1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Topic: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions (Read 2778 times) previous topic - next topic

Re: 1984 FORETRAVEL - New owner with questions

Reply #50 – June 09, 2024, 10:58:25 am

Here's whereI am at right now. I got the Duvac alternator and installed it. I had to do some modifying because I bought aa 160 amp model. When I got this, this whole system was connected together as one electrical system. In other words, there were not two seperate batteries, one for starting, and one for coach. Before I get 'too far, it looks to me like this was a Duvac system, originally, but for some reason, the owner apparently decided that it would be better to have it all combined, so at this point I don't understand how it is wired. I have 4 batteries all connected to each other + to + and - to -. At tjhis point I would just like to get it running, and figure out the entire system in the future. My question is, if I hook up all wires as they currently are, making sure that the correct wires go to the intended spot, can I run it that way without isolating the 2 battery system, just to run it until i get a chance to figure out how those wired should go without damaging anyhing? I intend to wire itr correctly as we move forward, I just dont want to take the time right now to trsce all of the wires. Thank you for your help

Re: 1984 FORETRAVEL - New owner with questions

Reply #51 – June 09, 2024, 11:18:06 am

Quote from: quickmagic – June 09, 2024, 10:58:25 am

My question is, if I hook up all wires as they currently are, making sure that the correct wires go to the intended spot, can I run it that way without isolating the 2 battery system, just to run it until i get a chance to figure out how those wired should go without damaging anything?

Can't comment on how it is wired-- sounds like a lot of "creative wiring" by previous owner(s).

But, addressing your specific question: Having one large battery bank (house and chassis banks combined) presents no problems other than both banks will discharge together, so no "the house bank is dead, but still have chassis bank to be able to start the engine".

And, depending on where the two banks are combined, you may be able to separate them while parked if so desired.

Re: 1984 FORETRAVEL - New owner with questions

Reply #52 – June 09, 2024, 01:22:31 pm

Thank you very much for your answer. I don't think that the wiring is goofed up, It pretty much looks like it came out of the factory this way with a couple of small w[ires that have been added or a replacement.

Re: 1984 FORETRAVEL - New owner with questions

Reply #53 – June 09, 2024, 04:19:47 pm

The batts are easy to combine. Could be at the boost solenoid Simply stacked cables.
Could be that you had 2 start batts , one under the steps next to a single house battery. Simply add a connector cable between the systems.

Re: 1984 FORETRAVEL - New owner with questions

Reply #54 – June 09, 2024, 04:21:58 pm

Quote from: Protech Racing – June 09, 2024, 04:19:47 pm

The batts are easy to combine. Could be at the boost solenoid Simply stacked cables.

Yes, battery boost/combine solenoid OR the diode-based battery isolator are both easy places to "combine" battery banks by stacking cables.

SPLIT: Re: 1984 FORETRAVEL - Vent fan question

Reply #55 – June 09, 2024, 04:32:46 pm

One or more of the messages of this topic, the ones related to the vent fan, have been moved to Foretravel Tech Talk - https://www.foreforums.com/index.php?topic=48051.0

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #56 – June 09, 2024, 08:29:42 pm

OK, Alternator installed, wired and its running. Here's the result, 13.3 amps at the alternator, and 12.5 at the batteries. I think that is normal?

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #57 – June 09, 2024, 08:38:45 pm

You need 14+ volts at the battery

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #58 – June 10, 2024, 09:02:23 am

Quote from: quickmagic – June 09, 2024, 08:29:42 pm

OK, Alternator installed, wired and its running. Here's the result, 13.3 amps at the alternator, and 12.5 at the batteries. I think that is normal?

And, the voltage drop between alternator and batteries suggests a problem that needs to be addresses first. Could be as simple as a poor or loose connection on either positive or negative side.

This ASSUMES you are not running B+ through a diode-based battery isolator, but as you mentioned previously that you are "combining all batteries". That means B+ from alternator and the cables to each battery bank on ONE lug. If so, voltage drop between alternator and batteries should be near zero.

If you are still going through a diode-based isolator, that suggests the SENSE wire is not connected to the chassis battery as it should be (or another place with large-gauge cable to chassis battery such as chassis battery lug on the isolator). Easy enough to run a temporary wire from chassis battery connection to alternator sense terminal to test.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #59 – June 10, 2024, 09:24:19 am

I bypassed the isolator to reduce charging and draw issues. Just stack the batt cables all on the same stud .
You don't need the isolator . This will charge everything to about the same voltage . It will also draw all of the batteries down .
My meters show about 13.4 for the leece Neville and 13.8 for the ac delco. When I have them separated.
I combine with the boost switch .
You need to figure out what cables go to what batteries first. And. Design from there . Imho

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #60 – June 14, 2024, 05:38:54 pm

The issue with lower voltage at the battery than the alternator I have had before in another vehicle. Other forums said to look for corrosion at basttery cable ends and if found, take them all apart and clean the cable ends, however one person said he had just added an extra cable from alternator to battery, I tried it, it worked, much easier than taking cables apart and cleaning ends.
On the current coach, it looks like the cable from the alternator to the isolater has been replaced, and it appears to be light, measured 3/8" diameter. Is that too light? Could that be the problem, also has some corrosion at cable ends. I think I can just add another cable, it would be helpfull to know what gauge that cable should be, from alternator to isolater. And if I want to wire this correctly, alternaator goes to middle post, one of the other posts handles the engine, etc, and the other post handles the coach. So io just have to figure out what each wire is for. Correct? does ti matter whether I hook up coach to either front or back post as lond as other cables all go to engine etc.?

