Turnigy Multistar - lightweight 10C cells

Thanks Chris. Connectors arrive today and I will put them on immediately and start cycling the batts.
otherDoc
Yeah I never go over 2C for these cells.

The 16AH are good up to 4C

I have tested the 16Ah cells and I approve for 3C or 48A use. I just did discharge tests and they hold above 3.5v for 15.8AH and deliver 16.7AH down to 3.0v. Im going to do 1 more test to 4C or 64A. This will let me me know if I can run 1P on a 65A Lyen Controller with acceptable sag. the 3C test surprised me.

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I just got done reading this hole thread and when I got to this point I was like "WOOHOO!"
I got 3 6s 16ah one's that have been sitting since I got them a month ago.
My one charger (other than the Imaxb6ac) the thunder 0620ac has been tied up bulk charging used 18650 laptop cells then cycling the 56 assorted grade B lipos that composed last summers 12s 40Ah pack + couple spares. (12-3s 5Ah,4-3s 3Ah and 40-3s 2.2Ah)
I DID find the one bad 3s 2.2Ah that was bringing it's corresponding bank down and causing the charger to sit and try and balance the pack all night.
And I'm on the last one now.
So I will start cycling the 6s 16Ah Multistars tomorrow morning.


I like to play it safe with lipos and set discharge to 3.55 and charge to 4.15 MAX when testing.
Then when in use I charge to 4.1 and discharge to 3.6 under load.

Questions
Do you think this is fine for getting an Idea of the capacity?
And How many time do you recommend cycling them?
And I read a while back someone mentioned they don't like to put any pressure on the bottom of lipos.
This is a bummer because I was planning on mounting one on each leg of the fork, upright, with padding of course.
Is this really that big of a no no?
I could try and put more pressure on the squeezable sides with some double stick tape.
Also about taking the wrapper off so the corners don't squish.
Do you do this?
Then the hard bottom.
Does this have to have a little gap between the bottom of the cells and Masonite or plastic? (I would assume a guy would use)

Sorry for the long post.

During my testing I was going down to 3.0v a cell and on average the pack were giving 16.5-16.7. I expect you to get 15.5 to 16AH starting at the lower voltage and ending early. Most of the packs were giving full capacity above 3.5v resting. I did have some low ballers that showed improvement after a few cycles. I normally cycle them once. Most of the time a pack should be leaving hobby king giving its capacity right out the gate. any pack that isnt is suspect and I dont included it. If its close I give it 3-5 cycles to show some improvement. If it doesnt improve I sell it off to someone thats accepts the issue and I buy another. I plan to run mine upright. I have in the past. I can tell you about longevity because I buy a new pack every season. Ideally you want them packed tight not loosy goosy. Dont take the wrapper off. A little protection and compression is better than none. You may wan to get masonite plastic and sandwich the pack in between two pieces and then take filament tape and wrap the pack very tightly and finish it with Gorilla Tape.

Thanks for the quick reply and tips.
Yah I like going a little easier on them cause I probably will be seeing these through for there deration.
The voltages I'm testing at I should still be able to spot a bad one just by comparing to the other ones. (unless there all bad )
Put the first one on this morning, all the cells were 3.91 except for cell 4 was 3.90.
8 hours later and 5300mah of discharge.
Good thing I have plenty of work left to do on the build.

Thanks for posting your tests.
I will be running 18s with an 18fet, using these Multistars and over 20Ah of the grade B lipo 20c.
But it's nice to know I could use just the Multistars if I needed to.

striker54 said:

Vector frame
I have to start a build thread :wink:

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Yes you should. Later today I can finally pick up the Vector frame. And AFAIK it is only 1 vector frame build thread so far. Would really be nice to see what others do and what they plan before I complete the inventory and start building.

Just do it, striker54

two tested to 14915mah and one to 14930, from 3.55V-4.15V.

Ice
What's your battery medic of choice?

Does anyone know if you can get build a pack with a safer chemistry than the multistars and still be as lightweight?

Offroader said:

Does anyone know if you can get build a pack with a safer chemistry than the multistars and still be as lightweight?

