Ebike "The Resurrection"

[doc007]

Snowchyld, thanks for the info!! It's a lot clearer now. I think I will use your method of wiring since I do intend to bulk charge. Also, there is less of a wiring mess.

Questions:
1) When I wire up the batteries like you have in your drawing, do I need to worry about the order in which I connect them? I was thinking of making a block of bullet connectors that plug into each side of the pack(20s1p) at the same time.
2) Also, do you think I will have to worry about a spark when plugging them into the controller or the charger?

Thanks a bunch for all the help!

 

[sn0wchyld]

Snowchyld, thanks for the info!! It's a lot clearer now. I think I will use your method of wiring since I do intend to bulk charge. Also, there is less of a wiring mess.

Questions:
1) When I wire up the batteries like you have in your drawing, do I need to worry about the order in which I connect them? I was thinking of making a block of bullet connectors that plug into each side of the pack(20s1p) at the same time.
2) Also, do you think I will have to worry about a spark when plugging them into the controller or the charger?

Thanks a bunch for all the help!

1.
if you mean what wires go where, then absolutely. yes.
the actual order in which you connect the main packs by their discharge leads doesn't really matter much (more at the end), but once this is done, you need to be extremely careful when connecting each individual pack's balance wires from one 20s 5ah string to its 'sister' pack in the other string of 20s5ah. if for example you connect pack 1's balance leads in string 1 to pack 3's balance leads in string 2, then you'll get a nice big flash, and you wont have any more balance leads on pack 3. There's a number of other dangers that exist, but rather than list them all, I'll simply say this...

Once you have each separate 20s 5ah 'subpack' wired up in series (via the main discharge leads) go through and label with a bit of masking tape or something, each packs #, counting up from the most -ve pack in each subpack. that way, when it comes to parallel the 2 sub packs via the balance leads, if the #'s dont match up, you know you're doing something wrong.

If you're still unsure of yourself, use a thin peice of wire (like, as thin as your hair) to test the connection before you actually connect it with the normal plugs. if somethings wrong, the thin wire will vaporise/spark but your packs and their leads will be unharmed.

2.
are you using bullet connectors? (ie 4mm?) if yes, I wouldn't worry too much. bullet connectors manage that spark pretty well, since it'll be right on the tip of the connector, and the main current path is through the sides. Still, if you have the time its worth it, its better for the controller's internals and means you're connectors will last longer... a 100-500 ohm 3 or 5w resistor should be enough.

as to the packs order again...
ideally, you want to measure the capacity and internal resistance of each individual pack in your collection (any decent lipo charger should be able to do this). then match them up as best you can weakest with the strongest, and working in form there. that way, you end up with a pack consisting of cells that are all, on average, fairly equal. this step isn't totally necessary, just helpful for getting the most out of your pack, and reducing the frequency of balancing.

 

[renago]

I'm doing something similar , but don't have any pic at the moment.
one thing that is not clear is about the balancing wires :
here we have 10 battery packs , but only 5 exit for balancing ?
how can this be ?

when you want to recharge all packs , you must break up the wiring and ri fix them later .
is there no way to to bulk charge them all together .

ps I am using LIPO 6s 5ah

Renago

 

[sn0wchyld]

I'm doing something similar , but don't have any pic at the moment.
one thing that is not clear is about the balancing wires :
here we have 10 battery packs , but only 5 exit for balancing ?
how can this be ?

when you want to recharge all packs , you must break up the wiring and ri fix them later .
is there no way to to bulk charge them all together .

ps I am using LIPO 6s 5ah

Renago

10 packs, arranged 5 in series, 2 in parallel. thus there are 5 pairs who have their balance leads connected to each other, hence why there's only 5 sets of balance leads.

 

[iovaykind]

Doc.. the last wiring diagram looks good.. you can series before parallel, just make sure that cell 1 of "pack 1" matches up with cell 1 of "pack 2". The only thing you can't do (well.. there's much you can't do, but anyway..) is have cell 1 from pack 2 paired with cell 2,3.. etc. The first cell.. most "positive" have to match up with the other pack's most positive cell as well.

 

[doc007]

Ok this wiring has been haunting me. It's gonna be too messy for me. I want something neat and clean. Not a bunch of connectors all over the place.
This is the pack in its metal housing. With the pack oriented like this (wires coming out from the middle rather than from the sides) I get some space to add padding.