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #61 – June 14, 2024, 08:34:17 pm

I would think 2 gauge wire would be good from alternator to the center post. All engine battery wires to one end post and all of house battery cables to the other end post. It doesn't make any difference which end is which.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #62 – June 15, 2024, 08:48:26 am

Quote from: quickmagic – June 09, 2024, 08:29:42 pm

OK, Alternator installed, wired and its running. Here's the result, 13.3 amps at the alternator, and 12.5 at the batteries. I think that is normal?

The 0.8 voltage drop is not due to wire loss, it is the normal voltage drop from the diode isolator. Adding additional wire won't hurt, but it won't raise the voltage at the alternator.

Did you get the "sense" wire hooked up? This is necessary with an isolator to boost the alternator voltage to cover the diode voltage drop and should give you better voltage at the battery.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #63 – June 15, 2024, 11:25:04 am

Quote from: prfleming – June 15, 2024, 08:48:26 am

The 0.8 voltage drop is not due to wire loss, it is the normal voltage drop from the diode isolator. Adding additional wire won't hurt, but it won't raise the voltage at the alternator.

Did you get the "sense" wire hooked up? This is necessary with an isolator to boost the alternator voltage to cover the diode voltage drop and should give you better voltage at the battery.

Yes, as I mentioned in post #58 it depends on whether alternator B+ is still wired through the diode-based battery isolator (in which case the voltage drop IS normal) or if B+ and at least chassis battery are wired to the same lug.

And, if wired through a diode-based battery isolator, the sense wire is NOT on the chassis battery side of the isolator as it needs to be.

In post #50, OP said: "Before I get 'too far, it looks to me like this was a Duvac system, originally, but for some reason, the owner apparently decided that it would be better to have it all combined..."

AND in the same post "if I hook up all wires as they currently are, making sure that the correct wires go to the intended spot, can I run it that way without isolating the 2 battery system, just to run it until i get a chance to figure out how those wired should go without damaging anyhing? I intend to wire itr correctly as we move forward, I just dont want to take the time right now to trsce all of the wires."

Something is still wrong, but we need to know how it was wired during the test!

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #64 – June 21, 2024, 12:31:10 pm

OK, got the alternator wired up, belt is tight, all connections are tight, the wire from the alternator goes to the center post of the isolater, but the wire seems to be lighter than a normal battery cable. The alternator reads 13.4 to 14 volts, but it reads 12.5 at the battery. i am going to get a heavier cable to replaced current one from isolater to alternator, but until i figure out the wiring to wire it as the two systems, I want to take the new heavier wire and run it from the alternator to the batteries, and leave the wire from the alternator to the isolater as it is. My question is, if i do that, will it cause any problems or hurt anything? Thank you for your help with this, electronics is not my strong suit and i really do appreciate you sharing your knowledge with me on this. it saves me a ton of time doing the research.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #65 – June 21, 2024, 12:49:57 pm

NO, if you have a diode-based battery isolator in place you can't both wire to it (center lug) AND directly to the battery.

The sense wire/function would be totally confused. The battery bank wired through the isolator would be undercharged/the battery bank wired directly would be the only one to get proper voltage. And if your sense wire happened to be on the "other"/house battery instead of the chassis battery and you wire directly to the chassis battery from the alternator, you would way overcharge the chassis battery.

Before considering replacing the wire from the alternator B+ to center lug of the diode-based battery isolator, Test from each to good ground and see if the voltage drop is from the alternator to isolator (in which case, you do need to address it) OR if the voltage drop is in the isolator. Remember, there will be around .7 VDC drop from B+ lug of the isolator to the two battery/outer lugs.

Voltage readings you posted with engine above idle of 13.4-14 is low with a diode-based isolator AND way too wide a range.

Again, please post readings from good clean ground to: alternator B+, center lug of isolator and each of the outer lugs of the battery isolator (which are directly connected to the battery banks) and lastly voltage readings at each battery bank with the engine at around 1,100 RPM.

Said another way, I strongly suggest you diagnose and fix the problem, don't totally re-engineer a system that has been tired and true for decades.

