Renewable Energy Questions/Discussion > Renewable Energy Q&A

Dead AGM Batteries

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OTG:
Yeah exactly - it meets 99.9% of my needs, and that's what matters. I've ordered a couple of 12V 170Ah Batt's, which should give me that bit of extra headroom so I'm not draining them so much anymore.

And yeah, mobile throws all sorts of other spanners in the works... particularly wrt the array. Though as you noted (and similarly to my initial fears and subsequent surprise) the panels have held up very well indeed. When putting this whole thing together  the array was the bit I'd think about laying in bed at night (how best to do it - without breaking the bank... or panels :) ).

For me, the first consideration was ventilation... how to get adequate air under them, without causing too much drag/uplift whilst driving. Hence I used the 25mm SHS to lift the array off the aluminium roof, whilst also supporting the long side of the panels too (and with the 40mm angle iron on the short side, all four sides of the panel frames are supported). The one exception here is the front panel, who's front side hangs slightly over the cab (per the middle pic above). It's hung forward of the tray to avoid rear kocks to the back panel/array frame, and to have this unsupported side in the middle of the truck so it's less affected by bumps and what not.

I think I had a similar idea to you with having some "spring" in the array frame. (Fortunately in a sense) the tray cab at some stage in it's life prior to me copped a whack from the back, which put a slight concave into it lengthwise (that silver square is me patching a related hole in the roof). This mean't my array actually "floats" in the middle by maybe 5mm or so - the two middle lenghts of 25mm SHS aren't actually in contact with the roof (only the ends are bolted down), and the frame flexes slightly at these two points, so with a slight gap either side of the middle panel (to prevent the panel frames rubbing) the whole thing can flex a bit on the bumps (a bit like a leaf spring). And to absorb some shock, each contact point with the roof (both the bolted and floating points) has a bit of EPDM Rubber strip under it.

It all seems to have worked alright thus far  :P - fingers crossed it stays that way.  ;D

Likewise, I'd be curious to hear how you went about it with your rig.

MadScientist267:
Not bad, sounds like it works.

With mine I used 4 angle aluminum brackets per panel, which slide up under retaining clips... They're staggered in such a way that they interleave in the center, the whole array riding on 3 rails made of channel aluminum spanning the entire roof from front to back.

The panels are not firmly restrained in any way, and are only suspended by "PVC rubber" underlayment material, allowing them to shift as the box flexes from bumps going down the road. This acts mostly as a "lubricant" to prevent metal on metal wear.

They're locked in place by keying clips that prevent them from sliding out from under the retainers, but can be removed if necessary for some reason. The lock clip details were intentionally left out of the original pics for security reasons, but in this pic, you can see how the suspension retainer scheme is set up...



Fully assembled, any panel can be removed individually without disturbing the others.

The main story on how all this comes together is in this thread.

It was definitely fun to come up with and implement the design, but it did indeed serve very well in the end and I never had any installation related issues come up after launch.

Pete:
Hi OTG you asked about fusible links. Not sure where you are but Jaycar have fuses that go up to 250 amps. They are pretty cheap and just bolt into a holder with two allen head screws. I use them on my stand alone system. In the event of an accidental short the batteries and cables won't go up in smoke. I have blown a couple of fuses using a heat gun run off my inverter. I found that I had a bad connection on one of my brass links. Fixed that no problems now.
As far as the meter goes, you could always take it apart and see if the switch is operating properly.
Some multimeters have pretty cheesy tracks on the circuit board that the switch operates on. Cleaning up the circuit board can sometimes bring them back to life.
I have killed a few cheap multimeters by measuring high voltage DC ( which they were supposed to handle) on Valve amplifiers. Basically the tracks are too close together and the sparks jump across them and blow the meter up.
It is odd that your meter reads so erraticaly  on your load tests. A 1.5 amp load should not be a problem. Maybe you should also test the leads on your meter, they can easily break where they go into the plug or probe and give odd readings because of the high resistance.
Have fun,
Pete

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