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New guy from Centurion


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Welcome Langman.

I presume all is connected properly?

Out of interest, as it is always a topic, what type of batteries do you have?
Do you have a BMV?

Ps. Like the bigger wattage panels. 355w what you have. Lekker man!

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2 minutes ago, The Terrible Triplett said:

Welcome Langman.

I presume all is connected properly?

Out of interest, as it is always a topic, what type of batteries do you have?
Do you have a BMV?

Ps. Like the bigger wattage panels. 355w what you have. Lekker man!

Thanks T.T, it was a bit of a mission for a first timer, But got 10mm PV cable, and MC4 connectors and splitters. Got 32mm cable for the inverter and batts series connects.

Budget was initially only 2x 355w and a little 30amp PWM, on a 1500VA 24v UPS with 2x 120ah Silver Calcium batts that I already had, just to avoid a bit of load shedding. But 90% through buying the kit I got hit by 18-hours loadshedding and realized It's won't have enough oomf to carry much, so quite pointless.

Batteries: 4x 120AH Truck batt recons, had my 2 existing ones renewed and got 2 extra.

Don't have a BMV and have some niggles that I'm trying to figure out. 1 of the 4 batts in series is about 0.5 volt under the rest at all times. Measured with a multimeter.

I have moved it to the 2nd in line in the string and it's doing better now. But overall, I am losing some batt capacity somewhere.

Charging chuggs along nicely at around 20amp up to 58.6v from 9am to 3pm, and then keeps it there all day, so that should be plenty to fill the tanks. but it drops down from 54v to 50v in just a few minutes once PV drops off in late afternoon before it stabilizes. I only have about 100w/2amp max load on it in late afternoon (3pm-6pm). From 50v to 46v back to grid takes about 4 hours with 300w/6amp load. so in total I get about 30amps draw from the batts before it goes back to grid at 50% D.O.D.

Any pointers?

My budget is blown completely at the moment, please be gentle :)

 

 

 

 

 

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2 minutes ago, Langman said:

Any pointers?

My budget is blown completely at the moment, please be gentle

O the guys are going to hate this ... and you. :D

Step 1: If I was in your shoes, with them truck batteries, I presume they are sealed(?), I would have them tested with a Hawkins tester. Autoshops have the tester, or borrow on.

One at a time, draw 600amps for a few seconds, see what they do?

Why? They are reconned, could be borderline therein your quick drop in volts.

Once you know exactly where you stand with the batteries, the next step would be to get a BMV battery monitor and the ICC software. (Look guys, a VICTRON supporter giving the same advice!) :P

Why? You can try and make the batts last longer and get some ROI ito saving daytime on Eskom by ensuring the batts are kept on a selected SOC setting as set on the BMV, at which time the ICC software switches your inverter back to grid.

Without the above you could end up with them batteries becoming lead weights (which you can sell) faster. And that is what you don't want right now.

So, you have to look at a BMV, they are about +-R1500 + VAT or something, and the ICC software ... guys will tell you where to get that.

9 minutes ago, Langman said:

90% through buying the kit

Ja, same here, many many years back I tried a lot of smaller systems.

Kept on upgrading (read wasting money) till I came to a "pletter stop" (deadstop) one day on solar systems and spending, drawing a line in the sand.

Same concept as what I am saying you must get above, mine just more mechanically, thanks to the BMV's relay, instead of using software to switch and save the batteries for the real emergency..

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18 minutes ago, Langman said:

My budget is blown completely at the moment, please be gentle :)

Systems with a decent upgrade path remains the holy grail of solar power, something where you can start small and gradually add more capacity. For the most part, we're not quite there yet. While there are cheaper inverters on the market now, the quality stuff is still rather expensive. Lead acid banks cannot be extended and a good quality bank costs upwards of 30k.

I think in the past we pretty much said there are only two ways to do this. The one is to buy a cheap inverter and invest in a decent battery bank. Then replace the inverter later when you have more dosh. The second method is to buy a decent inverter and run on crap batteries that you replace frequently until you can buy a nice set of LFPs.

Personally I took the second route: I bought a high quality inverter and crap batteries. I went through 3 different second-hand banks in 4 years (Royal FLA, Trojan FLA, Victron AGM) and finally went LFP.

This comment is to be taken with some salt, but given my loyalties: You went with both a cheap inverter and crap batteries. So you can still decide which way you want to go with this :-)

Prices have come down though, and LFP banks can be extended unlike their lead-acid counterparts (given you don't take too long and the old model gets replaced).

For now my only recommendation is that you get a Victron BMV battery monitor. The rest seems fine.

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13 minutes ago, The Terrible Triplett said:

O the guys are going to hate this ... and you. :D

"Step 1: If I was in your shoes, with them truck batteries, I presume they are sealed(?), I would have them tested with a Hawkins tester. Autoshops have the tester, or borrow on."

They aren't sealed, so I checked battery water etc on all of them, had one that just needed a few sips, but that one has no issues as far as I can tell.

 

"So, you have to look at a BMV, they are about +-R1500 + VAT or something, and the ICC software ... guys will tell you where to get that."

I will be able to get one of those at month end then. I thought they are around R4k each?

 

 

13 minutes ago, The Terrible Triplett said:

 

 

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At Current Automation (order number: BMV-700 AIR) the 700 are going for R1 522.00 

The 702 has more features like midpoint measurement, but then you could end up with battery balancers one day, so maybe you don't need the more expensive 702.

 

16 minutes ago, Langman said:

They aren't sealed, ...

Good!

I would still test the batts ... rather know now than wonder. 

Any car battery shop have the testers. Beg and plead to borrow one to test at home, as those 200ah truck batts are not a "bag of groceries".

I know them, as I have sold many of them many moons ago, for UPS'es. 

If you had gone a different route, like Plonkster alluded to, Victron MPPT's could have helped further ito equalizing, which helps towards maintaining lead acid batteries over long periods.

 

Edited by Guest
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Howzit all,

So some feedback after a few days more testing.

My little 3 year old was sitting on the battery bank on Saturday, and after giving me a hell of a fright because he was messing with the cables, I realized 1 clamp was loose.

Tightened the whole bank, and Voila!!!

I got 65Amps out at 50% DOD that night. No weird quick drops or anything, it goes down slowly, and charging also comes back up slowly.

Who needs a tester, Get a curious little guy to "test" your setup. :)

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27 minutes ago, Langman said:

3 year old was sitting on the battery bank on Saturday

They do go tinkering where they should not, right? I went into a local solar place some years ago, and there was a big bank of Trojan L16 batteries with the little float-stalk tops on the cells (there is a peg sticking out of the top to show you the water level). So my son went and pushed down on the pegs and watched in amusement as they bounce back... until the salesperson drew my attention to it and we put a stop to it. Two months later.... the wife asks: why is there an unusual hole in these pants?

*snigger*

Edited by plonkster
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