LiPo Balancing - Help!
 

Guys - I hate to ask this, but am new to this;

Can someone please explain to me the whole "LiPo balancing" thing? I want to get into this, however I want to make sure I do it right first.

Thanks

I'd tell you to use the "search" function. But I've had very little success using the search with this forum for some reason. It seems that most of the answers to my questions have been hidden within threads that don't have anything to do with the question I'm asking. Whatever....

Anyway, it's a good idea to do your homework on LiPo's before you dig in. They're still pricy and they can be dangerous if not delt with correctly. I think the prices will continue to drop over the next few years but with prices they way they are now, it's a good idea to treat them with respect so you don't damage them.

With the balance thing, it's simply another method of charging the battery. But instead of charging all the cells together like a NiMH or NiCD battery pack, balancing charges each cell individually.

There are a couple of reasons for this, the most important reason being that LiPo cells can be damaged if charged beyond their max voltage, 4.2V, and they don't resist a charge much, even when they get to that voltage. NiMH and NiCD on the other hand will resist a charge a bit more beyond their standard 1.2-1.5 volts and don't react quite so volitile when they are overcharged a bit. They'll ususally only warm up a bit whereas LiPo's will smoke or even catch on fire resulting in a burned down garage at the worst and a destroyed battery at the least.

Therefore they devised an easy way to individually monitor and charge each cell using a balance plug which is built in to each LiPo pack. There are a couple ways of doing it. You can buy a LiPo balancer which is nothing more than a low-amp charger that balance-charges the pack. It won't usually fast charge a battery, it's only meant to balance-charge which takes longer than standard charging. Usually you only have to plug in the balance plug, not the main plug. The easier method in my opinion is to simply buy a charger that has a built in balancer. These are all over the place. You can easily find one for less than $50. I've got this one and it works like a charm:


http://www.hobbycity.com/hobbycity/s...idproduct=7028


This way you can use the charger to fast charge without balancing if you're at the track and you need a charge quick, as well as use the balance function to balance the LiPo every few charges. You don't have to balance every time you charge, though some do this if they're not in a hurry since it usually takes longer to do a proper balance than if you charge without balancing. When balancing, the charger won't charge beyond 4.2V, in fact, it will discharge the cell if for some reason the voltage exceeds 4.2V. If using the standard charger function, the charger won't exceed 4.2V x # of cells (8.4v for 2 cell packs, 12.6V for 3 cell pack, 16.8V for 4 cell packs and so on). You might ask "why balance charge if the standard charge will only charge to the specified voltage?". The reason for this is if there is a faulty cell that say, will only charge to 3.8V, or there's a cell that takes a charge slower than the other cells, the charger will continue to dump amps into the pack which will over charge the other cells in the pack. This can cause the beforementioned smoking/damage/fire and all hell will break loose.

It's really kind of a cool method of charging. You can monitor each cells voltage, the mAH put back into the pack and the total voltage of the pack. It sounds kind of complicated but it's actually really helpful to charge this way since it gives you a more accurate display of whats really happening in your battery. Plus, with LiPo's, you don't have to worry about memory effects, zapping, matching or any of that crud we had to deal with when NiMH and NiCD were the best out there. Really, all you have to worry about is not charging beyond 4.2V per cell in the pack (which is built into the charger) and not dropping below 3.0V per cell when discharging the battery (which is built into newer ESC's by means of a power "cut-off" device when the pack reaches too low a voltage). By the way, the dropping below 3.0V per cell rule is due to the nature of the lithium batteries and while it won't cause any fires crap associated with overcharging, it can irreversibly damage the battery.

This is a good thing and a bad thing. It's bad because it presents an opportunity to damage your cells if you're not careful. Even with an auto-cut off, if one cell discharges much quicker than another, that cell could theoretically drop below 3.0V before the cut-off engages. I set my cut-off to a little higher voltage just for this reason which can be programmed into high-end ESC's like the MMM. It's rare when this occurs but it can happen. The good in this is that the LiPo will continue to provide a lot of power even when the battery is about due for a charge. This is because the battery isn't "dead" even when each cell has, say 3.1V per cell left. You'd almost be at the 3.0V cell cut-off but the battery would still be providing a lot of power. Therefore what you'll normally see is a slight power drop over time with a sudden cut-off of power when the cut-off kicks in. This is way better than the gradual power drop with NiMH and NiCD with the battery eventually dying. I hated it when I saw a big power drop, yet I still had half a charge left in my NiMH pack. You never see that with LiPo's. Ton's of power the whole time, then a sudden cut-off.

Also, LiPo's last WAY longer than NiMH and NiCD and they are capable of providing a lot more amps for high performance motors. They can pack way more capacity in them. 5000mAH isn't uncommon at all with LiPo's. I can bash for 45 minutes on a 5000mAH LiPo. I'd be lucky if I could go for 20 minutes with a NiMH, with a half power drop after 10 minutes. LiPo's have been a frickin god-send for me. This hobby is SO much better without all the hassle of the old NiMH's. They still have their place, in flashlights and kid's toys. I'll never go back to NiMH's for RC. Too little capacity with too little power.

awesome answer! thanks for the help!!

+1 on the search function. It is horrible!!

Would much rather have you ask then blow up a lipo or charger. When these things go, they take other items with it. I’ve seen people charge them wrong to get a couple extra tenths of a volt and it usually ends in catastrophe...

does any one know how to balnce charge the orion packs it has the port in the cell but i am not sure what items if any i need to balnce charge them.Orion says there is no need to do this but as stated with the price of lipos and for safty i would like to get the most life out of these i can thanks for any help you can give

Yeah, I've noticed the pictures of Orion batts don't have a balance plug. What's up with that? They think their LiPo's don't need balancing? That can't be the case. If so it's pretty foolish in my opinion.

they have a balincing port but i have not been able to get any info on how to use it not even from orion

Checkpoint has a balancer with the orion style connections built right in. However you can wire any style balance plug you want into your charging leads and add the 3rd lead with a 2mm(?) bannanna plug for the middle tap.

Check your balancer or balance charger for the proper pin out and wire it up.

Here's a picture of one I wired up and used in the past.

http://www.sportsmanoval.com/forum_pics/Adapter.jpg

post edited...was able to post the picture finally.

thanks for the info and the pic

Saddle Packs ?
 

What side (positive or negative) would you plug the 2mm bullet on your cable with the cable that bridges saddle packs ?

Sorta new to this electric thing, but really like the no nitro / tuning difference.