[electric85]

Hey everyone,

Here is my story, and my situation. (I will keep this part short) I have been working on converting a 1985 pontiac fiero for 9 years. 9 YEARS!! I know that is a long time but I wasn't going to give up. I actually ended up restoring the fiero because the further I dug, the more I had to do. I have been collecting parts for the car over the 9 years, and having some progress, but time and money were always slowing me down.

The car is completely together now and I am panicking because I think there is something wrong with either my batteries or my charger.

Batteries: 48 Sinopoly 200ah cells
Charger: Elcon pfc 2500
BMS: Mini BMS V2 modules

Now what I'm most afraid of is that I bought my batteries in spring of 2013. I had every intention of putting them in the car that summer...didn't happen. I was told that they can sit on a shelf for 2-3 years and not see any drain. I checked with a volt meter every once in a while because I was still worried. The pack was beautifully balanced from Sinopoly. All cells were reading 3.24v and never changed over the 3 years of storing them inside.

Once in the car the overall pack voltage was reading 154v. I did a handful of tests around the yard, and two down the street and back. The batteries were reading 140v when returning from my last cruise down the street and I could tell the pack was getting weak. (I have my zilla set to cut me back at 140v and shut down at 135v)

I'm going to pause right here for a second and say I know leaving them for 3 years probably wasn't good, and some may call me an idiot for investing so much in batteries and mistreating them. But I'm still just a DIYer and doing what I can. Also the test drives around the yard and down the street...again maybe that was a bad idea to do before charging them, but its been 9YEARS!! It was hard for me not to! Also I thought with each cell reading 3.2 the pack was sitting at nominal voltage and that it would be fine.

I plugged the car in and started charging it at about noon yesterday so that i could monitor it through the day. It went from 140v to 155v in the first five hours. Then it slowed right down. Creeping slowly up to 159v by midnight. I decided to let it charge overnight and when I woke up this morning it only reads 161v. The mini BMS modules are still reading fine, not shunting. The LED on the charger is saying its at full power and less than 85%. The sticker on the side of the charger says it should go green when it is finished. Its been almost 24 hours of charging and its not full?

My batteries (48 cells of Sinopoly 200ah) are supposed to be 3.2v nominal, 3.8v at full charge and was told they will settle down to 3.6v after charge, and 2.8v low voltage cutoff.

so 153.6v nominal pack?
182.4v after a charge and settling down to 172.8v?
and low voltage cutoff is 134.4

Sorry for the novel, but like I said, i'm worried I messed up my batteries, or is it my charger? Any help would be appreciated

Tim

 

[rwaudio]

First you have some old data on the charge voltage. Early on it was thought you should charge that high, same with the old thunder sky's however people destroyed perfectly good packs doing so.

http://www.sinopolybattery.com/userfiles/files/SP-LFP200AHA.pdf

You should charge single cells to 3.65v, you should charge a pack to 3.45-3.55v per cell. 3.5v x 48 being a good number. With the mini bms you could technically go higher but there isn't really a point.

I would expect them to settle in somewhere around 160ish V when full.

What's your charger programmed to charge to?
Is it actually 182.4 or 175 or?
Did you measure the voltage on all 48 cells? It's not impossible for there to be cells with slow self discharge that would have gone to zero after 3 years.

 

[electric85]

rwaudio

I have read newer updated data on the cells. But again I got most my of components 8 years ago, batteries 3 years ago, BMS 3 years ago, Charger 2 years ago. So everything I have is kinda set up on the old data ...i think...

I ordered the charger from canev.com and I gave Randy the info on my cells for the programing of the charger. I can go take some pictures of my set up, and of the manual that came with the charger.

My main question is though....why would the charger still be charging and not shutting off? lets say that the charger is programmed to bring my cells to 160 then cut off...why still charging with no change in voltage? 161v is where it is stuck at and that is only 3.35 a cell

I will go take pics now.

 

[electric85]

Just came back in from the garage. In the last hour all of a sudden one cell was at 4.1v !!!! YIKES! every other cell was at 3.33v. I immediately turned off the charger, then checked the voltage on the cells. That one cell that was super high has a version 3 BMS module because I broke one of my version 2 boards on installation. not sure if that has anything to do with the difference in that one cell being way higher than the others. Really hope there won't be any damage to that cell.

