Charging of Turnigy connected in series

[Uschi K.]

Hi guys,

I want to build a battery with approx. 96V, 10ah and at least 5C. I thought about using some Turnigy or something similar from another brand. Let´s assume I use ten of these pack (http://hobbyking.com/hobbyking/store/__10288__Turnigy_5800mAh_6S_25C_Lipo_Pack.html) to build a battery, resulting in 30s2p, 111V / 11,6ah. I´m a bit helpless with the connecting and charging of the pack. I would like to connect the kits with Anderson PowerPoles (or similar). Should I put a fuse (or whatever to protect bad things happening) between the batteries? What about charging? Do I need to charge each pack seperatly? Do I even Need to disconnect the whole battery before loading? Or can I (for example) charge "each side" (batteries in series) as one pack?

Any advise, help and recommendation is highly welcomed. Thanks!

Kind regards
Lars

 

[NeilP]

SO what you need to do first is go to thebattery section, and read teh stickies about care and feeding of Lipo packs.

You can use a fuse..some people do..it is a good idea, but I could never find a fiuse system that was good for the curent Iwas using , in a physical size that was small enough. So now I use no fuse at all ..and keeping fingers crossed.

Ideally you need to parallel first..series second, so connect in parallel, each pair of packs, via the balance taps. Either buy ready made or make your own. EP buddy, or similar store in your local area and get 5 of these parallel cables

You then make up 5 parallel packs of two single packs..They can then stay parallel for balance charging ..you do have a balance charger ..like a iCharger 3010 or Hyperion 1420...You really need a decent size one..1000W or more..the 50W units are OK for charging a single pack..but too slow if charging multiple packs in parallel.

http://www.buddyrc.com/icharger-4010-duo.html
http://www.buddyrc.com/icharger-3010b.html
http://www.buddyrc.com/power-lab-6-1000w-6s-40a-charger-combo.html


You could charge all 10 packs at once with a big charger ..all in parallel, byt then connecting all your 'blocks of two packs' in parallel again..with a 6 in to one adapter..
http://www.buddyrc.com/jst-xh-6s-parallel-blance-cable-x6.html

Just remember to disconnect the main pack wires before connecting the balance leads in parallel!!


Conecting the main discharge leads...two ways
1) make up individual 1 in to 2 adapters for each pair, then series those adapters
2) Make just two 1 in to 2 adapters and create two strings..just connected at each end with your adapters.


You do not have to balance charge each time you charge..you can 'bulk charge' so you you make up or buy a charger that is set to output your reuired voltage..so to be safe 4.15 per cell x 30 124.5 volts.
Search the forum for the Meanwell threads..these are constant current power suppliues that many people are using to bulk charge. You would need three of the 48 volt 350 Watt chargers..turned down to 41.25 volts each..and a current limiting device.. Search for Fechter CC/Cv boards..you woudl need one of these.

or go to a company that I have had no problesm with at all..they are slow, and do sting you for postage..but they will sell you a charger that will do the bulk charging job. I am talking about a company called BMS battery.
http://www.bmsbattery.com/18-alloy-shell

I have a 2000 watt, a 1200, a 600 and a 900..all work fault less so far.

So you could order a 2000 watt unit set to 124.5 volts..or what ever you choose..capable of charging at 10 amps..so a little under a 1C charge rate for your full pack.

My pack is 8 packs of 10S Nano Tech 5Ah LiPo set up as 20s4p. over 450 cycles now and 7500 miles..cnat even remember last time I balance charged.

Do buy some CellLogs from hobby king to monitor balance before you bulk charge. Ideally you would buy five of them, one for each balance connector

Good luck

 

[wesnewell]

30s2p is 126V fully charged. Do you really want that much voltage? Will your controller support it?
As for charging, I'd charge the whole pack as 30s2p using 5 2x 6s balance adapters to get cell level parallel, and then use 5 6s battery medics to balance the packs using a bulk charger. Don't need a fuse or anything between the 6s series packs, but you will definitely need a precharge resistor. I'd just put a fuse in the main + lead to controller.
View attachment 1

 

[NeilP]

Wesnells first pic is liek i was saying for my methiod two..just paralled at each end, and as he says, paralleling the balance connectors is optional..but usually considered a good idea.
But balancing with battery medics..yes it does work..I do it sometimes...but to be honest, Battery medics are crap and slow, they are just not particularly accurate. They do a job, just not very well.


