1 minute ago, The Terrible Triplett said:

O my ... did you want to come along! I just past Cairo in my Isuzu with the trailer. 

On a more serious note what happens to the batteries on all the towers in this country?

 

2 minutes ago, incagarcilaso said:

If 1-3 don't work give up, throw the towel in

Or disconnect the problem ones, use the rest as long as you can, then when you get a "new" 2nd hand bank, test the batts one by one before you install them, to get the really good ones identified. Seeing as one has to take all, use the worse ones first till they are dead, then the best ones and so you roll.

For 2nd hand batts are cheaper than utilities by far.

Just so you can see what we are talking about - here they are, with the 4 HA02s connected. Gives you an idea of how difficult it is to shift these things around at over 100kg a piece and the way they are tied in together (two copper plate sheet connections on each). It's impossible to keep the balancer wires any tidier because of the way they have to reach each cell in each cluster.

42 minutes ago, Chris Hobson said:

On a more serious note what happens to the batteries on all the towers in this country?

Have an itch to form a idea to get a thought to find out - tomorrow.

2 minutes ago, incagarcilaso said:

... shift these things around at over 100kg a piece ...

An idea is to put them on trollies / some kind of wheels, but only next time.

Did that with my 4 batts, put them in a wooden box on wheels. Got tired of their weight when I have to move them for whatever reason.

1 minute ago, The Terrible Triplett said:

An idea is to put them on trollies / some kind of wheels, but only next time.

Did that with my 4 batts, put them in a wooden box on wheels. Got tired of their weight when I have to move them for whatever reason.

Very nice idea. The trollies would have to be braked - if these start moving they don't stop for anything, not even a brick wall.

1 hour ago, Chris Hobson said:

On a more serious note what happens to the batteries on all the towers in this country?

They get stolen... and sold at R1700 for a 170ah battery on gumtree :-P

Seriously, I have no idea. I think there are already people trading in these, I see at least two guys on gumtree regularly selling anything from 100Ah to 1500Ah second hand at around a third of the price. For example the captured ad as attached...

I know many companies have rules about replacing things, insurance companies for example, I think they throw their stuff out every 18 months. The trouble is finding someone who knows someone.

A few years ago I visited Pater Noster (love that little town) and we went to see the lighthouse (I believe it is the last manned lighthouse in the country?), and while I was there I saw their UPS, battery bank and the big Diesel generator. The battery bank is only to backup some comms equipment, so it isn't very big, but there it is... there are probably rules about that thing. All I know is that the whole thing is supplied by someone called Marine Systems. I suppose I could call them... but its pointless right now... I'm very careful with the budget these days. There is a small kitty saved up for solar expansion, but I'm not blowing that on a battery bank that's too small :-)

9 minutes ago, plonkster said:

I know many companies have rules about replacing things, insurance companies for example, I think they throw their stuff out every 18 months. The trouble is finding someone who knows someone.

I was really lucky to pick these up - right place, right time. Most companies that use these have to follow strict policies on the age of these back-up banks, which is usually between 12 and 18 months. This should mean that there are a lot of nearly-new banks out there up for grabs every year, but they are not easy to find.

Conundrum: direction of current on battery balancers.

In an attempt to check that all is working correctly and the balancers are passing the current in the right direction between high and low cells I have taken some measurements, but I am a little confused as to the real flow of current. As always the "conventional" and "real" models for direction of current are confusing. Normally you just pick one and as long as you are consistent with whatever you do based on that, it should work. But after doing this, I'm still not sure.

I have a multimeter that tells you the direction of current, giving negative and positive readings accordingly. Based on this I have put together the diagram below of a test I have done on two pairs of batteries with very different voltages, connected to a single HA02. I hope everthing is clear on it. The blue arrows show the direction of current based on my readings and the multimeter's indications of direction of current (I understand this to be "real" direction, although the manual doesn't state this). From this, is the behaviour correct? Is the balancer passing the current from the higher to the lower voltage cells? I can't work it out.

It shows that the current is flowing out of the high voltage cell along the positive wire and into the high voltage cell on the negative wire. It shows that the current is flowing into the positive connection on the low voltage cells and out of the negative connection on these. Is this correct?

And what it is doing in the box is push current to the low voltage cell from the higher voltage cell.

The amps readings should be higher on the low voltage cell pos and lower on the high voltage cell pos.

