I waant to go LiPo!

[o00scorpion00o]

Hi David,

Yeah you're right, the C rate of the Zippy's are plenty, it's just the weak cell that's the problem!

I stick them on the Icharger every now and again if I use more than 7 ah out of the pack, they never go much out of balance if I keep to that.

Strange thing is though even if I don't use the Icharger the weak cell comes right up perfectly ?

I'm afraid of it going much lower than 3 volts. What's the minimum A cell will go before death ?

I was thinking about the V4 Fechter/Goodrum/Hecker BMS. It looks like a very solid design. It would give me peace of mind maybe ?

I could swap out the 4s pack , it's only 45 dollars from the German warehouse. I would find plenty of use for the pack, maybe for lights or something, or maybe even something as fun as LiPo fireball ? haha na that would be a waste!

I would love to get my hands on some of the 8ah but I will have to just use my pack now as it is, I could add an extra 2 x 6s and 1x 4s for around 15 ah, but I might wait until next summer before making a decision.

I just checked HK, it's 225 Dollars from China and 260 Dollars from Germany, anyone know why that is ? That's for 2 x4s and 2x 6s

It's only 54 dollars to ship from China and around that from Germany, via one of the couriers and 25 from another, still makes it a fair bit more expensive from Germany!

 

[theRealFury]

I'm afraid of it going much lower than 3 volts. What's the minimum A cell will go before death ?

The absolute lowest it shoud ever go, and this is a one off, not regular is 2.7v. Below this the cell starts to take irreversable internal damage that can make it vent / fireball when charged again. I would personally worry if my lipo got down below 3.0v

As for shipping, from china $54 would just be for standard air parcel post (which is by far not lipo friendly as it will be banged and jostled no end on its way to you. from germany for $54 you could get private courier shipping which will be alot safer than standard post if you ask me. I got my lipo delivered from Germany warehouse via courier and the box was like new, everyhting i get shipped from china turns up dirty and scratched / dented.

In UK the $24 shipping from HK Germany warehouse is done through EMS which is a subsidiary of Parcel Force, they also took good care of my charger and power supply on its way to me too.

The real problems come with China when you get a few duds, as you have to pay for post both ways which makes it very expensive if you order 4 and get 2 or 3 duds.

 

[o00scorpion00o]

Cheers fury,

I think I will just keep the pack, I wil keep an eye on it and decide what to do in the summer, if that cell gets worse I will have no choice then to get a new pack!

What's the warranty situation with HK ? In what situation will they allow a return pack ?

 

[theRealFury]

luckily i have not had to return anything to HK yet but i have heard a few reports of people saying that if its dodgy lipo they have just been credited with the cost of it after supplying proof that it is a dud. You will still have to pay for shipping on another pack in that case but really, if its a dodgy pack they should not be asking you to ship it back to them to be fair.

 

[o00scorpion00o]

Would they take mine back after having it for a while now ?

 

[theRealFury]

Would they take mine back after having it for a while now ?

id say not im fraid, looking at the returns and refunds section of the FAQ.

Returns & refunds
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Read our Lithium Polymer Warranty page.

 

[o00scorpion00o]

Thanks for that fury!

I suppose they don't know how people treat their LiPo!

If they came with a bms then that would have to be different, or should!

 

[theRealFury]

no i guess not, any it will mostly be because of the RC users and not us Ebike users that gernally give lipo a much easier life. I have seen people kill lipo in a couple of cycles at the local park what with deep discharging them and then immediately hitting them with a 2C+ charge rate hooked up to car charger while they drain another pack. for us that charge at 1C or less and discharge at 3-5C loads while not going below 3.5v the lipo will be nice and happy.

I worked out that my lipo is down to 0.50p per mile cost to me right now as i have hit 50 cycles and average about 7 miles per cycle so it won't be long before my lipo is cheaper than uk petrol haha.

 

[o00scorpion00o]

Hi everyone.

I went out for a spin yesterday motor only. After 25 miles lvc kicked in at 54 volts. I used 8.6ah.

I set the cruise to 20 mph and didn't go over 20 amps, so I was being very easy on the battery. Cycle analyst said about 21 wh/mi which is good at 20 mph. I use about 45-49 wh/mi at 35-40 mph!

Anyway these are the voltages of each cell after I came back.

