Charging amps through JST balance wires

ebike11

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Hi guys
Im trying to charge/balance my battery packs with ISDT Q6 pro.
I read that 1A is a safe amount of charge that is recommended to go through balance wires. The Q6 goes up to 14A.
I have the input connected to the wall socket and the main battery leads are connected to the output of the Q6 alone with the JST connected.
Since the main leads of my battery is connected to the output, does that mean i can safely charge much higher than the 1A ?? My concern is the limitations of the very thin balance wires. Its a 5s pack
Thx in advance!
 
Is that charger designed to charge that way?

BC168 apparently goes to 8A, but it's pulsing, lots less heat buildup vs CC/CV.

Many users say 4-6A is OK but must vary by batt model?

others re-solder heavier wires too.
 
john61ct said:
Is that charger designed to charge that way?

BC168 apparently goes to 8A, but it's pulsing, lots less heat buildup vs CC/CV.

Many users say 4-6A is OK but must vary by batt model?

others re-solder heavier wires too.

Here is a product link...i dont need to charge up to 14A but Id like at least up to 8A or so. 1A would take a while.
Do you mean they solder heavier balance wires?
This charger has a fan which goes off and on at a regular pace, im guessing its pulsing as you say

https://m.aliexpress.com/item/32950697667.html?pid=808_0000_0101&spm=a2g0n.search-amp.list.32950697667&aff_trace_key=fbb530e4d22946c58ee9c7d936bcf3d8-1546944932218-01234-cD4TW1tW&aff_platform=msite&m_page_id=6407amp-hikUbgHVhuQPHUyktHt-sg1547687673970
 
I don't see any indication it charges via the balance leads by design.

And I mean some replace the flimsy connectors on the BC168 in order to safely go above 4-5A.

And no I meant the BC168 is a pulsing type charge power output, which keeps those thin wires cooler.
 
I have three of these chargers and they do NOT charge through the balance leads. They won't even work unless the balance leads and the main power lead are hooked up properly.
 
Volt_Ampere said:
I have three of these chargers and they do NOT charge through the balance leads. They won't even work unless the balance leads and the main power lead are hooked up properly.
Ah ok thx for that...so charging at high amps should be fine if the battery can handle it
 
The connectors are rated for 3A. So i would say that's a safe limit for sure. I never go over that. Why? I don't know, but i don't trust those thin wires and i don't like to stress the charger itself. And most of the time it's fast enough. :)
https://www.digikey.at/en/product-highlight/j/jst/xh-series-connectors
 
when i've done this 20-22ga wires become uncomfortably warm somewhere around 3-4A

people do push it beyond that but not ms prudence
 
Volt_Ampere said:
I have three of these chargers and they do NOT charge through the balance leads. They won't even work unless the balance leads and the main power lead are hooked up properly.

Is it normal for Q6 to decrease its charging amps as it gets close to full battery capacity?
I set mine at 2A but its only putting out 0.4A or so
 
izeman said:
That's what EVERY charger does. It's called CC/CV. Meaning it's constant current in the beginning and near to the fully charged voltage (or whatever voltage you set for charging end) it reduces the current, more and more the nearer it gets to this voltage.

I see...
Its taking forever for my last cell to get to 4.20.
4 cells are at 4.20 now but the last cell is at 3.88.
 
You can get a phone charger and charge the one cell. Check the charger for real voltage and you must seat and watch so it will nevergo over 4.18volts. So you Must seat and monitor. Because as soon as you light up it will over charge . Bad very bad. Just reading the printed label on the charger is not good enough. Must check and check polarity.
 
ebike11 said:
Its taking forever for my last cell to get to 4.20.
4 cells are at 4.20 now but the last cell is at 3.88.
Then the last cell (group) is defective and should be replaced.

Such a huge difference in voltage means it is also different in capacity, so that cell will run out well before the others do, shortening your range.

Probably also means that it has higher internal resistance and makes the whole battery pack sag in voltage more than if it matched the other cells.
 
amberwolf said:
ebike11 said:
Its taking forever for my last cell to get to 4.20.
4 cells are at 4.20 now but the last cell is at 3.88.
Then the last cell (group) is defective and should be replaced.

Such a huge difference in voltage means it is also different in capacity, so that cell will run out well before the others do, shortening your range.

Probably also means that it has higher internal resistance and makes the whole battery pack sag in voltage more than if it matched the other cells.

