Monday, Jan 10, 2011 at 18:19
There is no need to move your standard accessories such as UHF, Radio and (driving) lights from your original
battery to your auxiliary.
They are all relatively low current draining devices, or usually only used while your are driving and therefore the primary
battery is being constantly monitored and charged by the vehicle alternator.
Accessories such as a fridge and additional sockets to plug things like lights into are ideal to be run from the auxiliary deep cycle
battery.
Worst case scenario (if not set up correctly) is that you may drain the auxiliary
battery and the fridge will not work and your beer gets hot.
A bugger, but hardly life threatening. At least your primary (starting)
battery will be protected and you can still start your vehicle.
A handy and cheap addition is a "
battery saver" or "low voltage cut out device" which will protect any
battery you have it connected to from over discharge, which will ultimately cause premature failure of your
battery to the extent where it may not recover. These are also available from ABR - Sidewinder.
As an example, the excellent Engel compressor fridge will "run of the smell of an oily rag" to the extent that the
battery may be completely flat before the fridge stops running. A couple of cycles like this and the
battery may be buggered beyond recovery.
I know, it has happened to me some years ago.
A $30 protection device will ensure this doesn't occur. It will cut the supply voltage when the
battery reaches around 11.6v or 70% discharged. This is as low as you want if the
battery is to recover to a full capacity when recharged.
Bill.
AnswerID:
441406
Follow Up By: Member - Phil G (SA) - Monday, Jan 10, 2011 at 18:51
Monday, Jan 10, 2011 at 18:51
Gday Bill,
Me again :-) The old engels used to cycle until the voltage was almost nothing - sounds like what you had. But the newer ones such as the F-series ( released about 10 years ago) will stop working when they reach 10 volts - its intended to save the
battery from death, and to prevent the compressor from trying to work at low voltage.
I've used a few low voltage cutouts in previous setups. They have their plusses and minuses. On the minus side, if you leave them powered in circuit, they will draw a low current (usually 10-30 mA) from the aux
battery and can flatten a
battery if the vehicle is not being used. I used to always disconnect the cutout when the fridge was not in use.
Cheers
Phil
FollowupID:
713458
Follow Up By: Sand Man (SA) - Tuesday, Jan 11, 2011 at 07:44
Tuesday, Jan 11, 2011 at 07:44
Hi Phil,
My Engel is about 7 years old.
At 10 volts the
battery would already be "at death's door".
10.4 volts is flat according the the reference scale I use.
I only use the low voltage cutout when connecting the fridge up to a circuit.
This is used for the auxiliary
battery when driving and also for the Thumper I sometimes use at
camp when stationary.
I now have a new equation to consider.
My newly aquired camper has two AGM batteries (2x80Ah) and a Waeco 65 litre upright compressor fridge, so I now have some new toys to play with and get used to.
(Won't be disposing of the Engel though)
Bill.
FollowupID:
713522