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[anotherkiwi]

Be VERY careful if changing the plug on a live Lipo as the slightest touch can cause KFF (Kentucky fried fingers).
It can also destroy the battery.
Far safer to get a lead off ebay and alter that before attaching to the battery.

It wasn't easy... But I now have a 38.6 V battery with XT60 plugs

I bought the new XT60 plus plugs with integrated insulation and as the advertising says the grip does make de-connection easier. The solder cups are pretty tiny compared to the XT90 which makes them a bit more fiddly until you get the right technique AKA the fourth and final solder... The neutral wire was protected with electricians tape when soldering the + and as the black plastic insulation thingy slid over it I left it on.

Now onto the charger, power supply to finish first.

 

[anotherkiwi]

A hard days work later:

- Battery box is a Skip ultimate washing liquid/powder box which holds the batteries nice and snug and perforation proof in a pannier bag.
- long 10 AWG lead from pannier bag to controller with Watt meter
- the charger is as bad as I imagined for 30€ but managed to charge both batteries from stockage voltage to 41 V in 1 hour 50 minutes at 0.5C not very noisy is its strong point can't set charge cut off to 4.15 V per cell is the weak point or I haven't found the trick yet in the instructions
- the controller and Li-Ion bottle battery lead also go XT60 plugs so I can switch between the two batteries (cutting the soldered lead off the controller got me sparks - the condensers hold charge for over 24 hours you fool! )

I only burnt two fingers with the soldering iron! TOP TIP: I haven't soldered in a very long time and it took a while to figure that there has to be a pool of solder on the iron to heat the XT60 cups quickly. Now that I know I don't have any more to solder... I destroyed one XT60 plug with the soldering iron (out of 10)

Road test later.

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.

 

[anotherkiwi]

Road test Hendaye station there and back:

Assistance level 5 everywhere except down hill: testing so not real world conditions level 3 and 4 are my usual levels except for a couple of short sections at 5.
41 V depart, 38.1 V return - packs remain balanced to within 0.01 V
175 Wh for 29 km = 6.03 W/km (9.65 W/mi for the metrically handicapped)

The first thing you notice is the lack of battery sag, my bottle battery is capable of going between 36.5 V and 39.5 V, a 3 V difference - the Lipo is a 1 V variation or less the whole ride. The watts just keep coming! Despite the controller being limited to 11 Amps I was seeing 480 W on the LCD in the steeper bits then I remembered on the controller sticker the (+ or - 1 Amp) so drawing a shade over 12 Amps there.

The voltage alarms work but are hard to hear in a box, in a pannier bag, in traffic. Maybe I'm going deaf or left side is my bad ear? I was controlling voltage on the LCD (screen 3) the whole way. The alarms are set to a conservative 37 V and as soon as voltage dipped to 36.9 they went off so they seem well calibrated. The voltage on the LCD and on the watt meter are identical.

One test I'm sold! OK there is a lot of discipline to be taken on board you can't just chuck the battery on the charger and go do something else or leave it on charge overnight like with Li-ION. But for my use that is just fine.

I will adopt Lipo for my current "Number Two" build. I am thinking that 4S2P (2 x 10 Ah packs paralleled) + 6S2P in series for 37 V 20 Ah as a minimum with the 36 V controller. 20 Ah won't fit in the triangle. I will need either a second charger or a better twin output charger.

Thanks to all for your advice and encouragement.

 

[awol]

its strong point can't set charge cut off to 4.15 V per cell is the weak point or I haven't found the trick yet in the instructions

I believe if you set the charger to li-ion mode it charges to 4.1v per cell. Might be worth a try but monitor it the first time.

 

[awol]

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

 

[anotherkiwi]

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 )

 

[anotherkiwi]

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.

 

[danielrlee]

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.

 

[anotherkiwi]

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?

 

[danielrlee]

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.

 

[anotherkiwi]

Ta much!

 

[anotherkiwi]

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.

 

[Bindo]

View attachment 13459

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!

 

[anotherkiwi]

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

 

[Bindo]

Fair enough!

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

 

[Kinninvie]

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.

 

[Deleted member 4366]

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.

 

[anotherkiwi]

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.

 

[Deleted member 4366]

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.

 

[awol]

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