The eBike thread

unkel

unkel wrote: »

Got a 6Ah 29.4V (7s3p)

Sorry Mad_Lad, those lipo batteries are not for me yet!

You will convert haha

unkel wrote: »

. This stuff is addictive

It certainly is addictive, at least you're having fun !

unkel

Picked up my fat bike in Longford this morning. It's fat!

Also picked up the above, it turned out to be an old direct drive motor (ABB branded) poorly laced in a 26" wheel, a brand new Chinesium 36V/48V 18A controller and he threw in an old twist throttle for the princely sum of €35 in total! I have a couple more 4Ah 36V packs incoming and together with this I can convert another bike at some stage

But the fat bike now has priority. Building my 58.8V battery this evening (14s3p)

unkel

The beast



Gonna go onto the charger in my shed now...

Looking good Unkel,

SlowBlowin

Looks like a giant liquorice allsort, I like it.

How do you find the kit to organise them, worth the money, how much was it ?

Are you doing balanced charging and no BMS on board (I think i read that somewhere) ?

Joe1919

NKON has kits below.
https://eu.nkon.nl/catalogsearch/result/?q=Vruzend+DIY+battery+kit
I dont know how they compare to other suppliers.

They also have cheap chinese cells at 1.69 each at present.( although I would still prefer paying extra for established branded cells)
https://eu.nkon.nl/review/product/list/id/3751/category/23/

unkel

SlowBlowin wrote: »

How do you find the kit to organise them, worth the money, how much was it ?

Kit is perfect, very easy to work it. The vruzend 2.1 kit is not cheap though at GBP40 including shipping and that's for a max of 30 cells. So I bought 2 of these kits. And I'm using 18650 cells that I got for free, yet it is cheaper to buy ready made cheap batteries from China

The kit does give you great flexibility in what type of battery you can make. I have already made 24V / 36V / 48V and 52V batteries with it

And it is part of the learning curve. Properly test batteries (internal resistance, self-discharge, capacity), build batteries and have respect for them, know the dangers and use them for various applications. If it ever stopped raining I'll go outside and try charge my car from this battery

SlowBlowin wrote: »

Are you doing balanced charging and no BMS on board (I think i read that somewhere) ?

If I ever buy the more expensive lipo batteries, I will get balance chargers. I believe they do a better job than BMS

For this kit I will use a BMS, I have a 13S and a 14S incoming from China. As you can see, BMS not yet on this battery, so I am using the big BMS in my brain
As you can probably see, I do have an inline fuse on the positive terminal

Joe1919 wrote: »

NKON has kits below.
https://eu.nkon.nl/catalogsearch/result/?q=Vruzend+DIY+battery+kit
I dont know how they compare to other suppliers.

That's a good price. But with the shipping it's about the same as I paid. The older kit is cheaper but I think it can't handle 20A continuous, a must for me

Calahonda52

Typically, how many charges would you expect from say a 12 V 65Ah car battery

Would run it through a 2kW inverter

unkel

You can't.

A 12V 65Ah car battery has a lot less than 30Ah actual capacity. And if you take 30Ah out of it a few times, it will be toast. It likes sitting at the higher end. I wouldn't take more than about 20Ah out of it and even that is pushing it, it will have a short life. Divide that by four if you are charging a 48V eBike battery of say 12Ah. That means you can only give the eBike about one quarter of one charge (after losses)

Why would you want to do this anyway, or are you just messin'?

I have 2 dead car batteries in series hooked up to a solar panel, which is charging them all day. This is lighting my shed with a 24V led powerlight at night whenever I enter (and switches itself off when I leave), which takes only a tiny drain on the battery. This is were these "dead" as in completely unusable in a car, batteries will still live for another 10 years I'd say

Calahonda52

Calahonda52 wrote: »

Typically, how many charges would you expect from say a 12 V 65Ah car battery

Would run it through a 2kW inverter

Typically you wouldn't want to use more than half the capacity of a Lead Acid battery or you might only see 100 Cycles.

