Hire E-Bike build thread

[Hickbeard]

Can you not cut off the solid tyre and drill a hole for the valve stem?

Probably. But it'll be easier for now to get a new rim.

Id need to replace the hub on the front to allow for a disc. For the sake of keeping a yellow wheel I don't think it's going to be worth it.

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[Hickbeard]

Which is the correct way to wire up my BMS? Do I need to do it on the + or is +- acceptable?

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[Hickbeard]

Just sketchupd busbars for battery. L142mm, W10mm, H4mm

Hopefully get them machined by Friday in copper

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[whereswally606]

well the negative obviously needs to be on the most negative and the positive goes on the most positive terminal but all of the ones in between it doesn't matter whether they are on the positive of the lower cell or the negative of the higher cell as that wire is at the same potential difference (negating the wire's resistance which is very low). Its one of those annoyances as you cant make a symmetrical pattern with it (unless you put the tap halfway between those connected +-'s) but ain't nobody got time for that. hope that all makes sense. eagerly awaiting pics of the finished article.

 

[Hickbeard]

Cheers wally.

Yeah I'm eagerly waiting for it to be finished [emoji1787]

We'll get there.

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[whereswally606]

I'm not sure I understand the bus bar you drew. I thought you are running 14s and if so that pic with seven holes in doesn't make sense to me. Are you cutting that bar into cell connectors (and if so didn't agnuism provide those, cause he did for my mate who did a similar 10s8p battery)

 

[Hickbeard]

I'm not sure I understand the bus bar you drew. I thought you are running 14s and if so that pic with seven holes in doesn't make sense to me. Are you cutting that bar into cell connectors (and if so didn't agnuism provide those, cause he did for my mate who did a similar 10s8p battery)

I couldn't fit them in, in one length so will run a u shaped bus bar.

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[whereswally606]

It still doesn't make sense to me. if you use a bus bar, this is to parallel cells, you have 14 cells packs and if you use a bus bar like the one in the photo you will be making 2s7p which is a 7.4v battery with a load of ah. It may just be me but I think that bus bar you are showing isn't what you need.

 

[Hickbeard]

It still doesn't make sense to me. if you use a bus bar, this is to parallel cells, you have 14 cells packs and if you use a bus bar like the one in the photo you will be making 2s7p which is a 7.4v battery with a load of ah. It may just be me but I think that bus bar you are showing isn't what you need.

Sorry. Each of the cell holders alternates +- on top. So that should give me 14s unless I've massively misunderstood something.

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[whereswally606]

if you want 14s you go
1 2 3 4 5 6 7 8 9 10 11 12 13 14
"-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+"

i.e. the pos of cell one connects to neg of cell two, the bms wires tap off neg of 1, pos of 14 and every connection in between.

with that bus bar (or rather 3 of them)
"-" "-" "-" "-" "-" "-" "-"
1 2 3 4 5 6 7
"+" "+" "+" "+" "+" "+" "+"
"-" "-" "-" "-" "-" "-" "-"
8 9 10 11 12 13 14
"+" "+" "+" "+" "+" "+" "+"
you have 2s7p,

I see no use for that busbar in a 14s pack

(it looked better in excel)

 

[Hickbeard]

if you want 14s you go
1 2 3 4 5 6 7 8 9 10 11 12 13 14
"-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+" "-+"

i.e. the pos of cell one connects to neg of cell two, the bms wires tap off neg of 1, pos of 14 and every connection in between.

with that bus bar (or rather 3 of them)
"-" "-" "-" "-" "-" "-" "-"
1 2 3 4 5 6 7
"+" "+" "+" "+" "+" "+" "+"
"-" "-" "-" "-" "-" "-" "-"
8 9 10 11 12 13 14
"+" "+" "+" "+" "+" "+" "+"
you have 2s7p,

I see no use for that busbar in a 14s pack

(it looked better in excel)

Is that not what I would have. Bar across the top would be -, +, -, + etc

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[Hickbeard]

You mean this.

