A Question of Power

Since my last post I’ve not done anything astronomy related, we have had a few nights that would have been good enough for some imaging, but these have been on work nights ( three glorious days during this week with record temperatures for February recorded ) and when the weekend turns up the weather without fail turns to rubbish again ( severe weather warning with storm Freya for the weekend, you dont say ). I have however been doing some work on my camper van, which in a round about sort of way leads to an upgrade for the observatory – I’ll explain. I have recently fitted a 160 watt solar panel on the roof of the camper, this leads to a solar charge controller which converts the 21 volts from the panel into a voltage ( 13.7v ) that can charge and then maintain ( trickle or float charge ) the condition of the 105 Amp hour leisure battery, I also wanted to install ( in Parallel, Positive to Positive and Negative to Negative, like you would jump start a car with starter cables ) a second 105 Ah battery, this would give the same voltage but double the usable Amp Hours – the problem is I did not know the age of the leisure battery that was already in the camper, this is an issue because when you fit two batteries it is highly recommended that both batteries are the same Amp hours, the same age and make, due to the older weaker battery dragging down the stronger newer battery, so in other words – two new identical batteries need to be fitted. I only found out about this little point later on.

Batteries wired in parallel
Leisure batteries wired in parallel, Grey old – Black new.

 The original battery was the grey 12v 105Ah Lucas, and I put in a new Numax 12v 105Ah battery which apart from the colour is identical but obviously not the same age, so I ordered another Numax. This leaves a spare Lucas 12v 105Ah battery, it just so happens that I use a 12v 60Ah car battery to run both my dew heaters and a DC focus motor for my guide scope, this battery is years old and on its last legs and does not hold a charge well, I have taken to charging it up a day ahead of when I need it. so I replaced the old worn out car battery with the not worn out Lucas leisure battery, this is also being charged up during the day by means of a 12v 20w solar panel and a charge controller.

 

So now my dew heater power needs are sorted, just want a clear Friday or Saturday night.

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