Forum Discussion

joelmyer's avatar
joelmyer
Explorer
Jan 06, 2015

Top Charge Question

Well it's been 33 days since I've seen hookups. The 245 watts of solar gets the Trimetric into the positive AH from full most days.

Specific gravity has dropped. A couple of cells to 1250, and a couple to 1260.

There are 4 x 6 volt batteries in two banks.

So at sunset tonight I'll switch to bank 2 and hit bank one with an hour of 15.3 volts from the Megawatt.

And then.... Bank 1 will have a higher voltage than bank 2. Is it ok to just switch back to 1+2? The voltages will equalize pretty quickly.

Or should I just stay on bank 2 for a week, switch to bank 2 and zap bank 1 with the megawatt? Then I can check weekly and zap the weaker bank as required.

The batteries are 232 AH so total nameplate rating is 464. Morning AH from full is averaging -30 so the batteries are living in their top 10%.

Joel
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Jan 07, 2015
    The 600 watt boost converter has an amperage limiting cermet pot with of course a metal adjustment screw. Dial it in. 16 volts limited to 11 amps. Make the booster + and -
    Wires so they have a big alligator clip to connect to the incoming power. Another 2 wires and another clips so they connect to the disconnected + and - battery post. These boosters are pretty inexpensive and tiny.

    Hope This Helps
  • joelmyer's avatar
    joelmyer
    Explorer
    Jan 06, 2015
    MEXICOWANDERER wrote:
    Unfortunately a formula must be used. 5% of amp hour rating in amperes until voltage rises to 15.0

    For 6 of your cells, 11-amps constant current would be appropriate. But top charging is designed to minimize sulfation not undo it. Equalization is needed. So continue on to 16.0 volts if need be. This means 11-amps at 15.8 volts should going that high be necessary. This is where most apparatus falls flat on it's face.


    That'sa nice, but I have what I have which is a 30 amp MegaWatt. It goes to 15.3 period.

    Experience says that it will push less than 5 amps into fully charged bank, gently bubble and raise the SG.

    Joel
  • jrnymn7's avatar
    jrnymn7
    Explorer
    Jan 06, 2015
    I had my bank split into two strings for a few months this past fall. And when I attempted to go back to series/parallel, I found I had to get the two strings to a very similar resting voltage, before they would play well with each other. For example, the two strings would continue to maintain different resting voltages, and the string with the higher voltage tended to hog most of the charge. It was worse, the further apart they were in resting voltage. And I'm talking only about .03v difference. Now they're sitting dead even, throughout.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jan 06, 2015
    Short answer: YES, it is ok. Only possible danger is a blown fuse, and that is not likely.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Jan 06, 2015
    Unfortunately a formula must be used. 5% of amp hour rating in amperes until voltage rises to 15.0

    For 6 of your cells, 11-amps constant current would be appropriate. But top charging is designed to minimize sulfation not undo it. Equalization is needed. So continue on to 16.0 volts if need be. This means 11-amps at 15.8 volts should going that high be necessary. This is where most apparatus falls flat on it's face.
  • mena661's avatar
    mena661
    Explorer
    Jan 06, 2015
    Just run off of one bank until you get the other full then switch to the full bank. Swap back and forth as required. There is another more complicated way too.

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