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Discussion Starter #1
I am going to buy a new charger soon to go with my almost-delivered TS cells..... The elcon PFC-1500 looks to be enough for my use with 38 x 100aH cells. I do not need rapid charge, but obviously want a Li-friendly charger.

The charge curves suggest are '611', which is a basic 2-stage cycle with CA to a set V, then slightly higher set v till amps drop to 1.25 . Target v is an average of 3.65v/cell, or just about 139v for a 38 cell pack (120v nominal). This seems simple and conservative.

Second popular curve '312' appears to be a more complex curve that is intended to bump the final average voltage up to 3.80 per cell. This seems little high for TS when I look at the predicted cell characteristics... with the upper 'knee' starting around 3.6 or 3.7 is seems that if one cell WAS out of balance the charger wouldn't see the average pack voltage high enough to slow down...

so my question is.... what 'final voltage' are people setting for conservative charge of Thundersky cells?
 

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The chargers that Thundersky themselves manufacture are set for 3.65 volts/cell, which I agree is the ideal charging voltage for them.
 

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Discussion Starter #3
The chargers that Thundersky themselves manufacture are set for 3.65 volts/cell, which I agree is the ideal charging voltage for them.
great! that makes the decision to use curve #611 an easy choice!
 

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Hi Dan,

It sounds like we are in a similar situation. I'm waiting on LiFePO4 batteries from EV Components and am trying to decide which charger to use. I've been looking at the ElCon 1.5KW charger as well. Where did you get the information about the charge profiles? Are you buying the charger from a Chinese vendor or someone in the States? I plan on running 40 cells in the pack with a CV value of 146V (3.65x40).

Ralph

P.S. We spent 14 years in ABQ. Really miss NM at times.
 

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Discussion Starter #5 (Edited)
Where did you get the information about the charge profiles? Are you buying the charger from a Chinese vendor or someone in the States?
I got curves from EvolveElectrics.com based in CO. They have been great, so I bought my charger from them too. Same price as re-labeled Chinese direct offer from Chennic, but with better documentation. ;)


I plan on running 40 cells in the pack with a CV value of 146V (3.65x40).
that is a little bit of a non-standard value... but I think they can accommodate. The usual count for 120v nominal is 38*3.2v

I am attaching both the 300 and 600 series curves I got. I'm going with the 611 as the simple conservative curve which brings the cells up to 3.65 and quits. I am NOT installing an active BMS with shunting so I don't want to use the multi-stage 312 curve to squeeze in that last bit.

For those of you looking at the 312 curve, it is suggested you only do this with an active BMS. Also, the values for I3 and I4 are a little misleading... they are not fixed amp values 50 and 100, they are supposed to read ah/50 and ah/100
 

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Charge curve selection largely depends on your BMS plans. TS cells can safely go to 3.8V and even higher, but 3.8V is typical cutoff on popular Elcon and Zivan chargers. If you plan to go without BMS, then more conservative 3.65V is better. There is virtually no capacity between 3.65V and 3.8V , but many BMSs use this gap for top balancing. So, again, depending on your BMS or lack thereof you can choose either 3.65V or 3.8V charger cutoff.

I usually recommend curve 312 for my MiniBMS customers since it was designed for that curve for ideal top balancing. If you don't care for top balancing, then curve 611 is a simpler choice.

Hope this helps.
 

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Thanks Dan and Dimitri for your informative replies. I've been going back and forth on the number of cells in the string. I have 42 100Ah cells on order so there is either 4 extra or 2 extra cells in case of a cell failure. I was originally going to use 38s, but then decided that 40s might give me a little more acceleration. But if it is easier on the charger to use 38s then I will do that and maybe put the four extra cells in a 12V configuration for solar energy storage. :)

Since this is a short-range commuter EV, I do not plan to use a dedicated BMS initially, but will monitor cell voltages with Celllog8s and will count Ah/Wh with a cycle analysts, unless Dimitri releases his meter soon! (hint, hint).

I think I will give EvolveElectrics a call.

Ralph
 

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Discussion Starter #8
If you don't care for top balancing, then curve 611 is a simpler choice.
I am starting without BMS.... installing a loom to monitor and maybe manually balance... so going w/ 611 curve which charges to 3.65 avg.
 