Can you wire around the diode-based battery isolator-- sure, but you would need to do it correctly so you don't either over or undercharge one of the battery banks.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #66 – June 21, 2024, 12:54:02 pm

Quote from: quickmagic – June 21, 2024, 12:31:10 pm

OK, got the alternator wired up, belt is tight, all connections are tight, the wire from the alternator goes to the center post of the isolater, but the wire seems to be lighter than a normal battery cable. The alternator reads 13.4 to 14 volts, but it reads 12.5 at the battery. i am going to get a heavier cable to replaced current one from isolater to alternator, but until i figure out the wiring to wire it as the two systems, I want to take the new heavier wire and run it from the alternator to the batteries, and leave the wire from the alternator to the isolater as it is. My question is, if i do that, will it cause any problems or hurt anything? Thank you for your help with this, electronics is not my strong suit and i really do appreciate you sharing your knowledge with me on this. it saves me a ton of time doing the research.

take your volt meter and measure from the alternator to the Isolator. If the wire is too small you will read voltage. Corrosion will also show up as indicated voltage. .2 volts lost here and there ends up being too much pretty quick. Quick and easy to check. If you read no voltage that's perfect , but everything has a resistance and will show some loss. I would retain the original intent

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #67 – June 21, 2024, 04:56:09 pm

After some warming up the voltage drop across the isolator will be over a volt, closer to 1.2 volts. The sense wire for the alternator needs to go to the chassis battery for a number of reasons. The most important is that it is the priority for not only charging the battery but ensuring adequate voltage and current is available for the chassis systems. From the practical view, the chassis batteries will normally be at a higher state of charge. As the house batteries may be at a lower state of charge and often of much higher capacities, and often with vary loads connected while driving/charging, this design will allow the house batteries to be at a lower voltage, rising as the state of charge increases eventually catching up to the chassis batteries. The current limiting effect during the bulk charge stage is actually better for the batteries and helps to reduce total load on the alternator somewhat. Foretravel is different using this diode approach. Most use some form of relay control, based on ignition on or alternator charging, or an automatic voltage-controlled relay, (my preference). A downside of the diode approach is another means is required to use a shore/generator powered charger to charge the chassis batteries. That is why Foretravel uses the maintained boost switch so the chassis batteries can be charged by the house battery charger. Hope this makes sense.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #68 – August 27, 2024, 06:54:55 am

UPDATE;
Here is where the entire project has evolved to;
Got the big alternator installed, had to modify the adjustment bracket, no big deal, reem out the adjusting
Slot with a grinder or whatever works best, add about a 2" extension to base of bracket. So mount up is great. Then the question was how to wire it. Found 3 different wiring diagrams, followed all of that best I could, it charges great, havnt run it on the road yet to see how it works. The issue I am dealing with now, is, when running vehicle on an outside generator, batteries seen to run dead prematurely, I am running 4 regular batteries, each individually charged each one, checked voltage, load tested them and replaced any questionable one, but doesn't seem to get enough juice stored in batteries to turn motor over, hook a jumper vehicle up to it, fires right up. When I wired this, some diagrams showed a hot lead comming from the onboard battery going to the coach battery. There was no such wire in my unit,
1. Do I need to add that wire to the entire scheme to make this work?
2. Is it possible that the onboard battery charger isn't operating correctly, it is original, would anyone care to make a recommendation on installing a new one, and which one that would be. Thank you all once again. As this unit comes together, with your gracious help, it becomes more and more comfortable every day. Thank you all very much for your help. I appreciate it.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #69 – August 27, 2024, 08:40:31 am

Trying to help as much as possible but difficult with modified systems.
For most of the Foretravel that use the battery isolator, Duvac system, the generator gets its power from the house batteries, and the either a power converter charger or inverter charger charges those. There is not auto connect for the generator/house power to charge the chassis batteries. To do this the "boost" relay gets closed and that ties both banks together.

If the chassis batteries are really drained down or weak for some other reason turning on the boost will not be able to transfer enough power to start the main engine, you need to allow some time. Confirm that battery voltage is rising, give an hour or so. Since you are doing this level of work you should have adequate metering tools including a clamp on DC ammeter. You can only diagnose so much using voltage measurements only. Learn Ohm's and Kirchhoff's laws, especially voltage drops with current flow and most everything DC will make sense.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #70 – August 27, 2024, 09:54:54 am

For us to assist you, you need to draw out and post exactly how your alternator/battery bank and starter are wired.

Re: 1984 FORETRAVEL - New owner with alternator/isolator/chassis battery questions

Reply #71 – August 27, 2024, 08:02:09 pm

Your chassis batteries are not charged from the charger that charges the house batteries. If you have the original battery charger that is I believe to be a magnetron 75 you need to replace it with one of the new chargers that are 3 stage. I don't remember, but pretty sure that the 84 did not have a duvac alternator. When you started the coach it got excite voltage from the wire feeding the shut off fuel solenoid and would not start charging until the engine was reved up to about a 1000 rpm once it started charging it would continue even at idle.

Affiliate Notice