Zivan NG3 Revealed (Not Completely)

[pvorlicek]

Okay, okay, I stole the thread title from Patrick ....

I just purchased a Zivan NG3 charger off Ebay ($350 with shipping) for a planned conversion of a VW Beetle. I read through Patrick’s “NG1 Revealed” thread so I’ve learned some stuff already. According to the seller, the unit came out of a Corbin Sparrow and the unit is configured for 58S LifePo4 cells. The unit is in great cosmetic condition and when I plugged it in (no load) I got flashing red lights which, according to the manual, are normal.

Below are some photos.

From what the labels look like, I have concluded that the unit was initially delivered to support the Corbin Sparrow “Optima Yellow Top” batteries (which came standard with the Sparrow. And sometime later it was re-programmed to support a 54-cell lithium pack. I’ve asked the seller about the history and the charge profile, but so far no hard data.

I called ZivanUSA to see if they might have the charge profile and they said it could take “weeks, months or even years to track it down” (I’m not kidding, this is what the guy really said). He did, however, confirm that the white sticker means the charger was re-programmed.

My plan is to use the charger in a 32S LiFePo4 (100AH Cells) or 32S (8P) Lipo pack. My hope would be able to use the charger without paying for reprogramming and just turn down the voltage as described in Patrick’s NG1 thread.

The good news: the unit seems to be working and the layout is quite similar to the NG1 (2 pot adjustments).

The bad news: I have no idea what the following means (and if they are even important to me):

“F5WDSQ”: according to the Zivan web site, the NG3’s should begin with an “F7” and not an “F5”

“Curve BR”: ???

“54Cell8A/50AH”: What does the “8A” mean?

“182.5V absorption”: What does absoroption mean in the lithium world?

 

[pvorlicek]

I'm trying to figure out the charge profile for this charger. Does anyone know when Zivan programs the charger for LiFePo4 batteries, would they follow a "standard" charge profile for "lithium" batteries?

I found some charge profiles for LiFePo4 and LiPo batteries on the all-battery.com web site and they are shown below.

Do all LiFePo4 and LiPo bulk chargers follow a similar profile to this? (adjusted for the overall battery pack voltage, of course).

When the Zivan charger says "50ah" ... is that information used to set a maximum timeout period (meaning, if the charger is putting out 10 amps, would the charger stop charging after 5 hours, no matter what the voltage is?).

I still have no idea what the "absorption" means in the context of lithium batteries.

Any thoughts/information would be appreciated.

Thanks,

Preston

 

[pvorlicek]

How do I get the attachments from above to display in the post?

 

[GGoodrum]

I'm not sure what "absorbtion" means either. If it was reprogrammed for a 54s Lithium setup, it probably means LiFePO4, but using 3.65v, which is somewhat "standard" for LiFePO4, the voltage would be 197.1V. If you divide 182.5V by 54 you get 3.38V, which is what many LiFePO4 cells end up at when the cell is full and the surface charge is burned off. Maybe it refers to "absorbing" the burnoff.

-- Gary

 

[liveforphysics]

It's a 9amp charger for a 54s string of LiFePO4.
It will charge them to 3.6-3.7v/cell, then wont try to hold them there (like we do when we just use meanwells to charge, it doesn't hurt a thing, just wastes a little power), but rather lets the pack drop to 3.38v/cell (which is the resting voltage of most fully charged large format LiFePO4 cells). If it were to drop below 3.38v/cell, it would run it's charge cycle up to 3.6-3.7v over again.

 

[BatteryMooch]

It's a 9amp charger for a 54s string of LiFePO4.
It will charge them to 3.6-3.7v/cell, then wont try to hold them there (like we do when we just use meanwells to charge, it doesn't hurt a thing, just wastes a little power), but rather lets the pack drop to 3.38v/cell (which is the resting voltage of most fully charged large format LiFePO4 cells). If it were to drop below 3.38v/cell, it would run it's charge cycle up to 3.6-3.7v over again.

I agree. I think the 3.38V/cell value is a "float" voltage for the charger.

 

[pvorlicek]

Thanks.

Okay this makes sense about what I know about LiFePo4 charging. And yes, the chemistry was LiFePo4 (seller confirmed).

