[PeterH]

I have a 4kw Econ charger that came with no info on what charge programs are loaded or which one is currently active. I used it for the first time today to apply a full charge on my pack of 45 calb cells.

I monitored the first charge and it clearly switched to constant voltage once it hit the high voltage cutoff of 162 VDC. However I expected it to shut down the charge once it reached about 6.5 amps. But it got to 5.3 amps before I shut it down manually. The second time I got distracted and it got to 3.7 amps before I shut it down.

After both charges I measured the voltage of each cell. I have three cells that were showed higher than the others. One actually reached 4.05 volts. After a quick drive down the road they were all down close to the same voltage of about 3.38 vdc.

How can I manually top balance the cells so they all each full at the same voltage?

And is there any way to tell what charge program is running? Because the current one is clearly not what I want if t doesn't end the charge properly.

My BMS is broken at the moment but I'd like to use my EV while I wait for repairs.

Thanks,
Pete

[onegreenev]

Originally Posted by PeterH

I have a 4kw Econ charger that came with no info on what charge programs are loaded or which one is currently active. I used it for the first time today to apply a full charge on my pack of 45 calb cells.

I monitored the first charge and it clearly switched to constant voltage once it hit the high voltage cutoff of 162 VDC. However I expected it to shut down the charge once it reached about 6.5 amps. But it got to 5.3 amps before I shut it down manually. The second time I got distracted and it got to 3.7 amps before I shut it down.

After both charges I measured the voltage of each cell. I have three cells that were showed higher than the others. One actually reached 4.05 volts. After a quick drive down the road they were all down close to the same voltage of about 3.38 vdc.

How can I manually top balance the cells so they all each full at the same voltage?

And is there any way to tell what charge program is running? Because the current one is clearly not what I want if t doesn't end the charge properly.

My BMS is broken at the moment but I'd like to use my EV while I wait for repairs.

Thanks,
Pete

Why top balance when you drive your car with your pack partly full anyway. The amount of extra usable amperage is minimal. Like maybe a couple AH's at best. Your cells that are higher in voltage are the low capacity cells in your pack and that is the defining AH for your pack. All the cells hold the same usable amount of AH's. You just have a minor ragged top and those cells most likely only got charged to that level with very low amperage and are in no real danger. You might however lower your end voltage so most of your cells are under 4 volts when you terminate the charge.

It is safer to have your pack balanced at the bottom than at the top.

Pete

[PeterH]

My only reason for wanting to top-balance is because as soon as my BMS is repaired and working, that is what it does. So I'm only trying to mimic what it does manually.

I'm not aware of any way to lower the high voltage cutoff setting on an Elcon charger (big short-fall for Elcon chargers!). It is current set for my pack of 45 CALB cells so in this case, that is 45 x 3.65 = 164.25. My Elcon does switch to constant voltage mode when it reaches 164.25 (+ or - a volt or two) but it doesn't shut down the charge when the current reaches 6.5 amps (130 Ah cells x .05C = 6.5 amps) which is what is pushing that one cell so high.

Is it really that the one cell is weak or is it that the cell is stronger, containing more stored energy and is being pushed to a higher voltage by the longer charge? I'm not an EE so I'm basing this solely on my laymans understanding.

Thanks,
Pete

[ndplume]

You bring up a good question here. I know that an Elcon can be "programmed" at the factory, has anyone been trained or figured out how to DIY?

I checked an to have the factory program (Configure) the charger, its $65 + shipping + time it takes. Would be a big selling point (to me) if I could DIY.

[Yukon_Shane]

Originally Posted by ndplume

You bring up a good question here. I know that an Elcon can be "programmed" at the factory, has anyone been trained or figured out how to DIY?

I checked an to have the factory program (Configure) the charger, its $65 + shipping + time it takes. Would be a big selling point (to me) if I could DIY.

If you run a quick search you'll find a number of threads here from folks wanting/trying to DIY program the elcon charger. To my recollection there hasn't been any significant success in this area and the only real option is to send the controller in to Elcon. Definately a HUGE downside to this charger.

Pete: where did you get your charger from? They should definately have given you a detailed run down of what the charge curve is.

While you can't completely reprogram the charger yourself the elcons (usually) have 10 different charge profiles automatically programed into them and you can easily change between those programs by simply holding the reset button when the charger is first plugged in. Once the Green LED flash count reaches the program profile you want you release the reset button and you're good to go.

Unfortunately this is only beneficial if you know what these ten preset programs are. In my case I asked the factory to program in options for increased/decreased finishing voltages based on the potential for me to either add batteries or potential lose a couple batteries.

Count the number of green flashes you get when you first plug the charger in and that will tell you what setting the charger is at atleast but really you'll need to find out from the vendor what these presets were set for.

All that being said, you may not have a problem at all. Charging strategies are a touchy subject around here and I'm not interested in starting a flame war so all I'll say is that, in my case, my charger doesn't cut out until it reaches 1 amp.

It kind of sounds to me like you're pack just needs to be manually top balanced a bit and without the BMS attached you should be very carful about charging your pack as it seems as though you definately have atleast one cell that's significantly higher then the others. The miniBMS would protect you from this by shutting off the charger but without it you'll have to manually keep an eye on all the cells while charging.

As far as manually balancing your pack goes I used a low Ohm resistor to bring down the charge in my highest cells. There's so little charge at the top end of the curve that you really only need to drain out fractions of an amphour to pull the voltage down. This is way trickier to do in my opinion without a BMS to let you know what cells are going high first. If you really know you're pack well I guess you can just keep an eye on those few cells you know will go high first but I found it much easier to just watch the red lights on the BMS to determine which the next highest cell was and drain a bit off of it. I have great admoration for folks that run there cars without a BMS; I'm far too skaterbrained to manually check 50 cells and keep track of which ones have lower capacity then others.

Good luck!

[PeterH]

Hi Shane,

Thanks for the input. With my "patch panel" part of the BMS, it takes me just a moment to check the voltage of each cell. Honestly, that is why I wanted that patch panel sort of thing in the first place... even tho my local vendor thinks it is a waste of space and overly complicates things. However, in hindsight, I like it a lot but would do it slightly differently if I had to do it over again.

Your Elcon shuts off after 1 amp?? Wow, maybe once my BMS is back in shape whatever charge curve is active will be appropriate after all. Meanwhile, I'll just keep an eye on the charge process. Don't find that hard at all... just like watching paint dry!

I'll bug my vendor about the charge info. I bought it from my local guy who ordered it directly from the factory. I'll see him over the weekend as he has my BMS board for repair and if that doesn't work, we have a club meeting Tuesday night and I'm going to trailer my EV to the meeting. It is about 60 miles from home so can't drive the EV .

This morning, I checked the voltages. EVERY cell was a 3.37XX volts. I took a short drive after finishing that charge that resulted in one cell at 4.05 volts and that did the trick to bleed off the top voltage.

I really don't care to go after that very last tiny bit of capacity at the end of the charge... so if I could adjust the Elcon, or switch to another charge curve, I would.

Wow, what a brilliant idea you had asking them to program in advance for alternate cutoff voltages!!!

Maybe we should start a sticky thread titled "In Hindesight: What I'd do differently."

It's a great day in Northern Idaho so I'm off for a drive into town to visit some more of the places that did any work on my project... been promising for months that I'd bring it around when it was on the road!
Thanks,
Pete

[onegreenev]

I'll sed you the instructions to change your profiles that are in your elcon. Mine is set for one algorithm and 10 different voltage settings. Cut off is still the same but at a different voltage. I can do 3.5 to 3.7 volts per cell.

You high voltage cell is your low capacity cell.

Busted BMS? Ouch!

Bottom balance and don't worry about your top. Like I said all your cells hold the same capacity as your limiting cell. What ever the other cells can carry makes no difference as you can't use it anyway.

So you have a 100 ah cell and a 110 ah cell. Both bottom balanced and sitting at 2.5 volts. I connect them in series. Charge them to 7.3 volts. The end of charge voltage of the 100 ah cell will be slightly higher but both will still have the same AH put in. So the limiting cell is the 100 ah cell and you don't get to use the extra 10 ah of the other cell.

[onegreenev]

So top or bottom balancing you are limited to your low capacity cell. No way around that and if we are talking cells of only an ah or two difference you will have no worries. Frankly I'd worry more about my BMS failing than a cell that is a touch on the high side after charging.

Remember you will run your pack low, guaranteed. So it only fits that you protect your cells on the low side vs the high side. When you run your pack low it is good to have them all reach the end at the same time. If one reaches the end first you will smoke that cell. Ask me how I know?

[dladd]

Originally Posted by onegreenev

Remember you will run your pack low, guaranteed. So it only fits that you protect your cells on the low side vs the high side. When you run your pack low it is good to have them all reach the end at the same time. If one reaches the end first you will smoke that cell. Ask me how I know?

Why do you say guaranteed? I won't run my cells low. I have an EVDisplay amp counter, and I know how much is left in my cells. My BMS also warns if a cell gets low. When they get low, I'll recharge.

Fwiw, I have not run out of fuel in my gas car in over 20 years. Why would I now do it with my electric car?

I don't have the EV experience of you or many others here, but I do have 6 months of daily driving 20-40 miles per day (with a 50 mile range), and have a BMS that top balances. I'm not worried, and I will not run my cells low. I'll stop and call a tow truck first.

These Lithium cells are SOOO consistent and predictable, it would be hard to be caught off guard on mileage/state of charge, assuming you are using a good amp counter (which is required instrumentation, imo).

anyway... I don't think top vs. bottom is really that big a deal as long as you have built in protection on the other side, but I do thing that balancing is! Top or bottom, but pick one and do it. And make sure you can monitor the other end of the charge cycle. If you are using a shunting BMS (I am) then obviously you need to top balance.

[PeterH]

All good information. At the moment, my strategy is to charge till it reaches constant voltage and the amperage is staring to decline to the point of about 15 amps. Then I start manually monitoring the weaker cells and will cut the charger off when they reach 3.7 volts.

On the discharge side, I'm VERY conservative. I just returned from a trip to town with some running around. Probably 30 miles total and each of the cells is sitting at 3.37 volts and very consistently across the entire pack.

Sure like having my "patch panel" between the BMS and the cells. Make it very easy and quick to check each cell with my Fluke.

I have two sets of instrumentation. One is reading volts and amperage and the other is reading volts but not reading the amperage correctly. It is one of the things I'll be working on over the weekend. The lowest my pack sagged was to 140 volts and at rest, it came back up to 145. When I left the house 2 hours ago, I started with a full pack with a resting voltage of 150.5 volts.

It is a little work at the moment, but at least I'm driving it while the weather is nice...

Thanks,
Pete