Battery holders / locations

[Joneser]

Hi
I've taken a lot of tips from this forum, largely from jerrysimon and D8veh.

Maybe it has been done before, but though I'd share an idea for a battery holder / location.

It is a 12xA123 battery pack with Watt meter all squeezed into a mobile phone frame bag. Not sure how waterproof it is but I can tape the zips as to charge it I just take the whole bag off by undoing the velcro.

My front wheel / motor is being built at the bike shop now, hopefully next weekend I'll have a working bike. I'll take photos of the 'finished' item to share too.

Cheers

 

[peerjay56]

Hi
I've taken a lot of tips from this forum, largely from jerrysimon and D8veh.

Maybe it has been done before, but though I'd share an idea for a battery holder / location.

It is a 12xA123 battery pack with Watt meter all squeezed into a mobile phone frame bag. Not sure how waterproof it is but I can tape the zips as to charge it I just take the whole bag off by undoing the velcro.

My front wheel / motor is being built at the bike shop now, hopefully next weekend I'll have a working bike. I'll take photos of the 'finished' item to share too.

Cheers

I'm a bit confused - what voltage/ah pack will fit in that bag? (sorry - I don't understand the various pack designations - 12s etc. That would make a useful and informative thread )

 

[Deleted member 4366]

I'm a bit confused - what voltage/ah pack will fit in that bag? (sorry - I don't understand the various pack designations - 12s etc. That would make a useful and informative thread )

It's dead easy as long as you can multiply. A123 cells are nominally 3.3v, so 12S is 12 cells end to end. 12 x 3.3 = 39.6v

You can see the size of these ones is 26mm dia x 66.5mm long for 2.3 aH, so you need two strings for 4.3aH, which would be 24 cells, which would make a block of 156mm x 104mm x 66.5mm

A123-3.3VB Lithium Ion 2300mAh Single Cell Battery

4.3aH will get you about 15 miles on an average 250w 36v bike.

 

[peerjay56]

It's dead easy as long as you can multiply. A123 cells are nominally 3.3v, so 12S is 12 cells end to end. 12 x 3.3 = 39.6v

You can see the size of these ones is 26mm dia x 66.5mm long for 2.3 aH, so you need two strings for 4.3aH, which would be 24 cells, which would make a block of 156mm x 104mm x 66.5mm

A123-3.3VB Lithium Ion 2300mAh Single Cell Battery

4.3aH will get you about 15 miles on an average 250w 36v bike.

So joneser is going to put a 2.3aH pack on his bike? Sounds like a good way to create a 'reserve tank' as discussed in another thread, but not really suitable generally unless you have a short commute.

 

[Deleted member 4366]

2.3aH wouldn't be enough for me to nip down to the shops and back, but if you're light, your roads are flat, you have a low cut-off speed, and you like to pedal hard, it could be enough. It'sthe same old thing: You can't get something from nothing. All the help you get from an electric bike comes from the battery. If you want a little help, a small battery's OK, but, if you want a lot, you need a big battery.

 

[Joneser]

I'm after just a little help. So the bike will only be about 2.5kg heavier than it was. The key to me is the free-wheel. It has to feel like a normal bike when not using the motor.

 

[jerrysimon]

I have just changed my 4 year old, 4000 mile Tongxin as per the other post. I have to say that after 4000 miles the Tongxin has a pretty good free wheel they certainly get even better with age. It was still working but was pretty rattlely when you spin it plus I have changed it with a 290RPM version it being a 260RPM. It gives me about 14-15mph over the 13-14mph of the original.

Re the A123 cells I started out with these and still use them off and on. They are perfect for my fairly flat 10.5 mile round commute. Admitedly the commute across Cambridge is pretty flat with just a few inlcines on the way. I now alway charge it at work and these cells I suspect will go on for several years. I do balance them about once every 3-4months.

The other cells I use are Konion cells in two 5s2p config connected in series for 10s2p. This give a little more capacity at 3Ah and easily cover my commute both ways without charging.

Shown below is a 2kg Konion 10s4p (split into 2 * 5S4P packs) giving 6Ah and the 1kg 12s1p, 3.3Ah A123s. Also shown is a 12s1p 1Ah A123 0.5kg pack but that is not much good for more than a few miles and I mainly use it for testing motors only. Given all my bikes are carried its important to keep battery weight down and I see no point in carrying a 10Ah heavier battery if I don't need the capacity. My requirements are of course more specialist than most for who battery weight is not such an issue. All my DIY packs also fit in the back pouch of my Brompton bag another reason why I build them myself.

The Brompton bag showing the two back pouches that take all electrics, controller right hand and battery left hand. This leaves the main back for carrying all my luggage

Regards


Jerry

 

[Joneser]

Thats fantastic Gerry. I have a Brompton too and if the Giant conversion goes well I might have the confidence to have a go at the Brompton.

