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How to quickly top balance EVE 280 cells?

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(@vaugi)
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@transparent 

This is the supply I used

http://www.amazon.co.uk/gp/product/B07P5KWPBM

61M5t+ypPIL. SL1500

When I did my home setup this PSU was a bit confusing with the Constant Current and Constant Voltage.  I set it up for constant voltage, at 3.6v and 10A.  When the load is put on,  It flicks immediately to Constant Current (LED lit) and display shows approx 3.6v/10A/30W during initial phase. however when the voltage (a number of days) rises it automatically flicked onto Constant Voltage (LED lit) and the voltage always reading 3.6v but then the Amps drop until zero.

I did a few google searches and came to the conclusion this is how this PSU works from other comments.  I could be very wrong on that, perhaps others have experience of these?

So, in this case I wasn't worried about it showing 3.6v/10A as I knew it was trying to get to that point - I had been checking with a multi-meter every day for the true voltage.

For info, I've got the cells down to 3.4v now - this was the guy who did a compression...I'm just not sure about using them now though, even I manage to get them compressed.

https://www.youtube.com/watch?v=IMWIkdInBTo&t=89s

This post was modified 10 months ago 3 times by vaugi

   
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(@chickenbig)
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Posted by: @vaugi

Argh!  I have properly buggered up.

Ooof, sorry to hear things have gone a bit wrong. Top balancing (the last bit of it?) is the only time the cells are operated without a BMS so are most at risk of extremes. I guess a very specialized 1s 10A BMS might have prevented problems (provided the limits are set correctly).

Perhaps there are more and less intuitive (and safe) power supply with regards to setting limits. I also saw on YouTube a problem caused when power supply dial was altered by something dropping on the knob while charging overnight.


   
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Transparent
(@transparent)
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Although it wasn't the case on this occasion, I agree with @chickenbig in not liking power-supplies which can be altered by accidental touch.

The cheapest/most effective power-supply which fits the requirements for top-balancing will be one from the Riden range.
These have voltage and current which can be set using either the hex keypad or the rotary dial.
But, once set, the dial can be rotated/knocked without altering those preferences.

Here's a photo of the 18A unit (RD6018), although they are also available with max-currents of 6A, 12A and 24A

image

You can get them on ebay or Amazon, but Banggood offer the 18A one direct from China at less than £85 incl VAT and carriage, which is very good.

The Riden approach is to sell the front-panel as a separate item.
You then add a standard switch-mode PSU unit which can offer at least the max current you wish to draw from that front-end electronics.

So for top-balancing cells to 3.6v, you'd need a PSU at no more than 12v 18A.

 

In contrast, you can get next-day delivery of a 10A bench power supply like @vaugi has from Amazon for somewhat under £70
plus £2000 for a set of replacement cells if it should go wrong. 😢 

 

Save energy... recycle electrons!


   
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(@misterb)
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i followed the advice given on this you tube video - i also followed the advice by his dad when he just used a simple wire setup to connect for the top balancing - its just 2.5mm cable with the insulation removed at the points that coincide with the cell terminals 

 

 

https://www.youtube.com/watch?v=itV-oaCBnvw

 

 

it took well over a week for me to do mine - so i dont think there is a 'quick way' to top balance the cells 


   
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(@vaugi)
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Just as an update to this - I was holding off replying until resolved.  I spoke to Ben the owner of Fogstar, who has very generously set me up with a new order at reduced price for 16 new cells, and also thrown in new foam pads and busbars.  Obviously I declared it as my fault and wasn't trying to assign blame, but it seems you can definitely rely on Fogstar to do good things for you.

The other set I have running as a single Seplos box, and I've not top balanced them.  I'll do the same with the new one as the Mason box is ready to go - and I can see how they run without being top balanced.

At some point I hope they will be part of a 60kWh set, so if I'm not quite getting near the top or bottom I don't believe it will matter hugely.

As for the 16 bloated batteries... I think I might try to compress and set up as 12v banks of 4 and see if I can find a more off grid use for them and see how they fair.  No idea what yet though!


   
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Transparent
(@transparent)
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Posted by: @vaugi

At some point I hope they will be part of a 60kWh set, so if I'm not quite getting near the top or bottom I don't believe it will matter hugely.

I don't think you need be concerned about that point.

The reason we top balance is to create an even charge in each cell. It means that the balancing action of the BMS isn't left struggling during the early months of use, especially if the balancing current is low.

But a BMS should eventually 'succeed'.

You're not condemning your battery to be forevermore operating at lower capacity than its true potential.
That issue affected Nickel-based rechargeable cells.

 

I used 12v batteries to provide energy for lights in a chicken coop.
A micro-controller turned them on about an hour before sunrise throughout the year.
It fools the chickens into laying more eggs because the day-length gets longer (earlier spring).

So if you'd like your bloated cells to provide you with useful payback, then that's one possible idea.

BatteryHenBSm350

It brings a whole new meaning to Battery Hens.

This post was modified 10 months ago by Transparent

Save energy... recycle electrons!


   
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(@vaugi)
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Topic starter  

@transparent 😀 

I had thought about 12v lighting, or even winter heat matting in a future greenhouse.  Would need to design for high and low temps, humidity though in a greenhouse so might end up putting that one off.  Either that or power for kids treehouse, if I ever get round to that project before they are adults! 🙂


   
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(@vaugi)
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Had a thought about the bloated cells (or even new cells) if they compress reasonably okay.  I need to buy a fork lift for a warehouse, the replacement lead acid batteries cost a lot (£2-£3k I hear), and from experience of one they seem a handful to look after anyway. 

I could get a forklift with no battery or a duff battery and replace with LifePO4 cells - match the voltage required with a 24/36/48v BMS, possibly multiple if higher Amps needed. I would probably have to set steel and concrete in the bottom of box as the weight is required for counterbalance purposes.  Could even be plugged into an inverter when not in use and smooth the solar that's on the warehouse.  I wouldn't need to match the capacity as such as we only use a fork truck every now and then.  2-3 hrs use would probably  suffice, and we'd probably get fairly quick charge out of an inverter for a quick top up.

Any immediate flaws?


   
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