Alternatively use Patricks battery protection kit..parallel boards, LVC/HVC protection all in a handy ready to go modular set of boards

http://www.methtek.com/category/battery-protection/

 

[NeilP]

http://www.methtek.com/2011/11/12/lvchvcparallel-boards-10/

 

[dogman dan]

Two 12s chargers would make charging a 24s pack relatively convenient. Even 24s is a LOT of voltage to play around with for a new guy. Kentucky Fried Fingers is not so bad when you make your rookie mistakes at 48v.

I have tended to go to leaving the original bullet connectors in place, but do make wire looms that parallel several packs that do terminate in 45 amp andersons.

Which connector you use depends on lots of things, I go to the andersons still, because I have multiple bike or other devices already set to that standard. Nothing I have draws more than 40 amps, so the andersons work for me.

 

[Uschi K.]

HI,

thanks for the quick reply. I know I want to build something ridicilous. Actually I using since roughly a year my first ebike build with a BMC V4S. According to the CylcleAnalyst I getting to approx. 60km/h with pedaling. So now it´s time for some bad ass thing.

@wesnewell: Is there a reason why the is a thick and another thin cable in your second Picture between connector 1 and the Controller? What it the reason for having two connectors and a 150Ohm resistor? To avoid sparks or similar when connecting / disconnecting? I will use a CroMotor V2 and a Freeway Controller from Lyen. So hopefully that kit will support the power I´m looking for.

Kind regards
Lars

 

[dogman dan]

Ahh, not so new, just new to lipo. 20s was my virgin ride with lipo. 30s would just melt anything I own too fast, so the most I ever rode was 26s.

FWIW, I still do lots of my charging by paralleling up 4 packs of 5s, and charging it with two low end RC chargers. It's convenient enough for weekend fun riding.

Once I get it all plugged in, I am charging 8 lipos at a time.

 

[NeilP]

HI,

@wesnewell: Is there a reason why the is a thick and another thin cable in your second Picture between connector 1 and the Controller?

I imagine the second thin wire between connector 1 and the controller is the controller ignition (on/off) wire. SO you can / should put a switch there to power the controller on and off. Preferable from the handle bar as an emergency kill.

What it the reason for having two connectors and a 150 Ohm resistor? To avoid sparks or similar when connecting / disconnecting?

Yes exactly.

Connect first the connector with the resistor. This charges the controller capacitors slowly to prevent a spark. After a few seconds, you can connect the main thick wire with connector 2 with no spark

 

[Uschi K.]

HI,

I thought a while about it and made a first draft of how I want to build the battery kit. Please have a look at the attached PDF. Does that make sense? Any risk or additional advise?

I´m still having a hard time to understand the usage of LVC and HVC boards. I will use a freeway-controller from Lyen and I do have a CycleAnalyst V2.5 at hand. I thought this would be "enough" to control the minimum voltage of the pack?! Can´t I program the CA / controller in a way that it will "shut down" the system when I reach a certain level of voltage (in this case a minimum total of 72V or 3V per cell)?

Additional I thought the charger will take care that the system will not exceed a certain level of voltage (in this case 100,8V or 4,2V per cell) during charging? How is the wiring of the battery packs to the charger done? I think about paralleling a set of four battery-packs with a parallel balancing cable. Second connect all four parallel balancing cables to a charger and connect the + / - leads to the charger as well. Any advise or recommendation for a charger and power-supply that could that job?



Kind regards
Lars

PS: This forum is really amazing. Thanks for all the help!

 

[dogman dan]

Other than the current level of availability, why the small packs? Your bundle of wires and connectors will be half as much if you just used 5000 mha packs.

It gets to be a shitload of wires and connectors.

Do set your LVC to the appropriate voltage, but it gives you no protection from a single cell diving to the cellar. The danger is when that happens and you never knew it. Then you find yourself recharging a cell that was ruined. Same thing on the charging side, the charger stops at the right voltage, but won't know the cells individual voltage if you are bulk charging. It will if you are using an RC charger set to balance charge.

