12 volt mysteries

Submitted: Wednesday, Jun 15, 2011 at 20:07
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Over the years I have always run 2 batteries under the bonnet. Both cranking batteries and it worked fairly well. I did all my own installations as I figured I knew what the red and the black wires stood for. In 2008 both my 5 year old batteries came to the end of their lives and so I invested in new ones of the same brand. At about 20 months into their 24 month warranty both started losing charge. So I went back to the retailer who ordered new ones free of charge. These two batteries (the Manufacturer shall remain nameless) started losing charge after 8 month to explain things s. I drove to the Battery Supplier’s Base at a neighbouring town and was told in no uncertain terms that cranking batteries were NOT to be used to run fridges and that there was no warranty on the replacements. Who mentioned anything about warranty? Funnily though, my system has worked well for me over the past 20 years, or so. I walked away having received no answer.

By and by in 2010 the time came to invest in a mobile tent. This contraption has 12/240 Marine Fridge. So I needed a battery for the van! I bought a Remco AGM and then ordered a Charge Kit from a well- known supplier. I wired the whole shebang up as per instructions and for a while everything worked well. Then my chariot started having starter motor problems and on the way home it need surgery at a reputable service centre. Shortly after I noticed that the isolator to the charge kit did not turn off when engine power had stopped. On a number of occasions this isolator stayed on during the night drawing my Cranking battery down by .5volt. I wrote to the supplier, who sent a paper of electrical computations to explain things, which meant absolutely nothing to me.
My auxiliary battery became very weak and I bit the bullet and bought a Redback Thumper AGM Battery as a replacement. Within a very short time my cranking battery improved and has held its charge over longer periods.

In the mean time I decided to go Green and bought an 80watt solar panel. This helped the batteries along although we didn’t see that much sun in the tropics last year. As the charge wires ended in alligator clips and as the caravan battery was positioned under one of the front seats, I made up wires the same as the Solar panel to the Remco Battery and the Auxilliary Battery whereby I could just plug the panel in and charge the respective batteries. Red to positive terminal and black to negative terminal through a hole drilled in the floor.

This year however we got going on our annual tropical sojourn a week earlier to expectations and I neglected to charge the van battery before leaving. This left the battery ‘hungry’ for charge as put by an Auto Sparky whom I met along my travels. This fellow suggested I buy a CTek Charger and Honda generator to run it to keep my batteries in peak condition. A cool $1700 just to keep the fridge running! I gave that idea a miss. The van battery struggled to stay above 12 volts and I wracked my brains trying to figure things out. I even swapped the AGM batteries over every two weeks so that they would get a good charge from the alternator. I decided that I should earth the battery to the caravan chassis as this was not in the wiring instructions. This improved things somewhat. I also earthed both the solar charge wires and car charge wires. A little more improvement had been achieved but still not good enough.

As our trip progressed we kept on hearing a clicking sound somewhere in the firewall behind the dashboard whenever the engine was switched off. I would leap out of the stationary vehicle, pop the bonnet but by that time the noise had stopped and we could only make guesses as to what was making the noise. Eventually after about three weeks we found the culprit. It was the caravan battery charge solenoid. So I removed it and extended the positive lead to be connected to my solenoid ( a run of the mill $40 solenoid) for my two batteries in parallel under the bonnet.

Suddenly the whole problem seems to be solved with both auxiliary batteries charging at 13.5 volts via the car charging system to the van and also the solar charging system doing the same when stationary. So patience and persistence and trying out new ideas have won the day.

One is never too old to learn………………………
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Reply By: P and JM - Sunday, Jun 19, 2011 at 13:30

Sunday, Jun 19, 2011 at 13:30
Hi SIF4x4,

All very interesting and glad you found the problem.
Would be interesting to know the brand name of faulty solenoid.

Cheers P&J
AnswerID: 457898

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