--Positioning--
Space for padding on each end (GOOD):

No space for padding, tight fit (BAD):

--Wiring?--
I am FINALLY considering permanently paralleling each pair of packs to cut down on the amount of connections and clean-up the wiring. This also negates me from having to worry about internal resistance and all that if I were to go series to parallel.

The discharge diagram of the entire pack should look something like this, definitely cleaner than before:

Bulk charging set-up should look like this (right? ):

Questions:
1) What are the pro's and con's of permanently paralleling? Anything I need to worry about? Anything I'm missing?
2) Essentially I will have to join two wires together and make it lead to one. What's a good way to parallel each pair of packs for a good/clean/strong/reliable connection?

 

[Ykick]

You seem to understand about using the balance connectors to balance bricks while connected in series groups. As long as you realize permanent connections would make it much harder to remove the brick and place on a conventional RC Balance charger I see no major drawback from permanent connections. In fact, fewer connections usually better for any high power circuit.

It's been well over a year since I've broken series groups up and all my power connections are pretty much locked together. I've brought up a few low cells over that time but just by using the balance connector and charging 1S directly to the low SOC cell.

 

[izeman]

Questions:
1) What are the pro's and con's of permanently paralleling? Anything I need to worry about? Anything I'm missing?
2) Essentially I will have to join two wires together and make it lead to one. What's a good way to parallel each pair of packs for a good/clean/strong/reliable connection?

1)

pro: no connectors, easy, no chance to connect them reversed
contra: if one of the paralleled cells is damaged, you won't realise that, or better said: as soon as you realise the broken cell could have damaged the good one as well

2)

solder two 14awg wires directly to the connector. or open the insulation of one wire at a length of 1cm, then remove 1cm of insulation of the second wire, put this wire next to the now clean wire, and wrap some centimeters of single wire (eg. cat5 cable) around the two wires. that way they won't move when you solder them together. then put some heat shrink over the wire for insulation.

rem: use the BIGGEST soldering iron you can find. 80w+ is good. the longer you put heat on the connection the worse. if you put too much heat into it, solder win run inside the cable and make it stiff.

 

[iovaykind]

I think the issue you have is that you have 5 packs on each side of the bike, making wires going over the top tube look really bad.

My best advice is to do the following:
1. Connect each of the 5 packs in series. Use one of them and cycle a few times, check for duds. Do the same with the other.
2. After weeding out duds, if there aren't any, charge them both up and then permanently series/parallel the groups.

It's a method which will allow you to still enjoy your bike while you test and build your pack. I did it for mine, and after finding out I didn't have duds, I went ahead and created the final battery pack.

For me though, it was 4 packs on each side, so it was easy to parallel. If you want less wire mess on top of the top tube, you're going to parallel groups that are next to each other, and the 5th pack on each side will have balance wires going over the top tube.. that's as clean as its going to get. aka one set of 4s parallel going over the top tube, and one set of power wires.

Let me know if it becomes too much to handle.. when I get into medical school I'll be much more free to help

edit:
the method i'm talking about allows you to have only 5 jst plugs to read from instead of 10. in fact, with 20s we can make 5s groups so you only have to read cells 4 times.

 

[doc007]

You seem to understand about using the balance connectors to balance bricks while connected in series groups. [dont be so sure lol ive never played with RC stuff before so this is all new territory for me] As long as you realize permanent connections would make it much harder to remove the brick and place on a conventional RC Balance charger I see no major drawback from permanent connections. In fact, fewer connections usually better for any high power circuit.

It's been well over a year since I've broken series groups up and all my power connections are pretty much locked together. I've brought up a few low cells over that time but just by using the balance connector and charging 1S directly to the low SOC cell.

So essentially what your trying to say in laymen terms is:

A) that I will be able to bring up low 1S cells individually via the balance connector while the pack is hooked up parallel to series?

Like so:

AND

B) that I will not be able to use the balance charger on a single 4s 5Ah pack since my batts paralleled? But I could use it on every paralleled pack (4s 10Ah) and even my entire pack as long as I remove all series connections?

Like so:

Are these diagrams right? Correct me if I'm wrong. Feel free to edit the pics, if you like. (Pics usually help me understand better and faster)

Also, where were you getting your 4V source from? and how were you monitoring it to make sure you didn't over charge?

