!!!!! HELP me with my 26" Bafang Rear Wheel Build please !!!!!

[Deleted member 4366]

If money is no barrier, then I would personally go for one of these:

50V 18.5Ah Samsung Triangle Pack

Paul, who runs em3ev, provides excellent after-sales, which you are unlikely to get from BMS BUTTERY- spelling intentional

The triangle battery would fit in perfectly in your 18" frame.

Stop trying to make us jealous.

I was happy with my rig, but now I've got to decide: New battery or let the poor Bali orphans starve.

 

[bilabonic]

Doing the math now.

50V 18.5Ah Samsung Triangle Pack
50v /18.5ah Triangle battery - £507.67 inc del (NO CHARGER but they cheap) - Li-ion.

BMS BATTERY - 48V20AH LIFEPO4 SHRINK TUBE EBIKE BATTERY PACK - £385
48V20Ah LiFePO4 Shrink Tube EBike Battery Pack - BMSBATTERY

Hobbyking - x6 turnigy - 44.8v/15ah -£231


Now obviously Hobbyking is best value for money BUT how long will they last ? Vibration/wires rubbing against bag etc, wish there was a way to tidily stack/connect them all to prevent this. There has to be a way to make it ft bag better.

I was happy with my first 'holder' i made BUT the excess wiring which would of been rubbing against side of bag had me worried tbh.

Ideally i would like to do a better 'custom' fit of the Turnigys.

 

[Deleted member 4366]

Something wrong with your maths. I just received that 20aH 36v battery from BMSBattery last week, and it came to £271 including delivery. Why are you looking at 48v ones? They'll be very fast. Both those batteries will make the motor try and spin at 34 mph. I'm not too sure how efficient that'll be.

Lipos take about 300 charges, Li-ion about 800, and LiFePO4 up to 2000.

 

[Fordulike]

Something wrong with your maths. I just received that 20aH 36v battery from BMSBattery last week, and it came to £271 including delivery. Why are you looking at 48v ones? They'll be very fast. Both those batteries will make the motor try and spin at 34 mph. I'm not too sure how efficient that'll be.

Lipos take about 300 charges, Li-ion about 800, and LiFePO4 up to 2000.

And 34mph is bad because....

Seriously though, bilabonic, please take the safety issue of Lipo into account.
The em3ev Samsung battery will be very robust and almost bulletproof. That's the way Paul makes them.
I know I'd rather go for that, than have half a dozen Lipos jingly jangling around in a triangle bag.
Also convenience of charging should be considered.

 

[bilabonic]

I was quoting the LiFePop04 batteries -

36V 20AH LI-ION SHRINK TUBE EBIKE BATTERY PACK -£255
36V 20Ah Li-Ion Shrink Tube EBike Battery Pack - BMSBATTERY

That's with XE currency converter.


What to order ????

 

[Deleted member 4366]

And 34mph is bad because....

I've never run a BPM at that speed, so I'm not sure how well it can handle it. Once actual speed drops below 20mph at high throttle, the motor becomes increasingly less efficient. Without changes to the gearing, you can't pedal at that speed, which is a bit of a give away. My only experience of those speeds was when I built my 27mph 2WD. It was fun, but, for me, it just wasn't right going that speed on a bicycle. If you just need to go fast between too points, it'll probably be OK, but I can't see it being right for busy commuting, off-roading or nice country rides,

Maybe you could comment on how you find yours.

 

[103Alex1]

And 34mph is bad because....

.... because Kraken is a standard hardtail MTB and not a full-sus DH bike or one with extra frame welding / slack geometry.

There isn't good stability on a standard hardtail bike for high speed riding. They aren't designed for it.

Custom-designed high speed bikes that are not racing road bikes are built round sturdy frames. Might just be at the lower limit where this is becoming an issue but nonetheless I subscribe to safety first.

(Waits for someone to jump in and say nonsense, we fitted a 2500W motor to a Tesco shopping bike run at 72V and ridden it for years etc etc. - but if you look at more powerful bikes like the Stealth Bomber there is a sound reason for their frame choice and reading around those bikes explains why... this is definitely a small moped at 48V with a 30A controller - and mindset needs to move from bicycle to consider the relevant factors to make the bike build sit comfortably with the motor, battery and controller choice - and still handle right at speed... imho).

This was the battery I bought - same as Saneagle's :

http://www.bmsbattery.com/36v/445-36v-15ah-lithium-ion-electric-bicycle-battery-pack.html / 200V - 264V obviously to get the right charger.

 

[Fordulike]

I've never run a BPM at that speed, so I'm not sure how well it can handle it. Once actual speed drops below 20mph at high throttle, the motor becomes increasingly less efficient. Without changes to the gearing, you can't pedal at that speed, which is a bit of a give away. My only experience of those speeds was when I built my 27mph 2WD. It was fun, but, for me, it just wasn't right going that speed on a bicycle. If you just need to go fast between too points, it'll probably be OK, but I can't see it being right for busy commuting, off-roading or nice country rides,

Maybe you could comment on how you find yours.