Actually all cells were at various voltages before balancing
I got 4 caught up to 4.20v...last one is slower but is still slowly charging
 
amberwolf said:
ebike11 said:
Its taking forever for my last cell to get to 4.20.
4 cells are at 4.20 now but the last cell is at 3.88.
Then the last cell (group) is defective and should be replaced.

Such a huge difference in voltage means it is also different in capacity, so that cell will run out well before the others do, shortening your range.

Probably also means that it has higher internal resistance and makes the whole battery pack sag in voltage more than if it matched the other cells.

While montoring the Q6 I noticed that it doesnt charge/balance all cells at once. It seemsnfocus on charging one or two cells at a time over the other ones.
 
Balancing a heavily disbalanced pack with a charger like the Q6 can take forever. I will NOT charge the low cells until it pulls down the high cells down to a reasonable level. The it charges ALL cells again. As the one low cell is somehow worse than the other (lower capacity, higher internal resistance) i will also not take charge a fast as good cells so it makes the whole process even slower.
As otherd stated: the battery may be already damaged to a point where it shouldn't be used as is anyway. But that's hard to judge w/o knowing all details.
 
izeman said:
Balancing a heavily disbalanced pack with a charger like the Q6 can take forever. I will NOT charge the low cells until it pulls down the high cells down to a reasonable level. The it charges ALL cells again.
It's the same way almost all common BMSs balance, as well.

When a cell (group) is as far off as that low one is, it's got a problem and is just going to get worse.

If it's an internal short in the cell it could eventually and indirectly lead to a fire.
 
izeman said:
Balancing a heavily disbalanced pack with a charger like the Q6 can take forever. I will NOT charge the low cells until it pulls down the high cells down to a reasonable level. The it charges ALL cells again. As the one low cell is somehow worse than the other (lower capacity, higher internal resistance) i will also not take charge a fast as good cells so it makes the whole process even slower.
As otherd stated: the battery may be already damaged to a point where it shouldn't be used as is anyway. But that's hard to judge w/o knowing all details.

I see what u mean
But 4 of the 5 cells are already at 4.20v
Wouldnt it be easier to just patiently wait for the final cell to charge/balance rather then having to discharge 4 cells?
 
That's how almost all balancers work--they drain high cells, then restart charging, etc.

It can take days, even weeks, for a badly balanced pack with bad cells to rebalance, and as soon as the pack is used again it's going to unbalance a little, and the more capacity is used, the deeper the discharge, the more unbalanced it will be.

All the cells are charged thru the main wires, in series, so high and low all get teh same charging current.

All the cells are discharged thru the balance wires, so it can drain high ones.
 
ebike11 said:
Wouldnt it be easier to just patiently wait for the final cell to charge/balance rather then having to discharge 4 cells?
For sure, but this is not how they work. It's easier to open a transitor gate that is connected to a little resistor and let it burn all the energy that is too much. Redistributing charge current is much more complicated.
 
izeman said:
Balancing a heavily disbalanced pack with a charger like the Q6 can take forever. I will NOT charge the low cells until it pulls down the high cells down to a reasonable level. The it charges ALL cells again. As the one low cell is somehow worse than the other (lower capacity, higher internal resistance) i will also not take charge a fast as good cells so it makes the whole process even slower.
As otherd stated: the battery may be already damaged to a point where it shouldn't be used as is anyway. But that's hard to judge w/o knowing all details.

The Q6 only discharges at a VERY slow rate. I thought it was gonna be a much more effective product.
If there is a gap in cells then youll have to wait for a long time to dischage before charging them again
 
ebike11 said:
The Q6 only discharges at a VERY slow rate. I thought it was gonna be a much more effective product.
If there is a gap in cells then youll have to wait for a long time to dischage before charging them again
I wouldn't call it ineffective. It's just that stored energy is converted to heat by little resistors. The heat generated is limited somehow if installed in little cases. So those resistors are quite small - but this is the same with 99% of all RC chargers i know of. There are some that can balance at a little higher rate, but still NOTHING compared to something like a BC168 or UN-A6 (which i prefer more), as those chargers basically are 6 completely seperated chargers in one case, so they can act independently and handle each and every cell individually. I have all different chargers that handle different needs: Big bulk chargers for fast charging of big packs with BMS, RC chargers for those little RC toy LiPo packs, and UN-A6 and BC168 to do balancing of big packs before assembly or also for charging small RC packs. Those chargers are really convenient and i wouldn't like to miss them.
 
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