 

[doc007]

1)
pro: no connectors, easy, no chance to connect them reversed
contra: if one of the paralleled cells is damaged, you won't realise that, or better said: as soon as you realise the broken cell could have damaged the good one as well

2)
solder two 14awg wires directly to the connector. or open the insulation of one wire at a length of 1cm, then remove 1cm of insulation of the second wire, put this wire next to the now clean wire, and wrap some centimeters of single wire (eg. cat5 cable) around the two wires. that way they won't move when you solder them together. then put some heat shrink over the wire for insulation.

rem: use the BIGGEST soldering iron you can find. 80w+ is good. the longer you put heat on the connection the worse. if you put too much heat into it, solder win run inside the cable and make it stiff.

1) interesting point. So does this mean that 2 lipo cell logs for each parallel pack will not work as intended (to monitor the individual cell voltage for each pack) bc the two packs are in parallel? Thus I would be getting an average reading of cell 1 in pack 1 and cell 1 in pack 2?? I was under the assumption that you would only get an average reading if the balance leads were in parallel (not the main terminals). im such a newb! lol let me know if this is right or wrong.

2) thanks for that tip

 

[doc007]

Let me know if it becomes too much to handle.. when I get into medical school I'll be much more free to help

Get in already!! Let me know if you hear anything positive! I'm rooting for you!

--yeah you pretty much hit the nail on the head, i dont want to have many (if any) wires going over the top tube for aesthetics and safety (dont want to accidentally cut a flimsy balance wire going over the top tube if/when i take a fall)

--i definitely need to start cycling my packs to check for duds AND i definitely want to get the bike rolling. If you have an extra wiring harness that I can borrow until im done cycling these pack that would be awesome!

 

[rui_fujino]

This maybe little off topic but i'll put some input from my experience with bulk charging and balancing.

Im currently running 20s2p (8x5s). I've created 4 of 5s2p and hooked those in series to make the 20s2p.
the bulk charger is just the fast way of charging upto 83.5v and I'm using 4 battery medic(balancer) to keep individual cells from going over 4.2v.
However. Once in about 6month I take all the batteries out of bike and balance charge them with my slow 200w RC charger to make sure all the batteries are perfectly balanced.

it is important that you balance charge and make sure all the cells are within 0.1v difference BUT i would say once you start cycling the battery packs, they will act predictably.

(the reason why you want to parallel packs before series is when two or more packs are in parallel, they balance individual cells* with each other and you can avoid once cell discharging too fast)
*given the fact balance leads are parallel connected with each packs while draining.

 

[Ykick]

Like so:

AND

Also, where were you getting your 4V source from? and how were you monitoring it to make sure you didn't over charge?

That's the general idea and obviously need to guesstimate a bit on how much SOC to add to a single cell. I usually bulk series charge the whole pack and then rig 1S connection from RC Charger to top off low cell. No need to break any connections and this also works with parallel group balance connectors.

I've used cell phone wall warts too in a pinch but the float voltage worries me on most of those so I turn to the RC charger which will offer much improved control for this type work. Another plus with the RC charger is that you can use discharge mode to drain off excess SOC if you add a little too much.

 

[doc007]

Cleaning up the mess:

So in hopes to help clean up the wiring mess, I've come up with modified bullet connector design to support paralleling packs. This is the result I am going for:

What do you guys think is the best way of making something like this?

I'm thinking of modifying the bullets as follows:

In order to make this part, some ideas I've considered are:
1) soldering horizontal 10awg wires and then crimping vertically,
2) soldering horizontal 10awg wires and then wrapping copper wire vertically, then solder again, or
3) soldering horizontal solid copper wires and then wrapping copper wire vertically, then solder again,
Lastly, cover the wiring with some heat shrink.

what might be the easiest (most durable) way to put something like this together?

 

[sn0wchyld]

My advice? carefully cut the bullet housings on the batteries in half, that way you dont need to make any special custom connectors other than the ones at each end of your 20s pack.

then you can just make 2 20s 5ah strings, and parrallel them at the final connection. job done.

(obviously you'll still need to parallel the individual cells via the balance leads, but you'll be doing that anyway... )

 

[doc007]

Hey SC thanks for chiming in!

I was planning on splitting each bullet in half. Glad to know I'm not the only one who has done this before.

As for the wiring, is this wiring set-up you are referring to?

 

[sn0wchyld]

Hey SC thanks for chiming in!

I was planning on splitting each bullet in half. Glad to know I'm not the only one who has done this before.