Here the pictures I said I'd get. One is a page that came with the charger.
One is a pic of the LED and what it means. (it has only been solid red while charging for me)
And the last two are of the box the charger came in.

 

[rwaudio]

Just came back in from the garage. In the last hour all of a sudden one cell was at 4.1v !!!! YIKES! every other cell was at 3.33v. I immediately turned off the charger, then checked the voltage on the cells. That one cell that was super high has a version 3 BMS module because I broke one of my version 2 boards on installation. not sure if that has anything to do with the difference in that one cell being way higher than the others. Really hope there won't be any damage to that cell.

Here the pictures I said I'd get. One is a page that came with the charger.
One is a pic of the LED and what it means. (it has only been solid red while charging for me)
And the last two are of the box the charger came in.

Just to be clear the cells didn't physically change when they revised the documentation to state a lower charge voltage it was determined that charging too high was destroying cells. If your charger allows you to select a different curve (lower voltage) do it.

During the middle of the charge process the voltage will be almost constant for a very long time. Is your charger plugged into 110 or 220?
If you are charging 200Ah cells off 110 it's going to take a very long time and could explain your results.

I only buy configurable chargers (love the Brusa NLG's) so that I can adjust to different cell counts or desired charge levels. There are likely a lot of people here more familiar with that charger who can provide more info on if it's configurable or not.

 

[dimitri]

Just came back in from the garage. In the last hour all of a sudden one cell was at 4.1v !!!! YIKES! every other cell was at 3.33v. I immediately turned off the charger, then checked the voltage on the cells. That one cell that was super high has a version 3 BMS module because I broke one of my version 2 boards on installation. not sure if that has anything to do with the difference in that one cell being way higher than the others. Really hope there won't be any damage to that cell.

I suspect you did not correctly wire and/or did not test if BMS shuts off the charger when first cell hits HVC, which would have prevented the cell reaching such high voltage. In MiniBMS user guide there is a test procedure after the install to make sure BMS shuts off the charger when cell loop is open, which is easy to simulate by manually breaking the cell loop wire.

As for your charger running long, you did not report the charge current, so its hard to tell how many hours it would normally take to charge 200AH pack, which was obviously empty when you did your test runs.

Also, 3.2V open circuit ( OCV ) means the cell is almost empty, so your tests were starting on an almost empty pack, which explains why voltage dropped so fast. Did you get any BMS LVC alarms during the drive? Again, something that should have been tested by breaking the cell loop prior to actually running the car.

Overall I think you are fine, just need to check BMS wiring, test HVC/LVC alarms and charger shutoff on HVC, then perform initial pack balance since your cells were in storage for so long and likely never been balanced.

That one cell which got over 4V would likely need bleeding off to get inline with other cells. The process is described in initial pack balance document we have on our Web site.

 

[dimitri]

If you charge from 230VAC mains, then charger should have ran at 15A, which means over 13 hours for a full charge cycle. Sounds about right based on your description of events.

EDIT: read OP again, your charge was much longer than 13 hours, so maybe charger ran at lower current? Did you use 230VAC or 120VAC mains? You really need to have current measurements to avoid guessing.

 

[electric85]

Dimitri,

I did all the test procedures for the Mini BMS, but there seems to be an issue with the loop. I checked every connection but the charger would not turn on, if i disconnected the BMS from the charger and tied the two wires together then the charger would turn on. I tried connecting and disconnecting a few times, but I think I might just have to check and recheck every connection and every crimp. If not I may have damaged the headboard during installation. So the cell reaching 4.1v was not fault of the BMS, I was running the modules only so it wasn't able to shut off the charger. It did settle down to 3.38 after, hopefully no long term damage. So Like I said I still have to track down where the break is.

I didn't get any BMS LVC alarms when doing the little test drives, but I had the zilla programed generously for now to keep from damaging anything.

