Is there a switch to be used for...

[overtonmath]

So I've got 3 15ah batteries that I'm pulling in a small trailer now. I've got a CA to gauge how much juice i've used and how much remains. What I'm trying to figure out is how I can run three separate red and black wires from each of the batteries to my handle bars so I can switch between batteries without having to stop and unplug and plug in by hand. I would prefer to run the three batteries down at about the same rate. I thought I would run 3 or 4 Ahours on one battery and then switch to another battery.

Is there some kind of a switch that I could mount on my handle bars and be able to switch between batteries with the flick of my finger?

 

[Punx0r]

Why not just connect all three batteries in parallel and run on them all at the same time? It's better for the batteries and will probably simpler than trying to find a high current, three-way switch.

 

[dogman dan]

I don't get it either. Why the need to switch so often, even if the batteries were too different to parallel connect?

I would not want my bike power going through a fallible switch, unless it was backed up by and easy way to unplug it and bypass it manually.

 

[999zip999]

Less is better even if you have to get off and switch. There is a heavy duty marine switch for two batt. But not three. And parelle for more ah is best as l.ess demand on all batteries longer life.

 

[overtonmath]

Why not just connect all three batteries in parallel and run on them all at the same time?

So I have those sunthing batteries that have the black three prong female chord coming out of battery. Can I hook the batteries up in parallel without cutting that chord? Can somebody walk me through it?

 

[Punx0r]

I recall a recent thread showing the inside of that connector and only two pins were used (positive and negative). I guess you ought to be able to simply parallel your batteries - the only thing I'm not sure about is the presence of a BMS on each pack. I'd let someone with exerience on this comment before joining any wires to save an unlikely but potentially expensive mistake.

If nothing else, free bump

 

[overtonmath]

Why not just connect all three batteries in parallel and run on them all at the same time?

I did a little research on connecting the three batteries in parallel. I'm going to use method 3 found in the following link:

http://www.smartgauge.co.uk/batt_con.html

I want to verify if this is correct before I do it. I also read some warnings about connecting in parallel batteries of different volts or chemistries. Like I might burn up the motor, the controller, or ignite a battery. Are those accurate warnings? My batteries are all the same voltage/Ah and are all LiFePo. Is there any concern with burning up the motor or controller using method 3?

 

[overtonmath]

Why not just connect all three batteries in parallel and run on them all at the same time?

I did a little research on connecting the three batteries in parallel. I'm going to use method 3 found in the following link:

http://www.smartgauge.co.uk/batt_con.html

I want to verify if this is correct before I do it. I also read some warnings about connecting in parallel batteries of different volts or chemistries. Like I might burn up the motor, the controller, or ignite a battery. Are those accurate warnings? My batteries are all the same voltage/Ah and are all LiFePo. Is there any concern with burning up the motor or controller using method 3?

Isn't there anyone who will answer a small question above?

 

[parabellum]

Yes, method 3 is OK, considering your statement of same voltage and chemistry.

 

[DAND214]

That should be no problem. All same voltage and AH so no problem.

Get 3 cords to plug into the batteries, splice them togeather, make sure you have POS and NEG correctly, then plug it into the controller. No change in voltage and since the controller doesn't know or care how many AH you have all is fine.

Unplug them to charge all 3 at the same time or get a bigger charger to charge them as one.

Only concern is, you will need to watch the temps of the motor and controller if you run a long distance or a long hill.

And you still can run 1 or 2 or all 3 if you want.

Dan

 

[Punx0r]

The only other thing is to ensure the batteries are at about an equal state of charge when you connect them in parallel. If one is fully charged and the other discharged then the charged one will attempt to rapidly charge the other, which won't do either battery much good.

 

[Matt Gruber]

i'd use a fuse for each pack, just in case!