disconnecting controller for charging Y/N

[guido]

almost done.................
well the bike is getting its final shape, and the charger will be integrated into the bike. And here I have been getting different info about, should i disconnect the battery from the controller before charging or can I leave it connected, the explanation with the kit said to disconnect before charging but not why, the spark with every connection made is quite strong so if I can skip this than that would be better for the connections I guess .

thanks for any advise in the matter

 

[John in CR]

Leave it connected. In 4 years the only time I've disconnected a controller is when I've blown one experimenting with how far I can push a controller past it's stock limits. The only time it might be a good idea is for longer term storage like if you don't use your ebike for the winter. That said you do need to turn off the controller. I wire in a keyswitch to the thin positive wire that is the low current power to the controller itself. That switch also act as my emergency cutoff in the event of a throttle failure that creates a runaway condition that somehow my ebrake cutoff doesn't stop (the only event I can think of that could do this is some kind of damage creating a short in my wiring going to the handle bars), so my keyswitches are conveniently located. For both safety reasons when you bike is unattended and to prevent a low current drain on your batteries, you need some kind of switch on the controller on/off wire when you leave the battery mains connected to the controller.

Note the safety part is applicable to brushless motors which can't operate without the controller brain functioning. A brushed motor only needs power, and they could have a runaway condition without a controller at all, so a brushed motor needs some way to be able to cut battery power completely in an emergency.

FWIW, that spark on connection is a rush of current to charge the capacitors, which creates wear on them. Get yourself a 100-300 ohm resistor to keep with your ebike tools, and use it to make the charge the resistors with no spark just before you complete the connection. The bigger the controller and higher the voltage the bigger the spark, and with higher power units it can be quite startling even when you're ready for it, so the precharge resistor of some kind becomes mandatory when connecting the battery.

 

[dogman dan]

You can leave it connected. But,,,, if you don't ride daily then you will want to either disconnect, or at least switch off the controller while parked for a week. If longer than a week, definitely disconnect the controller even if switched off.

Beats me why the resistor hasn't become standard equipment on Ebikes yet.

 

[Ykick]

I always disconnect battery/controller (don't need to) but 60V and below I don't bother with pre-charge circuit. 2-3 years daily commuting and no problems and actually seems to keep the Anderson's clean copper, LOL... However, I'd be much more concerned and likely to leave it connected or wire up pre-charge if running above 60V operation.

 

[guido]

ok thanks for the info, my bike has a fixed battery and disconnecting seemed pointless, a small switch in the thin red line is far more convenient to incorporate. so the decision to incorporate the charger into the bike is made, all I need now is an old vacuumcleaner so I can have an automatic roll up cord into the frame: plug and play

 

[dnmun]

.

 

[guido]

thanks, I will put 2 small switches between the pos and neg between the bms and the charcher as well, I should be save

 

[dnmun]

.

 

[guido]

problem solved
I`ve put in a keyswitch with 3 positions
pos 1 controller connected, charger disconected
pos 2 all off
pos 3 charger connected, controller disconnected

also found me an automatic roll-up cord so I`m all set

everything works fine, thanks for the input guys

 

[tedcs]

I observe that my 'xlyte' 72V40A controller draws about 16mA when connected to the batteries and not turned on.
When switched on and stopped, the current is about 56mA.
This gives a power dissipation of approximately 1 watt and 4 watts, respectively.

I don't worry too much about a watt here and there, but prefer that batteries are not connected to anything except when necessary.
That said, a charger which is capable of long term maintenance is advisable...
I might remember to disconnect it after 6 hours, but 6 months is also possible.

I like to limit the probability of something bad occurring when I'm not paying attention.
Murphy's Law: If something can go wrong it WILL go wrong.
My environment tends toward chaos, it is my middle name.
I don't have a problem with this, but mechanical and electrical devices may be adversely affected.

Your mileage may not vary, but my mileage does.

 

[NeilP]

What harm can come from NOT turning off the controller when charging if it is left connected? OK, all sorts of issues IF the charger was to fail and over volt the system, but assuming no charger fault I can't see an issue.

Reason I ask is that I was going to make up a charge lead to the controller, with negative wire going to the ''positive/ controller' side of the shunt. So then when I charge, with controller and CA turned on, I see charge current on Cycle Analyst display.

 

[MAGICPIE3FOCUSPOWER]

Waauww I wil do this mod, so I don't need precharrge resistor and a bunch of connectors

Thanks for info!

 

[NeilP]

I'd wait and see. I can't see an issue as long as the charger behaves itself.

If it is a no go, then just create a T wire for the charger and have the controller turned off

 

[MAGICPIE3FOCUSPOWER]

But I have to be carfeull when charging is progress and touching the throttle...

 

[Kingfish]

Once upon a time when I had an itty bitty pack - I disconnected the controller. Always hated hooking it back up. ZAP! Scare the piss outta me. But that woz a long time ago

Today I leave my controllers connected.

Sometimes I will use the charger alone without the batteries to debug a problem, but that is very rare.

It is also rare to charge and have the controllers "on"; I might be checking a stat on the CA, or maybe messing with the lights during the interval - but that's it.

Most of the time the controllers are off, and the lil' lipos are happy as Larry charging away.

Charging away, KF

 

[NeilP]

I was thinking of fitting the negative charge lead inside the controller, on the ' otherside' of the shunt. This way, with controller ON, charge current will appear on the CA as regen current.