Just ordered a 750w BBS02, my first electric bike !

[Topdonkey]

Hi all

Been lurking and reading and soaking up all the information on here for months now, and have finally taken the plunge and ordered a 750w BBS02 8fun conversion kit from Eclipsebikes, they arent getting them in stock till the 11th so have a few more days to wait yet.

I'm going to attempt to install it on my Carerra hellcat full sus mtb, has anyone installed a BBS02 onto one of these ?, any pointers or tips would be appreciated.

I have a long background in radio controlled models and currently fly quadcopters so it seemed sensible to use the same chargers that i already have a lipo alarms and i'm just about to order some of the multistar batteries, i was thinking about getting 2 of the 6.6ah 6s packs to power it with 44v, would this be ok ?

Is there anything else i might need for the conversion that i might not have thought about !

Thanks to everyone for all the helpful and informative posts

 

[trex]

I thought that the BBS02 750W 48V uses 13S battery.
Two 6S in series may trip LVC.

 

[mfj197]

Yes, I think the low voltage cutoff on the BBS02 48V is set to 41v by default. How far through the under-load discharge curve of two 6S packs would you hit 41V?

EDIT: Just looking at the discharge curves you might well be okay. 41V LVC equates to 3.4V per cell with 12S. That would be too low for Li-Ion but you might get away with it with LiPo.

Michael

 

[Topdonkey]

my lipo alarms go off at 3.3v and i usually stop flying at 3.2v unless its not safe to land when i have flown down to 2.9v but this is rare, so 3.4v shouldnt be too much of a problem.

The guy at eclipse did say that he could program it for me, so maybe he can set the lvc a bit lower, is this possible ?, if it isnt, i'll add another cell to the pack and make it up to a 13s

 

[D8ve]

One thing is the 750watt nominal motor may draw a lot more! Possibly 2kw at max this will realy eat into your range and may cause voltage sag too.

If 250 watt ones can pull over 800 watts peak.

 

[mfj197]

my lipo alarms go off at 3.3v and i usually stop flying at 3.2v unless its not safe to land when i have flown down to 2.9v but this is rare, so 3.4v shouldnt be too much of a problem.

I was actually coming at it from the other angle - the cutoff may be too soon and you might still have quite a lot of energy left in the cells which you haven't got access to. Sounds like you'd be fine even with it as it is, but ...

The guy at eclipse did say that he could program it for me, so maybe he can set the lvc a bit lower, is this possible ?, if it isnt, i'll add another cell to the pack and make it up to a 13s

Yes, it's perfectly possible and actually that would solve it completely - set the low voltage cutoff a little lower.

Michael

 

[Topdonkey]

Thanks Michael, I will email him again this evening asking him to set the cutoff a bit lower and stick with a 12s pack

 

[Deleted member 4366]

You don't need to set the LVC any lower. Once they've reached 3.5v per cell, there's virtually nothing left. They'll drop like a stone after that, and they go out of balance if you go lower than that.

 

[Kinninvie]

My BBS02 runs perfectly on 12S of Multistars and as Dave says dont go below 3.5V a cell or they will go way out of balance.
I have 48Ah of them and that will get me over 120 miles and thats charging to 4.15V and discharging to 3.6V.
I bulk charge them and if I keep to the 3.6v they stay in balance.
I did add a 2s battery to try 14S and although the bike was a lot quicker it did cause the chain to jump a bit .It does 32Mph on the flat at 12s and 38 at 14s!!

 

[Kinninvie]

One thing is the 750watt nominal motor may draw a lot more! Possibly 2kw at max this will realy eat into your range and may cause voltage sag too.

If 250 watt ones can pull over 800 watts peak.

My BBS02 peaks at 1100 watts.
It only ever gets that far when initialy accelerating uphill .

 

[D8ve]

Thanks for a figure. K.

 

[amigafan2003]

One thing is the 750watt nominal motor may draw a lot more! Possibly 2kw at max this will realy eat into your range and may cause voltage sag too.

If 250 watt ones can pull over 800 watts peak.

The most I've measured my 48v500w (programmed to 18a) BBS02 at is 1100w (on a 15s lipo pack). The 48v750w is programmed to 25a, so that's 1260w peak on a fresh 12s battery.

 

[Topdonkey]

Doh!, lots more to think about before i choose a battery then !

I think i'll go 13s using either multistar or zippy flightmax packs in either 3s+3s+3s+4s to make a 13s lipo of either 5200mah or 8000mah

My trip to work is only 7 miles, but is quite hilly, so a 14 mile round trip to work and back, I weigh a portly 104 kilos myself !!!, and whilst i would like to put lots of cycling input in, i need to increase my fitness and decrease my weight on the run up to this summer, so initially, i would say i want the motor to do about 80-90% of the work, but ideally, by the summer, i'd be doing half the work and the motor the other half, so any ideas or guesses how many amp hours i'd need on a 13s lipo battery pack to get me to work and back ?, i'm happy to convert watt hours if its done this way ?

thanks

 

[trex]

how hilly is your route? 48V 8AH should be enough for 14 hilly miles but I would go for 48V 11AH Lithium ion and save the bother with complicated charging.

 

[Topdonkey]

Its all hills really, i will be riding from Kilmington near axminster in devon, to Lyme regis along the A35 which is a long 2 mile uphill on the way there, then a long downhill on the way back, I wouldnt need power on the downhills so there would be 3 miles of downhill each way, so its only 4 miles of uphill power i would need each way

I would prefer lipo batteries as i already own all the balance chargers i would need because of my quadcopters i've got

 

[Deleted member 4366]

A pair of the 6S 8000mAh ones would probably do it, but it won't be long before you want to go further, in which case the 16000mAh Multistars would be better.

 

[Topdonkey]

Thanks d8veh, I'm going to order 4 x 4s 8000mah multistar and use the 4th pack to make one of the others a 5s, so that i get 2x4s and 1x5s 8000mah packs which i will join with xt90 connectors in series to give me a 13s pack, and next month (when my finances recover!!) I will order another 3x4s packs and use one of the cells from the first order to convert one to a 5s pack again which will paralell with the first set of packs to give me a 48v 16,000mah lipo pack once all done, hopefully that should get me to anywhere i want to go.

I do have a suzuki bandit motorbike which i ride around for the longer journeys, but it would be nice to be able to get to work by pushbike and slowly increase my fitness at the same time

 

[Deleted member 4366]

That's a lot of messing about and complicated wiring. I didn't realise that they had so many new multistar packs. With the 6S ones, all you need is a simple Y lead.

You won't notice much difference between 12S and 13S. Charging would also be much simpler. How are you going to charge 13S?

 

[Topdonkey]

I'm an electronics engineer by trade !, so the wiring is simple stuff for me, and i already have a 2x 6s charger and a 1x6s charger so dont have a problem charging or assembling the packs, and in fact, i would enjoy the challenge of building the packs, I have taken apart and reconfigured quite a few lipo packs in the past, so well versed in dissasembly and reassembly of them and the wiring between them too.

I'd definitely prefer lipo's over any other type of battery really as i've been using them for 5 years now and used to their characteristics

 

[Kinninvie]

Dont forget you will need protection on the batteries in case you fall off or drop one putting them on/off the bike.
I wrap my batteries in filament tape to keep them in compression then cover them in sections of vinyl floor tile and finally a covering in duct tape to hold it all together.
I started with a pair of Multistar 6s 16Ah then went to 2 pairs and am now onto 3 pairs which allows me to ride all day.