Testing a Shorai LiFePO4 on solar!

[PNjunction]

I understand the need for a balance charger with access to individual cells. However don't tell that to the Antigravity guys that use quality cylindrical cells and point out that crappy quality cells are the ones most likely to go unbalanced - hence Antigravity doesn't even offer a balance port to my knowledge.

This brought up something I thought about long ago - is the need for constant balancing really covering up poor cell quality issues? Not only that, but I'm only drawing 1A max from the cells. Perhaps that's the *real* reason I want to get a high-end balance charger - to see if there is a real-world difference among high-quality manufacturers and if my application will ever get to a point where balance becomes a real issue.

The Optimate TM-291 Lithium charger intrigues me - knowing that it will be attached to various 4S-XP cells, it seems interesting that they will just pulse the battery between 14.1 and 14.3 volts when it hits the miniscule absorb for their EQ. I'm not sure if that will be as effective as a single-cell balance charger, but I guess I'll see when that other charger arrives, and my budget allows - heaven knows I've spent far too much on a 1A misapplication. I notice the Antigravity guys offer this charger so maybe there's something to it.

This also has me wondering if the PWM waveform might actually be beneficial in a solar application to LiFePO4 - perhaps it might be considered an *aid* to balancing. Plenty of ways to go overboard with marketing here, so just know you heard it here first. hah.

I'm going to have fun hitting the bricks with this stuff that's for sure.

[Sunking]

Batteries which are intended for LA replacement for motorcycles, etc. will have an internal balancing system and overall charge control system, since they are expected to connect directly to the original charging circuitry which offers charging voltage control only, rather than staged charging.
Batteries which have a connector for external BMS (rather than just monitoring) will normally not contain internal balancing circuitry.

Spot on correct. In fact you can say a battery with external balancing plug must have balance charger. It may have a LVC, but does not have any capacity to balance itself.

From a user POV you want an external balance charger as it give you full control and access to the individual cells.

[inetdog]

Then again, I don't know if it will confuse those batts that actually DO have an internal BMS along with a real LVC, like the EarthX batts. So there you go - not only internal bms but also lvc! If I win the lottery, I'll have to pick up one of those EarthX batts to add to my collection.

When you have a battery with an internal integrated BMS that balances at the cell level, rather than just an overall LVC, voltage and current limiting, you cannot just connect an external charger that also connects at the cell level for balancing.
You need one or the other.
Batteries which are intended for LA replacement for motorcycles, etc. will have an internal balancing system and overall charge control system, since they are expected to connect directly to the original charging circuitry which offers charging voltage control only, rather than staged charging.
Batteries which have a connector for external BMS (rather than just monitoring) will normally not contain internal balancing circuitry.

[PNjunction]

Thanks for the comments on the balance chargers. I actually pulled the trigger on an Optimate-Lithium (LiFePO4) since it balances multiple cells not only by watching voltage alone, but also by monitoring the internal resistance and doing a pulse just under the typical top-balance scenario. We'll see - marketing never sways me, but it has to perform on the bench or it gets tossed. And no need for the hobby-bms type connectors. I'll still probably pick up a balance charger like the ones you guys mentioned just because I have to know.

I'm brand-agnostic, (as long as the quality is reasonable, I'll pay for quality to a point) and chose the Shorai for testing simply because it was available to me over the counter so I could inspect the balance pins, voltage etc. The battery shop guys see me coming swinging multimeter leads and know the score.

I haven't actually charged via solar yet since I was concerned about how the PWM waveform would affect the LiFePO4's, but seeing how Genasun has no problem, I'm a little more reassured. Then again, I don't know if it will confuse those batts that actually DO have an internal BMS along with a real LVC, like the EarthX batts. So there you go - not only internal bms but also lvc! If I win the lottery, I'll have to pick up one of those EarthX batts to add to my collection.

I guess I'll need a bike to put these in when I'm done testing. Speaking of which, I sure hope you've seen this 67-page thread from the heavy-hitters like Joel Wisman and _CV_ from Candlepower fame, along with some manufacturers who put numerous batts to real-world and destructive testing (to gather data, and not just to blow it up real-good) with procedures, pics and descriptions anyone can duplicate:

http://advrider.com/forums/showthread.php?t=757934

I got schooled, (along with some of the manufacturers apparently) pretty darn quick - even if I don't have a bike!

Still, my main concern is how the LiFePO4's handle PWM waveforms long term - both with or without an internal bms...

