New battery purchase questions...

[morphix]

Hi all,

As I'm running off one 5Ah battery now which I've had for a while, I'm a bit worried about it dying and so have decided to order a new battery this week. I have a couple of questions I'm hoping some of you self-builders can help me with..

I'm just about to place an order with BMS battery for a new 10Ah Lithium Ion battery which was kindly recommended to me, but I'm wondering if anyone has anything to say about BMS Battery and their batteries, are they reliable? I'd particularly welcome any comments on Lithium Ion which I'm not familiar with..

That leads me to my second question! The battery above is quite a bit heavier than my current 1.89kg battery, weighing in at 2.5kg. I have my battery housed in a handlebar bar and I've been using cheap ones off eBay. Only problem is they're not really intended for this kind of weight and I'm already on my 3rd bag even with the lighter 1.89kg battery! These bags have the straps sewn directly onto the bag material and they tend to tear-off over time as you go over bumps etc. My latest bag is just about to go and I have reinforced it with bungee cords but it looks messy and spoils the look of my bike

So short of reinforcing the straps around the bag somehow with webbing, I'd welcome any other suggestions for bags that might be more stronger/suitable, bearing in mind the size required for the battery. I know it makes more sense to put the battery at the rear on a rack but I'm really reluctant to go down that route as it means re-doing all my wiring and having cabling all over the bike frame.

Anyway thanks in advance for any reviews of BMS or suggestions on bag problem!

P.S. I'm wondering if the 10Ah will give me a bit more umpf compared to my 5Ah LiFePo4?

 

[flecc]

On your last query, a larger battery capacity generally gives a little more power, and an increase in range greater than the size ratio indicates. However, there are caveats due to the power of the motor and the battery chemistry.

The greatest effect in both is realised with the most powerful high consumption motors, conversely the less a motor needs, the smaller the gain with more capacity. On battery type, today's compound cathode Li-ion/Li-poly batteries deliver current more easily than LiFePO4, so in your case the switch is favourable if to the former type.

I've no experience or knowledge of BMS battery and don't know of a suitable bag for your application, so I'll leave those to others with the appropriate knowledge to answer.

 

[amigafan2003]

I've just ordered the 36v15ah version of the same battery (literally 3 hrs ago) so we'll see how long it takes to arrive - I've been advised by other members to expect 2-6weeks delivery time though.

You must be aware, despite what the specs say on the site, that these are true 1c batteries - so don't get the 10ah one if your motor will draw more that 10a for even a short period of time.

Regards bags, I'm using this to mount it. I already have the bag and can confirm it's well made with strong stiching but I'll get a couple of extra velcro straps to wrap around the bag/bike frame as 3.3kg is a fair weight to put in a bag.

 

[Scottyf]

The discharge rate indicated that the batteries are rated 10amp continous with max discharge of 20amp.

I'd imagine the smaller 5amp battery is already in a typical 250w setup is being pushed at 3c.
So the battery will give more grunt and less voltage sag. (Depending on the cells you are currently using).

These are also the polymer type rather than the cylinder style cells.

I ordered a kit of BMS battery and although they are enthusiastic there is always a language barrier. Mine took alot longer than just 6 weeks to make its way over.

Still I was pleased with the products and you won't find it for much cheaper else where.

Could you not buy a bottle battery one and fix it to a bottle holder rather than a bag?

 

[amigafan2003]

The discharge rate indicated that the batteries are rated 10amp continous with max discharge of 20amp.

I'd imagine the smaller 5amp battery is already in a typical 250w setup is being pushed at 3c.
So the battery will give more grunt and less voltage sag. (Depending on the cells you are currently using).

These are also the polymer type rather than the cylinder style cells.

I ordered a kit of BMS battery and although they are enthusiastic there is always a language barrier. Mine took alot longer than just 6 weeks to make its way over.

Still I was pleased with the products and you won't find it for much cheaper else where.

Could you not buy a bottle battery one and fix it to a bottle holder rather than a bag?

I think the challenge with using a bottle type battery is finding someone that sells one! BMSBattery have been out of stock of ages, 8fun don't know when they will be getting them in again and Cytronex wont sell theirs if you don't already own one of their bikes (and I suspect the same will apply to Oxygene).