I totally agree d8veh, for commuting, torque is what you need and not speed.
The faster winds would always be out of their efficiency sweet spot, lots of bogging down and wasted energy.
Mine will hit 26mph, but I wouldn't feel comfortable any faster.
The 3 speed switch tames throttle response at lower speeds, and is a godsend when maneuvering at low speeds.
It pulls like a train though, and as I have mentioned many times, the battery in the frame is the only place for a battery to be in my eyes.
I was never totally comfortable with the Cyclamatic and modded battery on a rear rack.

 

[103Alex1]

If you're going to do some riding off-road with that ideal bike for it, the Schwalbe Marathon Plus tyre comes in other tread patterns more suitable for that than the road pattern you've linked to.

Crossover road and off-road version

Full off-road version

The 'full off-road version' also comes in a 2.1 version and that's what I use on the Trek on tar as well. Very comfy / recommended .

 

[wurly]

Really sorry to see whats happened to your new battery pack. I have Lipo on one of my many bikes and i've already blown two packs, personnally i'm not going to use them any more. I don't think they are good value for money. Sure they pack a punch but for me they are too volatile (and you have found that out too).

I'm going to recommend Ping for the battery. It's lifepo4 and if used within a 1.5 c discharge rate it will last years. One of mine is approaching it's 5th year and it's still good.

I have a BPM code10 on a Marin hardtail 26" rim and it will top out at 24mph with a 36V 10ah ping battery. I haven't altered the gearing so it's 48/11 and i can hardly pedal fast enough to keep up. It's uncomfortable at that speed anyway so i keep the settings on medium(on the led display) and it's runs nicely at 17mph...perfect.

My other bike is also a code10 with a 48v 15ah ping, it's a full suspension so it's comfortable at any speed. Horses for courses etc the style of the bike makes a huge difference.

 

[bilabonic]

I've ordered the 36V 20AH LI-ION from BMS to get me going, plus a spare charger and every type of throttle they have, don't like the 'feel'of a full throttle on a bike when you also have to change gears.

On a good note i extended my brake pressure leads today, and resealed them with hot glue -

 

[rpurchon]

what size are the 20ah 36v batterys.
richard

 

[103Alex1]

They can vary depending on the batch (used to be long and thin I believe, but Saneagle and I both got shorter fatter ones over end of last year / start of this one). You'll only know for sure when you actually get it.

Mine is 155mm x 210mm x 90mm (approx). There's padding and shrinkwrap around so edges are somewhat rounded.

Hope that helps..

 

[rpurchon]

thanks, i presume the weight of 5.5kg re bms is just the battery.or is that the parcel weight inc charger.
richard

 

[103Alex1]

thanks, i presume the weight of 5.5kg re bms is just the battery.or is that the parcel weight inc charger.
richard

Mine weighs 4.85kg without charger. That's the Li-Ion not the LiFePO4.

 

[bilabonic]

Anyone recommend some decent epoxy glue or similar, want to glue voltmeter onto handlebar holder (the torch holder part removes, so its plastic against plastic.-

Waterproof Digital Voltmeter DC 15V To 120V Red Led Voltage Digital Panel Meter | eBay

Flashlight LED Torch Mount Holder Clamp Clip Cycling Bicycle Bike Handlebar | eBay

I have always used 'cheap' poundland stuff but nnever seems to set even with more hardener.

Cheers

 

[103Alex1]

The problem you've got with some plastics is that they're polypropylene or similar and very few adhesives are effective. It really depends on the plastic - 2 part epoxy will work on some.

Bondit B-45TH will most likely work very well, but getting hold of it in this country is another matter entirely. There are bound to be other similar bonding agents here.

You could try this - may have to be re-done now and again if exposed to damp or strain a lot.

http://www.amazon.co.uk/LOCTITE-Plastix-Plastics-Adhesives-Epoxies/dp/B0062MOMP4/ref=pd_sim_sbs_diy_3#productDetails

 

[bilabonic]

Well my new battery/gear arrived today, looks and feels like a concrete block !!!!

Gave it a charge and the green light came on as fully charged after 5mins, checked voltage with my Fluke and cheapy voltage indicator after half an hour and it's 41.2v.

I also notice the battery has under voltage protection, do people use this as standard ?

What do i not leave the battery drop below, was also expecting balance leads as they are still individual cells ?

Trying the think of how to make the battery safer/secure in the bag with controller, perhaps with extra padding.

 

[103Alex1]

That voltage is too low to be fully charged. It should read 42V. Mine reads this with my multimeter and Cycle Analyst outputs a reading of 42.1.

Does the fan come on when you plug in the charger ? Put your multimeter onto the pins of the charger to check polarity and also check the battery polarity to make sure charger and battery are compatibly matched. Don't trust anything from China as being correct without checking it first .

Also take out the fuse from the little screw in slot on the front and put multimeter across this. It should beep if it's good.

Did you get the extra charger ?

 

[bilabonic]

It was 42v immediately after charging, but i rechecked after a couple of mins, charger all working fine, fan came on, fuse is fine as is polarity.

How do i monitor the battery as to not to over-discharge or is there no need with these ?

I powered it up with bike upside again but with tyres on etc and the throw in the wheel is very visible now, i also tried it correct way up suspended by holding the bikes seat and it's very unbalanced.

I ordered an extra charger, will inbox details