Battery cables and On/Off switch

[AndyTyson]

Hi,
Ordered a Hailong battery to replace the failed one on an old ebike kit, only to realise that I now don't have an on/off switch in the circuit. I do want to modify the existing wiring on the bike to tidy it up so I can add in a switch at some point on the circuit (preferably on the battery feed so the controller isn't live all the time). So, three questions resulting form this...

1. What rating cable do I need for the battery feed for a 36V 250W setup?
2. Is it preferable for the circuit to be positive or negative switched?
3. Can anyone recommend a suitable switch capable of taking the voltage and current - something like this seems a neat solution but I'm not convinced by the wire gauge. http://www.ebay.co.uk/itm/16A-12V-Motorcycle-Handlebar-Headlight-Fog-Spot-Waterproof-light-On-Off-Switch-/291823175777?hash=item43f2044861:g:sSIAAOSwayZXjxhV (apologies if I am not allowed to post a direct link, please remove if its not OK)

 

[Benjahmin]

Hi Andy,
I'll answer from the point of view of an electrician rather than bike specific.
If you switch the positive and the switch is mounted on the bars, the current has to flow from battery to bars and back, before going to the controller. This would be at a possible full controller current (whatever that's rated at in your case), but may well be 15-20A possibly more. The cable on that switch doesn't look man enough tbh. Its resistance could cause a problematic volt drop at high currents, not to mention the heat generated. I would say, if you're going to switch battery main power, the cable should be as short as possible (to limit volt drop) and the same guage as existing wires.
The current rating of the switch you show would seem OK but its voltage rating is too small. If it was switched of whilst under load it may suffer internal arcing and damage.
Sorry, can't find a suitable switch.

 

[Nealh]

In line between battery and controller for shortest wire run on the live side. 14awg silicone 60a continuos or 16awg silicone 35a continuos. The batteries I've opened have been about 16awg for 36v, lipos have 10 or 12 awg for much higher current discharge for rotor craft.
Most batteries have a fitted switch low amp rated, wired with 22awg or so as this then goes via a pcb/bms where amps are reduced.
Keep searching for that switch though.

 

[Deleted member 4366]

Use 14 gauge wire for the battery. you can get 14g silicone wire from Ebay.

That switch won't be suitable, but it depends what other stuff you have. It will be suitable if you don't need it, but it won't if you do need it. The problem is the capacitors in the controller. They'll blow any contacts in the switch after a few cycles. It's probably better to use a pair of connectors, like Deans, and just unplug them. That's if you need a switch.

Most controllers have an ignition wire, which switches the battery with low current. The ignition wire is switched by any LED or LCD panel, or some use a switch on the throttle. Perhaps, if you show us what you have, we can advise better.

 

[Nealh]

A bit large will need mounting into something probably not water proof, cheap as chips though.
http://www.ebay.co.uk/itm/AC-DC-ON-OFF-ON-SPDT-9V-12V-24V-36V-120V-230V-CAR-BOAT-WINDOW-ROCKER-SWITCH-S-/180686204434?hash=item2a11bcae12:g:6XgAAMXQLw1Rynbs

 

[Deleted member 4366]

A bit large will need mounting into something probably not water proof, cheap as chips though.
http://www.ebay.co.uk/itm/AC-DC-ON-OFF-ON-SPDT-9V-12V-24V-36V-120V-230V-CAR-BOAT-WINDOW-ROCKER-SWITCH-S-/180686204434?hash=item2a11bcae12:g:6XgAAMXQLw1Rynbs

You can't use any switch like that. The instantaneous current is astronomical. the contacts will weld themselves together or blow apart. If you want a switch, you have to use the ignition wire or switch the battery's BMS.

 

[AndyTyson]

Thanks for all the answers, I'll get some of the 14AWG wire order as a start, together with some connectors. Will go and take the controller off this evening so I can have a better look at what connections I have. One thing I did wonder is if as well as using the dean connectors, I could use one of the switches I linked above connected to the brake cutoff circuit. That way I would get a cutoff on the bike and effectively an ignition switch. I'm not familiar with how the controllers are set up and but ideally what I would like is to be able to leave the dean connectors connected all day with the handlebar switch off - or is that likely to cause issues with the controller being live all day (I'll get more info on the controller this evening, just thinking aloud at the moment!)
It is quite an old controller (2009 I think) and uses a brushed motor so not the most efficient. I do have a 2011 kit as well with a brushless motor but thats currently in a 26" wheel and I need 700c for my girlfriends bike so would need a wheel rebuild.

 

[AndyTyson]

Just been and disconnected the controller, doesn't seem to help much, connectors are only labelled with numbers so nothing meaningful. It's an MSK301 apparently but i can't find any info on Google. Can't remember if this kit originally came with brake cut out, so not sure where i could put a cutout switch (it was my dad's originally).

 

[AndyTyson]

Pic in case that helps identify anything useful

 

[Deleted member 4366]

Is the controller new? If so, where did you get it from. It's unusual to find a brushed controller with a PAS connector. many people have searched for them.

Being a brushed controller changes things. I had assumed a normal brushless one. Those switches would probably be OK then.

 

[Nealh]

My assumptions are as there are so many different options available;

We know Red & Black bullet are battery supply.
We know Blue - & Yellow + are motor supply.
The 2 whites are a speed limit adjuster by the looks of it.
Top one next to 3 may be the throttle or LED.
4 brake switch ?
3 & 5 could be battery level and battery charger connector or a pair of brake switch's if 4 isn't.
Bottom Black connector is the pas which D8veh has noted if this is the case.