 

[banbury frank]

Hi the 10Ah Bms battery is 10 a continues 20A peak

so 40 volts X 10Amps 400 wats continues 800 wats peak

should run your 250 watt motor OK

If you want more amps order the 15 AH battery this has a 20 Amp continues BMS 40Amps peak the battery cell in both battery packs are the same But good for a 500 watt motor

Frank

 

[Scottyf]

Bottle battery and in stock

GREENWAY-Product_View | Professional Laptop battery ODM/OEM Service Provider

 

[morphix]

Thanks for the info and advice guys! I hadn't given any thought to a bottle battery but maybe I should. I'm experimenting with the heavier weight on front of bike today to see how much difference it makes to handling, my existing 1.89kg bat doesn't much a lot of difference.

Scottyf I'm envious of your 17kg build! I tried to do mine as lightweight as possible, but couldn't get it below 22kg.. mine you, it is a full size 26" MTB and a steel frame one at that! I'm considering doing a second 20" folding build and trying to get the weight down to 18kg or below, because my knee is really messed up and carrying this bike up and down 2 flights of stairs everyday isn't helping!

 

[amigafan2003]

Bottle battery and in stock

GREENWAY-Product_View | Professional Laptop battery ODM/OEM Service Provider

Doesn't look in stock to me - says "developing" and I can't see a purchase link.

 

[Scottyf]

Sorry A friend I'm helping build a bike for brought one from them... Here's a picture...




Also my build is only that weight becasue I carry a battery on my back as well as the controller. So dont get to envious.
The bike I'm using is not that light either I think it starts out in life at 13kg.

But compared to my first build its nicer to ride unassisted and rides very similar to a noral bike even when you dont carry batteries and controllers.

The hub has really loosened up the past few 100 miles or so. The only difference I notice is the gearing ratio's on my none hub wheel which has faster gear set and its easier to go over the bars as the center of gravity isn't as far back or low.

 

[morphix]

Ok a quick update on my battery purchase...

I received the Lithium-Ion battery pack from BMS Battery in China this morning, it arrived nice and early by FedEx in super quick time (less than 4 days).

The battery is 36V 10Ah, measuring 7.5cm X 14cm X 16cm and weighing in at 2.5kg. It's supposed to last 800 charge cycles.

Until now I've been running on 5Ah LiFePo4 batteries weighing 1.89kg as I wanted to keep the weight of my bike down and I mount the battery on the handlebar. This new battery is only 32% heavier for twice the amps power so it looks like a good trade-off and I'm hoping it will perform better and last longer.

I will put the battery on charge and maybe take it for a test run later on if I can, weather permitting. I will try and film it as I haven't made any videos for ages

Only problem is I don't think my handlebar bag will take the extra weight though without some modifications as it's already being pulled apart with my 1.89kg battery (I'm having to use bungee cords to support it). What I'm going to do is buy a cheap sewing machine and then try and reinforce the handlebar bag with some webbing around it.

Some pictures of the battery:

The battery and charger look a lot much professional than the LiFePo4 one I bought off eBay. The battery is really well sealed and has more sturdy connectors..the charger has an aluminium housing and fuse on the front (spare fuses provided).

Side by side comparison with my old 5Ah LiFePo4 (which has had the duct-tape removed). You can see that although the Lithium-Ion is 10Ah the size is pretty much the same.

 

[Scottyf]

Is there no where else that you can mount the battery?

The Lifepo4 chemistry should last longer than any given li-ion battery.
But as you where probably pulling 3C out of the old Lifepo4 this was probably stressing the cells quite a bit.

Li-ion BMS battery should naturally have a better C rate. (Depending on cells) and given that it starts at 10amp hrs means it will only be pulling 1.5c or 2c max extending your range and life of cells as they are not so stressed with the current draw.

Also chances are the distance you will do will be similar and if you top up the battery at the same intervals as the 5amp hr battery this will also extend life considerably.

Let us all know how you get on!

 

[morphix]

Is there no where else that you can mount the battery?

The Lifepo4 chemistry should last longer than any given li-ion battery.
But as you where probably pulling 3C out of the old Lifepo4 this was probably stressing the cells quite a bit.

Li-ion BMS battery should naturally have a better C rate. (Depending on cells) and given that it starts at 10amp hrs means it will only be pulling 1.5c or 2c max extending your range and life of cells as they are not so stressed with the current draw.

