Electrical help - fuse types, and wiring conventions for accessories

[pn_day]

Hi all,
Apologies for all the questions - I've been reading away both here and over at endless-sphere, but there are still some things I'm confused about.

I'm going to be building (when the bits arrive from BMSbattery) a 36V "nominal 250W (actually 500W)" CST ebike.

Adding fuses seems like a good idea.

I'm assuming inline 'blade' fuses like the automotive industry use are a good idea? Something like http://www.ebay.co.uk/itm/300640459432?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

Should I have one direct off the battery before it gets to the controller? If so, any idea what the inrush current is like for the S12S/S12P/S12SH are like? They are rated at 22/30/35 A respectively. I was thinking 40A fuse between battery and controller might be a good safety net?

Additionally how do folks usually wire in accessories like lights. Do you use a common ground through the frame, and just route +ve to all lights, or wire in + & - to all lights and tie the grounds together back to battery ground?

What are the thoughts on waterproofing handlebar switches and throttles? I've seen the discussions that suggest dielectric grease and a bag over the top, but was wondering if anyone else had any bright ideas?

Thanks,
Phil

 

[Aushiker]

In respect to the lights I was under the impression that a DC to DC converter is required. EM3EV for example sell one for US$10 that you wire up yourself or you can get more fancy ones from the likes of ebikes.ca for around $US50. eBikes.ca also do a DC-USB converter which looks nice.

EM3EV DC to DC Converter

Regards
Andrew

 

[pn_day]

Thanks Andrew,
I have a cheap DC-DC converter on order from fleabay for one of my lights (8.4V Cree), but the others I've ordered run off 20-80V supply so should be OK.
Thanks for the links - that ebikes.ca USB one looks nice.
Phil

 

[Alan Quay]

I also have a CST, with a 30a controller.

Fuse - I have a blade one, 40A. Install as close to battery as practical, before the controller.

This is the one I bought:
http://www.ebay.co.uk/itm/SPLASH-PROOF-LINE-STANDARD-BLADE-FUSE-HOLDER-TRUCK-HOLD-CAR-BIKE-BOAT-BIKE-/380863802235?pt=UK_BOI_Electrical_Components_Supplies_ET&var=&hash=item97645d0a1c
Don't use the 'Mini Blade' fuses, as they melt - mine did anyway.

0v - I have never bothered with using the frame for 0v, although I expect it would work for all but Carbon Bikes. As you suggest, just bring all the 0v lines back and common with battery 0v.

Hope that helps

 

[Deleted member 4366]

I prefer two wires for the lights. earthing the frame is not really necessary, and is a it more risky. That fuse-holder should be OK. The inrush current is very high, but for a very short time. I don't think it'll blow the fuse.You only need to connect once anyway because the S12S/P has a switch that can block the current down to microamps, or do you need to disconnect lipos for charging.

I'd use a 40 amp fuse if you run with 30 amps, which is about the max for a CST.

 

[pn_day]

Thanks chaps. Very helpful. Mike that fuse holder is better than the ones I've found - rated for 40A.

Unfortunately I am going to have to remove the battery for charging at work - thus the interest in fuses!

Thanks for the tips on lights as well - good to know what others who have successfully built CST based builds before have done.

On a somewhat related point, does anyone have a source for labels that state something along the lines of 250W nominal? Or does the CST have no visible power labels on it anyway?

Thanks again.

 

[Deleted member 4366]

You need a photocopier or laser printer and a roll of sticky backed aluminium tape about 2" wide

• Design your label
• Print it on plain paper. place a piece of the aluminium tape with its backing still on over the print
• Hold it in place with a couple of strips of normal selotape that just overlap the edges
• Put it back in the printer/copier in its original way round
• Print/copy again, and the new print should come on the aluminium
• Cover the label in wide clear selotape or clear sticky backed film to make it weatherproof.
• Cut out the label, peel the back off and stick it on

Here's one I've seen done like that. It's not on any of my bikes

 

[pn_day]

Thanks D8veh