Help with LiPo packs for velomobile

[Reflector]

Hi all, some questions for you from a novice,
I am building an aluminium velomobile from http://dutchbikes.nl/ and would like assistance regarding the batteries and configuration I should use. The Bafang BBS02 is my choice of crank drive, so I imagine that the battery pack would have to be at least 48V.
I'm interested in hill climbing ability and maximum range so I presume I'll need at least a 20ah pack. The velomobile's three wheels are 20 inch and original gearing gives a range of 2.1 metres to 12 metres using the 65T chain ring and SRAM 3 x 8.
Is it a good idea to use a separate battery pack for LED lighting (headlights, tail, brake and indicators)?

 

[izeman]

i'm not sure what your question is. you already sorted out that it's 48v and 20ah. are you asking for a chemistry advice, or if your numbers are correct? are you looking for a special form factor of the battery to fit the bike?
only answer that can cleary be answered: you can power all your addons (lights etc) from the main battery. there are dc/dc converts that can make 12v out of 48v. it's less compex that way and those 20w for front/rear light won't reduce your range by much.

 

[dogman dan]

14s, 14 cells in series is 48v. Many though, prefer 12s, because often 4s RC packs are cheaper. Most 48v ebikes will run fine on 12s, it's about 42v-44v.

Whichever you choose, a 20 ah size pack would mean 4 sets of 5 ah packs. 5000mha = 5 ah.

So take the example of a 12s 20 ah bundle. three 4s packs makes a 12s 5 ah pack. four of that would be 12s 20 ah. 12 4s 5000 mha packs in the whole thing.

14s is more awkward to get to, but three 4s packs plus one 2s pack will do it. Or two 5s one 4s, or two 6s one 2s.

15s is tempting, but doesn't charge with a hyperion 14s charger, and it could be slightly over the spec for the controller in the motor.

I can't add much about the lighting, I just put a flasher on the back, and use bike headlights for what little night riding I do.

 

[izeman]

I can't add much about the lighting, I just put a flasher on the back, and use bike headlights for what little night riding I do.

i do it the same. bike's battery powered head light (10w led) and a battery powered flashing backlight. those run forever on a single set of batteries. routing cables is much more effort then just changing a set of alkalines every few month (i don't ride a lot in the dark)

 

[Reflector]

The BBS02 500W motor's controller is rated at 15, 18 or 20a. How is the battery pack amp hr rating supposed to compare with the controller's current rating?
As I'm carrying injuries, this vehicle will still enable me to exercise and also help me up the hills. I'd like to use the PAS on a low setting but need to work out a realistic range if I am to use 12s which seems to be a common format. Thanks for the lighting tips - running a wiring loom would be a pain (and extra weight!).

So my setup would be;
battery packs
balance charger
Balance leads
power supply for charger
cell loggers
battery box(es)

Have I forgotten anything? What sort of fuse(s) would be advisable and how is the fuse value calculated?
You've probably heard all of these questions before, but I'm keen to learn.

 

[dogman dan]

Pretty good list.

Re the pack/controller equation, no problem. RC lico, even the cheap 20c versions can still take 3-5 c discharge rates fine. A 1c discharge rate on a 20 ah pack would be 20 amps. So you will seldom exceed a 1c discharge rate.

20 ah should be a big enough battery, even if you chose some really cheap 1c rated lifepo4. So that won't be a problem.

Re fuses, they are advisable, but I'm one of the dolts that doesn't bother. I mostly concentrate on arranging the pack so shorts never happen. Battery to controller wires are placed crash worthy, and protected from chafing if exiting a metal box.

Your bike should be fine with a 30 amps blade fuse, in a good holder.

 

[izeman]

Re fuses, they are advisable, but I'm one of the dolts that doesn't bother. I mostly concentrate on arranging the pack so shorts never happen. Battery to controller wires are placed crash worthy, and protected from chafing if exiting a metal box.

Your bike should be fine with a 30 amps blade fuse, in a good holder.

+1. fuses are nice to have, but am not sure if they really will help. i have one 60a fuse in the series wire from the first 6s pack to the 2nd pack. i once managed to make a short with a free hanging positive wire that touched the battery frame (which is connected to ground through the controller). there was a big spark, the 5mm bullet connector disintegrated (well about the half of it) but the fuse (that should have blown) was still intact.

