Need More Range

[calfee20]

I have decided that that I need more range. There are some long bike paths on Cape Cod and in RI that I can't do a round trip. I wouldn't want to go 40 or 50 miles all in one go but if it were cut in half with a long break or lunch in between I think it would be good.

I have a 52 volt 11.5 amp slim line on a rear rack. If I add a 52 volt mini with the same type of cells inside would I be able to run them in parallel? Or if I had 2 Minis in parallel could I put them in parallel with my main pak?

[spinningmagnets]

I would be very cautious about paralleling them. Batteries can be series-ed at any state of charge, but...in parallel? both mating packs have to be EXACTLY the same voltage, or there will be a rapid equalization (heat, maybe fire). Even if they are freshly-charged, they need to have the connection initially made through a "dumb" resistive load, like a 100W filament lightbulb.

But...once they are equalized, they will both charge and discharge as one battery. They should both be the same capacity and roughly the same age. If one is slightly smaller (or a lot smaller?), you will only get the range of the smaller partner, and then the pack will start to have enough voltage sag that it will trip the LVC.

If opportunity charging on the road is important, then that is one of the situations where you can benefit from high-current cells. The 25R is known as a "performance" cell, but it is lesser-known that it can also be charged faster than other cells. Common packs are charged at anywhere from 2-5 amps of current, without getting too hot. I would be comfortable charging a 25R pack at 7A up to about 80%

There is no caution needed to carry a spare battery pack, and then to swap them out when the first pack gets low. Unplug one, plug in the other...no paralleling necessary.

[Louis]

We decided there were to many potential problems and instead installed a switch. A simple on off on toggle and my buddy just flips the switch to move to the other pack.
Similar to this. https://www.amazon.com/Gardner-Bende...MS36K0X33QW9D4

[calfee20]

Oh I like that. I can do that................Thanks and thank you spinningmagnets for making me realize that these paks with built in electronics are a far cry from anything I have dealt with before.

[xnoitulos]

Oh I like that. I can do that................Thanks and thank you spinningmagnets for making me realize that these paks with built in electronics are a far cry from anything I have dealt with before.

Agreed! I've been running a second 72v 11.6Ah pack in parallel for a few weeks now. I unplug the batteries from each other and then charge each separately through the BMS. However, one pack is slightly older so charges to 80.9v and the newer 81.1v. Hopefully nothing is getting messed up, as I just plug them back into the parallel adapter. Should I be looking to rig up that dumb resister? I figured a small difference between identical packs would be fine to balance? Can I make a XT60 parallel adapter for the charging wires and charge both packs at the same time? (Using provided 72v luna charger)

[Louis]

Agreed! I've been running a second 72v 11.6Ah pack in parallel for a few weeks now. I unplug the batteries from each other and then charge each separately through the BMS. However, one pack is slightly older so charges to 80.9v and the newer 81.1v. Hopefully nothing is getting messed up, as I just plug them back into the parallel adapter. Should I be looking to rig up that dumb resister? I figured a small difference between identical packs would be fine to balance? Can I make a XT60 parallel adapter for the charging wires and charge both packs at the same time? (Using provided 72v luna charger)

CHARGE THEM SEPARATELY. The BMS aren't designed for parallel.

[xnoitulos]

CHARGE THEM SEPARATELY. The BMS aren't designed for parallel.

Ok. Can I charge each one separately while leaving them plugged into the parallel adapter together? Or will it start tricking across to the other pack? Thanks!

[Louis]

Separately means not together. Disconnect them.

[calfee20]

Separately means not together. Disconnect them.

That double pole double throw switch has them disconnected in the center position so there is no need to unplug anything. I am liking it more and more.

[Louis]

When I went out on the forums asking I got nothing but negative responses. Everyone said it wasn't a good solution. My buddy and I laugh about it overtime we do a project together. It's been more than a year now and no problems.

[Louis]

We added a meter, same one used on the Luna charger, but blue display.

[calfee20]

I was asked how to wire this in a PM. I am replying here so I can upload photos.

Connect the motor to the center and the batteries to the outside terminals. Keep the red on one side and the black on the other. Having said that test the switch with an ohm meter or an indicator light so you understand what is being connected when you throw the switch. DO NOT throw the switch while under power.

These switches generally look like this.

But it is easier to visualize an old fashion knife switch.

[AZguy]

I run two batteries and gave considerable thought about switches, relays, etc.

End of long story (few times I actually make the long story short =] ) I just put a pair of XT90s connectors. It's very clean and takes no more than a few seconds to switch between and frankly at 20-30mi into a ride who can't spare a few seconds?. Very reliable and KISS....

[Designerizer]

I was asked how to wire this in a PM. I am replying here so I can upload photos.

Connect the motor to the center and the batteries to the outside terminals. Keep the red on one side and the black on the other. Having said that test the switch with an ohm meter or an indicator light so you understand what is being connected when you throw the switch. DO NOT throw the switch while under power.

Thanks very much for the help Calfee20.

When you say don't throw the switch when under power, do you mean switch the bike off then switch?

Or maybe you mean switch the battery off on their own switch please?

I am stupid and want to be clear. Thanks so very much :)

[calfee20]

When I say while not under a load I mean like while you are pedaling. If you were drawing maximum amps from a BBSHD it may be as much as 30 amps and it could strain the integrity of the switch. There might be arcing and burning of the contacts. More likely the momentary break in current would switch off your display which will shut down the system but why take the chance. Just stop and flip the switch. You may have to turn your display back on but that is no big deal.

I never personally did this. I fixed my range problem by buying a larger battery. Luna's 52 volt 24 amp/hr triangle is a very nice battery and can potentially give you 80 miles of easy riding. I have been over 50 miles without draining it to the dregs.

Lately I have been paralleling two batteries for additional amps and performance but that might be another thread because I am going against the thoughts of many of the things that are believed that you may or may not do.

[calfee20]

I have a 52 volt 11.5 amp slim line on a rear rack. If I add a 52 volt mini with the same type of cells inside would I be able to run them in parallel? Or if I had 2 Minis in parallel could I put them in parallel with my main pak?

This is going to open a big can of worms. I wasn't going to post this because most people will disagree with me and I didn't want to get into a big discussion. I have kind of stopped posting on the forum because it is getting old.

I have three separate builds using parallel packs. Two Luna 11.4 amp/hr 72 volt PF cell batteries in parallel, two Luna 14 amp/hr 72 volt GA cell batteries in parallel, and finally one 17 amp/hr plus one 14 amp/hr GA cell packs in parallel.

I charge them the first time separately to the same voltage them connect them in parallel and leave them connected. I charge them both from one of the charging leads. I have done many cycle of this on all three builds with no problems. If I want to wack one of my hub motors with 100 amps of power each BMS will effortlessly share the load even during lower states of charge. Riding around with a 31 amp hour battery is a pure joy.

From what I understand Vector ebikes has been making a pack that has two different chemistries inside. One for high draw and one for longer range.

I gave this a lot of thought and looked at a lot of BMS wiring diagrams before I tried it. Ultimately you will have to make your own decision. If I were looking just for extended range I would just stop and connect the fresh battery either manually or with a switch. I was looking for a setup that could give me 100 amps on demand so I chose to parallel packs.

To answer your question yes I would do it. I have a couple of those slim-lines I plan on putting in parallel. YOU have to make your own decision and take responsibility for it. I can only tell you what I have done...……………..calfee