Two mysteries still remain to me:

1) why would 50ah need to be specified? Is it because it has some kind of cutoff timer (I.e. Not charge more than 6.5 hours at 8 amps which gives 50ah)?

2) any guess what "charge curve BR" means?

I will try to set up some kind of test configuration and test it this weekend and will post results.

Thanks again.

Preston

 

[liveforphysics]

Back in the ancient days of lithium batteries and lithium battery charging, they would limit the charge rates to things like 1/5C during the constant current stage, and then cut-off charging during the CV stage at some magical point they decided on, 1/20C was fairly common.

This was done in the days when the cells had terrible self-discharge and high internal resistance, so this was done to prevent a charger from never knowing when it had finished it's charge cycle.

So, an old-school charger would want to know pack capacity, so it could say, ok, 50Ah pack, I say I'm finished charging when I reach 2.5A current while in CV mode (1/20C).

It's just a left over artifact from the primative days of Lithium.
A simple meanwell power supply actually makes a lot more sense for modern lithium charge cycles.

 

[pvorlicek]

Here is the charge profile from the all-battery.com web site. life and Lipo are the sam except the max voltage (4.2 versus 3.65).

 

[pvorlicek]

Luke:

Great. Thanks for the history lesson.

As Patrick explained, there are 2 pots on the charger. One for voltage and one for current. I'm wondering if the current adjustment changes the current in the CC stage or the current in the CV stage ... or maybe it adjusts them both together. I guess the only way to know for sure is to set things up on a test bed and test them. Unfortunately, I do not have a large pack to test this on, so I will try hooking up 3 packs (2 X 13S packs plus 1 X 48V SLA pack) in series and cranking back the voltage adjust by 1/2 turn of the pot.

If anyone else has a better idea on how to test the charger, I would appreciate any suggestions. I just want to try to re-create the charge profile on this puppy.

Thanks,

Preston

 

[jonescg]

Let me know how you go with this one. I am considering a Zivan for my e-moto. I probably need a maximum output of 120 V (remembering I have 8 x 4S,3P A123 cell packs) to charge, and a nominal voltage of 105.6 V. I know they can be tuned before they leave the factory too. Unless the meanwells work just as well... Luke? Any experience here?
Cheers,
CHRIS

 

[pvorlicek]

Chris:

Have you read through Patrick's thread on the NG1? The NG3 looks identical to the NG1, except more amps.

I will certainly post my results, but I don't have the best set-up ... so will results will be slow in the coming.

My planned build is a very short range VW beetle conversion. I'm going for very light weight and thinking about paralleling up 6 or 8 of the Hobby King 8S packs (creating a 29.6 nominal voltage "battery" with 34.8 or 46.4 AH capacity) .. and putting four of these in series for a total pack voltage of 118.4V (nominal) with a total weight of less than 100 lbs (including charger and cases).

Right now I am just picking up some of the key pieces on the cheap. So far I have the motor and the charger ... looking for a good controller (up to 120V and 500 amps) in the $700 range (Curtis 1231C or equivalent).

Preston

 

[fechter]

"absorbtion" is the CV setting.
Yes, I believe they keep track of the amp-hours and will time out after the specified amp-hours have gone into the battery if the current never drops to the normal end of charge point as a safety feature.

You might look at Elcon chargers too. They are very similar. http://www.elconchargers.com/index.html I think they come from the same place.

Both Zivan and Elcon have a 'temperature probe' input option. Get this option. This can be interfaced to the HVC from a BMS to kill the charger output if any cell goes too high. I suppose you could also use it as an overtemp safety like its intended at the same time.

You have a choice of charging profiles in software, but I think you need to have them programmed at the factory. I'm not aware of any available software that would allow you to reprogram it yourself.

 

[amberwolf]

I called ZivanUSA to see if they might have the charge profile and they said it could take “weeks, months or even years to track it down” (I’m not kidding, this is what the guy really said).

Remind me never to use any of their products, if that's the way they talk to people. I could understand him saying something like "I'm sorry, but we don't provide support for secondhand products", as that is a common enough practice in many industries. But saying it the way he did is just blowing you off in a very rude way, and ensures that there are now some people (including me) that aren't going to buy their stuff (even if I ever have money for that kind of thing).

 

[fechter]

I think there's a way to read out the profile from the display.
Here's what the typical lithium profiles look like: