**NEW** FMA Direct Cellpro 4S Balanced Charger Review

[Jermo]

Just finished this. Sorry it took longer than expected. Personal issues caused a delay.

Anyway. Comments and Suggestions welcome Post/PM.
http://video.helifreak.com/?subpath=Jermo&filename=cellpro4sreview.wmv

[WhirlingBladesOfDeath]

I have the new 4A version already on the way. Cool to see it in action! Have you tried charging at the 2C or 3C rates (or as high as you could with a 3A charger)?

Thanks,
Jason

[Jermo]

Mine has the 1.4C auto charging rate so with a 2200 mAh pack I end up with the 3Amp rate :)

[WhirlingBladesOfDeath]

So if I set my 4A Cellpro to "auto" will it charge my TP 2070 at 1.9C? I know you've spent some time researching this, any concerns charging at 2C (or 3C) with this charger?

Thanks,
Jason

[Jermo]

Depending on your firmware version you may or may not have the 1.4C charge rate, however, with packs with high discharge capacities (don't recall the exact amount ..it's on FMA's readme) you can safely charge up to 3C rates with this charger because of how it charges/monitors/balances..etc...

The limit is the max Amps the charger can put out. The newest version does 4Amps.

[Bastian1337]

Nice review Jermo!
The only thing is that your drawing basicially shows a 6S configuration with reversed polarity.
So if you would connect a charger to the leads where it says plus and minus, you would short circuit the battery.
However, that isnt't so important to understand the idea of the balancing leads.

[DebianDog]

Thanks Jermo. Moved to Helifreak server.

[Finless]

Jermo, only correction..... Most chargers charge through the discharge leads and "Discharge Balance" through the balance port!

FMA chargers do charge through the balance port along with a FEW others. But most of the popular chargers dont work this way. They discharge the higher cells to match the lower cells.
This is the way the TP210, FligthPower V-balancer, and Hyperion, Blinky, etc work.

So not a big deal but really you should explain the difference between a discharge balancer and a charge balancer.

Also one of the benifits of a discharge balancer is you can balance WITHOUT charging. When packs sits a few days you might find they have drifted out of balance a little. With a discharge balancer you just hook it up and let it do its thing. You dont have to hook up a charger.

So the debate about which is better e.g. to discharge balance or charge balance is debatable.

Bob

BTW Dog... Nice intro :)

[Pinecone]

Jermo, where is that ReadMe, I checked, but can't find it?

I a mwaiting for their next product, they told me a while ago, they are going to do a 6S Cell Pro. I don't like the Balance Pro as there are no readouts so you HAVE to connect to a computer.

[Jermo]

ugh..I can't find it. It was a pretty low discharge rate.. like 12C or more. Just about anything the T-Rex would use should work fine.

Bastion, You are right in that I sketched a 6S array for the illustration and it's upside down. :oops: ... it's the concept that matters.

Bob,
On charge balancing vs discharge balancing: I'm not sure it truely matters except for minor amounts of time saved and perhaps efficiency since we don't lose pack energy through dissapation. Big picture wise I'm not sure that it matters for hobby sized packs plus with larger packs on quality chargers (one example that comes to mind is the TP1010) I believe the balancer actually sends cell levels back to the charger for monitoring....that's a total guess on my part but would be a reasonable assumption of why it has the telemetry cable other than to turn off the charger due to a cell fault.

[Pinecone]

The difference is when you go into constant voltage charge mode a charge balancing charger will only supply 4.2 volts to each cell. A discharge balancing setup sends 4.2 volts per cell to the pack, so you hope the discharge balancer can bleed off a high cell faster than the charger is charging it.

[ZX11]

I bought the 4amp charger so I could balance charge 4200mah packs at 1C for my Eflite Cub airplane. I also have the previous 3 amp cell pro. The side benefit is that now I have two cell pro chargers with four trex 450 batteries. It should give me a pretty continous stream of ready batteries.

I wonder if you could take two 4amp cell pros and charge a 4200mah 8S pack by giving each charger 4 cells to charge? Maybe by using a adapter on the balancer port? It would be cheaper than that crazy $300+ TP1010/balancer set up.

[Pinecone]

No you can't. I did see that in the FMA FAQ.

But in reality, I think you could if you made up the right adapter. But my solutionwould be one 101C with 210V and a couple of Cell Pros. Then you could charge more packs at one time. :)

[Jermo]

Just be patient. A little bird told me FMA is working on a larger version of the Cellpro. Hopefully I'll be back to work and can get one to do a review.

