LiPo charing is a PITA

[nastypoker4]

I current have 4x 5Ah 6S Lipos in a 2S2P set up. I use a turnigy 4x 100w charger that balances each pack individually but it is a pain. Every day I have to disconnect and connect the main leads and balance leads for each pack and then the charger has to be set up each time to my charging specifications.

What I want to know is if there is an easier way of doing this. I want to be able to just connect one connector and switch a charger on but everywhere seems to think balancing is the only safe way of charging lipos.
I am going to be building a new bike soon so I have a chance to rebuild my battery solution and I am open to anything simpler than my current set up. Does anyone have any recommendations on how to make my daily charging routine more efficient?

 

[Punx0r]

Yes: Fit a BMS (battery management system) to the pack. It's permanently to power and balance connections, you simply plug in a two-wire charger and the BMS does everything else: balances and stops the charge when the battery is full. Most also provide protection during discharge: automatically cutting off power if any cell goes too low. Some provide short circuit protection.

If you want to retain your balance chargers rather than use a BMS then you need a way of putting all those wires on one plug. There are some RS connectors (like the old computer serial cable connectors) that feature a few beefy pins for carrying power as well as signals.

 

[motomech]

For many of us, this is the perfered 12S charger;
http://www.hobbypartz.com/75p-1220-charger.html
Not sure about availability/shipping to the UK.
I run it with a surplus $20 server power supply.
At 300 Watts, it's not the fastest, but it is simple and very sturdy.
It would do your 10Ah pack in a little over an hour.
I didn't care much for the cheap balance wires and paraboard, so after top charge, if any cells are off by more than .03V,
I'll discharge/balance with Battery Medics;
http://www.hobbyking.com/hobbyking/store/__10328__HobbyKing_8482_Battery_Medic_System_2S_6S_.html?gclid=CKSj4eTG3MQCFU1ffgodZ5AAQw
Usually done in 15 minutes.

 

[Ykick]

Install and use BMS/PCM, done deal...

And btw, you've assembled 12S2P battery pack not 2S2P. Counting HK bricks doesn't make it 2S2P - we count the overall cell number in series strings and parallel groups.

 

[TotalConfusion]

Install and use BMS/PCM, done deal...

Does anyone have a link to a battery build for installing a BMS to Lipo at all as im about to but 3 packs of 6s and would like to read up a little 1st as i dont know what to do with the extra negatives on the balance cables when put in series.

 

[Ykick]

Install and use BMS/PCM, done deal...

Does anyone have a link to a battery build for installing a BMS to Lipo at all as im about to but 3 packs of 6s and would like to read up a little 1st as i dont know what to do with the extra negatives on the balance cables when put in series.

Total laze-ass here but it's really not too difficult once you start putting the pieces together. Just remember when the main power leads are connected you'll have redundant balance wires which I insulate and simply tuck out of the way.

I also buy and use balance extension harnesses and merely move JST contacts into housings which match what I'm using to connect BMS/PCM. People use different bricks and BMS so each situation is different but wrap your head around the concept and adjust the components to your situation.

Here's a picture of my 16S pack from 4qty 4S hardcase bricks like the OP's using:


As you can see I've basically created 16S1P pack. To preserve any warranty all the stock wires and connectors for the bricks have been retained.

When I attach this to a BMS/PCM, all I need to do is carefully determine the "redundant" balance wire(s) connecting cells #8 & #9. Leave one of those properly insulated and tucked out of the way - connect 16S BMS/PCM, good to go.

 

[dogman dan]

BMS will fix it once and for all. But meanwhile, why do you need to balance every day? Do you need to balance every day?

You can bulk charge all four batteries at once with that charger, by paralleling them at the main leads. There are easy to make adapter harness ideas for that.

If you are easy enough on your batteries, you can go literally months with no particular need to balance the cells. The non balancing quick charge choice on your charger will be tons faster each charge. Balancing 10 ah of pack with a slow balancer will always be like watching paint dry.

 

[Punx0r]

That's a good point. If your cells are good and you are conservative about how far you discharge them you shouldn't need to balance often. I found I could go about a year (about 200 cycles) before I had a 0.1V difference between any of my 12 cells. But I rarely went below about 3.7-3.8V resting voltage on discharge.

 

[dnmun]

the BMS will balance the pack. usually the pack is only out of balance significantly when it is new and when one of the cells begins to have higher self discharge rates from over discharge and abuse. i consider the BMS essential for protection against shorts on the output and preventing over discharge which is terminal.

 

[nastypoker4]

Can anyone recommend a good BMS system for my 12S2P battery pack. I draw ~50A peak.

So lets say I have my 4x 6S packs wired into a BMS, I am just left with 2 main charge wires. What sort of charger would be suitable for something like that?

 

[dnmun]

why do you use only 12S if you are drawing 50A?

 

[nastypoker4]

why do you use only 12S if you are drawing 50A?

Is there something wrong with that?

 

[Punx0r]

Certainly not if you have a 48V motor controller

 

[dnmun]

buy another 6S pack and split in two pieces and then build a regular battery out of the 15S2P and use a regular 16S lipo BMS to protect it. then your speed will go up and the current will drop.

 

[Ykick]

12S is absolutely fine and works well with many 48V controllers/systems. Since OP’s using 4S hardcase bricks the sensible and elegant move IMO would be to add another brick and just go 16S.

