BDO – Batteries Dropping Out

7pm Tuesday evening, all is good, cooked dinner, relaxing in the evening sun, bit of quiet guitar strumming , all mellow.

Then about 9pm Lianne pops her head in the van and says ” why is the fridge off ?”.  Why indeed…

(WARNING : the rest of this posting should only be attempted by readers of a technical disposition, great patience, and when there’s nowt on TV. Do NOT attempt to write this sort of stuff at home. It’s not big or clever or funny, and you will not get any thanks ).

The Nerdy Bit

It soon becomes apparent that ALL power is off – 12v, 240v and the basic van control system itself. 

I look at the ramshackle combinations of wiring running 50 yards down a wet field to our van and decide it must be that.  Connection at the socket in the pillar seems loose , I replug, and triumphantly report that all is now good. 

” Ah,” says L, who has been fiddling about inside the van, ” so why does it only work then this green light switch is on ? I turned it on and it works now”

( on the PSU there are 2 switches for circuits you can disable – an orange one for water heater, and a green one for charging current to the 12v battery. I have always left that green one off since we moved to lithium, trusting the new solar charger to do the job better than the old van charger which was designed for lead acid. So far, that has worked fine).

“Don’t be daft ” I say, (with unwise levels of conviction), “that green one is always off , and anyway it has nothing to do with whether the overall van electrics work “

But I am completely wrong and she is spot on. Nothing will turn on unless we enable the charger circuit. Even the fridge , which ought to be entirely independent of 12v supply AND control system ( avid readers may recall that we unplugged it from the control system  in a previous BDO chapter, to avoid excessive beeping). So – what IS going on  ?

Next shock is when I check the lithium battery itself, via its Bluetooth app.  The day before, when I last checked, it was about 75-80% charged …now it appears to be…0%.  Dead, snuffed it, it has shuffled off this electrical coil and gone to meet its manufacturer. Bereft of amps it rests in peace. You get the picture.

Eventually it starts charging from the 240v ‘green’ supply we have now switched on, so it’s not parrot-level dead . Leave it overnight to see if all will be good in the morning.  Or alternatively, if we go up in a lithium-fuelled conflagration in the wee small hours.  It’s all part of the BDO journey.

Partial explanation

We have found web posts from users who report that these lithium batteries can suddenly go into a shutdown state from being apparently half- full , if they have been subject to low-current trickle discharging for a while, and not had a full recharge cycle recently.  That certainly matches our usage for last 3 weeks ( just some lights and USB charging run off battery). Apparently the onboard meter for the battery’s State of Charge then loses track of the real state, until voltage drops so low it triggers the management system to shut everything down to protect the cells.

I still have no idea why this should have knocked out a fridge that was running on 240v supply, nor why the fridge now runs happily without the error light that has been on for the last 2 weeks ! Something in it depends on a 12v feed too ?

Update : battery did recover and fully-charge, but the fridge started beeping again a few hours later, so no, the Green Button was not a solution to that…..