Gotcha. [emoji2357]

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[whereswally606]

Yep the last image is right. The bus bar is unnecessary and dangerous if it is essentially shorting out the very high amp capable cells.

 

[Hickbeard]

Yeah I've no idea why I thought that big bar was correct.

The clue was in the fact agnisium sells the individual bRs lol.

That's a bit of a disaster avoided. Thank you for your persistence dude.

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[whereswally606]

The other thing to be careful with on your pack design is to made sure that your two halves that are connected together in the pelicase don't have terminals which can accidentally touch again shorting out the pack. Either use something to space them that is an isolator or have your terminals facing out from the middle with a longer wire in the middle to connect cell 7 to cell 8.

 

[Hickbeard]

Yeah I got some nylon to go in between the two

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[Hickbeard]

Hey guys.

Finally able to get back to work to get my ebike bits and get on with the build.

I have a quick question I want to just clarify quick.

Do I need to disconnect the controller from battery before charging?

The plan is the negative discharge from BMS and a positive from battery will go to controller.

Then the negative charge from BMS and a positive from battery will go to a seperate XT90.

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[goatman]

look at the sticker on BMS, big blue wire is P-, goes to controller
big black wire, B-, that goes to the battery negative.
little black wire coming out the side is C-, that goes to charger negative.

 

[Hickbeard]

look at the sticker on BMS, big blue wire is P-, goes to controller
big black wire, B-, that goes to the battery negative.
little black wire coming out the side is C-, that goes to charger negative.

I've made some pretty rookie mistakes so far so was just after a bit of confidence in my interpretation of what's what. [emoji2357]

Cheers dude. [emoji1317]

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[Hickbeard]

Battery is finally all connected.

Controller is all wired up to a multipin connector on the side.

Undecided what I'm going to do with the 3 motor wires. Probably XT90 connectors as I have a bunch of them.

Only showing 49v though. So cells are at 3.5v and ready for a charge. Case is weighty but not as heavy as I thought it would be.

Also run kapton tape in between both battery blocks and nylon screw in between to prevent both sides touching.

What I've learnt from this so far...

Shit I need to plan more. Like lots more. Ran into so many niggly little issues that could of been avoided.

I need to have a clearer workspace. It was carnage in my workshop. So many things in the way, piled on top of each other. Soldering iron next to batteries, next to tools, with scraps lieing around. Not ideal.

I need to focus on one idea, complete, then move on. This will be helped with a more detailed plan.

Next up is the handlebars and all the electrical connections from brakes, throttle, etc. They all need to be wired into the multipin.

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[goatman]

not sure if the mosfet heatsink screws to the side of the controller like the infinions i had but you might want the cross/phillips screws facing up to let the heat out.

looks like the controller is sitting on them?

 

[Hickbeard]

not sure if the mosfet heatsink screws to the side of the controller like the infinions i had but you might want the cross/phillips screws facing up to let the heat out.

looks like the controller is sitting on them?

You mean these screws?

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[whereswally606]

Nope those just hold the ends on he means ones that run along the side of the case and hold a piece of aluminium to the case which has the mosfets attached to it. To be honest if the pelicase is closed it wont matter which way up the controller is pointing. It will heat up the case and potentially overheat the controller and the batteries. Far better to put the controller outside the case in the direct airflow. Also its one less metal thing for the battery terminals to short on.

 

[Hickbeard]

Nope those just hold the ends on he means ones that run along the side of the case and hold a piece of aluminium to the case which has the mosfets attached to it. To be honest if the pelicase is closed it wont matter which way up the controller is pointing. It will heat up the case and potentially overheat the controller and the batteries. Far better to put the controller outside the case in the direct airflow. Also its one less metal thing for the battery terminals to short on.

General day to day the case will be cracked open, maybe couple inches while riding. I'm working on a better solution to ventilate the case just haven't come up with a way I'm happy with

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[thundercamel]

Nice work I was going to say, that's going to be a toasty pelican case, but I just saw that you plan to leave it cracked open.