[SOLVED] Balance Discharger... or is there anything else?

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Slipstream   10 mW

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Re: Balance Discharger... or is there anything else?

Post by Slipstream » Mar 31 2021 3:29am

Thanks for the feedback, John.

The ISDT Q8 unit...

First problem ... non standard balance port header... standard JST cable won't fit.

My solution ... burn out the non standard blocks with a hot probe... then add a standard male/female cable so the port itself takes less abuse when the balance cables are plugged/unplugged. Until I get one of these made I cannot check the balance function, but in all, so far, I like it.

Second problem ... there seems to be no way to open the unit up ... yes I looked under one of the tiny feet pads... no way to remove the cover and look inside... so what happens if the $1 fan gives up? yep.
Last edited by Slipstream on Apr 22 2021 4:50am, edited 1 time in total.

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Re: Balance Discharger... or is there anything else?

Post by LewTwo » Mar 31 2021 5:30am

Slipstream wrote:
Mar 31 2021 3:29am
Thanks for the feedback, John.

The ISDT M8 unit...

First problem ... non standard balance port header... standard JST cable won't fit.

My solution ... burn out the non standard blocks with a hot probe... then add a standard male/female cable so the port itself takes less abuse when the balance cables are plugged/unplugged. Until I get one of these made I cannot check the balance function, but in all, so far, I like it.

Second problem ... there seems to be no way to open the unit up ... yes I looked under one of the tiny feet pads... no way to remove the cover and look inside... so what happens if the $1 fan gives up? yep.
Well I managed to get my Q8 apart then I "cut out" the bottom side of the balance port. However I plan to do the same thing and install a male-female 8S (9 conductor) extension cable ... if for no other reason than because the balance cables are too damned short to begin with.
Image
See this thread: viewtopic.php?f=2&t=110724

The assembly screws are located under stick on label on the front.
see this video https://youtu.be/B6Mq6BoGiDg
Last edited by LewTwo on Apr 02 2021 6:01pm, edited 1 time in total.
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Re: Balance Discharger... or is there anything else?

Post by Slipstream » Apr 02 2021 5:38pm

Thanks LewTwo ... thought I had bought a sealed unit there so good news it CAN be dismantled.

A balance lead header is a good idea on the basis that if you balls up the connector it is a cheap and easy fix ... not so much if you break the cable header on the box itself!

Issue: On my 8s batteries the last row seems to be higher ... despite m8 displaying 4.01v across all cells...

eg
rows 1-7 = 4.01v
row 8 = 4.20v

I haven't pushed it up to 4.2 across all cells 'cos I'm chicken.

:warn: On the whole the device is doing a much better job than the toolkitRC one ... except ... no timer ... so IF the unit is forgotten ... it WILL result in a meltdown.

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Re: Balance Discharger... or is there anything else?

Post by LewTwo » Apr 02 2021 6:38pm

Hmmmm.....

I have been looking at "active balancers" on ebay and youtube.
Just wondering if they might resolve some particularly persistent persnickety problematic balance issues.
https://www.ebay.com/itm/313224828973
Active Balancer 8S(400).jpg
Active Balancer 8S(400).jpg (16.23 KiB) Viewed 207 times
https://youtu.be/Fb52fVaMeY8
https://youtu.be/40rAkqBz8Vk

The idea is they migrate power from the highest charged cells to the lower cells.
I believe that they do require a delta voltage between the cells of 0.1 volts.
Last edited by LewTwo on Apr 02 2021 7:18pm, edited 1 time in total.
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Slipstream   10 mW

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Re: Balance Discharger... or is there anything else?

Post by Slipstream » Apr 02 2021 7:08pm

Thanks Lew ... I hadn't seen anything like this up until now.

As things stand the m8 seems to be doing ok... I have yet to try the "calibrate" function which may improve matters.

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Re: Balance Discharger... or is there anything else?

Post by TrotterBob » Apr 02 2021 9:20pm

LewTwo wrote:
Apr 02 2021 6:38pm
Hmmmm.....

I have been looking at "active balancers" on ebay and youtube.
Just wondering if they might resolve some particularly persistent persnickety problematic balance issues.

Active Balancer 8S(400).jpg

https://youtu.be/Fb52fVaMeY8
https://youtu.be/40rAkqBz8Vk

The idea is they migrate power from the highest charged cells to the lower cells.
I believe that they do require a delta voltage between the cells of 0.1 volts.
I've got the 17s version of that. Works well for any number of cells. I use it on an older 6s 4ah lipo pack that doesnt like to stay balanced.

Have also used it on a 7s 10ah headway lifepo4 pack. Balances all the cells to within .01v within a couple of hours. I've also charged that same pack at 2a with the balancer connected with no issues.