No "only right way to do this". We all just make choices based on our perceived level of risk, and experience with packs gives you a better idea how to know when you have cells going wonky on you. A well sorted pack can stay amazingly balanced a very long time if you are not beating it to death.

 

[Uschi K.]

Yeah, you are right. I can use LiPos with a higher capacity to reduce cableing. But the questions I´m having is more related to charging and the usage of LVC / HVC boards. :|

 

[dogman dan]

I haven't used them, mostly because of cost, but also since I have the tendency to make up the pack I need for the bike I ride on a given day, or run other stuff, like a mower.

I'm a huge advocate though, of knowing what your individual cells voltages are doing, by one method or another. I just use a cellog 8 a lot, but not for no reason in the middle of the ride. I just monitor my voltage at the pack level with a CA, and then pull a cellog out of my pocket if I see something funny on the CA. Once you have watched some packs every cycle for awhile, then gotten rid of any underperforming ones, you get to where you can trust your pack not to have one overdischarged cell.

 

[wesnewell]

Additional I thought the charger will take care that the system will not exceed a certain level of voltage (in this case 100,8V or 4,2V per cell) during charging? How is the wiring of the battery packs to the charger done? I think about paralleling a set of four battery-packs with a parallel balancing cable. Second connect all four parallel balancing cables to a charger and connect the + / - leads to the charger as well. Any advise or recommendation for a charger and power-supply that could that job?

You can't parallel the separate packs balance cables together while the packs are still in series. You will burn everything up. If you could find a 24s charger, you could balance charge the whole pack as one, but sadly afaik they don't make a 24s charger. They do make 12s chargers though. And it's real easy to split a 24s pack into 12s sections to balance charge. In your pdf you'd just open the main connection between packs 2 & 3. Then you would charge them all as 12s packs. If you want to balance charge them as a single pack, then you'll either have to get a 24s BMS or use 4 separate 6s balancers and a 100-100.8V charger. Personally, I'd never use a bms on rc lipo. They tend to cause more problems than they are worth. I wouldn't want one on a lifepo4 pack either. I won't go into the reasons, but it is an option. If you want a fast charge, then bulk charging with separate 6s balancers is the best option as you can get 100V chargers up to 4000W. A 1000W charger would charge a 10ah 24s pack in about an hour. Their are lots of ways to charge. This is just a couple of the easiest and fastest. Using a bms would be the slowest method.

 

[dnmun]

using a BMS does not slow down the rate of charging. in fact you can charge much faster using a bulk charger with a BMS than using a balancing charger.

the reason none of these people use a BMS with lipo is because hobbyking does not sell a lipo pack with a BMS and they have all decided that it is not needed because they don't understand how they work.

a balancing charger is basically a bulk charger with the BMS built into the charger. but the balancing charger does not provide protection to your battery from shorting of the output or from over discharge.

a BMS will turn off the pack when you leave the pack attached to the controller and forget it so that it drains the pack to nothing.

 

[wesnewell]

Dnum, Plain and simple. You are full of crap. I know how a bms works. That's why I don't use one. Yeah, they make charging simple, but they are also the cause of most battery problems when they are used. Most lifepo4 battery packs come with a little 3-6A charger that takes hours to charge a pack. One reason it takes hours to charge in the first place is because the cell level cutoff is set way too low on them at 2.1V At 2.1V the cell is dead empty, and all useful energy was depleted at 2.5V. Once they start getting that low they are so far out of balance it takes hours to balance them. You can push crap bms's all you want, but the facts are they are crap, and just more crap to start a fire or kill a battery pack. Many battery pack fires are caused by the BMS. I'd venture to say most of them are. You're right about one thing for sure. A BMS left connected to a battery pack will drain it to nothing in time.

 

[Uschi K.]

Hi,

at the end of the day, my understanding is that putting (fully, equal charged) LiPo´s in parallel or series is not an issue. Low voltage cut off could be reached with the controller and / or CycleAnalyst.