 

[Reflector]

Thanks Dogman and Izeman,
Concerning earthing the electrics.....
How do I get on when my vehicle is aluminium? Do I just earth to the aluminium frame?

 

[cal3thousand]

Re fuses, they are advisable, but I'm one of the dolts that doesn't bother. I mostly concentrate on arranging the pack so shorts never happen. Battery to controller wires are placed crash worthy, and protected from chafing if exiting a metal box.

Your bike should be fine with a 30 amps blade fuse, in a good holder.

+1. fuses are nice to have, but am not sure if they really will help. i have one 60a fuse in the series wire from the first 6s pack to the 2nd pack. i once managed to make a short with a free hanging positive wire that touched the battery frame (which is connected to ground through the controller). there was a big spark, the 5mm bullet connector disintegrated (well about the half of it) but the fuse (that should have blown) was still intact.

What type of fuse was it?

Some are very slow and some very fast.

I think ANN type fuses should be fast enough for ebike use.

 

[Marc S.]

While I use RC LiPo packs myself every day, I wouldn't recomment them to anybody without some RC background. Reflector might be a total newbe to ebikes and LiPo. There are much safer lithium chemistrys out there that last longer as well, without costing much more.
Sony Konion LiMn US18650 V3 cells come to mind, for instance. They don't even need a BMS.
(my 3,5 year old 11Ah battery made from Sony Konion 1.100mA cells is still going strong)

Sure, power to weight ratio and raw power of LiPo is unchallenged. But he doesn't need particulary high power cells, nor a small and light pack.
There is a lot of space in an Alleweder A4 and this little aluminium rocket isn't particulary light (in velomobile terms).
(I like to have an eVelomobile myself in the forseeable future)

What I figured after 21,000km commuting with a trike:
-I don't want a PAS. A normal throttle is much easier to deal with and more precise.
-I don't want to supervise the charging of some fiddely LiPo packs every day. It sucks.
-I want a save, easy-to-deal-with battery that will last.
-I want a good quick charger. Justins new Cycle Satiator608 is probably the best solution out there.

 

[cal3thousand]

Thanks Dogman and Izeman,
Concerning earthing the electrics.....
How do I get on when my vehicle is aluminium? Do I just earth to the aluminium frame?

I just noticed this comment. I would NOT use the frame as a common ground.

 

[Reflector]

While I use RC LiPo packs myself every day, I wouldn't recommend them to anybody without some RC background. Reflector might be a total newbe to ebikes and LiPo.

True, I am a total newbie and would really prefer a plug-'n-play system like the LiFeP04 packs which come with the Akkurad PAS if it wasn't for the fact that the 36V 10Ahr pack is 700 Euro.

..he doesn't need particulary high power cells, nor a small and light pack.
There is a lot of space in an Alleweder A4

Maybe I have to take the safer route and not sit close to a LiPo pack for the time being.
I just had a read about Justin's new Cycle Satiator608 and I agree; anything to simplify my task.

 

[dnmun]

i have some 14S and 15S D126 BMSs if you wanna build a battery with the lipoly packs. or you can use the balancing chargers and pull the packs apart and plug them in one by one until the charger dies.

 

[izeman]

Thanks Dogman and Izeman,
Concerning earthing the electrics.....
How do I get on when my vehicle is aluminium? Do I just earth to the aluminium frame?

common ground was NOT on purpose. it "just happened". i don't know where/why the controller's ground was connected to the case, and if this is always that way. i didn't pay much attention, and normally you wouldn't do that anyway. this is common for cars etc, but not for ebikes.

 

[izeman]

True, I am a total newbie and would really prefer a plug-'n-play system like the LiFeP04 packs which come with the Akkurad PAS if it wasn't for the fact that the 36V 10Ahr pack is 700 Euro.

if you don't want to care about battery building and balancing and charging then go for one of these:
http://em3ev.com/store/index.php?route=product/product&path=35&product_id=132
it's around €700 as well, but at least it's 50v and almost 20Ah

 

[dogman dan]

Just for the record, I did not recommend Lipo/lico to a noob. I merely answered his question. A fine line, but had he asked what battery he should choose, I'd have pointed him to limn type chemistry.

