Hobby king multi star on offer

Just an FYI but hk put their ebike perfect Lipo (multi star) on offer today

 

Cheers

 

http://www.hobbyking.com/hobbyking/store/flash_sale_rc_hobby_products.asp?currentPage=5&Search=&utm_campaign=MR160122.UK&utm_content=2814447665&utm_medium=email&utm_source=EDM

Not bad a 37v /10s 13.2ah lipo for £102 if you know how to look after them.

For our education how does one assemble a 37V/10s 13.2 Ah pack from this bewildering array of packs? 2x3S + 1x4S?

Hello AK, use the least amount of packs needed to keep wiring/connections and charging to a minimum. In the example I used ; 4 packs 2 x 6s & 2 x 4s (6600mah), connect a 4s & 6s in series to get 2 x 10s x 6600mah ( 6.6ah ) packs then parallel them together to get a larger 1 x10s x 13.2ah pack. Buy premade leads or you could make your own if you can solder well. Pack weight is approx 2.7kg.

I did exactly the same as Nealh but mine are slightly lower ah at 5200mah giving a 10.4ah pack

 

It cost a fraction under 70quid delivered (November 2015)

 

I soldered my own leads but hk supply then for a few quid

I made/soldered a 3 into 1 parallel lead so at some stage will connect 3 in series in parallel to get a 10s x 15.6 ah pack.

The 5200mah have risen in price a little since Jan 16 but still offer good value and a 10s x 10.4ah pack weighs about 2.2kg.

Besides the lipo packs you have to factor in other costs such as a charger, a PSU for the charger, serial and parallel leads, 10/12awg wire, connectors, lipo alarms, watt meter for accurate usage and a way of carrying the packs on your bike. A bag that seems to be capacious and recommended by ES users and Kinninvie is the V2 crossbar pannier bag from Additive-bikes.com.

Edited January 23, 201610 yr by Nealh

Thanks, great explanation. All is clear now.

Before anyone considers these batteries I strongly recommend that you read the battery charging tutorial on ES

https://endless-sphere.com/forums/viewtopic.php?f=14&t=52240

 

You do need a bit of commonsense to use them safely.

I use 6 x 16Ah 6s Multistars for a 44.4v 48Ah battery and it only takes 2 hours to charge using Meanwell power supplies as bulk chargers.

Before anyone considers these batteries I strongly recommend that you read the battery charging tutorial on ES

https://endless-sphere.com/forums/viewtopic.php?f=14&t=52240

 

You do need a bit of commonsense to use them safely.

I use 6 x 16Ah 6s Multistars for a 44.4v 48Ah battery and it only takes 2 hours to charge using Meanwell power supplies as bulk chargers.

I see that the bike in your avatar features an EM3EV frame bag. May I ask, how do you carry that much battery?

Would regular lipo users say whether these are suitable for daily use?

Thinking my bottle vbattery was about to die I bought lipo's and all the associated gear and learned how to use them but then my bottle battery kept on working-and-working so I've had the lipo's in storage mode now for months (with monthly topups) and only really used them once/twice up the road and back to test them. Now my bottle battery is becoming weak I may soon replace it and was trying to decide whether to start with the lipo's soon or are they worth the hassle for daily use or to get a new plug/play bottle battery.

I see that the bike in your avatar features an EM3EV frame bag. May I ask, how do you carry that much battery?

I also use an Additive V2 bag.

The EM3EV bag holds one pair and is great for trail riding then if going any distance I put the V2 over and it can hold up to 6 batteries although I usually put 4 in and that leaves plenty of room for spare tubes,beer etc.

http://www.additive-bikes.com/the-backpack-for-all-frames.html

http://i109.photobucket.com/albums/n50/kinninviekid/e-bikes/CAM02275_zpscba89db3.jpg

Would regular lipo users say whether these are suitable for daily use?

Thinking my bottle vbattery was about to die I bought lipo's and all the associated gear and learned how to use them but then my bottle battery kept on working-and-working so I've had the lipo's in storage mode now for months (with monthly topups) and only really used them once/twice up the road and back to test them. Now my bottle battery is becoming weak I may soon replace it and was trying to decide whether to start with the lipo's soon or are they worth the hassle for daily use or to get a new plug/play bottle battery.

 

Not quite plug and play like li-on but nothing to lose if you have the set up already, stick to the principle of not deeply discharging them. How far are you travelling remember once charged it is best to use the charge down to 38.5v at least, may be a pita to monitor them every day to recharge.

Hello AK, use the least amount of packs needed to keep wiring/connections and charging to a minimum. In the example I used ; 4 packs 2 x 6s & 2 x 4s (6600mah), connect a 4s & 6s in series to get 2 x 10s x 6600mah ( 6.6ah ) packs then parallel them together to get a larger 1 x10s x 13.2ah pack. Buy premade leads or you could make your own if you can solder well. Pack weight is approx 2.7kg.

 

I have been reading...

 

Question: How do you limit discharge voltage to 3.55 V per cell as per the ES howto? The LCD-3 only allows 31.5 V cut off i.e. 3.15 V per cell which is kind of close to the 3.0 do not pass threshold. A voltmeter/watt-meter is compulsory equipment?

 

Question 2: How many of the theoretical 475 Wh are actually available for real world use with a pack like this?