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IMO only the 18650 batteries have better Wh/kg and better cycle life but is not so easy to assemble a pack.

striker, when you assembled your huge pack what gauge wiring did you use for your harness? I assume you used two sizes. One size to connect to the individual packs to put them in parallel, with xt90 connectors. And another main battery wire to connect the packs that are in parallel to the controller.

Maybe you even have a picture of the completed wire harness you made? I'm curious to see how you did if that is available.

Do both the 4s and 6s multistars have xt90 connectors?

Thanks again!

Offroader said:

striker, when you assembled your huge pack what gauge wiring did you use for your harness? I assume you used two sizes. One size to connect to the individual packs to put them in parallel, with xt90 connectors. And another main battery wire to connect the packs that are in parallel to the controller.

Maybe you even have a picture of the completed wire harness you made? I'm curious to see how you did if that is available.

Do both the 4s and 6s multistars have xt90 connectors?

Thanks again!

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Yes, the 4S and 6s have xt90 connectors.
I used 10AWG (same size of the packs) to connect the individual packs in parallel with the XT90 and then 8AWG with XT150 connectors to put them in series.

striker54 said:

I used 10AWG (same size of the packs) to connect the individual packs in parallel with the XT90 and then 8AWG with XT150 connectors to put them in series.

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+1
This is a very wise practice.

Realistically depending on how many packs you have in parallel you can drop down in size to save weight and have more flexibility. The amperage will be divided by how many packs you have in parallel. Ive used as low as 14G Silicon on the parallel and then parallel it to 10G. I rarely use 8G unless im building 100A harnesses for people. The reason also why I drop down in size is because it makes it easier to fit in copper crimp sleeves.

Yeah the 10 gauge and 8 gauge seem kind of high. But I have to take into account that these packs are much bigger at 16,000 MAH so there are far fewer than with my 5000 MAH packs.

I figure if I build a 32 amp hour pack there will be two parallel 16,000 MAH packs.

At a max battery amp usage of 100 amps, each pack will draw a peak of 50 amps.

I used 14 gauge on my 5,000 MAH packs but each pack had a max amp draw of 15 amps.

I guess the 10 gauge is not out of the question but you could easily get away with 12 gauge especially if you have wire runs at short distances like striker has. On the other hand if you have these short wire distances than why not just use the 10 gauge.

These are peak amps also, so most of the time you probably won't be pull peak amps. I'm not sure I may use the 10 or possibly the 12 gauge. 8 gauge is really thick. The 10 gauge will easily handle the amps so I wonder how much the 8 gauge will really benefit.

12g silicon can do 90A continuous without insulation degradation. Ebikes loads are usually burst so resistance in copper due to heat build up is negligible.

One way to do it is to keep the copper cross sectional area the same as the wires are paralleled. So if the output lead is 8 gauge, and you have four wires parallel feeding that, 14 gauge would be the same cross section. Each time you parallel two wires the gauge drops by 3 steps. Thus a pair of 10 gauge wires is 7 gauge, and four 10 gauge wires is 4 gauge equivalent. There's not much point making a 4 gauge parallel and then dropping to 8 gauge. I did that on my pack but ONLY because the commercial XT connectors with pigtails I bought came with 10 gauge, the extra copper caused the harness to be stiff and large and difficult to fit in, it would have been far superior to make the pigtails with 14 gauge wire and make a much easier to manage harness.

Alan that is interesting. I agree that people definitely over size the gauge of wire needed.

I'm making a new harness for a 10 gauge main wire, that has 7 packs paralleled. I was going to use 16 gauge but I figured I would use 14 gauge as it is almost the same size as the 16 gauge.

But are you saying that using 14 gauge offers no benefits over the 16 gauge in this setup? Using your formula I would need 19 gauge, but that seems quite small. Are you sure there are no benefits of using thicker wire for the parallel packs? Wouldn't they run a bit cooler and have less voltage drop?

If you plan to run fewer packs at any time in the future you prob wont beefier wires. Use 14g thats about as low as i would go normally.

If the runs are long there is advantage to minimize voltage drop by using larger conductors. The battery resistance is generally larger than the short copper runs on an ebike, so the copper loss is not a significant part of the total.

Generally a larger number of small wires will dissipate heat better than a single equivalent conductor. The larger surface area and more separate insulators have a lower thermal impedance (if they are not bundled tightly together). The voltage drop will be the same. The smaller conductors slightly larger resistance will also help to balance the currents from the separate batteries. A little.