There are only 2 leds on the board to let you know that its working. And if you put your ear right next to the board you can hear a very high pitch tone

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Re: Balance Discharger... or is there anything else?

Post by fatty » Apr 02 2021 9:30pm

If you're going to re-wire/re-terminate anyway, check out node charging with a BC168.
Don't take advice from:
there is no difference between a mean well CC/CV power supply and a device sold as a charger. they operate in EXACTLY the same way
Testing has demonstrated that ordinary rim brakes thermally outperformed all but the best disc brakes...You'll always add weight and cost, while not equalling the capabilities of comparable rim brakes, if you use discs

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Re: Balance Discharger... or is there anything else?

Post by john61ct » Apr 03 2021 8:20pm

Discontinued, haven't seen any for years.


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Re: Balance Discharger... or is there anything else?

Post by fatty » Apr 03 2021 10:42pm

john61ct wrote:
Apr 03 2021 8:20pm
Discontinued, haven't seen any for years.
I just got a new one.
Don't take advice from:
there is no difference between a mean well CC/CV power supply and a device sold as a charger. they operate in EXACTLY the same way
Testing has demonstrated that ordinary rim brakes thermally outperformed all but the best disc brakes...You'll always add weight and cost, while not equalling the capabilities of comparable rim brakes, if you use discs

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Re: Balance Discharger... or is there anything else?

Post by john61ct » Apr 03 2021 10:45pm

wow kewl thanks

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Re: Balance Discharger... or is there anything else?

Post by DogDipstick » Apr 04 2021 11:15pm

Dammit. Not knocking your purchase, but that charger sucks.. and the specs are all over the place. Is that like a glorified Opus charger? lol.

Is it 15v? or will 14v blow it up? Says 15v, but below says over 14v will blow it up.

It cannot do 6s (x) 8A balance current. nope. Can only 33w per. So there, the 8A is a lie.

It has a 80% buck boost shift efficiency. Every 250w you put in you only get back 200w. Thats alot of waste.

4.2w / 6 cell discharge... ?!?!?! WTH is that? Like.. 4 point two watt hours per hour discharge.. BahahahahGood luck discharging your 60Wh+ cells, let alone a 360Wh 6s pack.... at four-point-two watt hours per hour...
Also says "2020 New Released 4.35V Supported" ... but below is " 4.20v max"...

Im so confused. I wonder what its resolution is.

Not a very powerful hobby charger. I am soooo glad my Revolectric is U.s. designed. Thousands of watt discharges.... over and over... for years on end.. t has given me.


nput Voltage: DC 12 - 15V (you need an external AC Adapter)

Warning: Do not use a Power Supply over 14V of Voltage. There will be a repairing cost for over input current because the factory knows that when the particular ICs burnt out on the PCB.

Input Wattage: 250W
Charge Power: 200W (33W x 6Cells)
Discharger Power: 25.2W (4.2W x 6Cells)
Balance Power: 200W (33W x 6Cells)
Charger Voltage Adjustable Range: 1.50V 4.20V (Pre-set up 4.2V)
Charger Current Adjustable Range: 0.1A -8.0A (Pre-set up 1.0A)
Charge Temperature Alarm Adjustable Range: 20 80 Degree C (Pre-set up 80 Degree C)
Discharge Voltage Adjustable Range: 2.00V 4.20V (Pre-set up 3.80V)
Discharge Current Adjustable Range: 0.1A 1.0A (Pre-set up 1.0A)
Balance Voltage Adjustable Range: 2.00V 4.20V (Pre-set up 3.80V)
Balance Current Adjustable Range: 0.1A 8.0A (Pre-set up 1.0A)
Charge Voltage Precision: +/-0.001V
Discharge Voltage Precision: +/-0.001V
Balance Voltage Precision: +/-0.001V
Charge Shift Efficiency: =>80%
Charger Consumed Power: =<1.8W (12V 0.15A)
Suitable Battery Type: 1 6Cells (Working Well with LiPo / Lilo / Life)
Weight: 750g
Dimension: 165 x 123 x 52mm
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Re: Balance Discharger... or is there anything else?

Post by john61ct » Apr 05 2021 1:18am

Node chargers are a different category, maybe you don't think they are useful in general

but if you want to say it is a bad node charger, then specify those that are better please.

It puts out a pulsed current in order to measure the "reverse bounceback" delta, kind og like getting a bead on resting voltage.

nominally at 8A but in effect 4-5A if calculating delivered area under the curve.

Also why it doesn't melt the wiring and JST connector designed for balancing only current levels.

It does not do any balancing at all as usually defined, there is no comparing cells voltages, each cell gets an independent charge circuit.

It does not seem to be designed for discharging batteries of any capacity though.

