2nd Look: iSDT BG-8S Smart Battery Cell Balancer

[@pepper669]

Watching paint dry with Julian must be fun!

[@sNEAKYnIGHTmUPPET]

Hey Julian. I thought that maybe you would like to know that you do NOT need a diode. I have that same board and I use it pretty much like you do and have never needed a diode. There is no damage to the unit by having a battery connected without a diode, I can confirm this first hand. Originally, I used a diode because in your video you said that it was required, but then after a while of having to account for the voltage drop across the diode, I got fed up and thought that I would just try without and see what happened. I was surprised to discover that nothing happened, it just worked like you would expect. anyways, use it without a diode, there is no advantage to using one. :)

[@JulianIlett]

Good to know :)

[@mircoheitmann]

i have LiPos only. now i dont have a LiFe?

[@RWBHere]

Better than playing NiMH all day? Let someone else take the Lead?? But don't end it all with a NiFe! . . . O.K, I'll close the door when I leave.

[@SKElectronics]

The balance charging of 4 button charger like the imax b6. First it charge all the cell and when 1 of the cell reaches to 4.2v and rest of the cell are still bellow 4.2v then it stop charging and discharge the cell which reaches to 4.2v and then again it start charging all the cell until all the cell reaches 4.2v.

[@richardgrier4721]

Seems like a good idea to wire the diode INTO the cable (not exposed externally, so add some heat shrink). Then, if you short the "pins" together, nothing bang-like will happen.

[@harryjnr2335]

I fully enjoyed this, nice one Julian

[@AdamWelchUK]

Interesting video. I have bought one so no doubt I'll do my own session of sitting and watching the numbers. Earlier in the video the first cell was often lowest - do you think the unit powers itself from cell 1 and could that be different if the main battery connector is attached I wonder? Also might that adjust the screen sleep time - putting the screen load on the whole pack rather than one cell? Video three - discharge current please :-) Cheers Julian.

[@aspendell209]

I have to concur with Adam. Since this is essentially a glorified battery monitor, it only does 2 useful non-passive functions. The main one being balancing, although the up to 24w (12v @2A) output to a USB 3 is nice, if you don't already have devices with this feature. A couple evals done at RCgroups.com have suggested that the balancing is extremely uneven. This suggests that they are using an algorithm, to cycle through the individual cells and discharge each in sequence, that is not very robust. But we really need to see those discharge (ma) numbers to see if this is really worth 4-6X as much as the $6 8s battery checker that can only discharge/balance at 50-100ma, but also has internal battery resistance checker, which this one does not. ~Cheers~

[@markflack9191]

Your poor solar battery bank got a good workout doing this, we need more sunshine to keep them charged up, but hey, it is September.

[@pmkwiek]

Will it restart balancing in blue mode? The reason the led may have a harsh flash could be due to it pulling more power as opposed to when it is in true sleep mode. This harsh flash could be a good indicator of "hey im not actually sleeping" because you are more likely to notice the hard flash.

[@JulianIlett]

It doesn't go back to the green mode once in the blue mode, but it does appear to hold the cells in balance in the blue mode.

[@7328971]

I need a 16S device like that.

[@HannesMrg]

Nearly overlooked the video because there was no green cutting mat in the thumbnail :D

[@GustavSolin]

If you plug this unit in and put it on balancing. Will the unit continuing balancing as a battery monitoring system or will it eventually stop balancing and go in to view mode? Will it go back to green after the cell voltages differences increases when it's in blue mode? I watched the hole video hoping you could answer this questions i had. Can you please tell me?

[@jkenny1]

Just a word of warning, I checked the accuracy of the BG-8S I got and the cell voltages can be off by up to 82mV (at least the way I measured, applying a voltage across two adjacent balance pins but not applying a total "pack" voltage to the balance leads). I'll try it again with a proper 8S battery to make sure the test method is valid, but I wouldn't expect it to meet the +/- 5mV spec it claims. Data is here if you're interested: goo.gl/FYx1He

[@jkenny1]

Update, looks like with a real battery things are looking much better, only 8mV delta at around 3.8V per cell in an 8S string.

[@twotone3070]

Without looking I recall the max balance current for the unit was 400mA, so could you not, at the end of the charge, set the charge to 400mA and do the balance whilst charging, rather than stop start?

[@JulianIlett]

Yes, I've been watching this setup for the last couple of days. It seems the BG-8S discharges at more like 100mA, so using it to balance charge this big battery is taking forever :)

[@martink9785]

Sadly my weekend has been spent doing the same thing but with bigger cells :) I smile because I too enjoyed watching it. Thinking to shuffle some parallel pairs so i have the largest with smallest capacity so that the whole pack stays more balanced. What do you think?

[@MrBrymstond]

When balancing, the device should add the voltage and current from the higher charged cells to the weaker cells instead of just discharging to the lowest voltage cell.

[@simontay4851]

That is much more complicated to do that just simply switching resistors across the higher cells.

[@MrBrymstond]

I know how they do it, but it's a waste of energy and easily done with a IC Chip and some software. This would give the cells a long life

[@_Piers_]

This is probably a very simple thing, that I'm just not getting. How did he measure the voltage dropped by the diodes? I was thinking, you'd need to measure the voltage before and after, then subtract to get the reading. He seemed to just measure it directly.

