New enthusiast with some questions on getting a first bike.

[mlrosier]

Hot off the charger, with the multimeter, all of my packs are reading 28v except for one, and it's only giving 27v, and that's with either testing on the cables I installed, or using the prongs in the battery. So is the battery bad? I'm ending the charging cycle as soon as the charger light is solid green.
I put one of my series of batteries on the charger after my rided today, and it took them about 30 minutes to charge up. After that, I Put the second series on, and they charged up to solid green in less than 5 seconds, which is a solid indicator that they weren't being used. So I'm thinking about ripping the battery cases open again. Gonna have to remove the epoxy I put on the holes I made. Hope it's not too hard. Anyways, if I opt out of using andersons to connect the batteries together, can I permanently solder 3 in series, 6 in parallel, and still be able to charge them on the stock chargers? What I was thinking about doing was removing the cases, putting the batteries bottom to bottom, side to side, and only having Andersons at the lead cables that go to the Controller Andersons. I did up a quick picture. If I were to do this, would I be able to charge the batteries on the stock chargers, leaving them in series, or do they have to be removed from series before they can be charged? The idea is to charge one side or the packs, then flip and charge the other side. Viable? Here's the pic...

 

[lazarus2405]

About the pack staying at 27v, when you open it, measure each cell's voltage. Either they're all at ~3.85v, or one or two are low and the rest are at >4.1v.

Regarding charging them in series, I don't know. I've had some problems with it, though they could be because of how I was wiring things. I've had them on the stock charger in the wiring in your picture, but I was a little unease. Supposedly the chargers are isolated, but you'll notice a buzzing sound when charging them in series. They'll charge, though.

To be safe, you can work out a way to disconnect them. There might be no problem, but I'm afraid of recommending someone else do it without a higher degree of certainty.

 

[mlrosier]

Thank you Laz. I could put a fuse holder in between the series wires, so that way, when I go to charge, All I'd need to do is remove the two fuses, then they'd no longer be in Series.
I wish I was super smart like Maytag, and had the know-how to tear the packs completely apart, and make a solid brick. I have some copper pipe, so I could cut it and hammer it flat for Busbars. I'm just not sure how to arrange the batteries to come out with one or two packs, and be able to get away with using one or two BMSs and one or two chargers.
On the 27v pack, , if any of the cells are lower than the others, does that mean the battery is trash? How do I test each cell, since they're enclosed in foam and plastic?

 

[TylerDurden]

How do I test each cell, since they're enclosed in foam and plastic?

You should be able to get your meter probes through/under/around the foam to the cell ends.

 

[ngocthach1130]

you should put 2 cell in parallel first and then connect those pack of 2 cell in series. That way incase one pack fail the load is still distribute evenly between those 5 packs. Except the pack which was paralled with the failed one will take the load of 2 packs. With your current set up now, if one pack die then you only have 3 pack on the other series string to run on.

 

[fechter]

You might want to try testing the voltage of each pack with some kind of load.

A matched pair of automotive light bulbs in series, a big resistor, etc. Even a high wattage 120v light bulb will put some load on it.


Does anyone know what the BMS has for overcurrent protection?

 

[mlrosier]

you should put 2 cell in parallel first and then connect those pack of 2 cell in series. That way incase one pack fail the load is still distribute evenly between those 5 packs. Except the pack which was paralled with the failed one will take the load of 2 packs. With your current set up now, if one pack die then you only have 3 pack on the other series string to run on.

If I were to do that, it would only give me 84v3ah instead of the original 84v6ah I set out to achieve, which would mean the packs wouldn't last as long, right?

 

[lazarus2405]

you should put 2 cell in parallel first and then connect those pack of 2 cell in series. That way incase one pack fail the load is still distribute evenly between those 5 packs. Except the pack which was paralled with the failed one will take the load of 2 packs. With your current set up now, if one pack die then you only have 3 pack on the other series string to run on.

If I were to do that, it would only give me 84v3ah instead of the original 84v6ah I set out to achieve, which would mean the packs wouldn't last as long, right?

What he means is that you should bridge the negatives in your pack. In the diagram you posted, see how on the pair of negatives on the far left side you have the wire connected parallel across both packs? And see how you don't have the negatives bridged in "Pack Two" and "Three"? Ngo is saying to bridge those into parallel too, and the reasons he mentioned are correct. Still the same capacity, still the same number of batteries.

 

[mlrosier]

So, it should looke something like this then?

Also, after removing the stupid-I-Will-Never-Use-Epoxy-Again Epoxy from the battery cases, I was able to crack open the pack that is only measuring 27v. I tested each cell, and each one is measuring 4.08v. So I don't understand why the pack is only measuring 27v. Maybe the battery in my multimeter is going bye bye. I haven't changed it in a couple years.

But anyways, I won't start reworking these packs until I hear back from you guys on this latest diagram. I'm starting to feel defeated here. I wish I was smarter.

 

[lazarus2405]

Yup, that's what we mean. It'll help keep things balanced.