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Re: Balance Discharger... or is there anything else?

Post by TrotterBob » Apr 06 2021 11:44am

I'm familiar with Rc balance chargers. They usually dont have a whole lot of discharge current. Even Revolectrix doesnt. I have one and it does 50 watts of discharge when connected to a power supply. It goes higher if you use the regen feature but thats only if you have batteries as a power source. It wont feed power back into an ac/dc switching power supply.

For li-ion and lipos you shouldnt need a whole lot of balance capability if the pack is healthy. And those thin wires you find on a jst-xh balance lead only handle so much current.

The Rc aircraft guys tend to use gigantic resistor/heatsink combos that they make themselves for quicker discharging. Or sometimes they put 2 12v automotive bulbs in series to discharge 6s packs. I havent tried this myself so I dont have any specific recommendations, especially for the 12s and higher cell counts found on ebikes and other personal EVs.

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Re: Balance Discharger... or is there anything else?

Post by LewTwo » Apr 06 2021 12:33pm

TrotterBob wrote:
Apr 06 2021 11:44am
The Rc aircraft guys tend to use gigantic resistor/heatsink combos that they make themselves for quicker discharging. Or sometimes they put 2 12v automotive bulbs in series to discharge 6s packs. I havent tried this myself so I dont have any specific recommendations, especially for the 12s and higher cell counts found on ebikes and other personal EVs.
I came by two of these some time ago but have never used them. They are supposed to be "variable" but the insulation paint/coating tends to flake off and I do not trust them in that regard. Might try using the pair for larger battery packs.
uxcell 200W 12 Ohm Wire Wound Tubular Resistor(Series) (900).jpg
uxcell 200W 12 Ohm Wire Wound Tubular Resistor(Series) (900).jpg (42.42 KiB) Viewed 153 times
*** That drops down to 2 Amps and 96 watts at 48 volts.
So you are still looking at 5 to 6 hours for a 12 AHr battery pack.
The more I learn the more obvious the immensity of my ignorance becomes.
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Re: Balance Discharger... or is there anything else?

Post by TrotterBob » Apr 07 2021 5:19am

You could just buy an inverter with a 48v input. Then plug in a space heater or something. I've got a smallish window AC unit that draws about 450 watts. But keep in mind that some AC appliances have a current spike on startup.

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Re: Balance Discharger... or is there anything else?

Post by john61ct » Apr 07 2021 5:46pm

There is a huge difference between "rough" discharging packs for storage

and needing precise CC regulation for accurate capacity testing of individual cells.

The purpose of using chargers like FMA PL and 4010 is to get the latter control functionality.

Apparently at that 2-4V discharge range, 1 ohm is the correct resistance

and both the aluminum and ceramic units work great.

Heatsinking is critical, whether aircooled or tossing in a tub of circulated water.

For 200+ Ah cells, getting past 150W or so is required for reasonable discharge rates

Higher than that apparently some of the "dummy loads" can be paralleled, but have not seen detailed reports on that.

The final issue is getting good data logging to record pretty charts.

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Re: [SOLVED] Balance Discharger... or is there anything else?

Post by Slipstream » Apr 16 2021 3:55am

A few charges done now.

The ISDT Q8 charger has my rows within 0.01 of a volt of each other so no need for further balancing.

This is a bit of a miracle, actually, because my packs are made up of second hand cells, and a pretty good mix at that.

In fact ... this has solved my problem.

Niggles remain...

No timer on the Q8 means ONE lapse in charging routine ... forget it ONCE ... and you will have a nice indoor fire that your neighbours will remember for a long long time.

The balance port is proprietary so it will need to be reshaped.

Otherwise all good for charging 8s6p @ 2amps ... that's 65w.
The charger will go further (up to 500w apparently) but I do not have a DC PSU that will supply the current required.

PS. Thanks for the input guys.
Last edited by Slipstream on Apr 22 2021 4:51am, edited 1 time in total.

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Re: [SOLVED] Balance Discharger... or is there anything else?

Post by LewTwo » Apr 17 2021 4:23am

Slipstream wrote:
Apr 16 2021 3:55am
The M8 charger has my rows within 0.01 of a volt of each other so no need for further balancing.
I do not want to nitpick but I am curious which charger you wound up using ...
In a previous comment you said "ISDT M8".

I believe "M8" is an RCToolkit number.
"Q8" is similar charger by ISDT.

Can you clarify which you actually used?

Thank thee.
The more I learn the more obvious the immensity of my ignorance becomes.
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Re: [SOLVED] Balance Discharger... or is there anything else?

Post by Slipstream » Apr 22 2021 4:52am

Hi Lew ... sorry ... yes ... edited above with correct info.

I ended up with the ISDT Q8.

: )

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