If I am correct that is ... Mr Hobson...

11 minutes ago, Mark said:

And what it is doing in the box is push current to the low voltage cell from the higher voltage cell.

The amps readings should be higher on the low voltage cell pos and lower on the high voltage cell pos.

If I am correct that is ... Mr Hobson...

In this case it's the other way round. On the higher voltage cell's positive the reading is 3.5 A and on the lower voltage cell's positive the reading is 2.5 A. But I thought this might have something to do with the fact that the balancer is juggling more cells, not just these two, so it distributes the amps among all pairs?

On 28/02/2017 at 4:27 PM, incagarcilaso said:

Conundrum: direction of current on battery balancers.

..... but I am a little confused as to the real flow of current. As always the "conventional" and "real" models for direction of current are confusing. Normally you just pick one and as long as you are consistent with whatever you do based on that, it should work. But after doing this, I'm still not sure.

Benjamin Franklin in 1747 said current flow was from positive to negative. It was an arbitrary. He assigned two type of charge as positive and negative. No one at the time knew anything of electrons. JJ Thompson discovered electrons  in 1897 and we now know that they have a negative charge and if we apply a voltage electrons flow towards positive in a wire. But its not too difficult to remember that Franklin's convention is the flow of positive charge. If we dissolve table salt in water and apply a voltage the sodium ions (positive charge) flow from positive to negative. So if you think like a chemist and not like an electrical engineer everything is fine. 

 

Forgive my crude graffiti on your beautiful diagram.

On 28/02/2017 at 4:27 PM, incagarcilaso said:

It shows that the current is flowing out of the high voltage cell along the positive wire and into the high voltage cell on the negative wire. It shows that the current is flowing into the positive connection on the low voltage cells and out of the negative connection on these. Is this correct?

Current flow is always circular back to source. To ease our understanding of what is happening we are going to divide this into two discrete units (it is not but will help our understanding).

1. We have a battery (source) which is high "powering" the HA02. The battery comprises two cells so current flow is into the HA02. Work is being done powering the circuitry and there is current flow back to source. So in effect there is a very small discharge.
2. In the second half the HA02 is the source. Where the did it get is power from? The first set of batteries of course. We now are charging the low voltage pair and work is being done changing lead sulphate into lead and lead dioxide at the cathode and anode respectively. This chemical process raises the voltage marginally. Current flow is circular back to source which is the HA02 in this instance (not really but you get the picture).

So yes it looks correct.

 

Recieved my HA02 in the post today thanks to Chris.

Checked my batteries now, with the sun on the way down at about 52V on the bank and the individual batteries varied from 13.22 to 13.28V, so it doesn't look like I have a problem. 

Prevention is better than cure though.....

3 hours ago, Chris Hobson said:

So if you think like a chemist and not like an electrical engineer everything is fine. 

Lol

On 28/2/2017 at 4:19 PM, Chris Hobson said:

Forgive my crude graffiti on your beautiful diagram.

Don't worry about that - it helped clarify that all was OK. 

So, I am amazed! Yesterday, after just 3 days in operation (yes, just 3 days!), the marvellous little black boxes have brought my mid-point deviation down to 0.2% during bulk charge (which I have set at 55V at the moment while I am trying to get the batteries equalized). Even when these were first installed the best I saw was 0.4%.

So now, during the bulk charging phase, when the inverters hold the batteries at 55V for anything from 20 mins to 1 hour before settling them to float at 54V, I am getting a well balanced bank (although I still have to check the individual voltages in each of the 12 cells in the two strings). However, when in discharge and during charge up to around 97%, the mid-point deviation does increase to around 1% but I imagine that with time this will improve as well.

It seems appropriate that I bought these HA02s on aliexpress,com, the little brother of alibaba.com because they remind me of magic carpets, magic lamps and genies. They are like four little magic lamps that have flown in on a magic carpet and released the genies on my battery bank. I will never belittle inexpensive Chinese electronic boxes again!

On 28/2/2017 at 7:05 PM, DeepBass9 said:

Prevention is better than cure though.....

It is, and these HA02s work wonders. The sooner they are fitted to any bank the better.

17 minutes ago, incagarcilaso said:

It is, and these HA02s work wonders. The sooner they are fitted to any bank the better.

Thanks for the feedback @incagarcilaso. Yes, as I have stated before, battery balancers are not a nice to have. They are an essential part of any setup.