I could do with knowing this too since I've got some in storage mode for aprox 12 months.

 

I found an answer on a RC site (OK on several sites, they all seem to agree):

 

First 5 charges at 0.5C (5 Amps for my 10 Ah packs) then you can charge at 1C

First 5 uses don't ask for maximum C rate - I think we are clear here because we will never ever be pulling more than 2C from a pack with a 250 W pedelec

80% pack discharge is recommended as well as charging to 4.15 V per cell and never lower than 3.45 V - I am going to set my alarms for 3.6 V

 

80% of pack means at today's usage 50 km range. This confirms my idea of a 20 Ah battery = 100 km range perfect for my needs. And you can add more when you want (or each time there is a sale )

These things are awesome!

 

I did a run down the coastal road and back (26°C brilliant sunshine and head wind outbound). 22 km there and back taking it easy (7 W/km) so as not to sweat to much in the heat and... upped my average speed to 26.8 km/h from the usual 25.6 km/h with the Li-Ion bottle battery. The lack of sag is phenomenal and I don't even have an optimised configuration (more packs in parallel).

 

The packs puffed vary slightly because of the external temperature, all rides up till now were in the 11°C range. We shall see how they handle 36°C.

My lord has it taken some doing, but I've finally managed to fit 6x 16000mAh 4S Multistars into an EM3EV frame bag. It required some major reworking of my wire runs and I've still not completely finished the job (still have to relocate the GPS tracker and auxiliary DC-DC converter), but 1420Wh of LiPo into this bag can be done.

Stop showing off!

 

I am looking for another frame... I can just get 20 Ah in there in a box that looks like a tiny coffin. All that is missing for an integrated 60's chopper look is sissy bar, ape hangers and an Iron Cross rear view mirror... I regret a little that I didn't wait for the 5200 mAh to come back in stock before buying, they are much easier to fit into small spaces.

 

Do I parallel the 2 x 4S and 6S packs before I series them or the other way round for the best use of the 20 Ah?

Well..... yes, I guess I am showing off just a tad. Lots of folk use this bag and I'm happy to share the info on how to cram as many Wh as possible in there. I'd be interested to hear of any better ways to fill it though.

 

Unless you require the ability to break your batteries down into smaller packs, I'd parallel first, then series. It will make the job of bulk charging/balancing your packs easier.

Ta much!

First real world test of Lipo over a full charge. I rode up into the foothills in Navarra for a beer (you always need a serious reason for going somewhere ).

 

Conditions: reasonably stiff southerly head wind the whole way. Had to use granny gear - 48-34 - on a few hills...

 

The alarm went off after about 42 km - starting charge 41.4 V end charge 36 V which has come back up to 37 V after resting. The pack was warm to the touch, child's forehead oh dear you have a slight fever warm - it is in a plastic box in a pannier bag surrounded by rain gear, I think I would be cosy too. Ambiant temperature from 20°C to 16°C. All cells are within 0.02 of each other.

 

Loving it! Next step is to upgrade the pack to 20 Ah.

[ATTACH=full]13459[/ATTACH]

 

Question: is it necessary to condition the pack knowing that it will be used at 1C max? I can understand the need to condition packs used in drones/cars/planes/boats where it will be asked to provide 10 -> 20C right off the bat.

 

I've used lipo's in RC cars under very high loads, up to 50c, and drones at moderate loads, and I've never conditioned new batteries.

 

the critical voltage for lipo's is 3.2v per cell, below that it's a goner, the rule of thumb we used to use was about 3.4v per cell for the cut off voltage, 3.6v per cell is a little high imo!

I chose to cut off there because there isn't much juice left below 35.5 and my alarm doesn't do half volts...

Fair enough!

 

I love you idea, I'll be looking down this route come battery replacement time!

 

Loving it! Next step is to upgrade the pack to 20 Ah.

 

And then it will be time to go over to bulk charging.

I have a pair of Meanwell NES 350-48 power supplies along with a 400-48 and a pair of 200-24s so can charge all 48Ah in 2 hours.

http://i109.photobucket.com/albums/n50/kinninviekid/e-bikes/CAM02433_zpsof1f5rsy.jpg

I chose to cut off there because there isn't much juice left below 35.5 and my alarm doesn't do half volts...

I always set 3.6v per cell as a minimum because they go down so fast after that. There was a youtube video that showed a bloke trying out a pack. He took his eye off the ball, when his Cyle Analyst showed the voltage go from 3.6v per cell to close to zero in less than a minute. The lipos were then bricked.

 

It seems to me that you're missing the main advantage of lipos. Most 36v controllers can easily manage 12S without any modification. That gives you 20% more torque and 20% more speed. The difference is very noticeable.

