Can I Build & Plug A Booster Pack Into Charging Port

[sdavis]

I have a question. Would it be possible to build a booster pack that plugged directly into the charging port of my 24v Cyclamatic battery? The 3 prong plugs are readily available. Recognizing that it wouldn't be as efficient as directly adding cells internally to the existing battery pack, it would be pretty easy to do. Specifically, I'd like to use my 36V Makita power tool battery, which I have a dedicated charger for, reduce the voltage to 25V or so using a voltage divider circuit or buck regulator, and hook the battery up to the 3 prong plug that fits the current Cyclamatic battery pack. Thanks!

 

[RLT]

Would need much more info to tell if it is even possible.

It is probably not practical, and I doubt that it would be able to carry more than a few amps without melting down, even if you could do it at all..

 

[dogman dan]

No,, and yes. If you just plug into the charge port, and the boost battery is a higher voltage than the other, it will shove too much amperage into the main battery at once. This will damage the boost battery, the bms, and possibly the main battery as well. So don't do that.

But if you can run a device of some kind ( I'm not sure what, I'm a dummy), that would limit the amps to what your charger puts out, then you could charge one battery with the other. The device would also have to adjust the voltage down to the same as your chargers output voltage.

Once at the same voltage, via the device, you can just connect in parallel at the out put wires. That's both at full charge voltage.

IMO,, more trouble than it's worth even though you have the other battery in hand. I'd say just buying another battery the right voltage so you have more capacity is a better approach. Rig a second wire on the bike itself, so you can use any generic 24v battery to add range.

 

[999zip999]

I seen a TV commercial my booster pack just started 6 dead cars. Not 6 of my dead cars. Just a TV commercial. No magic genies. A good strong battery is the answer.
How many ah is your makita pack 2ah or 4ah ? You will loss energy in the process.

 

[sdavis]

Thanks for the feedback. Sounds like a rabbit hole not worth going down. I did find this on Youtube.

https://www.youtube.com/watch?v=PAKgDdcUeTs&list=PLlhA3cfcj0xA51pMZtX5XshR5SM6pynf_&index=39

This guy added a booster back and literally just spliced the pack into the wire that runs from the battery to the motor. I'm assuming he is splicing into the battery wire coming out of the controller... would love you thoughts on this approach.

 

[dogman dan]

Yes, that's commonly done,, it's a parallel connection. Always with paralleling, you must have the same voltage when you hook them up. So both full charged before you make the connection. They need not be the same size in AH, but they need to be at the same voltage. It's not so much a booster, as just increasing the size of the whole battery by connecting two together.

As you ride, it will pull from both, but despite them being different sizes, both will reach the end of discharge together.

they have to be the same type for this to work best, but don't have to be identical brand or anything. They just have to have the same voltage to start out, and have the same voltage when done. So if your battery is lifepo4, pair with lifepo4.

 

[sdavis]

Thanks! So, as shown in the video, you basically cut the + (positive) wire leaving the controller and plug the positive wire from the additional battery pack into one end of the cut wire and the - (negative) wire from the additional battery pack into other end? You're adding the power after the controller?

 

[dogman dan]

Personally,, I just build little Y connectors. One plug end fits my controller, the other two ends fit my batteries. Usually this is about 3" long, but sometimes I build one with a purpose in mind. One 3" long, the other leg as long as it takes to reach the location of a second battery. this is used when I have one battery in a right pannier, the other in the left, or one in back, the other on the handlebars.

In some cases, I have put the Y connection right on the controller, so the controller can take two batteries at once, or you can just move the battery to a second plug if one breaks.

 

[sdavis]

great idea. thx

 

[Ykick]

One of the 1st things we all run into with this technology discipline is making solid, quality, high current connections. It’s well worth the time, effort, study and money to learn about connectors & wire. Then make your best decision and go with that connector ecosystem.

If/when you progress enough, you’ll probably wind up with a crimping tool and possibly soldering gear. And of course, supply of connectors, shrink wrap and good quality, properly sized wire.

We’re not talking Home Depot stuff here. There's a few things Home Depot can supply in a pinch but most of the best items to use comes from the RC Hobby world and/or HAM radio crowd.

Anyway, while this may not be exactly “on topic” but it’s one of those major “things” which goes along with what you’re looking to do and will help make the end result more successful.

 

[dogman dan]

Yes,, the only thing I get at home depot is a thing called a crimp sleeve, and maybe the crimper. The same type crimper a lot cheaper at harbor freight though.

The crimp sleeve is the bomb, for making those 12 gage wire y connections in a solid manner, without the hassle of soldering. Then two layers of shrink.