Batteries not charging, but converter is good

Discussion in 'Wiring' started by mausmobile, Dec 24, 2019.

  1. mausmobile

    mausmobile New Member

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    I have two 6 volt batteries wired in series to create 12 volts. Batteries are not charging on shore power.

    When I disconnect the wires coming from the converter, I get 13.6 volts. This suggests the converter is doing its job. But when I connect those wires to their posts, I only get 12.3 volts at the battery bank (same as when the batteries are isolated from the camper).

    These batteries are less than a year old, and nothing about the wiring has been changed since our successful summer of camping, when everything worked fine. I have cleaned and tightened all connections at and between the batteries.

    What else could be preventing the batteries from charging?
     
  2. WrkrBee

    WrkrBee Well-Known Member

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    Check the batteries to make sure they can hold a charge. One could have an internal defect, pulling them both down.
     
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  3. SteveP

    SteveP Well-Known Member

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    Plug it in and let it charge for an hour before testing. It may take a while for the batteries to start accepting charge.

    If this is your only charge source your batteries may be heavily sulfated. You need to get a real charger that can output 14.6 to 14.8 volts, preferably at 15 to 25 amps, to properly maintain these batteries. Neither your converter nor your Toyota can provide this voltage level.
     
    Last edited: Dec 24, 2019
  4. shuang2

    shuang2 Well-Known Member

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    Check the water level, water dried out all the time in those 6V batteries.
     
  5. roybraddy

    roybraddy Well-Known Member

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    I do this all the time doing my walk around.... I measure DC VOLTS at the battery bank using my DC Voltmeter. I will normally see 12.5-6VDC telling me the battery bank is charged normal. When Plugged into shore power or generator I want to see 13.6VDC or whatever mode the smart mode charger is doing at the time. If I ever see 12.0VDC then I know my battery bank is at its 50% charge state and not to be used until charged back up to its 90% charge state...

    Roy Ken
    [​IMG]
     
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  6. tombiasi

    tombiasi Well-Known Member

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    You are reading straight battery voltage. The charger is not pushing any more in.
     
  7. Grandpa Don

    Grandpa Don Well-Known Member

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    I have a single 12 volt battery and am the second owner of the battery. When I bought the camper a year and a half ago the PO said the battery was about two years old. This year I wanted to replace the battery just because. I took it to Auto-Zone and had it tested. They put theie test unit on it and did a draw test. They said that it was still okay and that there was no need to replace it.

    In conclusion, take your batteries to Napa, or AutoZone and have them test the batteries. They do it for free.
     
  8. Anthony Hitchings

    Anthony Hitchings Well-Known Member

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    As a point of reference, my plug-in voltmeter in my Jeep shows 14.3-14.4V when running down the road, (+/1 0.1).
     
  9. mausmobile

    mausmobile New Member

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    Thanks everyone for the suggestions so far. I will get the batteries tested asap.

    My converter is a WFCO WF-8955. It has 3-stage charging:

    "The WF-8955 model provides 55 Amps and a clean, constant 13.6 VDC nominal output, for reliable operation of electronics and appliances. Automatic three-stage charging extends the life of your battery with output voltage modes of 13.2 VDC range “float” mode, 13.6 VDC range “absorption” mode, and a 14.4 VDC range “bulk” charge mode."

    Based on this, 13.6 on the wires to the battery box seems to be within specs. I do not leave the camper plugged in all the time. I check the batteries about once a month and charge as needed.

    Why would this cause my batteries to becomes sulfated or boiled dry?
     
  10. GreyFox

    GreyFox Well-Known Member

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    For those of us who have been around this sport for awhile it's common knowledge that a WFCO converter will rarely if ever output a bulk charging rate of 14.4 volts, as it's advertised to be capable of. [XX(] Bottom line, your batteries have suffered because they've never been bulk charged at this higher voltage. Do yourself a favour and replace that awful WFCO converter with one that is capable of properly bulk charging the batteries.
     
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  11. NavarWynn

    NavarWynn Member

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    My suspicion is that the converter may be malfunctioning. If there is no change in system voltage when you plug into SP (NOT 'minimal' change, but 'NO' change), then the system is not being charged. Your WFCO uses electronically controlled current protection, which means that under high current draw, system voltage will normally drop. However, it is possible that an internal fault is causing the system voltage to drop too low under high load to actually charge the battery bank... smart chargers are great - until they outsmart themselves ;) . That is a reasonable suspicion.

    I would try to charge the battery bank with a separate charger, as well as check the water first of course (as a normal 'inspection' type check, not because your symptoms indicate this fault). If another charger won't charge them, then you'd be right to suspect them, but if another charger charges them successfully (even your car hooked up with jumper cables would work for this test), then the problem is either the connection or the charger.
     
  12. mpking

    mpking Well-Known Member

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    I'm thread hijacking. I've never heard this before. What brand would you replace it with. (New converter is on my shortlist of upgrades, and the WFCO was high on the list)
     
  13. GreyFox

    GreyFox Well-Known Member

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    Just about anything BUT a WFCO would be better but a lot of RV owners choose a Progressive Dynamics converter equipped with a charge wizard.

    https://www.progressivedyn.com/

    Randy at Best Converter can be a great resource also for converter guidance - just don't let him sell you a replacement WFCO. :eek:

    http://www.bestconverter.com/
     
  14. MNTCamper

    MNTCamper Well-Known Member

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    The WFCO chargers work just fine and in fact they rarely put out a 14.4V bulk charge just like they are designed to do. Bulk charging at 14.4V should only be used when Lead Acid batteries are severely depleted - under 50% charge and then should only be used to bring them up to ~80% state of charge. At that point, they go into absorption mode and then eventually float as the charge state nears 100%. In virtually all camper 12V applications, the battery is never (should never) run down to such a low state of charge such that bulk charging is needed and if you don't run down your batteries to a low state of charge, then it would be highly unusual to get sulfation. All of the converters out there will provide 13.6 volts to the 12V circuits when plugged into shore power - but they may still be only supplying 13.2 float to the battery, that all depends on the battery state of charge.

    The best thing you can do for long battery life is keep your batteries charged up. If you do have a situation in use where they get discharged below 50%, charge them up again as soon as possible. When you are storing the batteries, put them away fully charged and top them off for a few hours every month or two or use a low ma battery tender attached to the stored battery..
     
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  15. Anthony Hitchings

    Anthony Hitchings Well-Known Member

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    I replaced my Centurion converter with a Progressive Dynamics unit.
     
  16. mpking

    mpking Well-Known Member

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    I too have a Centurion. Which model PDI did you end up with? Was it a direct fit?
     
  17. Anthony Hitchings

    Anthony Hitchings Well-Known Member

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    I removed a Centurion CS2000XL (20 Amps DC output) and replaced it with the Progressive Dynamics Model 4135. If only because I wanted something that was more modern in terms of battery charging profile. Which ultimately was a bit silly because the converter is rarely plugged in as the two house batteries are constantly charged and maintained by our Renogy Rover 30 Amp charge controller (and sunshine). The old Centurion is up in our attic.
     
  18. GreyFox

    GreyFox Well-Known Member

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    The rest are up in heaven ... errrr, actually down in HELL. [LOL]
     
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  19. HeatherTS

    HeatherTS New Member

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    Do you want to sell your old Centurion? We are actually living in our pup now for a bit and need one but can’t afford a new one right now with everything going on.
     

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