Yes I heard you when you explained to me about 12 S, I understand my initial error on going with 10 S and I will be moving in that direction as soon as I can. My 36 V 09 battery controller has a 50 V cap and I am worried that it is just a little too close to the limit with the battery hot off the charger at 49.8 V. Maybe if I only charge to 4.0 V per cell (48 V)? I will be looking for an electronics shop in S. Sebastian next month to see if I can swap it out for a 60 V cap.

 

The custom battery box I have drawn up will take 15.6 Ah maybe even 20.8 Ah of 5200 mAh 6 S packs and definitely will take 20.8 Ah of 4 S packs at the cost of quite a bit of extra wiring. It will also hold 20 Ah of 10 Ah packs at 10 S, just...

 

I can't imagine the feeling of a 20% torque boost because the difference between Lipo and Li-ion is already fabulous! I was watching closely the other day and where Li-ion sags by volts on the steep hills around here, Lipo sags by tenths of a volt! Being able to climb hills at the 25 km/h limit has already increased my average speed by about 1.8 km/h.

I first built my Dahon with 36v. Being a light bike, it was quite good like that, but when I went up to 12S, it became a beast. It could maintain 20 mph even up slight hills without pedalling. That was with a tiny Q100 motor. I think I'd soldered the shunt in the controller too, so about 18 amps, which would be about 600w at the wheel.

Anyone any idea of the shelf life of these when kept at storage volts?

They last ages if you don't use them.

Charger question:

 

My PSU is a 480 W model with 18 Amps on the +12 V output. Can I use one (1) PSU to power two (2) R/C balance chargers? My thought is one charger with parallel charging board/cables for 2 x 6S packs and another for 4S. I have an 80 W charger which has 7 Amps output which would be good enough for the 4S packs and looking at an 80 W 10 Amp charger for the 6S. 160 W needed and 17 Amps, I have 200 W and 18 Amps available (nominative of course... ).

 

I am not going to do/need bulk charging for the foreseeable future, I get home and recharge to storage voltage (if neccesary - the ride to Hendaye and back leaves cells at around 3.8 V so don't need to charge to storage voltage) and before setting out in the morning bring the packs up to 4.0-4.1 V per cell which takes about 50 minutes (per pack), time for breakfast, second breakfast and a quick collation... <hobbit smiley goes here>.

 

The second charger option is a multi-channel AC powered charger at around 100€ + shipping.

<<<<My PSU is a 480 W model with 18 Amps on the +12 V output. >>>

That doesn't really compute, does it?

 

12V X 18A = 226W

 

I am assuming you want to run a 80W & a 180W charger off that single power supply, so factoring in losses, you need at least 300 Watts.

 

<<< I am not going to do/need bulk charging for the foreseeable future>>>>

If, by that, you mean you are "breaking" your Lipo packs, you might want to rethink that. Breaking" the pack not only promotes wear and tear on the connectors and opens the door to nasty mistakes, it reduces the Lipo bricks natural tendency to work together.

Right now, I'm doing discharge "break-in" cycles on 20Ah of new Multistar and I'm seeing cell Voltages all over the place(but no bad cells). But, I know from experience, that if I leave my 12S/2P pack together, over time(cycles), the bricks will learn to play together nicely and the cells will fall into lock-step. By staying w/ the 80% D. of D. rule and leaving the pack intact, eventually, the number of straying cells will become less and less.

Lipo likes routine:)

Running 10S does have one major advantage, there are plenty of quality 300W balance chargers available, something that can not be said for 12S.

I've been thru many cheap charging solutions over the years to get to the reliable and fool-proof system I have now and I know would have been dollars ahead if I had just started w/ quality components. I'm also a fan of Battery Medics. For me, they are easier to use for checking and minor balancing than a balance board and a handfull of leads.

All 6s nearly half price again, 16000mah 4 & 6s a bargain at the mo. 10s of 16000mah for £92 or 12s for £114. LIHV 4s 16000mah and 6s 10000mah reduced as well.

<<<<My PSU is a 480 W model with 18 Amps on the +12 V output. >>>

That doesn't really compute, does it?

 

12V X 18A = 226W

 

You are right I was having a Doh! moment mathematically. I'm feeling better now It is a computer PSU with a -12 V ramp etc. which makes the total of 480W.

 

I am assuming you want to run a 80W & a 180W charger off that single power supply, so factoring in losses, you need at least 300 Watts.

 

Another PSU is the best idea. Thanks. Another 80 W 10 Amp charger at 27€ was my plan.

 

<<< I am not going to do/need bulk charging for the foreseeable future>>>>

If, by that, you mean you are "breaking" your Lipo packs, you might want to rethink that. Breaking" the pack not only promotes wear and tear on the connectors and opens the door to nasty mistakes, it reduces the Lipo bricks natural tendency to work together.

 

I will be "breaking" them at the serial level only and charging the 2 packs in parallel. I am going to have to solder up parallel balance wires as they are on permanent "back order" at HK. I looked at parallel charging boards but as I only have 2 packs of each size they are overkill.