[Pinecone]

Yeah, I said it above. :)

Fred Marks, IIRC or someone else at FMA, told me about the 6S version months ago.

[Probedude]

Yes, there is also an LCD version of the BalancePro that is being worked on - that news came out in January.

Regarding can you charge an 8s pack with 2 cellpros - yes you can however you need two independent power supplies, one for each cellpro and there can NOT be any connection between the two supplies. You'll also need to make an adapter to break out the balance taps into 2 qty Cellpro balance taps.

Dave

[ZX11]

Regarding can you charge an 8s pack with 2 cellpros - yes you can however you need two independent power supplies, one for each cellpro and there can NOT be any connection between the two supplies.



That makes more logical sense than FMA's simple warning not to. Having both groups of cells connected (to make it a 8cell pack) and both charger power leads connected would cause a problem :D

[Tosto]

I'm new to the exciting and dangerous world of lipos...

Can the Cellpro 4s charge a 3S 11.1V battery? the instructions say (word for word):
"battery chargers must be used with constant current and constant voltage, and have a parallel connection charging function, charge current should be less 1C5A, the charge voltage per cell battery prohibit more than 4.5V." whatever that means.

[ChasHeliCop]

4.5 volts per cell

[kamtsa]

FMA chargers do charge through the balance port along with a FEW others. But most of the popular chargers dont work this way. They discharge the higher cells to match the lower cells.
This is the way the TP210, FligthPower V-balancer, and Hyperion, Blinky, etc work.

So not a big deal but really you should explain the difference between a discharge balancer and a charge balancer.

A 'charging balancer' can still be implemented using two virtually independent charger and balancer, placed in the same enclosure. The charger charges between the two end points and the balancer bleeds as needed.

The DN charger has 4 coils/toroids which lead me to think that it is a real 'charging balancer'. I am not sure about the CellPro. It will be interesting to do a 'teardown' of the Cellpro to figure out how it works.

Kam

[Jermo]

Kam you described a "discharge balancer"

[kamtsa]

Kam you described a "discharge balancer"

Exactly, but read Bob's posting. He implies (or at least this is how I understood it) that if a charger such as FMA charges through balancing connector than it is a 'charging balancer' and not a 'discharging balancer'.

The FMA charges through the balancing connected and yet be implemented as 'discharge balancer' as you noticed.

Kam

[Probedude]

Kam you described a "discharge balancer"

Exactly, but read Bob's posting. He implies (or at least this is how I understood it) that if a charger such as FMA charges through balancing connector than it is a 'charging balancer' and not a 'discharging balancer'.

The FMA charges through the balancing connected and yet be implemented as 'discharge balancer' as you noticed.

Kam

Think of it another way.
If the charger has transistors across the cells, then if the pack was series charged, a cell that is higher in voltage than others can have the charging current 'shunted around it' so that the lower voltage cells can come up in voltage.
This is in fact how the cellpro works.

Proof of this is if you hookup a pack with 1 cell much lower than the rest, the low cell is charged up to the level of the others, not the higher ones discharged down to the lowest one, before fast charging takes place.


Some info on the guts.
http://www.rcgroups.com/forums/member.php?u=107322

Specifically the board layout with major functions identified.
http://www.rcgroups.com/forums/attachment.php?attachmentid=1284494

[Probedude]

A 'charging balancer' can still be implemented using two virtually independent charger and balancer, placed in the same enclosure. The charger charges between the two end points and the balancer bleeds as needed.

The DN charger has 4 coils/toroids which lead me to think that it is a real 'charging balancer'.

Sorry, I should have included this in the previous post.

The DN charger consists of 4 independent circuits, completely electrically isolated from each other. Completely independent operation of each other.

There is no 'active' balancing - each cell has its own charge circuit that takes the final voltage to 4.20V no matter how long it takes so it is intrinsically self balancing.

This is why you can charge 2 completely separate 2s packs on the DN charger, even completely different mAH 2s packs.

It doesn't charge only on the outer two leads, but instead on each and every lead on the tap connector.

Dave

[Probedude]

I'm new to the exciting and dangerous world of lipos...

Can the Cellpro 4s charge a 3S 11.1V battery?

Yes, it will charge 1s - 4s packs and depending on which model you get (3A or 4A max version) will do it at:

3A max Cellpro:
3A max for 1s-4s packs

4A max Cellpro:
4A for 1s - 3s packs
3A for 4s packs (the bury this in the owner's manual)