Thread: Battery problem?

Originally Posted by Tins

You forgot the voices in my head.

Mine were telling me I wasn't being ignored.

Originally Posted by Tins

OK, this is very much a "newbie" question. Does the controller/charger ( any, not just yours ) display the actual battery voltage, ie the potential difference between +ve and -ve posts, or does it display what the chip in the battery says it is?

I'll venture that they're separate loads, between the +ve and -ve "posts". They each require a minimal current through a known resistor to obtain a reading. The Victron BMV712 smart meter for example is guaranteed to draw 1mA or 700mAH/month. The BMS must by implication, likewise draw minimal current given the long 'self discharge' times for LiFePO4 batteries. Within the order of accuracy for both, one might expect the respective readings to be within a few thousandths of a volt if both are operating correctly....

EDIT: Notwithstanding the above... I then realised that some fancy highend BMS setups have a bluetooth output...which draws current in its own right to add to the load, in which case the external controller might well utilise the BMS bluetooth signal to play traffic cop with the free flowing electrons

In which case the answer to "does it display what the chip in the battery says it is" is akin to the question of the existance oe Schrodinger's cat.... maybe yes...or not... (I hope this is a typical adult answer

Originally Posted by Hoges

In which case the answer to "does it display what the chip in the battery says it is" is akin to the question of the existance oe Schrodinger's cat.... maybe yes...or not... (I hope this is a typical adult answer

"Typical", certainly. The jury is still out on "adult".

According to Sir Terry Pratchett, there was a third option for said cat: "bloody angry". Or perhaps, in my case, slightly frustrated.

A short but sweet move to the Cricket Oval at Donnybrook...
connected my charger to the batts, set it at 15A and went to the pub...

After a freak storm that made us do an emergency awning take-down at 1am I checked the BMV and it was at 13.4V..

At 7am the batts were in relatively full sun and over 14V.
Switched the charger off and its now showing 13.5..

Originally Posted by Pedro_The_Swift

A short but sweet move to the Cricket Oval at Donnybrook...
connected my charger to the batts, set it at 15A and went to the pub...

After a freak storm that made us do an emergency awning take-down at 1am I checked the BMV and it was at 13.4V..

At 7am the batts were in relatively full sun and over 14V.
Switched the charger off and its now showing 13.5..

Hi Pedro, if you can, you should leave the charger on and let it go into FLOTE Mode.

This is when your batteries will actually be fully charged.

When the charging voltage is below 14+v, the charger is in BULK charge mode.

When the charge sits at a constant voltage of say 14.2v, this is the ABSORPTION Mode

The ABSORPTION Mode usually starts when the batteries are about 80 to 90% charged and continues charging the batteries until they are fully charged.

During the BULK charge stage, the charge current will be constant at your charger's 15 amps but the voltage will continue to rise up to where the charger goes into the ABSORPTION Mode.

In the ABSORPTION Mode, now the voltage remains constant and the current reduces as the batteries get closer to a fully charged state.

NOTE, in the ABSORPTION Mode, the batteries themselves control the amount of current being draw from the charger

Once the batteries draw less than about 1 amp, the charger will go into the FLOAT Mode and sit around 13.6 to 13.8v and then and only then will your batteries will then be fully charged.

The ABSORPTION stage of the charge can take quite a few hours but is necessary to achieve fully charged batteries.

Thats tonights mission. Will switch it on at dusk and let it run till we de-camp tomorrow around 10ish..

Originally Posted by Narangga

After using the light for 30 mins the voltage read 13.44.

22 hours after the 13.44 reading the voltage read 13.43.

The batteries are in the camper trailer and there is no load on them as everything is switched off. There is no radio in the camper trailer.

A week later the reading on the BM2 is 13.34V so still some 'settling' occurring.

First part day with the Victron Battery sense connected...

Thats 706W's out of the array.. a 3.36KW day..
didnt get installed till 10 and theres an hour of sun still left...
Shunt says 13.36, controller still on bulk..

Mind you.. a wind generator might have made more today...