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Expert advice on 12v Solar/24v systems anyone?

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  • Expert advice on 12v Solar/24v systems anyone?

    Again PSB experts, I am at your feet begging for advice and perhaps some guidance with my 24v Toyota Coaster motorhome.

    IT is long winded , but I just can't explain things any other way.

    We purchased the bus a little while ago , however work and illness has mean that any familiarising with the buse's innards have been put on the back burner.

    The bus has had 2x 130w panels installed with 2 huge 130 a/h batteries fitted.They are bloody heavy and are 500mm long by 300mm wide each. Both are wired in parallel in an aluminium frame on wood and charge is controlled via a REDARC system. This swithces automatically with solar, AC and the buses 24v system when driving. After this tey are totally seperated..

    All this is fine , HOWEVER. Looking underneath the bus, I discovered that the area around the 2x12v [24v part of the bus] seriesed bus batteries has taken on a reasonable degree of oxidation [rust ] on the hollow channel supports. Not into the substrate[?] but the surface definitely shows signs of stress.

    The 2 bus batteries also appear to be a bit swollen but it is difficult to tell due to their location and the fact that I cannot compare similar batteries..
    To add to this, there seems to be a push button switch that reads 25.6v TOWARD the charge controller. Could be some form of jump starting system for flat drive batteries , but I can't track and trace the wiring configuration

    Testing with a meter shows correct volts in series, but it is difficult to load test for me.

    Sooo, is there a chance that the charging equalisation from the solar and redarc have stressed the batteries at some stage? The motorhome installation is only 18 months old.
    Alternatively , could they have just gassed up at some stage due to excessive discharge at some point? Could this acid have caused the accelerated corrosion around the batteries?? There is no rust anywhere else on the rest of the body or chassis, just a 500x500 square section.

    Finally, if there is a chance that shit just happens due to the location of the 24v area , would adding some sort of scarificial anode on the chassis or battery trays perhaps prevent any form of oxidation appearing in the bus in the future?

    The location of the solar batteries and the way they are grounded APPEARS that they may loop somewhere and I am thinking that they are chasing a better ground and perhaps causing faster oxidation in the process to add to the process.

    So, please. please, please give a brother some advice.
    Sventek, being a predominantly lazy fuck can you please purchase some for me, bring me the stuff, create something I want after you think of it for me then clean my house, wash my car, dog, bike breathe for me.

  • #2
    spilling of battery acid might be possible cause ( boiling of batteries)
    get the batteries load tested would be my advise
    Repair the corrosion.
    other than that ohm test the connections in question
    high reading= bad connection


    • #3
      Do some research on the galvanic effect, over than battery acid I can't think of anything that would cause the local rust problem


      • #4
        If you are using solar input into the batteries, there will (should) be a solar regulator in there somewhere, but I didn't see any mention of it. Solar panels will output at around 20VDC, and the regulator should convert to 13.xx VDC output, and regulate charging current into the solar batteries as charge level rises. I can't see how they could charge into your start batteries as you state the 130a/hr solar batteries are in parallel, hence 12v. And the Redarc will regulate output, shutting off (in a 12V system) at about 11.8V, to preserve the starting batteries. So if you are charging back into the solar batteries while the engine is running, you would need a 24v-12v reducer downstream of that Redarc, or you are charging your solar batteries at 24v.? So I don't think the solar panels are actually charging into your start batteries, for these reasons. I run an all-12v mixed system no problems, Redarc-controlled start battery output feeding into charge input terminals on solar regulator, which are different to solar charge input terminals. Whole system is in a battery box, and plugs are arranged in such a way that you cannot accidentally mix the inputs. You mention "looping" from the solar battery that you cannot follow--worth remembering that solar controllers usually switch the negative (ground) leg of the output.
        To sum up
        1) if you don't have a 24v-12v reducer on your Redarc output, you are not charging your solar batteries from your vehicle alternator as you drive.
        2) Unless you have some form of voltage doubler (12v-24v) your solar batteries are not charging your start batteries when you are stopped. Look for your solar regulator.
        3) Redarc relay should save the start batteries from over-discharge while stopped, meaning no solar input should be needed.
        Your problem may simply be overcharging from a faulty vehicle alternator, causing the swelling ( which can ALSO be caused by low electrolyte level, causing plates to buckle) . Corrosion sounds like the batteries are not properly mounted, in a box to contain discharge. Is it the OEM setup, in that respect? Proper containment and venting arrangements usually keep that to a minimum.
        " Lightly Seared On The Reality Grill"


        • #5

          Great information thanks ranma.

          As this was not the system that I ordered, I will need to poke around some more to see what and where things are. The REDARC is this model Battery Management System - 15Amp system (BMS1215S2) - REDARC

          I am of the opinion that low electrolyte levels on the batteries may be the culprit due to the bastard of a spot that these batteries are fitted at factory, plus the fit out on top.

          Am replacing them tomorrow so will look at the levels when they are removed.

          Thanks gents, think I have been pointed in the right direction to sort the issues out…
          Sventek, being a predominantly lazy fuck can you please purchase some for me, bring me the stuff, create something I want after you think of it for me then clean my house, wash my car, dog, bike breathe for me.