Also chances are the distance you will do will be similar and if you top up the battery at the same intervals as the 5amp hr battery this will also extend life considerably.

Let us all know how you get on!

Thanks scotty, that's good to know. I use my bike every day for work and travel about 5 or 6 miles round-trip and normally have to charge the 5Ah every day.

I uploaded some pictures of the battery above, I'm astonished the size is almost the same as the 5Ah battery.

Re mounting the battery... I'm not sure if I'm going to be using this bike much longer, I'm currently considering a second build again and looking at buying a lighter and more compact 20" folder with a rack.. so it's possible I could mount on the back...but I think I prefer the handlebar still. I will see how I get on reinforcing the handlebar bag and report back, just ordered a cheap sewing machine

 

[Scottyf]

Front Rack possible?

 

[morphix]

Never considered a front rack, in fact never heard of them! I'll have a google..

 

[morphix]

Things don't always go as smoothly as expected!

I've just finished installing the new battery onto the bike. What a fiasco!

I expected just to drop it into the handlebar bag. Ha, was I in for a surprise!

No sooner had I managed to squeeze it in I realised it had the wrong connector type for power out..it was the female kettle end instead of the male end. Luckily they provided a spare male end connector with the battery so I had to change the female connector on my controller. What a nightmare that turned out to be. I couldn't find my "helping hands" and had to manage with a vice and pair of pliers, needless to say I was sweating and swearing a lot handling the loose wires knowing that the controller still had 37v in it showing up on the meter! Soldering the wires onto the pins proved very tricky indeed my soldering iron wasn't really hot enough or up to soldering onto metal but I did the best I could and it looks quite secure.

Then the first of two disasters happened..while I was putting the connector together on the controller I accidentally shorted it out with the pliers. Got a little spark and crackle and thought "oh shite there goes my controller." I plugged it into the battery and powered it up from my LCD console. Nothing. Nada. Blank screen. My heart sank as I thought I had definitely blown the controller. Then on examining the kettle connector from the battery I noticed the silly buggers had put the pins in the wrong way round! The connector was labelled on the outside L and N so naturally I expected that to be true and had wired my controller end accordingly. On opening the battery connector I saw the pins were in the opposite way so had to fiddle around changing them over.

Put it back together, powered up and to my relief it powered up fine!! Phew.

I lifted the front wheel and cranked up the throttle to full pelt to see what it sounded like.. seems a tad more powerful than my LiFePo4 but the real test will be on the road later.

The other problem though is the weight. The extra 600g of weight on the handlebar makes a huge difference! Steering looks like it might be affected and even lifting the bike is more tricky. Looks like I'm definitely going to have consider mounting on the back with this bigger battery. It looks almost certain now I'll be needing a lighter bike too as no way can I be carrying this up and down stairs everyday. Unless I re-do my wiring and modify the bag to make it easily removable.. hmm some things to consider anyway.. I will do a test ride later and report back hopefully with some camera footage.

 

[flecc]

Never considered a front rack, in fact never heard of them! I'll have a google..

Often used for bicycle touring so that four panniers can be fitted. Here's an example photo:

 

[Deleted member 4366]

If you decide that your only option is to move the battery and controller aft, or on your next build, you could do it like this. Buy a football boot bag. You need one that zips around the top - ideally one zip on each side. Make sure that the bag doesn't have mesh in it for breathing otherwise it won't be waterproof (mesh can be sealed with black silicone sealant). Get a seat-post rack. Cut a piece of 3mm plywood to go inside the bag. Bolt through the bag and plywood to the rack. This gives a very secure bag that will house both the battery and the controller. You can put a small padlock between the two zips to keep out the fickle-fingered. If you want it to look really neat, cut a couple of internal plywood sides that match the shape of the bag. Voila!

 

[morphix]

Very neat solution d8veh!

 

[catsnapper]

If anyone is still interested in elusive bottle batteries, they're in stock here: 36V 12Ah Inframe-Mounted (Bottle-shape) LiMnO2 Battery Pack for E-bikes_Li-Mn Battery 36V_LiMnO2 Batteries_E-Bike Batteries_Batteries_A123 batteries,motorcycle battery,golf cart batteries,car batteries,car battery

They do free delivery, and seem to have a decent reputation. A friend has purchased from them without problems.