Aesthetically for my Giant I prefer the saddle bag look as attached. But may be less logical in terms of wiring.

 

[jerrysimon]

Nice. So many more options for larger bikes. The Brompton has such a fussy fold.

Jerry

 

[banbury frank]

Hi We use a 7.5 AH call that we can have made into a 36 volt pack we are having some made for next year but 48 volts 7.5 AH as we are going to do a rear brompton convershion

The 36 volt 7.5 ah Li-ion pack will weigh 2.5 kilos and size 65 deep 80 wide 130 long this includs a 15 amp continus BMS cost £ 350

Frank

 

[peerjay56]

I'm after just a little help. So the bike will only be about 2.5kg heavier than it was. The key to me is the free-wheel. It has to feel like a normal bike when not using the motor.

OK, I understand that. Do you intend using the wattmeter to let you know when the battery pack is 'exhausted', so you don't kill the cells? And will it give you sufficient power continuously, or will it quickly 'slump' in use? Sorry for what may appear silly questions, but I'm interested in the concept as a reserve for my longer rides

 

[jerrysimon]

Important to find out how much of the capacity left in a small pack so as you say you don't kill the cells. That said the A123 ones are very robust. I abused them (ran them flat) most days and they still survived 12 months of daily use before I lost a couple of cells at a cost of about £8 pounds to replace DIY. Now I tend to only run them down to about 2/3rds capacity and as I say balance about once every 3 months or so. I have not had a single cell failure in 2+ years since doing this. Having checked my regular commute route and knowing how much it uses I don't use a watt meter every ride.

The A123 cells can discharge at something like 60-80amps continuous and so don't lag at all until they almost go flat. The Konions are not so good this way the voltage drops more after the pack is down to half capacity. I think if I wanted a good small pack I would choose a 12s2p A123 (43.2v, 4.6Ah) pack. I guess a BMS included would make it plug and play but then it would probably cost as much as a £200 pound ish 36V 10Ah standard bottle battery.

Regards

Jerry

 

[jerrysimon]

Hi We use a 7.5 AH call that we can have made into a 36 volt pack we are having some made for next year but 48 volts 7.5 AH as we are going to do a rear brompton convershion

The 36 volt 7.5 ah Li-ion pack will weigh 2.5 kilos and size 65 deep 80 wide 130 long this includs a 15 amp continus BMS cost £ 350

Frank

Interesting Frank will be interesting to see what you come up with. A few have tried rear wheel conversions which prove problematic both in terms of weight on the rear swing mechanism straining bushes and of course restriction of the 112mm spacing which if spread cause the tire to rub on the chain stays cross member and compromise the fold. Battery sounds interesting. I think at those measurements it would fit in the rear pouch. Care to share what cells you plan to use ?

Regards


Jerry.

 

[banbury frank]

Hi jerrysimon

I made a bobo we are using a front motor only 75 wide

The batterys we use is top secret Sorry taken me 3 years to find them

Frank

 

[jerrysimon]

Hi jerrysimon

I made a bobo we are using a front motor only 75 wide

The batterys we use is top secret Sorry taken me 3 years to find them

Frank

Thanks for the clarification.

Re the batteries, well of course it has also taken taken me four years to develop my light Brompton conversion of which I have openly share every detail of its development on this forum and others. Then I again though I guess this is not my business or livelihood

Regards

Jerry

 

[Joneser]

How can you keep batteries secret? Its like saying we sell the best quality beef but can't tell you where it comes from. Except if you want to know you can buy one and look so its not really secret.

 

[banbury frank]

Hi they have the XIPI name behind them and we dont supply batterys unles they are part off a kit or finished bike as far as I know we are the only company in the UK suppling 48 volt and 70 volt High powerd kits over the last 5 years Many have tride to copy our kits and failed

And yes our kits are very beefy


Frank

 

[Joneser]

OK, I understand that. Do you intend using the wattmeter to let you know when the battery pack is 'exhausted', so you don't kill the cells? And will it give you sufficient power continuously, or will it quickly 'slump' in use? Sorry for what may appear silly questions, but I'm interested in the concept as a reserve for my longer rides

Hi Phil
3rd time I've tried to reply. Some reason keeps failing. This is my first bike conversion. I'm going to try the batteries that jerry has used successfully on his Brompton. BUT I'm trying a full size bike (13.5kg) over twice the distance (20 odd round trip) and there are big hills. I currently cycle it unassisted but I would like a bit of help to take the edge of it. Its an experiment. Will let you know how I get on. I also have a 5.5 Ah 1.5 kg Forzatec battery to try.
Cheers
Joneser