Is there a throttle or led ?

 

[AndyTyson]

Is the controller new? If so, where did you get it from. It's unusual to find a brushed controller with a PAS connector. many people have searched for them.

Being a brushed controller changes things. I had assumed a normal brushless one. Those switches would probably be OK then.

Unfortunately this is a relic from the past (2009 vintage) so I don't have any details of where it was sourced from (came as part of the Alien Ocean kit).

NealH, thanks for the suggestions ref the connectors, when I get more time this evening I'll put together what I do know to narrow down the unknowns.

One interesting thing on the right hand side (black/white wires with black heatshrink) is a potentiometer which if I remember correctly can be used to give it more power - although to be fair, as its for my girlfriends bike and she gets scared over 10mph I doubt thats going to be needed!

 

[Nealh]

Quite right potentiometer couldn't think of the name .

 

[flecc]

Ezee bikes have always used a keyswitch in the positive line from battery to controller. They easily handle over 20 amps and like all Ezeebike owners I used mine on and off with two models every ride, with no problems over years of use.

So you could buy one of those as a spare from Cyclezee, its the second item down on the right in this image.

It can be mounted in a small panel or box close to the battery and controller.
.

 

[AndyTyson]

Being a brushed controller changes things. I had assumed a normal brushless one. Those switches would probably be OK then.

Sorry, my knowledge of current and how it effects circuits with brushed or brushless motors ranges from non-existent all the way to vague. Can you explain in numpty terms how this changes the goalposts with regard to the switch?

Flecc, thanks for the link, unfortunayely I can't work out which component you mean on the pic you linked, can't see enough detail to decide which is a switch and can't find it on their site.

Had another look at wiring on the bike tonight and one thing that did stand out was that the feed from the battery to controller is 14 gauge but after the flyleads feeding the motor it reduces to some fairly weedy looking wires.

 

[Deleted member 4366]

Sorry, my knowledge of current and how it effects circuits with brushed or brushless motors ranges from non-existent all the way to vague. Can you explain in numpty terms how this changes the goalposts with regard to the switch?

The problem with brushless controllers is that they have one or more large capacitors across the battery connection inside the controller. The capacitor charges instantly when you connect, which means that you get an instant massive current that makes a large spark and a zap noise. The spark erodes any contacts. The higher the voltage, the bigger the spark. It can be quite intimidating trying to connect a 64v or 74v battery to a controller.

AFAIK, brushed motor controllers have their capacitors on the output side of the controller, so you don't get such a spark when you connect it.

 

[Charliefox]

Hi,
Ordered a Hailong battery to replace the failed one on an old ebike kit, only to realise that I now don't have an on/off switch in the circuit. I do want to modify the existing wiring on the bike to tidy it up so I can add in a switch at some point on the circuit (preferably on the battery feed so the controller isn't live all the time). So, three questions resulting form this...

1. What rating cable do I need for the battery feed for a 36V 250W setup?
2. Is it preferable for the circuit to be positive or negative switched?
3. Can anyone recommend a suitable switch capable of taking the voltage and current - something like this seems a neat solution but I'm not convinced by the wire gauge. http://www.ebay.co.uk/itm/16A-12V-Motorcycle-Handlebar-Headlight-Fog-Spot-Waterproof-light-On-Off-Switch-/291823175777?hash=item43f2044861:g:sSIAAOSwayZXjxhV (apologies if I am not allowed to post a direct link, please remove if its not OK)

I bought a cheap Universal ATV/Motorcycle on/off switch from Ebay and used it instead of a cut off brake lever switch since I have disc brakes. So the wires went to the same place in the controller that the brake lever switch wires would have. A low voltage connection with no arcing problems. It is positioned on the right next to the brake lever. If my throttle ever gets stuck I will use it or the 3 power level power facia on the left hand side. It is also handy to switch off power when pushing through gates etc when an accidental twist of the throttle can send the bike literally rearing!

 

[Danidl]

For a battery power switch Maplin have some heavy duty 30amp DC toggle switches. This can go directly in line at the battery red connection. Can be mounted even in the battery housing.
The weedy type connections to a power switch on the handlebars is intended to send an inhibit command at computer logic levels to the controller. Either 5v or12v and at 10 to 1000mA level .
Maplin can also supply the high current cables from the battery tothe controller.

 

[danielrlee]

If you just *have* to use a switch on the main power line, then you might as well just use a circuit breaker and get some real benefit out of it.

 

[Deleted member 4366]

I bought a cheap Universal ATV/Motorcycle on/off switch from Ebay and used it instead of a cut off brake lever switch since I have disc brakes. So the wires went to the same place in the controller that the brake lever switch wires would have. A low voltage connection with no arcing problems. It is positioned on the right next to the brake lever. If my throttle ever gets stuck I will use it or the 3 power level power facia on the left hand side. It is also handy to switch off power when pushing through gates etc when an accidental twist of the throttle can send the bike literally rearing!

I did that on my first electric bike because it only gave full-power when I pedalled, which can be a bit inconvenient at times. It works as a sort of "standby" switch.

You have to be mindful that the controller uses about 4W of power all the time it's connected to the battery, so that's not like a switch on the ignition wire (when you have one), which more or less isolates the battery.