Converter died, need advice.

Rickf1985 · March 01, 2014, 10:27 AM

I went to work on the genny the other day and the batteries were dead. I thought that was strange since the coach had only been unplugged for a week and nothing was on but I started the coach and fired up the generator to work on it and when I was done I shut off the coach and plugged it in. The following weekend (today) I go to start the generator and dead. I check the batteries and they both are at 7.8 volts. The converter is humming. I dug my way to the converter wires inside and where I could get to a power and ground I was getting 11.7 volts so I know there is a problem. Granted the voltages should be the same but I figure the converter is 25 years old so I am not even going to play with it. I will replace it and check the rest of the wiring at the same time. This is what I would guess is a stand alone unit? I am used to slide in campers where the A/C and D/C are all together. This one has a plug on it and is plugged into an outlet next to it. Do you guys have a brand that you prefer? I have seen Boondocker mentioned and I see they have a 60 amp model resonably priced.

Rick

M & J · March 01, 2014, 10:53 AM

The Boondocker is what most swear by.

DaveVA78Chieftain · March 01, 2014, 12:06 PM

Many setups in this era used the Magnetek Power Center which had the converter located in the bottom section of the Power Center. Other models had the converter seperate from the power center. Is yours located in the power center or seperate?

If seperate, then most use the Boondocker or Progressive Dynamics 9200 Series converters. Both are modern 3 stage converters which is want you want.

If in the bottom of the power center, then you can still adapt a Boondocker or Progressive Dynamics 9200 Series converter however, due to the older design, it is not a straight change out.

Dave

Stripe · March 01, 2014, 02:42 PM

Don't forget to check your wiring too. If you have a grounding short like I had and you replace the converter before fixing the cause of the problem, you will STILL have that problem only with a newer converter installed.
I found my short repaired it and now I don't need to spend any money on something that is working just fine..

The short did not manifest itself for a long time after getting the RV. So give 'em a once over for your own peace of mind.

If you still feel you want a new converter I'd say go for it, probably less weight but I would still make sure the electrical wiring is all good.

Rickf1985 · March 01, 2014, 02:53 PM

Dave, Mine is separate. My power center, I guess that is what you call the breaker box, is under the bed in the rear and the converter is under the passenger front seat. I just got it out and it is a Magna-Tek TU-740-2. Average charge rate 4 amps. Looks like I will be ordering a Boondocker. Let's see.... 60 amps vs. 4 amps. I had upgraded my slide-in with the Magnetek/Parrallax 6300/7300 upgrade kit and what a difference modern technology makes! Stripe, I will be checking all of the connections before installing the new converter. Even if this old one still works you have to figure that a steady 4 amps will take forever to charge to gel cells plus when they are charged it continues at the same rate overcharging them. With the new setup I will have desulfation mode along with it and a much faster charge time which means less generator run time.

DaveVA78Chieftain · March 01, 2014, 03:46 PM

Winnebago does not post wiring diagrams prior to 1990 however, on a 1990 rig, it has either a 40 amp fuse or circuit breaker on the output of the converter. Not sure where it is located. For 1990, that then goes to a battery disconnect relay. Those would most likely be either in or very close to the battery compartment. Based on a 700 Series converter design (no output fuse), I suspect you also would have either fuse or CB. Make sure you do not have open fuse or CB.

Dave

Manual: http://www.bdub.net/manuals/triad-utrad.pdf
See rear portion of document for TU-740 data.

Rickf1985 · March 01, 2014, 05:22 PM

Sorry for the delay, had to get the snow blower going for the next D*** snowstorm on Monday. I have to plow it for days and then, and only then, do I get to come home and clean up there.There is nothing in the box that the converter was in. The positive wire went to a stud where it joined two other heavy wires which I would guess were the supply to the batteries and the supply to the DC control center where all the breakers are. This is located over my fridge halfway back the coach and all the breakers are good. The negative wire was tied into two wires, one was grounded to the chassis in the box and the other went out the bottom with the positive wire. There was also a ground wire from the case to the chassis. I have not plugged it in here in the house yet but I will to see what the open circuit voltage is and then I will hook it to a battery that is low and see what that does. The 11.9 reading I saw on the main wire out of the unit makes me think it is crisp.

ClydesdaleKevin · March 01, 2014, 10:48 PM

I love our Powermax Boondocker...we got the highest amp unit since we do a lot of boondocking and I wanted the fastest charge rate for battery charging with the genny running, but 60 amps is more than enough for most people's needs.

I highly recommend talking to Randy and bestconverters.com. Awesome prices, and the best customer service you'll find anywhere.

Kev

Rickf1985 · March 02, 2014, 01:36 PM

I talked to Randy when I bought the replacement for my slide in and he was right on the money so you bet I will be going back to him again.

Rickf1985 · March 06, 2014, 07:14 AM

Called Randy at Best and he was busy so he called me back while he was on his way home! He verified what I pretty much thought that the original was junk. He also told me I did not need the more expensive Boondocker I was looking at and sold me a cheaper model. Took the info right then and there. I hope he pulled over to do it! THAT is why I go to, and send people to, Best converters.

