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Seplos Mason DIY Kit - Ancillaries - Advice

 
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Last Post by MisterB 2 years ago
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 Transparent
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08/12/2023 7:16 pm  

@makia2023 - by my reckoning your LiFePO4 cells from China should be heading out of the Mediterranean around now.
Are you following the ship online?

For any others who are interested in pursuing this DIY strategy, I'm told that the EVE A-grade 280Ah cells are now being offered at $75 +VAT.
That's a 13% price reduction in the last 6-months.

Shipping costs (maritime) for a batch of 16 cells would be somewhere around $225-$250 DDP. That means import taxes will have been paid by the sender.


This post was modified 2 years ago by Transparent

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 Makia2023
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Topic starter 08/12/2023 7:32 pm  

@transparent hey hey. Yes.....note my silence as I focus on other things while they float over here. They are due in to Felixstowe 16th Dec. Any insight as to if I will receive before 25th?

Once in I will do a write up of the install .....and almost certainly need some help from you fine gents to set up!



   
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Transparent
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08/12/2023 7:42 pm  

Yes, I would fully expect them to be with you before 25th.
In my experience a courier with staff permitted to work inside the customs zone at Felixstowe will get busy unpacking the container in which they've been shipped.
They will then present them to customs, and put them straight onto one of their own vehicles, which takes them to the national sorting hub.

It takes the dock workers about 3 days to unload the UK containers from a typical Far East vessel.

The unknown part of the delay depends on where your shipping container was positioned within the cargo. But I've never had to wait more than 6-days between the ship arriving at Felixstowe and the boxes being delivered to my door.

 

I'll assume you want to top-balance each set of 16 cells in series before you build them into a Seplos enclosure?

How prepared are you with a suitable power supply to tackle that job?


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 Makia2023
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Topic starter 08/12/2023 7:46 pm  

@transparent that is my next question. How do I go about top balancing 48 cells.......?



   
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 Makia2023
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Topic starter 08/12/2023 7:47 pm  

Also providing they are within small voltage of each other, could I just build?



   
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08/12/2023 8:09 pm  

If they're all from the same manufacturing batch, then there is unlikely to be much difference between the SoC (State of Charge) between the cells.
There's little point measuring the voltage to see their status on arrival. You won't get a decent answer unless you're drawing 20+ Amps over several minutes.

There's no such thing as them being 'pre-charged' by the manufacturer.
They will simply exhibit the charge-status which reflects the chemistry of the electrolyte when they were made.

I generally reckon on them being around 20% SoC.
So it could take a week to bring a set up to full-charge, depending on the available current from your power supply.

As you've got four sets of 16-cells, you could start building one set into a Seplos box immediately,
and have a go at top-balancing the next set of 16 using a power supply.

If you have problems with the Seplos BMS taking ages to balance the first set (because the balance current is so low), then it won't matter so much because you'll be able to get on with assembling the other units.

The power supply needs to have

  • high current (at least 12A, and preferrably more)
  • low volts; you're going to leave it set on 3.6v whilst the balancing operation is in progress
  • a voltage-setting knob that you can't accidentally alter by brushing against it!

 

I use (and recommend) the units from Riden.
They have a front-panel with an LCD and digital set-up controls, which is effectively a programmable DC-DC converter.
You feed that front-panel from an off-the-shelf SMPSU box like this:

image

You can buy a steel enclosure that houses the SMPSU and suits the front-panel, or you can make do by fixing them to a piece of plywood.
The only bit you need to be careful of is the mains input to the SMPSU.

Do you want more detail than that?

TopBalancing960

This post was modified 2 years ago by Transparent

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 MisterB
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08/12/2023 8:13 pm  

@makia2023 i would advise you to top balance them ..... it will take over a week, prob nearer two weeks.



   
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08/12/2023 8:20 pm  

You still might have time to fly in a Riden RD6018 unit from China with a guaranteed 12-day delivery.
That's an 18A max output.

But there are also some sellers who seem to have stock available next day from Amazon for not much more cost.

The Riden system comes in multiples of 6-amps:
RD6006 is 6A max output
RD6012 for 12A
etc


This post was modified 2 years ago by Transparent

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 Makia2023
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Topic starter 08/12/2023 8:42 pm  

@transparent ok bear with me. I'm still up for top balancing......but if I didn't and set the minimum discharge to 30% protect the cells which might have a lower voltage? I would then let them self balance over the coming months slowly. Or am I totally missing the point?



   
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 Makia2023
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Topic starter 08/12/2023 8:42 pm  

Essentially what are the downsides of not (for my education).



   
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 Makia2023
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Topic starter 08/12/2023 8:53 pm  

Could I install a neey 4aml active balancer and set the voltage range on the pack to slightly lower until it is balanced?



   
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Transparent
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08/12/2023 9:40 pm  

As you'll have the Seplos units in parallel, you can't just set the voltage range lower for one unit.
They're all eventually going to balance out over time.

I don't understand the cost benefit of buying four Active Balancer units rather than investing in a very reasonably-priced digital PSU.
Isn't the cost about the same, whichever way you go?


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