[@JulianIlett]

I just connected my meter across each of the diodes in turn

[@sylvainlazare1114]

If one cell starts having a non regular behaviour, the voltage balancing is a sort of protection but not a curing, is'n it? This cell has to be replaced or do you continue using it? Thanks Julian!

[@ahaveland]

The effective capacity of the whole pack is reduced as it must be disconnected or recharged when a weak cell reaches its minimum voltage. Ideally it's time to replace the bad cell if the discrepancy reduces the effective capacity of the battery too much. The good thing with top balancing is that when cells that differ widely at the bottom are recharged, they should come back in balance when full. Bleed balancing is ok if all the cells are closely matched but terribly wasteful if not, and the balancer may never even succeed, especially if internal resistance of the cells has increased and leakage increases. Balancing on top and bottom is just madness, because much of the batteries charge is wasted just trying to keep them in sync needlessly! A much better but more expensive method is to use multiplexed solid state relays to monitor each cell and use a flying capacitor to redistribute the charge by slurping from high cells and injecting into low cells as needed, usually at the top. Technically this could balance at high currents, and see a battery all the way to the bottom with all the cells still balanced, though there are still losses involved during charge transfer. Would be a nice project for someone to make...

[@joinedupjon]

Isn't there a setting for increasing the length of time the screen stays lit up? seems like a real annoyance. nice that the screen colour coordinates with the breath light but colour codes could be regarded as a bit iffey - not colourblind myself but a lot of people are

[@JulianIlett]

Unfortunately, there's no display timeout setting - I'd like to keep the display on permanently.

[@duncanyoung8688]

Hi Julian,where can I get the power supply you have in this video? what voltage does it require in?

[@SpeccyMan]

Search for B3806 on eBay and since it is a buck/boost it'll happily work with a 12V input.

[@ahaveland]

1amp charge rate? Life is far too short - you could charge them at 20A, as I do with mine almost every day!

[@LUCASMACHOWSKI]

is it possible to set up max voltage charge to 4,1 V on each cell on this balancer /charger ? Thanks Julian

[@fysafysa]

Can this be used to keep LiFePO4 batteries balanced that are connected to a solar charge controller and have no BMS otherwise? (PWM or MPPT?)

[@bigfilsing]

For colours we have grey, green , blue and....terracotta Oh the contrast (pun intended)

[@markward4176]

anyone know where i can find that boost converter? does julian have a better one?

[@GroovyVideo2]

I have 100ah Calb Lifepo4 battery 4 cells - Bottom balanced at 2.75 volt using a car headlight as load for last part of discharge - then charged to 3.6v - after a few charge /use cycles the cells have stayed within 6mv - charge balance only happens in last 5 minutes of charge cycle - Im charging battery at the moment and cells have 2mv difference - watching charge is fun but after a few cycles the thrill is gone - watching the balancer at end do its thing is still entertaining tho --- using Icharger 4010 duo

[@ufohunter3688]

I finally ordered a MingHe D3806 Buck/boosts yesterday. I wondered if you knew of a good multi-Chemistry All-in-one Charger/Balancer unit?

[@JulianIlett]

I've got a new iSDT unit being delivered tomorrow - it's an 8S charger - it looks interesting. How many cells in series will you be using?

[@ufohunter3688]

Nice! I was hoping to replace my 48V SLA batteries for my electric e-scooter. I am tired of buying 4 batteries ($250) every year. I am looking for an alternative to the $1500USD battery pack from PingBatteries. You are lucky to have a 24V system :)

[@MrNursi]

Yup, very, very nerdy. love it :-)

[@ZillionPrey]

I just spotted a Google Home powerbrick :P 23:25

[@max246]

If someone wants it. I got it in stock in the UK. Sending first class

[@vmailtk5]

It looks like you have a phone stuck to your face

[@mikeoliver3254]

Nerds unite I watched the whole video.

[@SidneyCritic]

3 vids totalling 1 hr and a lot repeating - why do most EE hosts repeat the same info constantly -, I had to skip most of it. Maybe I should have skipped the ad at the start too.

[@RWBHere]

Sidney, isn't the whole video an ad for Bang Good and the Mingy buck/boost converter? All adverts use repetition, so that viewers remember the company and its products.

[@debug9424]

+RWBHere It is not a advert for MingHe; it's just what he uses.

[@SidneyCritic]

I meant more that they say the something, and then say the same thing again - usually in the same vid -. The first 9min of this vid practically is the first 2 vids. Lots of EE YT guys do that, it's like they don't realise the same sentence is being constantly repeated, even in edit. Try watching KainkaLabs, that guy drives me insane with repeating.

[@andymouse]

funny isn't it ya can have fun just watching electronics do its thing.....I'm a proud nerd

[@Eratas1]

Lifepo4 is quite obsolete technology for ebike already. 18650 lion is 2x lighter, 2x cheaper and 2x less volume. Real world cycle life is about the same.

[@7328971]

That was very cheap ..

[@ufohunter3688]

absolutely false. Post here when your ass catches fire...

[@TheRealSasquatch]

Regret to say i'm getting v.bored of battery charging, battery tech., battery chemistry, and the batteriser :-) what with quadcopters etc. on so many channels... how about more of the vocoder, penny organ, pic assempler etc.? nevertheless thanks for the video.

[@JulianIlett]

Oh dear - another battery charger video coming next!

[@TheRealSasquatch]

lol - I'll watch it anyway ;-)

[@kakeergodt4609]

3rd