Battery Isolator HOT

Same issue applies to the ARB solenoid as well. Until the main battery voltage drops to the predetermined level the solenoid maintains the two batteries in the engaged position. If you draw some power after turning off, eg lights/fan you will hear the solenoid disengage after a few moments. This is one way of disengaging them. I have put a switch on the earth lead to overcome this issue and basically can leave the battery off charge particularly where the trips are short around town. On a trip away where I need to get it up to a full charge and maintain it I just simply leave it switched to earth. Cheers

Hi Bugalux,
Is yours a 3L motor (2.8Ltr) or 3Ltr, did you fit your aux' battery on the side behind the left headlight, near air filter box? You said that was the biggest aux' batry?

Regards
Andy

(Quote extract)Following on from advice from this forum I have just finished fitting a dual battery system with a Redarc Isolator between the start and aux batteries.
The isolator gets pretty hot when the vehicle is RUNNING.
For those interested the costs (in Canberra) where
Redarc Isolator (the cheapest price I could find in Canberra) $180
BATTERY cables $70
Buggerlux(end quote)

timber, essentially you have paid $250 for a solenoid system after you have received advice from this forum, bugga, it would have paid you to buy one interstate, pay the postage and save yourself at least $80… or buy something else?

Said very simply, heat is the consequence of power (voltage) which is being used directly by the isolator to maintain its ability to operate, eg; open and close the metal contacts against the mechanical force applied to it; therefore this power is not being used to run your fridge, so quintessentially it is only being wasted.
Isolators, due to their very technique of operation and because they are using your battery directly as a power source to remain closed, do get ‘warm’ in use, the difference between warm and hot is what is questionable.

After reading your post I checked if my rotronics became warm/hot [70c seems bloody hot to me] while engine running and with engine off ,no temp change either way , my way of thinking would suggest that the heat your unit is generating is a FAULT [nevermind that redarc say is normal]. To generate the heat you are losing power ,amps/volts that should be flowing into your aux battery ,

Bugger Lux,

The Redarc dissipates about 5.5W when ON[control unit has negligible loss]. This translates to about 450mA. The reason it feels hot is because the themal path is not as good as a metal-jacket solenoid. I measured the impedance of an Ashdown hd silver job = 15.6ohms c.f Redarc = 28.2ohms, which means the Ashdown generates even more heat[sees alternator voltage while my Redarc sees 12.5V]

At ambient of 21.9oC the + terminal was 39.1oC after 1hr [supply@14.1V] As the unit was not mounted on metal, this is a 'severe' test?

Redarc could improve the control unit by dropping the holding-current.

Anyway as the vehicle is usually moving when the Redarc is ON there will be some cooling from airflow?

cheers

My Redarc runs hot too. Not a fault, just normal operation according to Redarc. Been in nearly 2 years now and no problems.

Cheers, John.