6s no1-----3.65, 3.65, 3.64, 3.63, 3.65, 3.64
6s no2.....3.66, 3.66, 3.62, 3.65, 3.66, 3.65
6s no3.....3.53, 3.57, 3.60, 3.53, 3.57, 3.56
6s no4.....3.53, 3.57, 3.60, 3.53,3.53, 3.57

4s no1.....3.27, 3.26, 3.38, 3..33
4s no2.....3.03, 2.86, 2.74, 2.93


So it seems like I have a weak pack, that lw cell is still going low along with another cell.

Am I looking at replacing the 2 x4s packs ?

Again it's not much of a problem if I keep to around 7am.

I thought I was being conservative with setting the lvc to 54 volts, but obviously not.

Should I be getting more than about 8.7ah?


Mark

 

[Ykick]

How are you doing the 4S-6S connections and what capacity bricks are they? It's probably somewhere in this thread but 12 pages, ya know?

If calculated pack capacity is around 10Ah, 8.7Ah ain't bad. Especially, if you're only top charging to 4.2-4.15V/cell.

If somehow you're not discharging the 4S bricks faster than the 6S bricks (I don't know how they're wired) your 4S bricks obviously have less capacity than the 6S bricks. You may just have to figure out how to charge the 6S bricks a little less and the 4S bricks a little more so that they all hit LVC at roughly the same time. But first, please explain what 6S & 4S brick capacity you're using, how they're wired and the expected Ah capacity?

For daily use I only ask about 50-60% from my 10Ah packs. 'pull 'em down near empty once in a while to better see which cells hit LVC 1st and record pack capacity but for daily use 50-60% DOD leaves you some breathing room for detours, cold temps, cell aging, etc.

 

[o00scorpion00o]

Hi Ykick,

They are all 5ah bricks. I have 2x 6s and 1x4s in series and same again connected in parallel to make 16s 10ah.

Yes I charge to 4.15. Bulk charge mostly these days, except for occasions like this when I use most of the ah, I balance charged them on the Icharger after.

 

[Ykick]

Hi Ykick,

They are all 5ah bricks. I have 2x 6s and 1x4s in series and same again connected in parallel to make 16s 10ah.

Yes I charge to 4.15. Bulk charge mostly these days, except for occasions like this when I use most of the ah, I balance charged them on the Icharger after.

Alright, that helps. So your 4S bricks basically have less capacity than the 6S bricks. Different batches, I suppose? The limiting factor to overall pack Ah in this case is the 4S capacity.

Might try charging the 6S bricks to 4.10V/cell and do the 4S to 4.15-4.2V/cell? Run another gentle LVC test and see if things get a little closer to empty at the same time?

Doing that will probably see little, if any, overall Ah improvement. Bottom line - 8Ah is about all I'd expect from your combination and 4-6Ah is all I'd regularly use from that pack on a daily basis. Plus, checking each brick carefully after use for a while and especially that 4S #2 brick.

You can also use the iCharger discharge function, make graphs of each cell, etc. I dunno how to do that but some folks swear by it...

 

[o00scorpion00o]

Hi Ykick,

They are all 5ah bricks. I have 2x 6s and 1x4s in series and same again connected in parallel to make 16s 10ah.

Yes I charge to 4.15. Bulk charge mostly these days, except for occasions like this when I use most of the ah, I balance charged them on the Icharger after.

Alright, that helps. So your 4S bricks basically have less capacity than the 6S bricks. Different batches, I suppose? The limiting factor to overall pack Ah in this case is the 4S capacity.

Might try charging the 6S bricks to 4.10V/cell and do the 4S to 4.15-4.2V/cell? Run another gentle LVC test and see if things get a little closer to empty at the same time?

Doing that will probably see little, if any, overall Ah improvement. Bottom line - 8Ah is about all I'd expect from your combination and 4-6Ah is all I'd regularly use from that pack on a daily basis. Plus, checking each brick carefully after use for a while and especially that 4S #2 brick.

You can also use the iCharger discharge function, make graphs of each cell, etc. I dunno how to do that but some folks swear by it...

Yeah I had a feeling the 2x 4s packs were a bit lower on capacity!

I don't think I would be bothered charging them at different voltages. I think I'll just use them as they are and try not use more than the 8ah. If I loose much capacity I will consider changing the 2x 4s packs.

Still 25 miles is pretty good at 20 mph no pedalling!

 

[Ykick]

Very good efficiency! I've squeezed 20 miles from my 10Ah Lipo but only averaging around 15MPH and some pedaling.

At least now you know which cells to keep an eye on...

 

[o00scorpion00o]

Yeah I'll keep an eye on them alright.

I use continental sport contact 1.6" tyres, pumped to 90 ps. They make a huge difference pedalling over nobly tyres, so I'm sure they make a difference efficiency too.