 

I understand that the advantage over Li-Ion is higher C-Rate and lesser sag. Slightly less weight (no metal case) but almost no cost advantage / Wh once you factor in the charger and bits and bobs to make it work and keep it safe when it is working (unless you buy at sales price). Am I correct in these assumptions?

Currently using small lipo alarms ( About £2) set the value to your preference between 3.3 -3.8v, they give out a high pitch alarm when a cell hits the LVC threshold., watt meter not arrived yet but this will be used to monitor ah used.

Can't answer Q2 without a watt meter, Kirstin may be able to let you know the useage from his 10.4ah/ 374wh lipo pack or Kinninvie from his 16ah/768wh packs.

Your assumptions are about right but once you have the kit future cell pack replacement will be very cost effective, the only downside is its not plug and play so no good for local errand riding.

Damn this is a good thread! Learning stuff, not going to die a complete idiot!

I once took a pair of 16Ah Multistars down to 3.34V and got 16.7Ah out of them!

This is borne out by tests on ES that they do actually have more than the stated capacity in them.

I can get almost 700wh going from 4.12V down to 3.62V.

The thing is that the initial voltage drops quickly then they give most of their capacity around nominal voltage before suddenly dropping off the "lipo cliff" around 3.6 volts.

http://www.neptronix.org/forumpics/lipotutorial/24_dischargingmechanics.gif

Here is 15 pages of everything you ever wanted to know about Multistars from the experts over on ES

https://endless-sphere.com/forums/viewtopic.phf=14&t=61672&hilit=multistar

 

My 48Ah 44.4V battery (6x16Ah Multistars) cost me £500 (try and find a ready made battery that size and see how much it costs you).

I bought 2 fake Imax B6 balance chargers for £11 each and a cellchecker for £3 and that was me up and running.

Later I bought a pair of 350 watt Meanwells at £25 each for bulk charging and later still another pair at £12 each and now I can charge all my batteries in under 2 hours.

If you are using them every day things become second nature and you can add things like a simple time clock to plug your charger into so its charged just as you are ready to set off.

If you are using them every day things become second nature and you can add things like a simple time clock to plug your charger into so its charged just as you are ready to set off.

You got me thinking about this as it would be a dialy routine same times so did you mean timer switches charger on just before I get home then I manually set it charging and the timer switches the power off after a set time known the batteries will be fully charged in? then timer switches power on just before the regular getting home time again? or is there a way to get them to charge later in the night by timer?

Say it takes 2 hours to charge your batteries and you set off at 8am.

\simply connect the batteries to your charger on the evening and set the timer to switch it on at 5.50am and off 2 hours later.

Then just unplug and away you go

Some math:

The multistars are 14.8v * 6.6mAH = 97.68wh

 

Cost= 21.25gbp so you get 4.59wh/gbp

Weight= 537g so 181.89wh/kg

 

Now let see the ncr18650pf from nkon:

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650pf-3-7v-2900mah.html

 

Cost (if buy 500) = 2.65euro or £2.02 for 10.44wh. So you get 5.16wh/gbp.

Weight = 47g so 222.12wh/kg

 

So the 18650 cells are 11% cheaper and 19% lighter than the multistars....... have you also forgotten that they are also safer, easier to maintain and with a better lifecycle? For no reasons other than high discharge capacity I'd buy lipo!

 

Now, if you want high capacity... the famous ncr18650b used by Tesla:

http://eu.nkon.nl/rechargeable/18650-size/panasonic-ncr18650b-made-in-japan.html

 

Cost : 3.29 euro or £2.51 for 12.24wh so 4.87wh/kg

Weight: 48.5g so 252.37wh/kg

 

These high capacity cells are still 5% cheaper than the multistar you get 28% lighter cells!!!

 

 

So why om earth would you want unsafe lipo?

Just organise a group buy of ncr18650pf or ncr18650b and you'll thank me later! And get a neptune lite to check cells too!

 

I ordered 200 ncr18650pf last year and the pack is still strong. I'm considering to upgrade to 72v so I'm considering ordering a hundred more. Anyone interested?

Just to summarise for those who don't want to read it all...

 

All 1000wh battery of...

- multistar cost £218 and weight 5.5kg

- ncr18650pf cost £197.8 and weight 4.5kg

- ncr18650b cost £205.33 and weight 3.9kg!

Then add the cost of a welder and cell holders and all the strips to join them together and of course the technical knowledge to actually build one safely.

 

Lipo are not unsafe when handled properly,just like petrol in a car,if you mistreat it then it can hurt you.

The welder do cost and I bought one....

But cell holder i don't use them anymore it takes too much space. I glue them with separator on cell group for chaffing risk.

The strip does almost cost nothing once you get some.

 

Like lipo, there is a cost to get started (lipo you need balance charger....), but once done, it saves time, money and space.

 

My ncr18650pf pack of 196 cells made last year hasn't been balanced a single time.... and i use it daily

I've got rid of all my lipo (zippy compact battery and cheap 4s turningy) more than a year ago and never regretted it.

 

- no more spagetthi wiring

- no more jst paralleling and cell log constant check

- no more cutting all the plug from a new battery pack to connect to new ones

- no more balance charging

- no more fear of fire at work while charging

- no more fear to that any small shock may damage the pack and cause fire

- no need hard case to protect the battery and apply compression

 

Even without the price benefit, the gravimetric density benefit and the higher lifecycle benefit I would prefer the 18650.

I think its more of the building it part that puts most of us off. Especially when there's a chance of burning the house down.