Forum Discussion

Tambs's avatar
Tambs
Explorer
May 16, 2020

Magnetek series 7300, Model 7345 Converter

Hello all,

I have a 1998 Lance Legend 500 truck camper that uses the above converter. I’ve been having battery issues lately, and after removing the 12V house battery I found it is sitting at 6.5 volts. The camper has been plugged in to 120V shore power. The battery is an Optima Blue Top, but it is 8 years old so I’m confident it is shot and needing to be replaced.

After removing the battery I checked the battery leads with a voltage meter and only got 5.2V coming through the leads. I then checked the truck batteries and found them to have 5.75V. I disconnected the truck pigtail from the camper and voltage at the battery leads was 0 (with shore power plugged in and confirmed to be hot). So apparently the converter isn’t supplying any power to the house battery. The converter output terminal (circled in red in the pic below) at the fuse panel adjacent to the converter itself registers 13.8V when plugged into shore power, but the battery lugs (circled in blue) coming off of the same fuse block read 0V. All fuses are good.

Is it logical to conclude that the converter has failed, or is there something else I should check before seeking out a replacement converter?

If a replacement is in order, what would you recommend? I’d prefer an AGM battery, and from what I can tell they require smart chargers. Is there a direct replacement for the 7345 that incorporates smart charging technology?

https://www.amazon.com/photos/shared/1ezGjXdbRHyDjPsf2rGuog.pKf0JdNicc67CftZXuLkCJ
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    May 16, 2020
    No picture. Try this.. http://photoposting.is-great.net/?i=3
  • BFL13's avatar
    BFL13
    Explorer II
    May 16, 2020
    When it has 120v input, the 7345 should have 13.8v across its blue and white DC output wires. The fuse panel has lugs for those and also for the battery wires.

    First confirm you are getting 13.8 from the converter (OP seems like it is, but not clear) If not getting that on the battery lugs of the fuse panel, there is a problem with the wires at the fuse panel--perhaps a set-screw is loose and a wire fell out ( lugs are also on the back of the panel so you can't see there unless you unscrew it (two screws)

    Not clear what is going on with the voltage from the truck. It should be whatever the engine battery is at.

    AGMs do not need a "smart converter", but they do need 14.4v which the 7300 can't do, being single stage 13.8v.
  • BarneyS's avatar
    BarneyS
    Explorer III
    May 16, 2020
    Here is your picture.


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  • Tambs's avatar
    Tambs
    Explorer
    May 17, 2020
    Thanks for the reply. I've responded to your paragraphs below...


    BFL13 wrote:
    When it has 120v input, the 7345 should have 13.8v across its blue and white DC output wires. The fuse panel has lugs for those and also for the battery wires. Didn't see the blue/white output wires, but I will take another look. The output lug on the fuse panel does have 13.8. The lugs on the fuse panel for the battery leads are dead. I'll pull the fuse panel to check the connections behind it.

    First confirm you are getting 13.8 from the converter (OP seems like it is, but not clear) If not getting that on the battery lugs of the fuse panel, there is a problem with the wires at the fuse panel--perhaps a set-screw is loose and a wire fell out ( lugs are also on the back of the panel so you can't see there unless you unscrew it (two screws) As above, I'll pull the fuse panel and check connections behind it.

    Not clear what is going on with the voltage from the truck. It should be whatever the engine battery is at. The truck battery was drawn down while sitting for several days without being started. The battery disconnect switch in the battery compartment of the camper was closed, so it drew from the truck batteries while sitting.

    AGMs do not need a "smart converter", but they do need 14.4v which the 7300 can't do, being single stage 13.8v. I was following the guidance on Optima's website that indicated an AGM that falls below 10.5V may need a smart charger to bring it back to full charge. I've also read this elsewhere, but there seems to be confusing info about the matter, as I've seen other guidance that suggests a smart charger is not needed. https://www.optimabatteries.com/en-us/support/charging/charging-agm-battery
  • BFL13's avatar
    BFL13
    Explorer II
    May 17, 2020
    The blue positive wire from the converter is usually with a ring terminal on the end, attached to the front of the panel at the top middle nut and bolt, where you show nothing on yours. It might be on the back. Blue wire shown at the bottom going up somewhere. EDIT- the wire in the photo going to that top terminal at the back looks black not blue? There is a blue wire below in the middle of the panel way behind there that looks like the right one.

    Where are you putting the neg on your meter to go with that positive terminal to get 13.8v? Since the two battery lugs show zero volts, it might mean the converter's white wire is not screwed into the back lug behind the front neg battery lug. You see a white wire there but it seems to go by the front lug to where? Is it loose?

    If the positive path on the panel between that top converter terminal and the battery positive is broken somehow, you can put the blue and white converter wires in the battery lugs with the battery wires. Not sure if that by-passes the two reverse polarity fuses though. Better not to do that if you don't have to.

    Are the two RP fuses ok? That's the two green 30a ones by that top terminal
    I don't know if they are blown if you can still get 13.8v at the top terminal, but not at the battery lugs.
  • Tambs's avatar
    Tambs
    Explorer
    May 17, 2020
    The output terminal (top-center, no wire on front, black wire on back) has 13.8V to ground.

    The lugs inside the blue circle in the pic have 0V to ground, and 0V lug to lug.

    Yes, the wire connected to the output terminal on the backside of the fuse panel looks black to me as well.

    The black and white wires on the battery lug terminals on the front side of the fuse panel are snug. I'll check the back side tomorrow. I'm assuming the other white wire that disappears behind the panel is the feeder from the converter that is probably landed on the back side of the panel on the negative lug. I will verify this tomorrow as well,and make sure it is snug.

    All of the fuses in the panel (including the 30A RP fuses) checked out with a light tester.

    Thanks to all for the assistance. I'll update my findings tomorrow.

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