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Charge curve selection largely depends on your BMS plans. TS cells can safely go to 3.8V and even higher, but 3.8V is typical cutoff on popular Elcon and Zivan chargers. If you plan to go without BMS, then more conservative 3.65V is better. There is virtually no capacity between 3.65V and 3.8V , but many BMSs use this gap for top balancing. So, again, depending on your BMS or lack thereof you can choose either 3.65V or 3.8V charger cutoff.

I usually recommend curve 312 for my MiniBMS customers since it was designed for that curve for ideal top balancing. If you don't care for top balancing, then curve 611 is a simpler choice.

Hope this helps.
Hi Dimitri,

I am using a Elcon PFC 1500. Which charging curve setting do you recommend with a miniBMS with a HVC of 3.6volts. I am finding that the charger never goes into CV mode due to a HVC event. Would changing the charge curve to 312 help to get the charger go into CV mode? Maybe I need to increase the HVC to 3.8v to allow CV to occur. In my case would you recommend a charge curve 315?
 

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Hi Dimitri,

I am using a Elcon PFC 1500. Which charging curve setting do you recommend with a miniBMS with a HVC of 3.6volts. I am finding that the charger never goes into CV mode due to a HVC event. Would changing the charge curve to 312 help to get the charger go into CV mode? Maybe I need to increase the HVC to 3.8v to allow CV to occur. In my case would you recommend a charge curve 315?
Changing the program implies sending the charger back to Elcon, which I presume you want to avoid. I think you simply need to lower your CV voltage so charger can reach the end of the program. I don't know if you got your Elcon from US or China. US sold Elcons are now programmed with 10 steps of CV voltages, allowing you to change cell count, hence moving CV point up or down. If yours is programmed with 10 steps, then you should step down one level, reducing CV by one cell voltage.

The curve is not that important, they are all similar, what's important is to match CV point with BMS shunting voltage, so CV point can be reached when pack is balanced.
 

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Changing the program implies sending the charger back to Elcon, which I presume you want to avoid. I think you simply need to lower your CV voltage so charger can reach the end of the program. I don't know if you got your Elcon from US or China. US sold Elcons are now programmed with 10 steps of CV voltages, allowing you to change cell count, hence moving CV point up or down. If yours is programmed with 10 steps, then you should step down one level, reducing CV by one cell voltage.

The curve is not that important, they are all similar, what's important is to match CV point with BMS shunting voltage, so CV point can be reached when pack is balanced.
My Elcon charger was purchased from EVassemble.com. When I power it up I get one red flash before it goes green. So I probably need to add a couple more cells to my battery pack so I get to see CV mode. According to the label it has a max voltage of 256, so CV was setup for 3.65/cell. It was supposedly setup for 70 A123 pouch cells but I never get to see CV mode no matter how well balanced the battery pack is. Since HVC is set to 3.6v it will never reach 3.65v/ cell. Thanks.
 

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US sold Elcons are now programmed with 10 steps of CV voltages, allowing you to change cell count, hence moving CV point up or down. If yours is programmed with 10 steps, then you should step down one level, reducing CV by one cell voltage.
Do you have documentation to support this statement? Looking at the charge curves provided by others this does not appear to be so.
 

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Discussion Starter #13
Do you have documentation to support this statement? Looking at the charge curves provided by others this does not appear to be so.

if you get an Elcon programmed with a 620 curve, the v steps are 1 volt for fine tuning, with curve 631 it is 3.2v per step.
 

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if you get an Elcon programmed with a 620 curve, the v steps are 1 volt for fine tuning, with curve 631 it is 3.2v per step.
The only issue with using curve 620 is the default timeout for the constant current phase (Elcon calls this parameter T_S2_max) is 2 hours. You will need to ask for a longer timeout (up to 30 hours) when you get the charger programmed. The default is a real pain, and after restarting my charger every two hours for the last two months to charge the pack, I'm sending my unit in to get the timeout extended. They make you pay $45 + shipping each time to program. This closed programming is the only negative thing I can say about this charger (well almost - I did have to mount a small fan on the fins to keep the unit cool during operation).
Mounted Charger and cooling fan.jpg
 

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Discussion Starter #16
The only issue with using curve 620 is the default timeout for the constant current phase (Elcon calls this parameter T_S2_max) is 2 hours. You will need to ask for a longer timeout (up to 30 hours) when you get the charger programmed.

huh? CC is supposed to last until CV is reached. I've never hear anything about a 2 hour time limit on the front side of the charge cycle.