To supply 2 Kw the Battery and power leads would need to supply 166 amps. You would drain that 56 Ah battery fast 40 mins for full 100% charge on that lead acid 25 mins for 50% charge, so you'd need a pretty large battery bank.

166 x 12 = 2 Kw and wouldn't be suitable for 1 x 65 Ah car battery.

what are you trying to run from the inverter ? a lot of inverters have a filthy power output, get a pure sinewave clean inverter and your devices will be much happier.

2 x 100 Ah leisure batteries will give you 1.2 hrs at 2 Kw or 60 mins with 50% charge. This would be a far better setup.

Go with 24 volts for much less current.

Joe1919

Deleted User wrote: »

Typically you wouldn't want to use more than half the capacity of a Lead Acid battery or you might only see 100 Cycles.

To supply 2 Kw the Battery and power leads would need to supply 166 amps. You would drain that 56 Ah battery fast 40 mins for full 100% charge on that lead acid 25 mins for 50% charge, so you'd need a pretty large battery bank.

166 x 12 = 2 Kw and wouldn't be suitable for 1 x 65 Ah car battery.

what are you trying to run from the inverter ? a lot of inverters have a filthy power output, get a pure sinewave clean inverter and your devices will be much happier.

2 x 100 Ah leisure batteries will give you 1.2 hrs at 2 Kw or 60 mins with 50% charge. This would be a far better setup.

Go with 24 volts for much less current.

Re Lead acid batteries, dont forget to take Peukert's law into account i.e. Typically, a 100ah battery will deliver 5amps for 20 hours, 10 amps for 9.5 hours, ...........as little as 50 amps for 1 hour.
Thats why lead acid batteries (besides their weight) perform so poorly in ebikes, as typical journeys (and discharges) are relatively short.
Lead acid batteries are suitable for large current for very short time (e.g starting engines.) but there is a huge loss.

Calahonda52

unkel wrote: »

The beast



Gonna go onto the charger in my shed now...

So how many of these would I need ?

unkel

Just one is fine. But 4 in parallel or even 5 would give you more range (instead of the 3 I am using in above picture because I have less than 14 good batteries left over.

For what you want to do - charge your eBike batteries with your van - that will work fine but the engine needs to be running.

Joe1919

A small (petrol) generator?

BarryM

Could those who show or have showed vruzend kit batteries indicate the size of what they show? A ruler alongside?

Helpful to know where they would fit

unkel

Do you not get a good idea of the size of the kit from my picture? With my hand in it and (a better indicator) a small cheapo multimeter beside it? I'm using 14 * 3 = 42 cells. One vruzend 2.1 kit has space for 30 cells

Edit - I have just done some measuring for you

An 18650 cell has a diameter of about 18mm. One block of the kit is about 22*22mm.

An 18650 cell has a height of about 64mm, between the vruzend blocks that is about 90mm. You can do the sums then, the pack will be 22mm * S wide, 22mm * P deep and 90mm tall :cool:

With S the number of cells in series and P the number of cells in parallel

My pack is then about 31cm * 7cm * 9cm

SlowBlowin

Its called an 18650 because it measures 18 x 65.

BarryM

Thank you both, very useful. I have a trike with a 250v battery and a Clubcar as discussed earlier on this thread and I am considering batteries for the clubcar and possibly the trike.

unkel

For insurance reasons, the owner of my local bike shop will not lace the hub motor into the wheel for me. Which is understandable. PITA as a staff member had told me they would.

So what next? Try another bike shop? If not successful, I could lace it myself and they could true if for me, they will do that. Seems like a daunting idea, but it does not seem to be too bad:

https://www.youtube.com/watch?v=CKrzp39XPVE

unkel

unkel wrote: »

For insurance reasons, the owner of my local bike shop will not lace the hub motor into the wheel for me. Which is understandable. PITA as a staff member had told me they would.

So what next? Try another bike shop? If not successful, I could lace it myself and they could true if for me, they will do that. Seems like a daunting idea, but it does not seem to be too bad:

Why won't the lace it ?

Ask around, I'm sure some bike shop will do it.

