Unsolved battery problem

[Nightjar]

Was using a Cobra 105ah deepcycle/cranking battery too run the fridges charge detector batteries etc.
The last trip in 2013 found it would run the fridges all day while the solar was topping it up, come the night it would be dead within a couple of hours after dark.
Got home took it down to Battery World and their tong test came back positive?
Took it home trickle charged it in the shed over summer and the voltage hovered around 13V.
Getting prepared I hooked up my old 39L Engel to give it a test, within 3 hours it had stopped on low voltage.
Took the battery back to the experts and they told me it was in perfect working order and that there must be a heavy drain dragging the battery down.
Thinking the worst that my old Engel may be the culprit.
At home the c-tek battery charger was hooked to it for three days to go through a recovery cycle.
Next trial I soldered a couple of wires to a tail light globe and left that burning, about 4 hours later once again the battery was down.
Fitted the battery back in the ute and took it to the shop. The attendant came out with all their checking gear and I turned both fridges on., while we stood there you could see the voltage dropping off very rapidly even though the solar was putting in 2.5amps.
A tong test on cable running to accessories showed a 6 amp draw down which was consistent with two running Engels.
The long and the short of it I bought a new battery, left the ute in the sun to enable solar charge until dark. This morning both fridges still running, one on freeze (-7C) the other on fridge (+3C)

Any battery gurus out there who can explain why a battery that passed all the load tests at the shop failed to perform?

Cheers
Peter

 

[hardyakka]

Having identical problems, except they replaced my battery under warranty no questions asked. Now 3 months later and its doing it again. I have a 200 watt panel permanently fitted to the top of my canopy, a 50L Waeco set at -1 and a ROC-SOLID MPPT regulator.
No problems through the day but it does shut down over night due to lack of voltage.

Look forward to hearing your views on this

Cheers
Dale

 

[the duck]

It will be a weak cell very hard to pick up but 1 cell sounds like it has failed and thats why it stops quickly a voltmeter connected should show the answer as each cell is around 2.2 volts so a maximum should be around 13 .8
and a weak cell will drop it to under 12 volts

Sometimes a cell shorts due to vibration of the plates

 

[slowflow]

Could they be sulpating due to low draw and charge rates. You could be pulling 40-60 amps out overnight, it that all being replaced. Those amps out are a bit much for a 105 according to dischsrge/life charts.
Amps in & out is the only way to get accurate charge condition except for flooder cells.
Engel low voltage cutout is set too low to preserve your batteries.

 

[Hagsy]

I have experienced a similar problem twice , once on a solar battery and 2nd on a new motorbike battery, both times it was broken off the bottom of the terminal inside the battery ( power in no problem, current draw problem ) if you still have the old battery pull top off for a look.

 

[thedigger]

I think you will find the duck has the right answer.
Funny thing is I am have the same problem with the battery in the van 200ah, voltage drops and will not start the fridge when it gets down to 12.6 volts,where as before it would run it below 12volts,it cannot deliver the current.
Looking at biting the bullet and going to lithium ion.

Regards Thedigger

 

[Diggerdude]

Having identical problems, except they replaced my battery under warranty no questions asked. Now 3 months later and its doing it again. I have a 200 watt panel permanently fitted to the top of my canopy, a 50L Waeco set at -1 and a ROC-SOLID MPPT regulator.
No problems through the day but it does shut down over night due to lack of voltage.

Look forward to hearing your views on this

Cheers
Dale

Nothing to do with the battery but I have seen this problem before. The wiring supplied in my van was too thin, when the voltage dropped below 12.4 ( as it does overnight ) my fridge would cut out. I put 6B&S wire in and have never had a problem since.

DD

 

[condor22]

I'm not one for using a combined deep cycle/cold cranker, you would have to believe that it won't do both as well as the specific versions.

I don't mix them, deep cycle for the accessories/fridge and cranker for the car.

 

[hardyakka]

G'day Diggerdude,

I'm running 6 B&S cable....

Hardyakka