I have had no problems with chargers using curve 620 taking however long they needed to during CC to hit the target CV. are you SURE you told them the correct ah of cells and everything else?
 

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huh? CC is supposed to last until CV is reached. I've never hear anything about a 2 hour time limit on the front side of the charge cycle.

I have had no problems with chargers using curve 620 taking however long they needed to during CC to hit the target CV. are you SURE you told them the correct ah of cells and everything else?
Dan, This was the unit I bought through you. Here was our last email exchange:

> On 1/23/2013 4:29 PM, Lebow, Joseph wrote:
>> Hi Dan,
>> I'm back home now.
>>
>> Let's do the pfc 1500 for $xxx, with the parameters you listed:
>>
>> Configured to default voltage OEC of 210 V, and a range of 204 to 213
>> V in 1 volt steps (curve 620v). My pack is 60 x 180ah cells
>>
>>Joey


And here is what ElCon sent to me when I told them the charger was stopping after 2 hours:



From: Electric Conversions
Sent: Friday, June 07, 2013 4:49 PM
To: Lebow, Joseph
Subject: Re:ElCon Stops Charging


Joey,

RGR - - - - - means time out for that stage. Solid red time limit is 2 hours and slow blinking red is 1 hour. If the charger doesn't reach the required voltage in solid red or the current doesn't drop down to Amp Hr / 50 in slow blinking red stage, the charger will time out.


For now you can keep restarting the charger until the batteries are charged.


Regards,

Sayyed A. Bashir
ELCON / Electric Conversions



Sounds like they are saying the default CC phase is 2 hours max and the default CV phase is 1 hour. But they can increase the timeout for a fee:

Joey,

Actually we can change T_S2_Max to 30 hours on your existing program so everything else stays the same. Cost will be $45 plus shipping back to you. Send it to my attention at the address below and make sure your name is on the box and a copy of this email is in the box.


Regards,

Sayyed A. Bashir

 

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Discussion Starter #18 (Edited)
huh, that sounds strange.... either they didn't understand what (we) asked for, or your being at the very top end of allowable voltage messed them up. I will help you argue with them that they should have known enough to allow a 30 hour timeout just based on your pack capacity. You CAN'T ever get a full charge they way they set it up if it actually times out after 2 hours. I would be of the opinion they missed the boat on config, and ought to re-do it for free.

knowing that you have 60 x180ah cells, thats 34.5kWhr on board.... if you were 100% empty, it would take 23 hours or so to charge with the 1500 watt charger....
 

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huh, that sounds strange.... either they didn't understand what (we) asked for, or your being at the very top end of allowable voltage messed them up. I will help you argue with them that they should have known enough to allow a 30 hour timeout just based on your pack capacity. You CAN'T ever get a full charge they way they set it up if it actually times out after 2 hours. I would be of the opinion they missed the boat on config, and ought to re-do it for free.

knowing that you have 60 x180ah cells, thats 34.5kWhr on board.... if you were 100% empty, it would take 23 hours or so to charge with the 1500 watt charger....
I'm not sure how technical they are. Their first response to my inquiry was that the 1500 was too small for my park, and to be under the three hour limit (2 hours CC, 1 hour CV), I would need to get their 2500 charger. I pointed out that the 2500 would take 14 hours with my pack capacity. I would need at least a 12 kW charger to charge in 3 hours. That was when they came back that the time limit for curve 620 could be opened up 30 hours.

I'm not sure what is going on with the timeout for curve 620, but the time outs for curves between 600 and 612 ranges between 24 and 30 hours.

My main goal posting here was to make sure others knew to ask for the proper timeouts. I do like the charger a lot. I'm getting 7.2 amps charge current out on 110 VAC in (1410 watts out at 196 VDC pack) and 8 amps out on 220 VAC in (1570 watts out with 196 pack volts). Doesn't seem to be an issue running at this pack voltage, even though they had claimed I would only see half power at these voltages.
 

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Discussion Starter #20
I guess my point is they should have been able to figure out you needed the 30 hour max time limit. I never had to tell them that, assuming they figured that out from pack capacity we told them. I'll be sure to include that in future re-programming requests.... and would encourage you to ask them for free tweak since they should have known better. Perhaps they'd be willing to eat the re-programming fee and postage back to you at the least.
 
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