8S or less alternative to top balance with potential future awesomeness.

sunshine_eggo

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This charger, 20A 1-8S balance charger:


8S balance leads (no, you don't need 10, and you'd only use 5 of the 9 wires for 4S):


and XT-60 cables/connectors:


40A 12V power supply (will need a little more if you want to use the full 500W on a 24V LFP):


(EDIT: ebay has lots of 12V server power supplies for cheap, see below)

EDIT: I had inadvertently linked XT90 connectors. Fixed.


A little more spendy than the 30V/10A power supply - about as much as another Overkill, BUT it has multiple benefits.
  1. Up to 20A charging at battery voltage vs. 10A charging at 3.65V max when balancing.
  2. For 8S or less, you build the battery ONCE.
  3. Automatic balance charging
  4. Hands-free operation, set it and forget it even if you know you're going to check it obsessively.
  5. Future balance convenience for 8S or less batteries.
Even if you have more than 8S, you can XPYS (X = # of parallel cells, Y = # of cell groups in series) and enjoy 1, 3 and 4.

Fab balance leads
Fab main charge cables
Attach to PS and battery
Set Balance charge parameters and peak current (stay within limits of power supply)
Press start
Walk away
Unit will charge at the lesser of 20A or the limit of the 40A power supply, and you'll need to set the charge current @ 16A for 8S.
Once first cell(s) hit(s) limit, current is tapered to hold that voltage, and it begins balancing other cells.
Once cells are all at peak and current drops below threshold (usually 10% of start current), charger stops, battery balanced. Done. Drop your mic and take a bow.

For 8S and smaller batteries, you could leave the balance and charge leads attached. If you ever need to top balance again, such as after a period of storage, you'd simply plug in, turn on, press start and walk away. PROFIT!

Yes, more expensive and less flexible than a 30V/10A supply for other stuff... but be honest, if you had to buy one for this, you probably won't use it for anything else, BUT it offers maximum convenience and SPEED for initial and future top balancing. :)

Thoughts?
 
Last edited:

Bob B

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Sep 21, 2019
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I didn't try to find the manual for this charger ..... do you know how much balance current it has?
 

Bob B

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Sep 21, 2019
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Thanks for the manual link ..... it is listed in the specs in that manual.

1636767019624.png
 

fafrd

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Thoughts?
My thoughts are that if BattGO offered this model when I bought my passive BattGo monitor / balancer: https://www.amazon.com/ISDT-Battery-Meter,LCD-Capacity-Balancer/dp/B07797N9BG/ref=asc_df_B07797N9BG/?tag=hyprod-20&linkCode=df0&hvadid=198090249012&hvpos=&hvnetw=g&hvrand=9924076092106313150&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9057125&hvtargid=pla-391484147019&psc=1

I probably would have sprung the additional $30 / 75% for this active balancer.

As it is, once I realized that the BattGO’s passive balance function was essentially useless, I got a Heltec Active Balancer for about that same additional investment (it’s cheaper if you purchase directly from Heltec): https://www.amazon.com/Heltec-Equalizer-Balancer-Transfer-Capacitor/dp/B08D9D4NGW

For getting a pack balanced once, either will work, but the advantage of Heltec’s active balancer is two-fold:

1/ does not need a separate 20A or 10A charger - it actively redistributes charge between cells powered directly by the cells/battery itself (so more efficient).

2/ it can be controlled by an external relay to either top-balance whenever the battery is fully charged or to bottom-balance once the battery is fully-discharged. So it can be left always-connected to maintain a balanced battery even in the case that cell self-discharge rates are mismatched (within limits).

But I’ll certainly say that the BattGO battery monitors are a good way to monitor cell voltages and balance and for the modest premium involved, this new active balancer model is probably worth the modest premium.
 

sunshine_eggo

Happy Breffast!
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Skip that powersupply. Looks like a cheap chinese one, and generally I don't like their reliability.


Instead, get yourself an old server PSU. Can be found for $15 on Ebay.
Cheaper, much better quality, and more amps (a HP 700W PSU does 56A @ 12V, their 1200W models do up to 100A @ 12V)

Example: https://www.ebay.com/itm/265252164197

Thanks for that. I completely forgot about those. I have a couple of server PS that put out 12.4V/85A, which are ideal for my particular use, but I paid around $80 for them, so I dismissed it. I completely forgot how prolific the lower power ones are. Definitely the best choice!
 
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