BUT, that would require a mild custom controller upgrade. Most people appreciate programmable controllers using components capable of handling 72V battery packs. 16S RC Lipo with a BMS/PCM can safely full charge to 67.2V.

As far as BMS/PCM strategy is concerned, I’ve installed and used 16S Bestechpower D167 Li-ion on 12S RC Lipo packs. Works fine so if you stick with 12S for now, go ahead and buy the 16S BMS. Later on if/when you decide to add the 4th brick for 16S you’ll have the BMS for the job.

For bulk charger I mostly use Alloy chargers from BMSBattery. But I've also rigged up Meanwell supplies - basically anything I can get my hands on and/or series together to reach 67V.

 

[dogman dan]

Depending on the c rate of the packs, 50 amps could be a bit harsh on them using just 10 ah. But only likely to really drive them out of balance if you run them down to the lowest voltage, below 3.65 or so. What happens in effect, is you get a lower c rate as the batts reach full empty. So back off the throttle on the last mile helps.

By all means get a bms. If it wasn't so clear, I meant you don't have to balance every cycle while waiting for the bms to arrive.

 

[Ykick]

OP - how do you know your controller pulls 50A? Do you use an inline meter? What controller?

 

[hxcadam]

You can do BMS or connect your 4 packs in paralell for charging.

http://www.tjinguytech.com/charging-how-tos/parallel-charging

All you need to do is create a paralell harness for the 4 batteries and then make a balance harness that connects all the balance leads.

 

[dogman dan]

The charger he has does 4 packs at once. 4 channels. Which means separating them out completely, a pita.

When he gets his bms, he'll still need lithium charger to go with his bms. The one EM3ev sells is a good choice. I think he could get the bms there too.

 

[cal3thousand]

Are you using bullets or Andersons?

If you want ease of connection/reconnection, Andersons are the way to go. Especially for anything not requiring high current levels. But they do require a special crimper to install properly.

With Andersons and the dovetail connection between connectors, you can assemble them in blocks that all connect in one motion as if one big plug.

I have a run cable that serializes 2 12S modules into a 24S pack and another cable that parallels the 2 modules for charging. Plugging and replugging is as simple as using a wall outlet.

 

[markw]

With Andersons and the dovetail connection between connectors, you can assemble them in blocks that all connect in one motion as if one big plug.

I have a run cable that serializes 2 12S modules into a 24S pack and another cable that parallels the 2 modules for charging. Plugging and replugging is as simple as using a wall outlet.

This. icecube57 has some great youtube videos detailing a setup much like this. I would pilfer Chris' youtube for information/methodologies. He's very liberal with showing his processes for the creation. Alternatively you could ask him to build you a harness!

Tools you'll need are the Anderson crimper. Hydraulic crimping tool/copper crimping sleeves are helpful too if you know you might need to connect many packs. 10awg/12awg silicone wire.

What becomes challenging after this is to simplify balance connections. You'll want them disconnected when discharging but paralleled during charging. I've been brewing up solutions using a 40pin connector. Balance leads connect to a 40pin female plug, male plug connects the balance leads in parallel appropriately and end in a standard balance plug. I've been stalking this thread for more solutions, maybe other pros have seen examples of this fail/succeed. Let me know.

 

[mark5]

With Andersons and the dovetail connection between connectors, you can assemble them in blocks that all connect in one motion as if one big plug.

I have a run cable that serializes 2 12S modules into a 24S pack and another cable that parallels the 2 modules for charging. Plugging and replugging is as simple as using a wall outlet.

This. icecube57 has some great youtube videos detailing a setup much like this. I would pilfer Chris' youtube for information/methodologies. He's very liberal with showing his processes for the creation. Alternatively you could ask him to build you a harness!

Tools you'll need are the Anderson crimper. Hydraulic crimping tool/copper crimping sleeves are helpful too if you know you might need to connect many packs. 10awg/12awg silicone wire.

And here's descriptions (1, 2) with pictures of the charge/discharge Anderson blocks cal3thousand and markw write about.

 

[JoyRiddin]

You can do BMS or connect your 4 packs in paralell for charging.

http://www.tjinguytech.com/charging-how-tos/parallel-charging

All you need to do is create a paralell harness for the 4 batteries and then make a balance harness that connects all the balance leads.

It been covered many times but anyway here it is again. You have to be extremely careful that the charging harness cell voltages are very close in value before connecting in parallel so that they don't try to equalize cells when connect them together. Never parallel the charging harnesses of series Packs.

 

[Offroader]

In all honesty, if you want simple charging buy yourself an Adaptto mini-e and easily charge with just two wires. This makes it so easy to charge and has better control than a bulk charger which may overcharge your cells.

Plus you get all the good features of the controller, including silent motor operation which is great.

 

[markw]

In all honesty, if you want simple charging buy yourself an Adaptto mini-e and easily charge with just two wires. This makes it so easy to charge and has better control than a bulk charger which may overcharge your cells.

Plus you get all the good features of the controller, including silent motor operation which is great.

This is a great suggestion, as the user is operating with 4s packs it would be a fine fit... But does the fact that he runs 2p complicate things? Is it okay to go ahead and parallel balance leads for that application? I honestly dont know anything about how things connect wih LiPo and BMS.