 

XT60's seem to prevent the mistakes and wear and tear issues. If the connectors get a bit iffy I can swap the series and parallel cables out at less than 3€ a pop. I have one XT60 that saw some heat in my only "incident" to date with a multimeter and the connection is still fine. They are so much better than bullet connectors - the ones on my controller were crap, one snapped off in the first week and the second one soldered itself together permanently.

 

I have a Battery Medic and will buy a couple more, Do you have a fan on yours? First time I tried balancing the 6S pack I thought I had fried it, it go very hot and the screen went black... Can I use two Battery Medics on the balance wires of packs that are connected in parallel, my guess is yes because all the cells will be at the same voltage give or take 0.02 V.

 

PS I have read several of you posts over on ES, you are one of my guides on the road to Lipo

I have a bunch of BM's, the older Blue ones that don't over heat and the new black ones that do. Unfortunately, the blues ones are no longer available.

I just received 4 of the 40 mm X 40 MM 24V fans that I will hot glue on the back of the BM and wire into an ext. for the full 22.5 Volts;

But I have found the black ones can be used in balance mode w/out over-heating. I also parallel 2 or 3 BM's for faster discharge;

They also seem to resist over-heating a little longer this way.

 

I make my own main wire "Y" adapters from #12 wire. It's kind of hard to solder the 3 wire junction w/ my 30 Watt iron, so I use a 4 mm bullet there;

I don't actually cut the wire that loops around, just strip off some insulation and fold the bare wire. I don't use a solder gun/iron when attaching 4 mm bullets either. I just use a sm. torch to fill the bullet's receiver cup w/ solder and push the striped wire in. I don't use the covers, just cover the bullet w/ shrink-fit. These adapters are longer than the ones from HK, but I like the #12 wire here.

Very easy

Edited April 19, 201610 yr by motomech

My first real world test has just ended: 118.8 km from a full charge on both batteries. 70 km on the Li-Ion battery and 48.8 km on the Lipos.

 

One of the cells in the 4S pack (#3) got out of balance (0.1V) and dragged the rest of the battery down below the 36 V cut off otherwise I think I was good for at least 55 km on the Lipo. At 36 V there is still plenty of juice left in the pack, I was pulling 460 W constant coming back up my steep homeward hill. Off the charger now back up to storage voltage the cells is within 0.02 V of the others, still the lowest cell in the pack.

Lipos are getting close to empty at 3.6v. Be careful. A normal Li-ion ebike battery is nearly half full at the same voltage.

The LCD was showing 36.0-36.1 V but the alarm was screaming for the last 50 metres of the climb. When I checked that one cell was at 35.9 all the others at 36.0-36.1 V. At home on the Battery Medic the voltages were confirmed so cheap crappy HK alarms do have their use!

I have a bunch of BM's, the older Blue ones that don't over heat and the new black ones that do. Unfortunately, the blues ones are no longer available.

I just received 4 of the 40 mm X 40 MM 24V fans that I will hot glue on the back of the BM and wire into an ext. for the full 22.5 Volts;

[ATTACH]13694[/ATTACH]

But I have found the black ones can be used in balance mode w/out over-heating. I also parallel 2 or 3 BM's for faster discharge;

[ATTACH]13695[/ATTACH]

They also seem to resist over-heating a little longer this way.

 

I make my own main wire "Y" adapters from #12 wire. It's kind of hard to solder the 3 wire junction w/ my 30 Watt iron, so I use a 4 mm bullet there;

[ATTACH]13696[/ATTACH]

I don't actually cut the wire that loops around, just strip off some insulation and fold the bare wire. I don't use a solder gun/iron when attaching 4 mm bullets either. I just use a sm. torch to fill the bullet's receiver cup w/ solder and push the striped wire in. I don't use the covers, just cover the bullet w/ shrink-fit. These adapters are longer than the ones from HK, but I like the #12 wire here.

Very easy

Well, none of my Battery Medic dirt floor mods worked well.

Splitting a balance lead and running two BM's on the same bank of cells won't allow balancing. Each cell value bounces back and forth between the two BM's and won't stabilize.

The 24V mini fan won't run off the 22.4 V 6S brick. I'm using some 12V fans and they really hum. I can smell them so I don't think they will last long @ that Voltage. Still, at least the screen doesn't go black and they provide a faster discharge.

Turnigy has a new discharger/checker that is reported to work well;

http://www.hobbyking.com/hobbyking/store/__26136__Turnigy_DLUX_LIPO_Battery_Cell_Display_and_Balancer_2S_6S_.html

I'm liking my new Multistar pack more and more every day. The cells have stabilized and with my low powered system, see virtually no sag.

I was able to fit 20 Ah into a space that was previously filled to capacity with 10 Ah of regular 20C Lipo.

Edited May 5, 20169 yr by motomech