Battery problem?

[Pedro_The_Swift]

From the limited pics, anyone guess why the batts show 12.9 most mornings,
3 x 200ah lithiums.

apart from two tellies, a sirroco fan or two and the odd LED light the only draw after sunset is the (brand new) Bushman fridge.
no inverters.

If I am reading the info correct it takes the system about 2.5 hours to recover to float ( according to Itech 13.5v)
They seem to lose 70% in 2 hours but then hold steady for the rest of the night...

[drivesafe]

Hi Pedro, that voltage is way too low for any lithium battery in good nick and with more that 20% capacity.

Can I make a suggestion.

Try running your system on one battery at a time.

The simplest way to do this is to remove the negative ( - ) lead from one battery and run everything off the other battery for a day or two.

Then take the negative ( - ) lead off that battery and reconnect the negative ( - ) lead back to the other battery and again, run your system of that battery and see what voltages you get.

I have been running a combination of a 100Ah lithium battery continually connected to a FAULTY cranking battery for well over two years and the lithium battery ( actually both batteries ) has never had a voltage reading below 13.15v.

NOTE only last week I replaced the cranking battery with a new one and have removed the lithium battery for testing.

[gavinwibrow]

Hi Pedro, that voltage is way too low for any lithium battery in good nick and with more that 20% capacity.

Can I make a suggestion.

Try running your system on one battery at a time.

The simplest way to do this is to remove the negative ( - ) lead from one battery and run everything off the other battery for a day or two.

Then take the negative ( - ) lead off that battery and reconnect the negative ( - ) lead back to the other battery and again, run your system of that battery and see what voltages you get.

I have been running a combination of a 100Ah lithium battery continually connected to a FAULTY cranking battery for well over two years and the lithium battery ( actually both batteries ) has never had a voltage reading below 13.15v.

NOTE only last week I replaced the cranking battery with a new one and have removed the lithium battery for testing.

Hi Tim - maybe leave that phone call you owe me until after Christmas (or new year even if you are still flat out)!

[Pedro_The_Swift]

Just to set the scene, I have two batts in the rear tunnel and one in the front.

I took the easy one first and disconnected the neg cable off the single batt last night just as the charge rate dropped to zero.
Batt reading of the system this morning was 12.6.
After reconnection it was 12.9

This is the rear tunnel situation,
the far right neg seems easiest,
I have to bolt the two neg cables (and others) together right?
I am ASSUMING the red you can see will be heatshrink.......

[Tins]

I am ASSUMING the red you can see will be heatshrink.......

Suck it and see. If it shrinks you'll have your answer

[drivesafe]

I am ASSUMING the red you can see will be heatshrink.......

The RED heat shrink looks to be on the POSITIVE ( + ) Cables.

BTW The 12.6v reading is still way too low for lithium battery.

The 12.6v would indicate a very low ( below 20% ) lithium battery.

[Pedro_The_Swift]

Hmmm, there are lots of red power cables running off that right hand side battery... none of them will work after I take the neg cable off,,, right?

[drivesafe]

Hmmm, there are lots of red power cables running off that right hand side battery... none of them will work after I take the neg cable off,,, right?

Correct!

Unless there is a cable running from one battery's POSITIVE ( + ) to the other battery's POSITIVE ( + )

If this is the case, then you will still SAFELY isolate the battery you remove the NEGATIVE ( - ) cable from.

[Pedro_The_Swift]

So todays plan of attack is---

About to do some er carpentry? to get access to the terminals of the rear two.
This pic is of the arrangement of the cables, rather than try and move both batts outwards to get the terminals within arms reach
I' thought I'd go in from the top, under the lounge.

Anyway, my plan is, turn the caravan 12V off, pull the two neg leads off the batts, pull all the ACCESSORY POWER cables off the test batt and somehow add them to the other terminal, maybe a small "extension" cable? not much room under the gen batt bolts... bolt the two neg leads off the test batt together, bolt the neg lead back on the remaining array.

I hope this makes sense, I understand its Saturday, all opinions would be valued...

[Pedro_The_Swift]

I took the opertunity to check the other batts bolt tightness and the neg wasnt loose but needed a nip.. So, good!
The batt you can see has been disconnected, will let it charge all day and see if the voltage drops after sunset..