What it makes complicated (and has the potential to become real dangerous) is the charging part. From what I´ve understood is, that I cannot parallel the balancer-cable as long as the LiPo´s are connected in series (as shown in the PDF above). I can parallel the balancer-cables of (for example) two LiPo´s connnected in parallel. But as soon as I connect the pack (consiting of two LiPo´s) in series with another pack, I will have an issue. I cannot balance and charge packs which are connected in series. Your advise is to disconnect them in packs, which are only connected in parall, not in series.

Could someone please elaborate a bit about "bulk charging without balancing"? How dangerous is that? I would like to avoid a fire in my appartment-block. Thanks.

Kind regards
Lars

 

[dnmun]

@lars: bulk charging lipo without a BMS to monitor the voltages on the cells is an invitation to cause a fire.

if you have a balancing charger the BMS is internal to the charger so it can protect the cells from overcharging but if you bulk charge without a BMS then the risk of fire is essentially 100% over the lifetime of the pack.

eventually one cell will go dead and short to zero volts so the remaining cells will be overcharged by the amount of voltage missing in the dead cell.

for a 6S pack that has one dead cell the 25V from the bulk charger is spread over 5 cells so the final voltage on them averages 5V. this is how fires start.

that guy can insult other people all he can because that is natural for him, but all of the battery manufacturers build their batteries with a BMS. it is only on this place that they harangue people about the 'battery murdering system' because they think the slogan is so cute.

hobbyking makes batteries for RC planes, not for EVs so they do not use a BMS because the fire is not a big consideration as it would be for an EV.

it is cheaper and faster than a balancing charger to use a BMS with a bulk charger since you can charge at higher rates and also in operation the BMS will protect from shorting the output and from over discharge. that is why they are used as well as for balancing the pack and preventing over charging.

 

[NeilP]

to avoid confusion between an actual individual 6s1p pack as bought, and your 6s4p block of 4 packs. When I am referring to your block of 4 packs i shall use the word UNIT..not PACK as you have called them

at the end of the day, my understanding is that putting (fully, equal charged) LiPo´s in parallel or series is not an issue.

Correct..ish
For putting them in parallel. I even often put unbalanced not fully charged packs in parallel, to help balance them up. Connect the main leads first to take the majority of the current that will flow between the packs, then a few minutes later connect the balance taps too. If you connect just the balance taps together first, and there is a massive voltage imbalance then you do run a slight risk of damaging/melting the balance wires. but for that one pack would need to be totally drained and the other fully charged...so connecting the main leads first equalises the whole pack voltage first over the main high current leads.

As for putting them in series..no harm can come of it, till you forget they are in series and mis balanced, then you ride the bike thinking you have a reasonably charged pack, and you then take one pack down below safe voltage,, because the overall voltage is high due to the fully charged pack.

Low voltage cut off could be reached with the controller and / or CycleAnalyst.

Yes, overall pack voltage will be taken care of by the LVC of the controller or the CA..but that WILL NOT stop one individual cell going below voltage.

From what I´ve understood is, that I cannot parallel the balancer-cable as long as the LiPo´s are connected in series (as shown in the PDF above). I can parallel the balancer-cables of (for example) two LiPo´s connnected in parallel. But as soon as I connect the pack (consiting of two LiPo´s) in series with another pack, I will have an issue.

I think you MAY..be getting confused here.
Your diagram is perfect apart from the fact you show a charger charging a 24s pack...not possible.see further in my writing.

In your diagram..you have FOURUNITS..labelled as pack 1...4.
Each individual UNIT (or pack as you have called them) can be paralleled up as you have drawn. Once that is wired up in parallel, (that is it, unless there is an issue, more of that later,) you NEVER need to un parallel them again. You could solder all the balance leads together and make a permanent 4p packs, as you have drawn. That can now be treated as one single battery pack, put it in a box, wrap it in tape..that is it..job done it is a single battery ..end of story. it can be wired in series with as many of these individual UNITs as you have made..in your case four.

The problem with your diagram is that it is showing FOUR of these UNITS connected in series to a single charger...Each of your UNITS are 6 series...6 x 4 =24 cells in series. There does not exist (as has been pointed out earlier) a 24 series charger
Your total battery is now a 24s4p pack

BUT there does exist a 14 series charger...called the Hyperion i1420. Since its max is 14 series it can also charger lesser numbers.