With the 27v pack, where exactly are you measuring 27v? And try replacing the multimeter battery; it won't hurt.

 

[mlrosier]

On the 27v pack, I tried measuring the wires I soldered in, Positive and Negative. I measured from the charger plugs on the pack, Positive and NEgative. And I measured from the Postive and negative tabs inside the pack where I soldered my leads on. Funny thing is on the tabs inside, It was fluctuating somewhat between 27v and 28v.
I'm going to go start tearing these down and putting them back together. Wish me luck.

Thank you again for everything.

 

[mlrosier]

Ok, I just got done re-configuring my packs. I removed the cases, and the epoxy. I will never use epoxy again. Ever...
I've got them oriented the way I want now. However, my last diagram that I put up was wrong, because the packs were mirrored in photoshop, and well, I'm not physics genius, so I didn't take that into consideration. lol.
Anyways, took a new pic of the real packs. They are two to one. I glued then with hot glue together, and will add some permanence with duct tape after I do the re-wiring job. So my next question is, is this the rewiring job I should do.....

3 packs in series on top, and 3 packs in series on bottom. Each pair of packs is connected in parallel as well. Then the lead offs to the controllers come from the last pair of packs in the series. Will this configuration give me the 84v6Ah still, or will it blow up in my face? I'm going to go to Radioshack and see if I can get some different connectors for the series connection. Hoping for something that has a locking click-clip, that can only come undone if you press the tab down to release it's hook. That would be ideal.
Gonna go buy the supplies I need to finish these. I won't start rewiring until I'm positive on what I need to do after hearing from you guys.

Thank you again.

 

[TylerDurden]

Boom.

Sorry.

 

[EMF]

Here is a way to use series and parallel batteries, similar to what you are trying to do. I just show a couple extra batteries. When you charge- to be on the safe side, open the series circuit between the two parallel sets, pictured top and bottom, where the open set of contacts is pictured, right in the middle there. That way, you wont have a short possibility when you charge.

The other set of open contacts on the far left, represent a switch as well, to kill the pack with. A neat way to do this is with a 2 pole circuit breaker or a two pole switch.

 

[TylerDurden]

3s2p = 84V 6ah

2p3s= 56V 9ah

pos2neg + neg2pos= boom

 

[mlrosier]

Ok, if I read that diagram right, then this would work....

If I didn't read it right, then what about this....

Finally, I think this is how I had it set up before....Should I just stick with it?

 

[EMF]

I don't know the voltage on those packs. So I can't tell you.

 

[mlrosier]

Will that configuration give me 84v6Ah?

 

[EMF]

As Tyler Durden said already - 3s2p = 84V 6ah. So I guess these are 28 volt batteries. 3 x 28 = 84

 

[mlrosier]

Whoops, I didn't see his post. I'm just scared to do this I think. I've already had one near tragedy with this, and I'm afraid I'm going to hook something up wrong and blow it all up. I don't have anymore money to invest in this project either, which makes it even more frustrating.

 

[EMF]

Well, you should make a drawing first. Then work from that after you are sure you have it the way you want. You can cause a lot of damage if you make a mistake. If you really want 84 volts, then you have to have three batteries connected positive to negative like a string or daisy chain. Think of flashlight batteries in a flashlight. They go from positive to negative one after the other until they achieve the correct voltage.

Once you make a series string of three batteries. Then make another. Then all you have to do is connect positive to positive and negative to negative to make up your amp hours, as this is the parallel part.

What you ought to do, as it is going to be a pain in the ass to charge this setup, is put female plugs on each battery and then make a wiring harness, with corresponding male plugs to plug them in. As you are going to have to break this thing up to charge it, unless I am missing something. I didn't read most of this thread. I don't know how you are going to charge an 84 volt setup. Even then, you will have to be careful with the male ends until you get all your batteries unplugged. As until you do, they will be hot.

 

[mlrosier]

a series string of three batteries. Then make another. Then all you have to do is connect positive to positive and negative to negative to make up your amp hours, as this is the parallel part.

Now on the parallel part, do I connect positive to positive and negative to negative on each of the battery pairs, or just the positives on one pair and the negatives on another pair after they're connected in series?

Ok, what about this. With these packs being 28v each, six of them all together, done in 3 pairs....

Would that give me the 84v6Ah? And is that wiring configuration right? Sorry if I'm asking too many questions. Just want to cover all bases before I go soldering this stuff together again.

 

[TylerDurden]

Here ya go:

 

[EMF]

THANK YOU!

 

[kbarrett]

Let's try again.

If you join two batts, + to +, and - to -, That is called parallel. You now have a single 28V batt, with doubled amp-hours of duration.




If you join 2 batts, + to -, and draw power from the unused - and + ends, you have put the cells in what is called series, and made a 56v batt, with normal duration.


If you want 84V, you have to put 3 in series:


Make two 84V strings ... then parallel them into two separate strings of 3 series cells to get a batt with 84V and doubled Amp-hour duration.


If you look carefully at Tyler's drawing, that is what he has done.