Re: get rid of battery isolator? Reply #25 – June 26, 2013, 12:14:15 am Quote from: J. D. Stevens – June 26, 2013, 12:02:18 amMiddle terminal will be where alternator output is connected. One side on isolater will be positive to house batteries. Other side will be positive to chassis batteries. Grounding is normally through the metal frame of the vehicle.Thanks. Ordered one. Quote Selected
Re: get rid of battery isolator? Reply #26 – June 26, 2013, 01:46:17 am As it happens I did this yesterday... unhooked the idolater and wired in an Andina ACR. (basically a voltage sensing relay) I left all the stock components in place, moved the alternator cable to the chassis battery post on the isolator and put the ACR across the two battery terminals. Simple, works well and reversible in about 3 minutes with a crescent wrench. Quote Selected
Re: get rid of battery isolator? Reply #27 – June 26, 2013, 11:53:12 am This Foretravel article should give a good explanation how our alternators differ from big rig alternators and why they are sometimes miswired :"Foretravel Alternator Foretravel Motorcoaches use a Leece-Neville brand alternator that is externally excited. These alternators are not the same as what the big semi rigs use that run up and down the nation's highways. This is commonly confused in truck repair shops. Foretravel motorcoaches and a lot of other brands use what is known in the industry as a battery isolator, this allows the alternator to maintain two battery banks at a set voltage. You also have to excite the alternator externally. Meaning that when the engine is not running there is no voltage present on the large positive outpost terminal. The alternator has two large terminals one positive and one negative on the back side of it along with two small terminals. The two small terminals tell the voltage regulator what to do. One terminal is labeled DUVAC and the second is labeled IGN. The DUVAC terminal is what monitors the output voltage, the sense wire is located on the engine battery side of the isolator (2000 year model FT's and later models, earlier models sensed from the remote start panel). The ignition terminal is what tells the alternator to start charging. The ignition circuit is powered up when the key is turned on. When checking voltage directly at the alternator it will read higher than what is at the batteries, this has to happen due to voltage drop through the isolator and wiring to the batteries. Example; when reading output voltage at the alternator with fully charged batteries your readings could be 15 volts dc (+/-) thus allowing for a normal 1volt dc drop in voltage through the isolator, this in turn will allow for a maximum voltage at the batteries to be 14.1 vdc (batteries). The only way ignition terminal voltage will affect charge output voltage would be if no voltage present, it takes minimal voltage to start the alternator charging (7-7.5 vdc). Foretravel Motorcoach technical.assistance@foretravel.com" Quote Selected
Re: get rid of battery isolator? Reply #28 – June 26, 2013, 02:36:06 pm Quote from: Pierce & Gaylie Stewart – June 26, 2013, 11:53:12 am...The alternator has two large terminals one positive and one negative on the back side of it along with two small terminals. The two small terminals tell the voltage regulator what to do. One terminal is labeled DUVAC and the second is labeled IGN. The DUVAC terminal is what monitors the output voltage, the sense wire is located on the engine battery side of the isolator (2000 year model FT's and later models, earlier models sensed from the remote start panel). The ignition terminal is what tells the alternator to start charging. ...A side note: Be careful when you replace these two smaller terminals. If you mix them up, the alternator just cranks away, feeding the batteries at high level. They'll get toasty, really quickly. I know. Quote Selected
Topic: get rid of battery isolator?