But good packs are pricy, especially in the 1000wh ballpark. It's a big part of why I decided to buy more lico in the last two years, rather than get a cellman pack I'd like a lot better.

 

[Reflector]

i have some 14S and 15S D126 BMSs if you wanna build a battery with the lipoly packs. or you can use the balancing chargers and pull the packs apart and plug them in one by one until the charger dies.

Thanks for the offer dnmun, (although the terminology escaped me after 14s and 15s) and I think freight to a small country town in Australia may be cost prohibitive.

 

[Reflector]

I now see that experienced e-bikers have their preferred battery chemistry and I'm wondering if I should have posted this topic as "Help with velomobile battery pack'. What I'm looking for is a no-nonsense, cost-effective electrical supply which will give me a good range and the extra help to maintain a modest speed.
Seeing as em3ev.com gets consistently good feedback, would I be better just getting a motor and battery combo. http://em3ev.com/store/index.php?ro...?route=product/product&path=45&product_id=175

 

[izeman]

exactly. if you haven't order yet i would order everything from paul/cellmann/em3ev

 

[dogman dan]

Guess I'm going senile, I'd have sworn I read you ask about RC packs in post one.

Yeah, good plan, a pack from cellman, pingbattery, in 15-20 ah will work great on that motor.

 

[Reflector]

Thanks Izeman, Dogman.
I did ask about RC power in my first post and I'd still like to go with it for the cost / weight advantage and..... I've just had a look at Tischer's 1HP electric bike build.
I could use exactly the same setup as he is using;

BBS02 750W
3 x 5Ah 4S (Hard case) in series, so no additional wires required
HK Parallel charging board
Imax B6 charger

I already have a computer power supply which could provide the 12V for the charger.
If I need extra range in the future, I could just buy another 3 batteries and hook them up as 12s2p.
(Then all I need to do is source a safe container for the batteries while they are next to me).
If I only balance charge the packs and ensure that they are never overcharged or over discharged, all should be good should it not?

Would it be advisable to have a cell-log monitor on each pack?
Also if I am light on the throttle and use low PAS settings, should my SRAM 3 x 7 be up to the task?

 

[dogman dan]

Ahh, you edited the post. Back to lico talk.

Don't buy a 50w charger like the b6. One thing about lico, you don't want to plug in a charger and go to sleep. You might have to go put out a fire. So you need a charger of at least 150-200w so you don't have to wait all day to charge.

This is a big part of why we switched our tune to, just get a pack with a bms. You still want to charge any battery safe, like don't set it on a pile of newspapers, or in the babies room. But seriously, RC packs have to be watched, and stored like they are cans of gasoline.

A safer chemistry, you can then just charge it right on the velo, and go inside to do whatever with no real worry.

 

[Reflector]

A safer chemistry, you can then just charge it right on the velo, and go inside to do whatever with no real worry.

Yes I did edit my post. I really appreciate your experience in these matters and your concern regarding the potential hazards for a noob / LiPo combination.
The easier, safer path for me must then be the cellman kit as the frame pack already has a case and a mounting device so that I can easily fit it to the vela.

I notice that his 11Ah pack comes with a charger that can not accept any more than a 3A charge rate.
Would there be any advantage in me getting a pack which has a 5A charger, and would an 11Ah pack have half the range of a 20Ah one?

 

[izeman]

I notice that his 11Ah pack comes with a charger that can not accept any more than a 3A charge rate.
Would there be any advantage in me getting a pack which has a 5A charger, and would an 11Ah pack have half the range of a 20Ah one?

if 3a is the maximum then this is because the bms or the batteries can't take any more.
and yes. basically an 11Ah pack is around half the range of a 20Ah one.

 

[Reflector]

if 3a is the maximum then this is because the bms or the batteries can't take any more.
and yes. basically an 11Ah pack is around half the range of a 20Ah one.

By comparing the cost of a 500W 11Ah pack from em3ev with the same motor and an 8Ah pack from Akkurad,
the former appears to be about a third of the price of the latter.
Does anyone know if cellman's frame pack has provision for running a power supply to lights from it?