So in order to charge your pack with a 14 s balance charger you would first have to re configure it.
So what you do is split your big battery in half..between UNITS 2 & 3. So you now have two blocks of two UNITS that are 12s4p.

You now put UNIT 1 in parallel with UNIT 3 and UNIT 2 in parallel with UNIT4.

Parallel the main wires first.
the most positive wire of UNITS 2 & 4 together
the most negative wire of UNITS 1 & 3 together.
Now you can parallel the balance wires
..2 & 4 together
..1 & 3 together.

you now have a 12s4p pack that you can plug in to your 14 s charger.
AFTER CHARGING, WHAT YOU MUST NOW NOT FORGET IS TO UNPLUG THE BALANCE WIRES BEFORE YOU RE CONNECT PACK 2 TO PACK 3, otherwise there will beBIGFLASH BANGand you will melt and destroy many of the balance wires . that is if you are lucky.

I cannot balance and charge packs which are connected in series. Your advise is to disconnect them in packs, which are only connected in parall, not in series.

Not quite sure what you are meaning but hopefully my previous paragraph explained well enough

Could someone please elaborate a bit about "bulk charging without balancing"? How dangerous is that? I would like to avoid a fire in my appartment-block.

I think most of us here who use LiPo regularly bulk charge without balancing. I can't remember the last time I balanced charged my 20s4p pack. BUT I DO REGULARLY CHECK THE BALANCE using a CellLog or a Battery medic

Celllogs are better, more accurate, and they allow you to fit them to the bike, start logging and go for a ride. Get back home, stop logging and plug the Celllog in to a computer and download the battery voltage data for the whole ride . This allows you to see which if any cells are weak and drop really low in voltage (Voltage sag) under heavy load.

BULK charging is only dangerous if you do not check the balance before charging and do not monitor the charge.
I live in an apartment and have to bring my battery in the apartment to charge. have over 450 charges now in more than two years..no issue. BUT DON't Leave them charging-un attended. If you have to charge indoors do it in a 'Least Risk' location...by an open window..in the bath, in the oven..somewhere fire proof..on a fire proof surface. have some means of carrying/ throwing the burning pack out a window, smothering in sand ..
There is a very high chance that if you are careful you will never need any of these precautions...but be careless just once..try and charge a pack you have dropped or physically damaged, taken below safe voltage..is over puffed..what ever.. and there is a danger..and if these do burn, they burn big time..check out LIpo Fire on Youtube.

 

[NeilP]

Or as dnmun suggests..find a BMS that works for LiPo.

BUT I do have a box of three or four..maybe more BMS units that people have destroyed . One single spark or misconnect of a BMS and you risk damaging it. Then the only way you know it is damaged is when it allows your pack to catch fire.

BMS units are the best thing ever if they work, but you can't test them easily without knowledge that you do not have. Not being rude, but you do not have the knowledge to test a BMS unit yourself, if you did then you would not have the need to asked the basic questions you have about wiring the packs.


A BMS is great if you can guarantee you are not going to make any mistakes when wiring it up, and assuming it arrives from the seller in a working condition. If it does not work..or fails at some time you will not know until your pack catches fire or the bike does not go.

This is not assumption..this is experience from three local e-bike builders who have destroyed packs by trying to do further wiring themselves..made a spark by disconnecting something in the wrong order, reverse connecting the charger to the BMS..then connecting correctly..bike goes so it must be OK. But no..charge side had been destroyed on BMS so each successive charge / discharge cycle took the LiFePO4 pack so far out of balance, one or two cells went reverse polarity and caught fire..that was 'SAFE' LiFEPO4 chemistry.

With no BMS you are not relying on electronics to keep you safe..you are relying on yourself.

But saying all that..next LiPo pack I build..I am using a BMS..because I trust myself not to (hopefully ) do anything stupid when building it up. But be assured even with the BMS I will still be unplugging it regularly and checking cell voltages myself with a celllog.

