performance of deep cycle battery.
Submitted: Wednesday, Sep 28, 2005 at 01:22
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Spade Newsom
Would like to advise of recent trip and performance of my deep cycle. Would appreciate some comment feedback from others.
Recent
camping trip of four nights. I have a 75 ah wet cell deep cycle auxilliary in the car connected to cigarette lighter socket in the rear. It has only normal cig lighter cabling. For the four nights I ran an 80 litre waeco fridge set at 0 degrees (kept frozen bottles frozen but would not freeze
water). The cig socket was not actually designed to run a compressor fridge, more for the lap top, and 12 volt cooler. Was forced to use this as the intended fridge battery died on the morning before leaving. Lights have seperate 7ah batteries each which also last about four nights.
I am not really sure how the deep cycle battery lasted the four nights. The waeco low voltage cut off was set at about 11.5 volts. I expected it to last two nights maybe three especially with the voltage drop and was then intending to buy a block of ice for the last night or two.
It was a five hour drive to the
camp and we drove for about an hour after night two. (Surely an hour drive would not put that much charge back in the battery).
Multimeter seemed to consistantly stay at about 12.5 volts, which seemed odd in it's own right. Fridge was
well ventillated, shaded, insullation cover and mild days. Kids opened it regularly enough.
Any thoughts here?
Spade Newsom
Reply By: drivesafe - Wednesday, Sep 28, 2005 at 08:02
Wednesday, Sep 28, 2005 at 08:02
Hi Spade, without knowing what the current draw of the fridge was and how it cycled, there is no real way of telling just how much power the fridge actually consumed and there are other conditions that have to be factored in to get anywhere near an idea as to how your battery performed.
Things like how cold was it at night, how warm was it during the day and so on.
It still sound like you got a good run out of the battery and by the way, most batteries will get the bulk of there charge in the first few hours of recharging off an alternator, so that hour drive you took it for may have put a considerable amount of charge back into the battery, but as I said, there is no way of really knowing how ANY battery has performed without fitting something like data loggers on the battery to monitor both voltage and current for both discharge and charge cycles.
Bottom line is, it did it’s job and that's what you want.
Cheers.
AnswerID:
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Reply By: Member - Jeff M (WA) - Wednesday, Sep 28, 2005 at 11:28
Wednesday, Sep 28, 2005 at 11:28
Sounds like you were taking the multimeter reading while the fridge was not "running" (ie it had got to 0c and had switched the compressor off). 1 Hour for a 75amp hour battery could potentially get it back up tp about 70% or so, depending on the alternator capcity and other loads running (ie headlights etc etc). Sounds like it did
well. Obviously the ambiant temp would have made a big difference, both in the voltage reading and the performance of the fridge.
AnswerID:
132146
Follow Up By: Spade Newsom - Wednesday, Sep 28, 2005 at 12:22
Wednesday, Sep 28, 2005 at 12:22
Jeff/Drivesafe,
Take your point about taking reading when the fridge cycled off. The night time was 9 - 10 degrees and day 20 - 22 degrees. Car parked
well shaded. You could say perfect weather for
camping.
Maybe more about ideal operating conditions than an over achieving battery (or even fridge for that matter).
Thanks for the feedback
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Follow Up By: drivesafe - Wednesday, Sep 28, 2005 at 19:32
Wednesday, Sep 28, 2005 at 19:32
Hi again Spade, could I make a recommendation.
Before your next trip, install some thick cable ( 8 B&S minimum = 7.9mm2 or 10mm2 would be ideal) from the front of the vehicle to your battery and that’s both positive and negative and if you intend to remove the battery, fit some Anderson plugs at the battery to make removal easier.
Using this type of cable will mean that after your 5 hour drive, even if your battery is low when you start, your battery should be somewhere between 80 and 95% charged by the time you reach your
campsite and if you do another hour drive, you will put even more power back into the battery.
Cheers.
FollowupID:
386468
Reply By: porl - Wednesday, Sep 28, 2005 at 13:29
Wednesday, Sep 28, 2005 at 13:29
I have a prado and people told me that eventually the cig lighter would bugger up, i didn't believe them cause i read it was rated to 120watts but they pointed out the constant current draw of a fridge in a hot environment would be too much for the miniscule wiring. Sure after a dozen trips my cig lighter is buggered. Took me only an hour and $30 of gear to wire up a higher duty fused line direct to my battery.
I know this is not what you asked about but just pointing out don't be too excited by the cig lighter performance on your trip cause it won't last.
AnswerID:
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Follow Up By: Spade Newsom - Wednesday, Sep 28, 2005 at 19:24
Wednesday, Sep 28, 2005 at 19:24
can't disagree with you.
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Reply By: Mainey (WA) - Tuesday, Oct 04, 2005 at 11:16
Tuesday, Oct 04, 2005 at 11:16
How was the DC battery wired / connected to the Alternator ?
Quote -> (Surely an hour drive would not put that much charge back in the battery)
AnswerID:
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Follow Up By: Spade Newsom - Tuesday, Oct 04, 2005 at 12:45
Tuesday, Oct 04, 2005 at 12:45
Mainey,
The car battery is simply standard Pajero connection. Dual battery is connected to the main battery via an isolator fitted by local auto lectrician. Not a fancy system that simply puts charge into the dual battery when the main battery is full. Dual battery is a wet cell deep cycle 75ah. Main battery consistantly read 12.5 volts when off so am confident that no charge was getting through from here.
Probably have to agree with other comments that ideal operating conditions would have assisted greatly. I also take on board that a cig socket probably not designed for long and large current draw however this was a plan B.
Any advice you have would be appreciated.
Spade
FollowupID:
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Follow Up By: Mainey (WA) - Tuesday, Oct 04, 2005 at 16:12
Tuesday, Oct 04, 2005 at 16:12
I would use a "Hella Low Voltage plug" for your fridge connection, they look like the conventional 240 round 'female' power plug that is used in power connections in your garage, the only visual difference is the 'male' end has only two prongs, not three, and they sit one under the other, the top one sits accross (east-west) the plug and the lower one sits right angled to it (north-south) they are done this way so that a conventional 240 plug cant be inserted by mistake. is just a matter of fitting them to the end of the relevant wires which are marked as positive (red) and neutral (black or blue) and obviously, you also connect a male 'Hella low voltage plug' to the end of the fridge lead by removing the existing cigy lighter end.
As to the rest of the system, don't touch it as without knowing the exact voltages at specific time frames it looks like it's working fine.
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