As for the wiring, is this wiring set-up you are referring to?

yep thats it
and if you're already planning on cutting the bullets in half, why are you making these?

just plug the -ve of one pack strait in to the +ve of the pack below it. No need to make those connectors at all.

 

[rui_fujino]

I don't know if what you're planning would work with balancer...but I really think you should make 5 of 4s2p then series them after...I have not had experience to explain why it should be this way but I do know we had quite big discussion on this couple years back.

 

[sn0wchyld]

I don't know if what you're planning would work with balancer...but I really think you should make 5 of 4s2p then series them after...I have not had experience to explain why it should be this way but I do know we had quite big discussion on this couple years back.

it would be a bit of a pain if your balancing your pack every charge, but with bulk charging it works a treat, and you can always balance with a bm. afterall, after paralleling the packs via the balance leads, you've done the exact smae thing as paralleling them via the discharge leads.

 

[cohberg]

I don't know if what you're planning would work with balancer...but I really think you should make 5 of 4s2p then series them after...

Agreed. Why bother paralleling the cells on a temporary basis if they going to live and die as a pair? Parallel them permanently at pack and cell level and watch them at cell level. If you see a pair of cells way below the others you'll know that one/both are bad etc. You already have them in the correct orientation to easily do 4s2p.

Also for balancing, your setup is pretty ideal for a tench like system.

 

[sn0wchyld]

I don't know if what you're planning would work with balancer...but I really think you should make 5 of 4s2p then series them after...

Agreed. Why bother paralleling the cells on a temporary basis if they going to live and die as a pair? Parallel them permanently at pack and cell level and watch them at cell level. If you see a pair of cells way below the others you'll know that one/both are bad etc. You already have them in the correct orientation to easily do 4s2p.

Also for balancing, your setup is pretty ideal for a tench like system.

the reason is you save yourself allot of work building connectors, and allot of space due to unnecessary connectors. also, it will help with your overall efficiency - less connectors = less resistance = less voltage drop under load. the last point isn't a huge issue at lower power levels but it all adds up...

 

[rui_fujino]

I don't know if what you're planning would work with balancer...but I really think you should make 5 of 4s2p then series them after...

Agreed. Why bother paralleling the cells on a temporary basis if they going to live and die as a pair? Parallel them permanently at pack and cell level and watch them at cell level. If you see a pair of cells way below the others you'll know that one/both are bad etc. You already have them in the correct orientation to easily do 4s2p.

Also for balancing, your setup is pretty ideal for a tench like system.

the reason is you save yourself allot of work building connectors, and allot of space due to unnecessary connectors. also, it will help with your overall efficiency - less connectors = less resistance = less voltage drop under load. the last point isn't a huge issue at lower power levels but it all adds up...

Are you planning on bulk charging or individual balance charging?
if you are bulk (balance) charging then your setup is worst way to bulk charge since you can not balance cells.
if you are balance charging individual packs then surely it takes a long time to charge and hustle taking in/out the batteries all the time...

 

[sn0wchyld]

.....
Are you planning on bulk charging or individual balance charging?
if you are bulk (balance) charging then your setup is worst way to bulk charge since you can not balance cells.
if you are balance charging individual packs then surely it takes a long time to charge and hustle taking in/out the batteries all the time...

just to clarify, we are refering to 'bulk' charging as in keeping the pack (in this case) as a 20s 2p pack, and hooking it up to a 84v charger right? if thats the case, then its just as easy to balance as with the usual parallel then series setup, as the balance leads still get paralleled, so there's just 5 x 4s packs to balance using a battery medic or whatever.

if you're breaking the pack apart to charge it as say 4s 10p every time, then like I said, series then paralleling wont be the best option anymore. its only worth while if you can balance them while in their 20s 2p format.

 

[doc007]

First of all, thanks for all your input guys. All this is very helpful!

I have been wavering between parallel before series -OR- series before parallel as wells as considering different charging solutions. The next few posts will list some of the pro's and con's and help clarify some things.

I think the issue you have is that you have 5 packs on each side of the bike, making wires going over the top tube look really bad.

Iovaykind hit the nail on the head. I'm also concerned that if I go with the series before parallel setup (as show in SC's diagram, below), I will have a bunch of thin/delicate balance wires coming over the top tube to parallel with its "twin". The type of riding I plan on doing might put the 5 sets of balance wires in jeopardy (from quick bails off the bike, tree trunks, rocks etc).