I also spoke on the phone today with Randy from Canadian Electric Vehicles. Went over a bunch of things and one of the things we talked about was how to properly bleed high cells and balancing the pack. Like you said the pack had been sitting a while, even though they were reading balanced at 3.2

I was charging off a 120 outlet for first charge so that nothing would happen too quickly if something went wrong. And again Randy said that could be why it was taking so long to bring 48 200ah cells to full charge.

I appreciate all the help everyone!

I'm going to spend the weekend balancing and checking crimps!

Any progress, or lack there of, I will report back

 

[Moltenmetal]

You need an ammeter capable of measuring your charge current. I use my intelligent Ah meter to monitor charging current.

When you open the BMS loop, the charger should stop. The charger won't restart until you cycle the keyswitch. The high voltage cutout latches, keeping the charger from restarting until you cycle the keyswitch, assuming you've connected your relay to the H contacts on the BMS headboard.

Randy's schematic has the BMS relay connected in parallel to the buzzer, which allows the charger to bounce on and off, hitting the HVC again and again until the charger turns off- not a good idea, as when shipped to me the charger was set to turn off at something like 3.6 or 3.65V per cell total. If your pack is at all out of top balance, it will never get to such a high voltage without one cell going into HVC. The charger shutoff voltage should be set lower than that... I haven't bothered yet, I just rely on the BMS to trip the charger when my lowest capacity cell hits HVC. So far, it has worked well.

Don't panic- even with one bad cell, your pack is still huge and you have no shortage of voltage. If every cell was at 3.2 V before you started, as long as your BMS was properly installed and tested you didn't reverse any of your cells. But if your one cell went to 4.1 V without the BMS shutting off the charger, your. BMS wiring is wrong. Make sure the bms trips the charger properly before you go any further.

 

[EVfun]

I plugged the car in and started charging it at about noon yesterday so that i could monitor it through the day. It went from 140v to 155v in the first five hours. Then it slowed right down. Creeping slowly up to 159v by midnight. I decided to let it charge overnight and when I woke up this morning it only reads 161v. The mini BMS modules are still reading fine, not shunting. The LED on the charger is saying its at full power and less than 85%. The sticker on the side of the charger says it should go green when it is finished. Its been almost 24 hours of charging and its not full?

My batteries (48 cells of Sinopoly 200ah) are supposed to be 3.2v nominal, 3.8v at full charge and was told they will settle down to 3.6v after charge, and 2.8v low voltage cutoff.

so 153.6v nominal pack?
182.4v after a charge and settling down to 172.8v?
and low voltage cutoff is 134.4

It could take over 24 hours to charge if your current is 8 amps or less. So the time doesn't surprise me. The quick increase at the start is a sign of very low cells and expected. The long time of nearly flat voltage is expected behavior. It should then shoot up quickly at the end, to the chargers set voltage limit.

Mostly, you are not charged at these voltages. If you get in your car to drive shortly after a charge is complete you should see 160 volts for the pack. When you drive it should spring back to about 158 at first and that slowly drops each throttle release. After some miles that will drop to 155 volts shortly after a throttle release. The pack is going to start dropping more rapidly after that point. LiFePO4 cells are very flat in voltage through the bulk of their capacity.

I suspect the controller settings protected the pack from any cell reversals, but that is not assured. The good news is you can spare a cell as your pack is large and if you reversed a cell it will be easy to find. The down side is you should find it soon as cells that have been reversed get increasingly unstable. Any reversed cell should have a noticeably lower capacity and often will have some self discharge too.

Just came back in from the garage. In the last hour all of a sudden one cell was at 4.1v !!!! YIKES! every other cell was at 3.33v. I immediately turned off the charger, then checked the voltage on the cells. That one cell that was super high has a version 3 BMS module because I broke one of my version 2 boards on installation. not sure if that has anything to do with the difference in that one cell being way higher than the others. Really hope there won't be any damage to that cell.

4.1 volts for a short period of time does not hurt a cell. There is some increase in cell wear at that voltage, but short term damage seems unlikely below 4.3 volts. When getting my pack balanced I had cells hitting 4.0 volts for 20 minutes a cycle for 10's of cycles. You cannot tell any difference in their behavior now.

Functionally, it seems that you do not have a functioning BMS. You should get that fixed, either by removing the BMS or making it work. The worst idea, IMHO, is a nonfunctioning BMS because the individual modules will draw slightly different currents, slowly forcing a pack out of balance. A tenth of a milliamp for a year is almost 1 amp hour. Because LiFePO4 cells charge almost flat in voltage, until they try to refuse additional current because they are full, 1 amp hour would be a cell at least 1/2 volt above the rest if pushed until the rest where comfortably full. If you have a BMS I recommend you regularly get all the modules to light, so they regularly fix the top balance (with a BMS you have no choice but to top balance.)

I do not run a BMS and I top balance (one of several methods used -- we don't need to get into that here.) Here is how I set things up. I have a 39 cell pack that I charge to 134 volts and hold that voltage for 30 minutes. That would be 165 volts for your pack. The hold time is based on getting the current down to 2 or 3 percent of the pack capacity. This will get the pack about 98% charged and that is good enough. There is no benefit in fully charging these cells, if fact they will last longer if you don't. I regularly (every couple months) check cell voltages in the last 10 minutes of charging to make sure they stay in balance. They have been doing well.

I have the low voltage limit set to 98 volts, that would be 121 volts for your pack as the minimum voltage under load. I would leave your setting higher, where they currently are, to provide extra protection while setting things up. I have my low voltage warning light set to 108 volts, about the same point as your low voltage cut off. It has never been on with my foot off the throttle. Lower voltage limits are handled differently by different controllers, I only have a single minimum voltage, not separate limits based on load. You need to stop your discharges at a higher resting voltage. With your foot off the throttle and nothing significant running in your EV the pack voltage should be at least 148-150 volts. There is simply no significant capacity available below that point and it is not good for the cells to force the issue.

 

[Coulomb]

There are likely a lot of people here more familiar with that charger who can provide more info on if it's configurable or not.

These chargers come with from 1 to 10 settings; you can cycle through the settings by letting go of a hidden button at startup at the right time (see the web site and/or documentation for details). But usually, if you have more than one setting programmed, it will be for different number of cells or Ah capacity (the Ah capacity only determines when it turns off or goes to the next stage). So you may be able to switch to fewer cells. If you are set up for 48 cells at 3.8 V*max now, you could change to 3.65/3.8 **48 ~= 46 cells. It's not quite ideal, because it will have a slightly too-low threshold for starting charging (e.g. it usually won't charge if the pack is at say 2.0 VPC, so that should be 2.0 x 48 = 96.0 V, but now it will be 2.0 **46 = 92 V, so it might charge a pack that it really should refuse to. But that's not likely to be a problem. There are other transitions from stage to stage that might happen at slightly too low a voltage, but it should still charge pretty well.

To find out what settings are programmed, you really need to find your documentation, or quote your serial number to the charger supplier and hope that they kept the records. You can find out by reverse engineering the firmware, but that's so much work you may as well just reflash with new firmware. Elcon in California should be able to reprogram new settings for a fee, if needed. If you go that way, make sure you ask for several total number of cells settings, so that you future-proof yourself. For example, ask for 44/45/46/47/48 cells at 3.65 V/cell max. That way you can experiment with not charging to 100%*SOC*all the time, or can leave off a cell or two if you lose some.

You can also attempt the re-flash yourself, if you have programming skills and a little hardware:

http://www.diyelectriccar.com/forums/showthread.php/elcon-tc-charger-firmware-facts-134225.html

In summary: the Elcon (and TCCH) chargers have very limited flexibility. If the right settings are there in the firmware, then it's very easy to switch to another setting. If nothing suitable is already present, then you need a reflash. Elcon can do that re-flashing for you, or you can attempt the re-flash yourself, but it's not for the faint hearted, or people who aren't familiar with Arduinos.

 

[electric85]

Update!

The charger is working fine, and the batteries are balanced! Checked for a break in the loop for my miniBMS, didn't find one. It seems to be the head unit. I checked and I have a closed loop at the board but it won't let my charger charge. I might have to order a new one, (probably something I did during installation) The cell modules are working well though and once the cells start shunting (they all come on pretty close to each other) the charger finishes up and shuts down!

Thanks again for all the help!