[thastinger]

I use a turnigy charger/balancer to balance my 16cell 12(14.4 really)V drag bike battery made from A123 2650 cells. I just charge it either from the bikes onboard system or a standard B&D battery charger. I balance it about once a year but the cells are never very far unbalanced.

They don't like the cold at all and if you drain them down to 50% like you might a FLA, they will be done.

[SunEagle]

Oh yeah - that's probably why my application isn't supported - with powersports one assumes that it will be hit with a recharge from the alternator after a start - not so with my slow draw-down. Not sure why there is no LVC on these things in the industry.

I'm already not happy with the provided balance charger - but that's because I'm a propeller-head and want to actually see the difference in balance, voltage and so forth. Also to make sure that the balancer is in fact balancing, and I'm not running some ancient firmware etc.

I'd be interested in QUALITY balance chargers. About the only one I gave serious consideration to was a Hyperion, or a CellPro Powerlab 8. I'm sure there are others that are quality. From what I've read, the Shorais pinouts are backwards from right to left, so I'd need a special adapter? Haven't taken it that far yet.

What I can say is that I'm BLOWN AWAY by all the online videos, even from major EV builders and so forth, spending $10K on packs, and using a $5 dimestore voltmeter to set / check the bms. A *minimum* requirement for accuracy for these things I think would be the venerable Fluke 87V.

I use a Revolectrix Cellpro Multi4 battery charger for my RC LiPo batteries. It is on the low end of their product line as compared to their Cellpro Powerlab 8 that you mentioned but I am very pleased with it's ability to charge a lot of different types of batteries including a LiFe type I use in one of my transmitters. It also provides battery data from the start to the end of the charging cycle including battery % charge condition.

I'm not saying it is the best product out there but I am very happy with it.

[PNjunction]

That is a real risk with Lithium as you know take them down to far and there is no going back.

Oh yeah - that's probably why my application isn't supported - with powersports one assumes that it will be hit with a recharge from the alternator after a start - not so with my slow draw-down. Not sure why there is no LVC on these things in the industry.

I'm already not happy with the provided balance charger - but that's because I'm a propeller-head and want to actually see the difference in balance, voltage and so forth. Also to make sure that the balancer is in fact balancing, and I'm not running some ancient firmware etc.

I'd be interested in QUALITY balance chargers. About the only one I gave serious consideration to was a Hyperion, or a CellPro Powerlab 8. I'm sure there are others that are quality. From what I've read, the Shorais pinouts are backwards from right to left, so I'd need a special adapter? Haven't taken it that far yet.

What I can say is that I'm BLOWN AWAY by all the online videos, even from major EV builders and so forth, spending $10K on packs, and using a $5 dimestore voltmeter to set / check the bms. A *minimum* requirement for accuracy for these things I think would be the venerable Fluke 87V.

[Sunking]

It will be a fun ride - I just hope I didn't crash my wallet. Without an LVC cutoff, I'm going to have to be on top of my game.

That is a real risk with Lithium as you know take them down to far and there is no going back.

FWIW if you know about power electronics and understand the principles you can buy one of the many chargers used in the RC world. Many are capable of up to 2000 watt input and can charge any battery chemistry intelligently up to around 30 volts. Many you can program any algorithm you desire. Mine I can even balance discharge Lithium up to 6S at 20 amps. It will tell me exactly how many Amp hours are put in or discharged. PM me if interested and I can give you a few manufactures to look at. Prices are reasonable starting at around $100 and up.

[PNjunction]

Wish me luck - I just picked up two Shorai's and have immediately voided the warantee with a mis-application.

The first one I got for free, a 3-month old new LFX (Lithium Iron phosphate) 14A1-BS12 from a guy who was afraid to use it. The second one is another 3 month old LFX36L3-BS12.

These are basically SLI powersports batteries, but I'm going to try and see if I have the skills to keep them alive with a continuous 1A draw within specs. Wish me luck since this voids the warantee if you use them as the sole source of power. Since they are so expensive, my hands were shaking when I took this home. And uh, yeah, in my slow-draw misapplication, the PbEQ capacity value is about 1/3 to maybe 1/6 that rating. We'll see.

I also splurged by getting the BMS charger to balance the cells before I try solar charging them. In both cases, they took awhile to balance out. The plan here is to use them on weekends like normal with my panel and pwm controller, and then upon return balance the cells again. Maybe I'll look into a Genasun MPPT controller for LifePo4 later. At least I can hit them somewhat hard, which I got addicted to with Odyssey AGM's, and on the smaller side, Hawker-Cyclon agm's.

It will be a fun ride - I just hope I didn't crash my wallet. Without an LVC cutoff, I'm going to have to be on top of my game.