Questions on Pre Charge?

[waynebergman]

Just got my battery and controller and what not from Cellman. I have some questions for Paul that I will send his way but it may take a while as he is busy for the response. I may hook this pack up to my current bike before I set it up with all the new components on my new bike. My questions are related to the 3 anderson plugs coming out of the new pack. I see the two andersons that also come out of the pack are for charging but there are three plugs coming off the battery to plug into the controller. Is this something to do with pre charge. I read about the pre charge that cell man offers but was not sure what it was all about. So a couple of questions please....

1.What is this pre charge, and is this why I have 3 wires coming out of the battery to plug into the controller instead of the two I am used to from my old battery pack? I have read that the pre charge is for not sparking connections or something but not sure how it is physically set up or how it works?

2. If I just use two of these three red black and white andersons to test it on my old bike am I OK to plug it into my existing controller that only has the two anderson plugs on my old bike. Amps and volts should on this new battery should be compatible to my old test bike so I am not worried about that , the new battery has 50v 14.3ah with I think 5 c rating and my old controller I am wanting to test it on is set up for 35amps so should be OK there..I have red and black andersons only on my old bike and controller so I am guessing to leave the white plug comming out of the new battery just unplugged but I am not sure and dont want to mess anything up?

Thanks for this......wayne

 

[mark5]

Maybe the below will help. So either you have or should have gotten a matching 3 Anderson connector for the controller side to plug into the battery, could make one of your own to work around not having one, or use only red and black from the battery for a while.

ebikesrfun: Re: cellman battery help hooking up to controller.
http://endless-sphere.com/forums/viewtopic.php?f=2&t=40106#p585982

 

[waynebergman]

Thanks Mark5 this explains a good part of my questions. I now know what the pre-charge is for, but I am wondering if I don't disconnect my batteries from the bike (say only once or twice a year do I unplug the Andersons and take the pack off) is the pre charge really nec. Does it only help when you unplug and plug in the andersons or does it also help the controller every time your power up your system?

If I am understanding right, and if I only use this new pack on my old bike for a test ride or two I could just leave the white anderson plug from the battery out of the equation and just plug in the black and red to my old controller and it should be no big deal for just a couple of rides....is this correct? And yes I do have the matching 3 colors of andersons on my NEW controller but the issues is when I use it from time to time on the old bike and that controller is the same type but only the two andersons red and black on that old one.

 

[mark5]

There is the idea of the precharge resistor sparing the controller a large current inrush so the precharge resistor wouldn't be just to preserve the connector. My novice opinion is to use the precharge resistor with your new controller if you want to. Might as well since it's there. And just use black and red with your old controller. Later on, graft a white Anderson and wire onto your old controller's red wire but only if you want to. I think it was just the other day that a well-respected ES member commented that he hadn't used a precharge resistor for several years and everything was still fine.

 

[waynebergman]

One thing I still do not get,and I have read the literature from cellman etc ...... ON my new set up that will have the wiring set up for pre charge....Do I go through the pre charge procedure every time I turn the power switch on, or just every time I re hook up my batteries. I most likely will leave the battery pack on the bike and charge it on the bike and only turn off the power switch on the handle bars for recharge about 99% of the time. When I am following this routine I am not unplugging my anderson connectors from battery to controller. I am just powering down the batteries (which may mean the same thing as unplugging them but I am not sure) so I am not sure if this pre charge procedure is just for when you first initially connect all your andersons up for the battery to the controller or every single time you turn on your power switch?

Its not a big deal to go through the routine every time I power up but I dont want to be unplugging and re plugging in one of the battery anderson conectors every time I power up the bike if I don't have too.

 

[dnmun]

inrush to the controller is not the problem. the idea is to use a resistor to allow the capacitors to be charged up before making the connections with the andersons so the andersons are not pitted and damaged by the hi current spark when they are connected and the caps on the controller are not already charged up.

i tried to get people to just turn the battery off by turning off the mosfets when they make the connection, but they prefer to use these precharge resistors and have built some elaborate precharge circuits. with even more mosfets in the main current path even though they refuse to use a BMS because there are mosfets in the main current path.

the BMS on the cell_man batteries use the newer 'headway' BMS and it is more difficult to hack since the screws holding the heat sink on are glued in place but you can add a switch to the circuit current on it also if you need to. just more hassle than with the ping or other BMSs.

 

[waynebergman]

Thanks Dnmun. I am sure what you have just said here makes perfect sense to those that understand these systems. I will say sorry ahead of time for not grasping all the issues. I do not see how to apply this knowledge you have just shared here to my question I posted just before your last post. Again sorry for not getting this but I simply want to know if I do not unplug my andersons from the battery to the controler do I need to go through the routine that is built into my system with the pre charge built into it. IF I initially do the routine as suggested from cellman by plugging in the three anderson leads from the battery in the suggested order, do I need to re do this every time I power up the system by turning on my power switch on the handle bars.

I guess the problem here is I am getting more info than I can digest right now and I dont know how to apply it to answers I am getting to the above question. If I can have a simple answer to this above question I think I am good to move on to the next item to deal with on my current build.Two possible answers I am looking for below..... Is there one of these two senarios below that would be true?

1.Go through the pre charge routine every time you power up the system even though it was plugged in initially in the suggested manner.

2. No, once you plug in the andersons from the battery in the suggested sequence you can forget about it until the next you unplug your batteries for what ever reason.

 

[mark5]

If you mostly ever just turn on your bike at the handlebar switch and rarely break the battery-controller connection I don't see why you should redo the battery-controller connect and precharge routine every time you want to use your bike. Just do the precharge routine whenever reconnecting the battery to controller. I think that matches your #2 scenario above.