I want a BMS so I can set a lower LVC on controller and CA, so get a bit more capacity out of each charge and still be safe at a cell level

 

[dnmun]

this is so true. neat that you can be so honest about how the problems with a BMS arise. just a loose connection for a brief microsecond can damage a BMS as well as the intiial wiring errors.

i am just concerned that so many newbies are told to go directly to lipo because it is cheap.

people who have no idea about how to manage a battery, and suddenly some poor guy is stuck with a fire he never expected.

we have seen several fires here recently so we know how devastating they can be.

i have had two house fires in my rentals and do not consider it it a trivial problem. one of my house fires was caused by a lipo fire in a charging laptop so i am more aware than most about the risk.

 

[NeilP]

this is so true. neat that you can be so honest about how the problems with a BMS arise. just a loose connection for a brief microsecond can damage a BMS as well as the intiial wiring errors.

Yep, especially when I am pleased to say that they were not my errors...newbies again!!. one was not actually his fault...well it was but he did to do the damage to the BMS,,he gave BMS packs etc to a metal worker to build a frame box..all great..till the metal worker chap tried to fit the pack and connect up the mass of parallel wires that 6 x 7s 5800mAh packs can produce..shorted BMS, dropped and squished the corners of two packs.

So my mistake..i said three sets of damaged BMS's..that actually makes a 4th..they are so delicate..set up and left alone they are jut fine..but mess with them , get it wrong just once and they are toast.


And to the OP...as mentioned before..why use such small capacity packs? instead of 4 small packs in parallel, use just two bigger ones..like a pair of 5800mAh packs

Oh..14 s BMS for Li-Ion..not quite LiPo, but the levels are good enough for a LiPO BMS .would be nice if the LVC setting was a bit higher..but this should be a last ditch defence..main LVC sorted by controller and/or CA

http://em3ev.com/store/index.php?route=product/product&path=42&product_id=75

14S Li Ion Type BMS with 40A Cintinuous dischargecurrent

Specification:

3 wire type, separate Charge and Discharge connection
Charge Voltage 58.8V
Charge Current 12A
Discharge Current 40A (continuous)
Protection Current >100A
Typical current consumption in standy mode, 15uA
balance current, 48mA
balance voltage, 4.18V
Overcharge protection Voltage, 4.2V
Overcharge recovery Voltage, 4.1V
Over-discharge protection Voltage, 2.75V
Over-discharge recovery Voltage, 3.0V
12AWG Discharge Cables
16AWG Charge Cable
108 * 60 * 12mm
~120g

 

[dnmun]

yep, i look at the LVC as an escape mechanism. nobody would go there normally but if one cell is really low it will catch it as it sags way down to nothing on it's last gasp. that will shut off the BMS and hopefully the person using the battery would stop then. they would have to. it is really there for the times when the battery is left to drain down on its own by accident imo. not for the rider to use the pack to the max discharge. i would use 3V resting and 2.7V for 1C sag.

 

[NeilP]

Escape mech ..perfect.

I have my CA set to an LVC of 70 volts, but controller LVC set to 60 volts. If I am desperate, i can knock the CA LVC down use very small throttle movements and still get get home and controller won't cut out.

A BMS with 2.75 volt cell LVC would be a final layer of cell level protection if I have to drop the CA LVC.

 

[wesnewell]

What it makes complicated (and has the potential to become real dangerous) is the charging part. From what I´ve understood is, that I cannot parallel the balancer-cable as long as the LiPo´s are connected in series. I can parallel the balancer-cables of (for example) two LiPo´s connnected in parallel. But as soon as I connect the pack (consiting of two LiPo´s) in series with another pack, I will have an issue. I cannot balance and charge packs which are connected in series. Your advise is to disconnect them in packs, which are only connected in parall, not in series.

Look at my previous diagrams. You can parallel the green leads top to bottom while the packs are in series, But you can't parallel a pack that is in the same series together. And they don't have to perfectly equal voltages, just close.

Could someone please elaborate a bit about "bulk charging without balancing"? How dangerous is that? I would like to avoid a fire in my appartment-block. Thanks.

You can bulk charge perfectly safe using balancers on each parallel group to avoid overcharging a single cell group. Bulk charging without cell monitoring could cause a problem. And while I've done it many times without a problem, you need to be aware there could be one and not leave it unattended while bulk charging without balancers. There are lots of youtube videos on bulk charging. Look at them.
http://www.youtube.com/results?search_query=bulk+charging+lipo