Joe1919

unkel wrote: »

............I could lace it myself and they could true if for me, they will do that. Seems like a daunting idea, but it does not seem to be too bad:

The biggest mistake often made when building a wheel is getting the spoke length measurement wrong. The spoke length is among other things, dependent on the depth of the rim, which effects the erd (effective rim diameter).
You need to order your rim first.
There are spoke length calculator on line. I would use two or three different ones. You need to triple check spoke length before ordering.
Use 2 cross pattern for 26-28 inch wheels (imo).
13 g (gauge) spokes is the norm for smaller hubs but I have successfully used 14g spokes which are cheaper and easier to get. The 14g are also lighter but more flexible than 13g.
PS If you can get as far as building the wheel, you will probably be able to true it ok.

unkel

Thanks Joe, I have the rim. It's the wheel that came with the second hand fat bike I picked up last Sunday.

I was hoping the shop would take out the existing spokes and use new spokes to lace the hub motor into it. When I googled last night, I came across a spoke length calculator. Still a bit daunting for me to do, I guess I'll be ringing a few more bike shops first.

Deleted User wrote: »

Why won't the lace it ?

Insurance. If anything happened and that wheel collapsed, they are afraid that I would sue them. I wouldn't of course and I suggested I'd sign a waiver, but he reckons that's not a legal defense for him (he's probably right). I can fully understand that. Small family business and his insurance premium is probably already very high. Have to be careful, not take any risks.

unkel

unkel wrote: »

Insurance. If anything happened and that wheel collapsed, they are afraid that I would sue them. I wouldn't of course and I suggested I'd sign a waiver, but he reckons that's not a legal defense for him (he's probably right). I can fully understand that. Small family business and his insurance premium is probably already very high. Have to be careful, not take any risks.

Jaysus, Insurance is a cop out for everything in Ireland.

unkel

Something needs to happen about insurance alright. It's beyond ridiculous. But I said that 25 years ago. Can't blame it on the small family business being careful though. Plenty of businesses have had to close down as people couldn't afford the insurance anymore.

Joe1919

There is a substantial danger for ordinary bike shops when dealing with ebikes. Take for example repairing a puncture or fitting new tyre or tube to motor wheel. This can involve disconnecting of wiring etc. What happens if motor does not work properly after reconnection?
The second and bigger safety risk is broken dropouts/ front forks if the trust washers/torque arms are not properly fitted, or are possibly inadequate in the first place.e.g alloy forks.

unkel

Yep, I fully understand where they are coming from. And I'd say no other bike shop will lace the wheel for me except maybe if a bike mechanic would do it as a nixer from his own house or something like that.

unkel

I managed to charge my car with it :cool:





Slowly at just 860W and just for a few minutes, for proof of concept as with this small battery, the cells are taking 3C, which is far too much anyway to use for more than a few minutes and I'm not using a BMS and as you can see, I have a fuse on the main battery positive, but that's on my XT60 connector, not on the inverter clips that I'm using here

But even using (abusing) this small battery - I would get enough charge for about 3km of driving gently

I'm getting in 4 * 24V 6Ah packs with BMS that I will put in series and parallel for use with my eBike that will be far more suitable for this as it will make a 52V 12Ah pack of 700Wh

Lumen

Looks like a bomb.

unkel

Haha, yeah. I have seen that mentioned more than once when doing various googles about the Vruzend kit

Another update, a certain contributor to this thread PM'd me the bike shop that laced wheels for them. That's where my fat bike is now. Hopefully job done in the next few days. He is also upgrading the shifter as that is the single worst bit of the fat bike (and very easy and cheap to upgrade). Might go for another few budget upgrades. Having read up quite a bit more about the Mongoose Dolomite fat bike, it is great value for money (I paid €225 for it, almost brand new condition) - it has been for sale sometimes in the likes of Walmart for an incredible $199 :eek:

A bit OT,

Got my 4S 8.4 Ah LiFeP04 from Hobbyking for my Radio Transceiver. Much lighter than carrying around a 45 Ah car battery lol.

It has a 2C max charge rate, I set it to charge at 15 amps and it charged 7 Ah in a little over 30 mins. Fantastic.