Re: Prosine 3000/Alternator not Charging House Batteries Reply #25 – October 10, 2010, 10:47:35 am QuoteCan anyone tell me where the isolator is no my 93 U300 and how to check itKent, I dont know for sure the location of your isolator but after looking at several older coaches at the rally I saw it by the rear wheels under the coach (not a good place for it)"here's how to check the isolator using a DC voltmeter. First, measure the voltage at all three terminals of the isolator with the engine completely off. You should be able to read each battery voltage independently on each of the outside terminals. If there is voltage on the center terminal, one of the diodes in the isolator is faulty and the complete isolator must be replaced. (Some VOMs do have a diode test circuit to double check the diodes in the isolator). If voltage is only read on one of the two outside terminals, there is an open in one battery system. Next, start the engine and check the voltage at the center terminal of the isolator; it should be at least 13.8 volts and there should be an increase in the voltage measured at the two outside terminals, though it will be less than the center terminal. If you have access to a clamp-around DC ammeter, you will be able to measure the charging current on the alternator output wire. Additionally, be sure to check all the cable connections at each battery & in the circuit very carefully. I just ran across the same symptom as yours and found a corroded ground cable from the engine battery to the frame ground. If you are sure the alternator is functioning as it should and the isolator tests good, you just may have a cable problem." Quote Selected
Re: Prosine 3000/Alternator not Charging House Batteries Reply #26 – October 10, 2010, 12:50:25 pm Barry, I found the isolator. It is behind the battery cage behind the rear wheel drivers side. I have power on the right lug near the relay. I have no power on the center lug. I have slightly lower voltage on the left lug, no digital VM so it looks like less than 1 volt difference. When I disconnect the house batteries, I have no power on the left lug. When I put the VM on the disconnected battery leads I get no incoming power so somewhere the charge coming from the Prosine is not getting to the house batteries but the power from the batteries is getting back to the house. What is between the charger and the batteries other than the isolator? I cleaned all connections. They all looked good and clean but I cleaned them anyhow. The house batteries are now under 12 volts disconnected. I am going to get the largest external battery charger I can find and start recharging them while they are disconnected. I fear I will ruin these old but still good batteries if I let them keep running down and I don't want to hurt the alternator either. Is there a way we can still have 12V to the house running off of the charger or alternator without having the batteries hooked up?Help! Quote Selected
Re: Prosine 3000/Alternator not Charging House Batteries Reply #27 – October 10, 2010, 12:59:21 pm Kent, Sears has some good battery chargers. Do not buy the cheapest one. Mine has a digital readout and does 3-stage charging. It cost either $99 or $129. Quote Selected
Re: Prosine 3000/Alternator not Charging House Batteries Reply #28 – October 10, 2010, 01:36:37 pm George, thanks for the tip but I have a multi-stage charger at home so I bought a 40 amp shop style charger for this emergency. It works off of a timer and puts out a full 40 amps so a recharge should not take too long. I will keep an eye on it. 40 amps will not harm the gel cell as long as I keep an eye on the battery's voltage will it? Quote Selected
Re: Prosine 3000/Alternator not Charging House Batteries Reply #29 – October 10, 2010, 01:40:56 pm Isolator on that year is behind the drivers side rear tire. Same place as the start and boost solenoids. Quote Selected
Re: Prosine 3000/Alternator not Charging House Batteries Reply #30 – October 10, 2010, 03:17:07 pm Hooray! Crisis is over. Thanks to a conversation with Barry Beam, I looked for and found the Primary Fuse Panel for the 12V System. Last year the coach had a Prosine 3000, and yes it is a Xantrex, installed. It looks to me like they did not increase the capacity of the primary fuse to accommodate the heavy load of a 3000 watt inverter or maybe even the 150 AMP charger so the old 175 watt fuse is blown. This prevented the house batteries from getting any charge from either the Prosine or alternator. This panel is on the wall in the main passthrough compartment on my 1993 U300, drivers side near the Bay door. It had a white fiberglass cover over it and is held on by two 1/2" nuts. It is in the battery compartment on the right wall on my 93, U225. Tomorrow I will purchase and new, higher rated fuse and a spare and be on my way.Thanks Dave, the isolator is in the same place as my 93, U225 except the battery cage is between the rear wheels and the isolator. Thanks to all who helped. This probably saved me $500 in labor charges alone. Quote Selected