Wednesday, 13 February 2013

It must be Christmas Again!

No… not because of the snow.  Some local has started to decorate the tree on the towpath beside Waiouru with small black plastic bags containing ‘gifts’!  Perhaps they contain chocolates?  Or maybe the owner forgot to take them home.  We shall keep our eyes open and if we can identify the owner we’ll try and give them a pleasant surprise by posting their missing chocolates back through their letterbox! 

Smartbank Advanced Error Message

I may have solved yesterday’s Smartbank Advanced problem.  The display was reporting an ‘E11’ error code which indicated there was a potential cable problem due to different voltage readings between the domestic and starter batteries.  The first step in attempting to solve this was to clamber around inside the garden shed engine bay checking cable connections.  You have to be a bloody contortionist to peer into some of the nooks and crannies.  Trying to hang upside down and peer over one’s right shoulder at some cable connections is damned difficult.  Particularly when you only have one eye and your spec’s keep falling off your face.  In the end I couldn’t find anything that indicated there was a problem.  I then attempted to start the engine….. NOTHING….. The entire Beta panel was DEAD!  Now it was working yesterday,,,,,,,,, so why wouldn’t any of the panel lights illuminate? 

Reading the Beta Marine manual didn’t help.  It might be that I accidentally knocked off a wire or pushed a lever in the engine during my earlier trapeze act.  Back down the engine compartment with multimeter in hand.  Nothing appeared out of place!  The next step was to start fault finding from the source.  The engine starter battery is located in its own plastic container in the cockpit locker.  On opening the locker doors I noticed the battery isolation switch had been knocked to the half open position when the windlass and club hammer had been removed after starting the engine.  I turned the isolation switch fully on and the engine panel lights illuminated.  It was then possible to start the engine.  On checking the Smartgauge display the error message had disappeared.  So the starter battery may have been disconnected yesterday when I removed the windlass and hammer but the engine would have continued to run.  Because the starter battery wasn’t receiving any charge it would have a different voltage reading to the domestic bank as the latter would have been on charge.  The mystery may have been solved!   

More efficient use of the solar panels

I’ve noticed something about the solar panels.  If we don’t have the engine running and the domestic battery bank is less than 100% charged the solar panels will send electricity into the domestic bank (they are only connected to the domestic bank).  Because we haven’t seen much sunlight and when the sun does appear it’s quite low on the horizon, we have only been getting <1 amp.  I’ve been able to slightly angle them towards the sun by tilting up one side with an inflatable fender and this increases the panel output to 3-4 amps.  However when the engine is running to charge the batteries the panels normal don’t contribute any power.  My assumption is the solar controller has a “cut-off” voltage level which is lower than the output voltage from the engine.  After downloading and reading the Tracer MPPT Controller manual I’ve noted the controller Boost Voltage is 14.6V and the Float is 14.6V.  The low voltage reconnection is 12.6V.  The engine alternator voltage is 14.8V.  My assumption is the moment we start the engine and produce 14.8V the solar controller thinks it’s in an “over voltage” situation and disconnects the solar charge from the batteries.  It then doesn’t reconnect the panels to the batteries until the voltage drops to 12.6V which is about 90-100% charged.  However the batteries will show up to 14.5V immediately after being charged whilst they “recover” from the charging. 

What does this mean it us?  If we are going to get the maximum benefit from the solar array we should avoid running the engine whilst the panels are charging the batteries.  They may not fully charge the batteries in the time available so we need to monitor the battery state of charge and, if necessary, allow sufficient time at the end of the day to top up the batteries using the engine. 


Geoff and Mags said...

Hi Tom.
Who's a lucky bunny, then! If you'd have had dedicated alternators for the starter and domestic batteries you'd have been looking for a new one now! Disconnecting the battery while the engine is running is a sure-fire way to cook the alternator. You've a charge controller fitted which effectively connects the two alternators together, I think. This would have saved the day. Maybe a cover over the isolator?

Tom and Jan said...

Hi Geoff
Yes.... or empty the locker!

One Thing After Another said...

We have 690w of solar panels Tom and in the summer especially we were letting the panels top the batteries up. Think about it. Let your panels charge whilst there is sunlight and then if they're still not fully charged by early evening when the sun has disappeared, put your engine on then! You'll be saving diesel then too!

Clive said...

Re the, errr, bags, its a pity you can't post photos of the culprit for everyone to see and shame. Why DO they damn well do it? (Just wait till you get to Blake's Lock, Reading).