Rickf1985 · March 11, 2014, 07:32 PM

New converter got here but while I was waiting I found that apparently the coach batteries were not connecting to the system. I checked and cleaned all the connections and installed the new converter. It puts out a solid 14.6 volts to the coach, the battery meter on the dash tells me that the batteries are at 14.6 which I know is wrong since they measure 7.9.. The battery mode switch seem to be working since without the converter it would put power to the coach when switched. The only problem is that the batteries will not connect. I have checked everything I can think of. I have accessed the solenoids and the two fuses are good, there is 14.5 volts on both sides of the smaller of the two and on the one with the fuses there is 14,5 on one side and 7.9 on the other. So I know it is connected to the batteries but I cannot get voltage to the either of the two small activation terminals on that solenoid. I have tried everything including manually jumping them. I have tried every switch position known to man between the two switchs on the dash. On main issue I have is this entire setup is wired with purple wire! No identifiers, just purple. Impossible to trace without a signal tracer. I need help! I am sure it is something simple I am missing but I just can't find it. I am thinking that with the coach not running, the battery switch on the dash in the on position and plugged in to shore power it should automatically connect. Am I right or overthinking it? If you think it is a bad solenoid then where do I find one?

Rick

Stripe · March 11, 2014, 07:50 PM

What about the battery isolator? Does your rig have one of those?

DaveVA78Chieftain · March 11, 2014, 07:59 PM

You said

QuoteI have accessed the solenoids ....

You have 2? One would be battery mode solenoid (x-connect coach and chassis system)

The other will be a battery disconnect. It is a special solenoid that uses a mechanical latching mechanism. It does not have a constant voltage across it. A reverseable voltage pulse is sent to it go from OFF to ON and ON to OFF. The mechanical latch keeps it in the ordered position. Looks simular to this:

Dave

Rickf1985 · March 11, 2014, 08:33 PM

Dave, Yes, I have two and your assesment of them is correct. The bottom one you show is the one I am apparently having issues with, the battery disconnect. Looking at it exactly as it is shown here I have converter power at right main terminal and coach battery power at the left main terminal. I have zero at the two small terminals. I have followed the procedure for jumping the relay to get it charging with dead coach batteries but to no avail. Also on the right main terminal is a small approx. 20 gauge wire going into the loom. I am thinking that this is the wire that triggers the relay to shut when shore power is applied? I retired as an ASE master tech and my specialties were electrical and carburetors. That is what makes me think that I am over thinking this so I had to walk away and ask those that have been there. The wiring all being the same color does not help any. I have power at that small wire but none at the small terminals so something is interupting the flow. What am I missing here?

Rickf1985 · March 11, 2014, 08:36 PM

I just realized that I gave you upside down information! It has been a very long day. Picture the relay being turned over with the fuses up and that is how I am looking at it and describing the wiring.

Sorry, I am headed for bed. Got to be up at 04:00.

Rick

DaveVA78Chieftain · March 11, 2014, 09:02 PM

Battery disconnect switch is a 3 position switch.

It is spring loaded such that it always returns to the center OFF position when released.

When you depress it to USE, it sends current to the relay to latch it in the ON position. When you let go the current is removed and the switch returns to center OFF

When you depress it to STORE, it sends current in the OPPOSITE POLARITY to the relay to latch it in the OFF position. When you let go the current is removed and the switch returns to center OFF.

The mechanical latch inside the solenoid keeps the solenoid in the ordered position

Dave

Rickf1985 · March 12, 2014, 07:08 AM

Got it ( I think ). So if I jump power to LH the relay should switch to the house batteries and if I jump to LG it should switch off of house batteries, correct? I can try that to at least verify that the relay is good or bad. Where it is located I have very little room to work so I do not want to try to many things with the batteries hooked up, especially the main wires. Don't want to let out the magic smoke. I am beginning to suspect that I may have a bad battery since I charged them while I was waiting for the converter and they are down again already. I have not used them for anything. I should still be able to charge them though so I want to find out all that is bad before buying stuff.

DaveVA78Chieftain · March 12, 2014, 04:25 PM

Not actually

Per the circuit diagram:

With LH grounded and B+ applied to LG, the solenoid should turn ON

With LG grounded and B+ applied to LH, the solenoid should turn OFF

You only have to make the circuit momentarily to get it to latch in the ordered position. This mechanically latched solinoid is used so that when you are boondocking you do have to keep power applied to LG/LH. Prevents a drain on the battery that way

The major contacts in these solenoids are a know weak point. Lots of people have had problems with them

Dave

Rickf1985 · March 12, 2014, 06:23 PM

Thanks Dave, I was going to post that same info when I got home. I found a description of how it works on a E-bay site that was selling them. I had dealt with latching relays before but not very often so I forgot about the reverse polarity deal. That explains why I got nothing when I jumped them individually. It is 60 degrees and raining now and will be 25 and snowing tomorrow so I am back on hold again. This is NJ, If you don't like the weather just wait ten minutes, it will change. That saying should be amended though, if you don't like the season just wait a couple hours and it will change.

DaveVA78Chieftain · March 12, 2014, 07:03 PM

I am in northern Va. Wait till the wind reaches you!

Dave

Stripe · March 12, 2014, 07:43 PM

So no isolator then?

DaveVA78Chieftain · March 12, 2014, 07:53 PM

Fredrick not sure what you are asking. The Battery Disconnect relay we have been talking about can also be referred to as a Coach Battery Isolator Solenoid. Used to isolate the coach battery when you store the rig.

Dave

LJ-TJ · March 12, 2014, 08:05 PM

Somebody might find this handy. Hm?
http://www.bestconverter.com/assets/images/Powermax/PM3B%20Manual.pdf

Stripe · March 12, 2014, 08:09 PM

This is the battery isolator I'm talking about.

This is the one I have in my battery Compartment. My '77 had one as well but never replaced it.

Somewhere in that jumble is the Solenoid as well..

This is a pic of my new replacement should I ever need it in the future..

Got this at an O'Reilly's

cook elandan · March 12, 2014, 08:13 PM

Rick, I had about the same problem with the solenoid not locking in. My problem was the switch on the dash. Being old, needed to be cleaned, the contacts were dirty and had to activate the switch several times to get it to catch.