a 10 yr old charger, im assuming the circuitry for a multi stage charge is more complex than a fixed float charge and some part of it has given up.

its not volt drop, fridge wires are ok, they are longer than id like as they run up to a control panel rather than the battery, i feel redoing those wires with a relay would improve things but its been fine as it is.

 

[FYPO]

If your sure the charger isn’t working I’d highly recommended replacing it.

AGM batteries are designed to require 14.6v – 14.8v when performing a full charge from a state of discharge, whereas standard lead acid batteries need 13.8v – 14.4v

Your charger in Float mode is only providing 13.8v therefore will only recharge the battery to around 85% and this will cause a memory effect in the battery reducing its life.