You want to have adequate mechanical strength in these wires, they should be strong enough to part the connector before failing in most cases. Sometimes that will drive toward a heavier wire.

Icecube's comment about using less packs for the same output current is another reason to go a bit larger per-pack. If you know how many would be the smallest set you can calculate that size of course.

10 gauge is 5.26 square mm, divided by 7 would be 0.75 sq mm, which is a bit smaller than 18 gauge at 0.82 sq mm. (You mentioned 19 gauge, sounds about right, the table I was looking at didn't have that size). So you could use 18 gauge, but mechanically I would go for 16 or 14, and a good mechanical choice is to go as heavy as the parallel connecting element will take. A connector that will take 7 each wires on one side, and an 8 gauge on the other is one way to do the parallel transition, or a crimp ring with a good crimper.

When I made the MultiStar pack for the CroBorg the 10 gauge wire pigtails on the XT90's really pushed the connections to a larger size and quantity, which made it hard to fit and route the harness. Smaller would have been better there for fit purposes, but I certainly don't have to worry about voltage drop in the wiring.

Making the runs short is also a bonus, both from bulk and voltage drop.

Putting really high currents through silicone insulated wire is possible, but it generates considerable heat. I would not do this in close proximity to the batteries.

Do you guy's do T-connections?
I have 40 2.2ah 3s batteries that I'm still trying to get use out of. (Maybe sell off too)
My first pack was 4 banks of 3s batteries with 14 in parallel.
The way I did it was I cut the connections off and soldered the leads strait to a 10awg stiff speaker type wire T style. (I wish I would have use turnigy)
Then just used that liquid electrical tape crap to isolate. (minimum 3 coats)

A connector that will take 7 each wires on one side, and an 8 gauge on the other is one way to do the parallel transition, or a crimp ring with a good crimper.

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This sounds like a good solution. Also if the smaller wires are just big enough for the need they could double as fuses incase something nasty happened. I'm currently using Anderson 75 with 8 gauge for the long series link and the main controller leads. So these would work good for this. I like the Idea of paralleling 6 this way to match the 6 parallel balance tap harnesses.

Making the runs short is also a bonus, both from bulk and voltage drop.

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That's one advantage of a T-connection. It keeps everything short and localized.
Just wondering if there is a good way to do it?
Or some trick with shrink wrap or something.
The liquid electrical tape is sketchy. I have 3/8" foam in between the rails too.

I did T connections on my MultiStar pack for the Borg. Four #10 wires are brought into the #8 main in a pair of "T"s that are more like "Y"s using a large crimp sleeve and double layer heatshrink which contains a layer of hotmelt glue. Works well, but is somewhat stiff and bulky. It is not bad if you have room for it.

Offroader said:

striker54 said:

Offroader said:

striker could you measure the thickness of two of those 16,000MAH packs. I am wondering if I could squeeze them in a raptor 140, which may be only 136mm internal frame width.

Thanks!

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You need 4mm more. They measure 140mm.


I tried to compress them with my hands and the best i acheved was 139.5mm

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Thanks, that's perfect.

I'm going to have to find out the exact internal width of the raptor 140 frame.

based on Qulbix demension chart it looks to be exactly 140mm, kind of cutting it close.

http://www.qulbix.com/images/documents/Qulbix_Raptor140_BatteryBoxOpenning.pdf

Normally I would consider building a 18650 pack if it is the same weight but the above two posts make me not want to consider it if I can use the multistars. I also like to pop out my packs and individually test them and repair cells when needed.

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Do you need to leave room for the packs to swell? What happens when they swell into the frame?

Wrap them with filament tape to prevent any swelling.
I also use vinyl floor tile for puncture protection and finally a covering of Duct tape to hold it all together.

KINNINVIEKID said:

Wrap them with filament tape to prevent any swelling.
I also use vinyl floor tile for puncture protection and finally a covering of Duct tape to hold it all together.

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This seems familiar....

I'm using 2 layers of coroplast and wrapping with filament tape. Since I went to smaller motors and smaller controllers I am sticking with 12 Ga. Automotive wiring. Seems adequate and does not get warm. Of course my controller limits my amps to 15 or so.