Best charger for headway cells

[johnnyz]

Ok...I have a 28 Cell headway battery pack for my trike. I had a generic bulk charger for it charging to 102 volts at 6 amps. This was sufficent untill suddenly it stopped. I have a race this weekend in Toronto. I need to come up with something fast...

I have another 72 volt charger (pictured). It has 3 blue potentiomiters?...that are adjustable. I think they are for voltage and min and max values. The problem is that the caps are rated for 99 volts (so someone told me). If I change these out then can this be adjusted to 100 volts or so?....thats the first question..

In the mean time I can split the pack for now with 24 cells ( and the 72 volt charger will charge these just fine...its the other 4 that I have to charge..problem is this: My IMAX charger even when charging just one cell on FAST charge reduces the charge to around 1.5 amps and this is TOO low..its gonna take days for these 4 cells...is there some way to up the amperage?....its suppose to be a 5 amp charger..not sure why this is happening. The cells in the 4 cell group are all around 3.29 volts...

Lastly I guess for now I can charge the 24 cells and use a "bulk" charger for the last 4 and charge them seperately but need at least 4-5 amps at 15 volts....cant find anything around here. When this is done then I will probably buy a nice RC charger but need one that will do at least 10 cells at a time BUT at at least 5 amps so it doesnt take forever.

Does anyone have any ideas?

 

[BVH]

The icharger 4010 Duo will do 10S and 40 Amps - with or without balancing. A bit pricey ($300+) but there isn't a lot out there for 10S and big Amps. It has 2 channels and will do 2 packs at that rate. The icharger 3010 will also do 10S at about 27 Amps. Much cheaper.

There's also the Cycle Satiator - well almost. It is out and fully programmable but will only do about 63 Volts and 8 Amps. They are working on a higher voltage version - around 100 give or take but will be less Amps proportionately so probably no where near your requirement. It's a mobile charger designed for and to be carried on bikes. It's a very nice niche charger. I have the one that's out since my LiFeP04 packs are 16S.

 

[johnnyz]

The icharger 4010 Duo will do 10S and 40 Amps - with or without balancing. A bit pricey ($300+) but there isn't a lot out there for 10S and big Amps. It has 2 channels and will do 2 packs at that rate. The icharger 3010 will also do 10S at about 27 Amps. Much cheaper.

There's also the Cycle Satiator - well almost. It is out and fully programmable but will only do about 63 Volts and 8 Amps. They are working on a higher voltage version - around 100 give or take but will be less Amps proportionately so probably no where near your requirement. It's a mobile charger designed for and to be carried on bikes. It's a very nice niche charger. I have the one that's out since my LiFeP04 packs are 16S.

Thanks for reply. I checked out all of these chargers and they all appear to be ok, although for now im leaning towards the Satiator, although at $300 us, it isnt cheap either but looks like a quality unit...plus the adjustablity is great...for now I can split the pack with 2 XLR plugs for each..charge each and at 8 amps it wont take long..and then when finished just plug them together.

John

 

[BVH]

That's what I'm doing with my two each, 16S/12 Ah packs that I run in Parallel.

 

[johnnyz]

After doing some research, it seems that the more powerful RC chargers also need a hefty power supply as well...something more than just plugging them into the wall socket. This makes them very expensive indeed and much more complicated then the Satiator for example. It is simple, probably reliable, informative etc...it just needs a BMS to be hooked up in conjunction or in my case, splitting the pack into 2 48 volt units and charging twice...but at 7 amps it will go quick...then hooking them back up and your ready to go.

John

 

[wesnewell]

For the last 4 cells, just use a standard 12V car battery charger to bulk charge. It won't balance, but will charge them to ~14.5V, which averages to 3.625V per cell if they are balanced. If you don't have a standard charger, you can get them at any auto parts store.

 

[johnnyz]

For the last 4 cells, just use a standard 12V car battery charger to bulk charge. It won't balance, but will charge them to ~14.5V, which averages to 3.625V per cell if they are balanced. If you don't have a standard charger, you can get them at any auto parts store.

Thanks for all the replies guys...Ive decided to buy the Satiator. Even though it only charges up to 60 volts, I can easily split the pack into 2 48 volt units each with an XLR plug and then when charged use a quick connect to connect both and viola 92 volts. I have another question however...and might actually post this as another discussion..

I was looking at the Battery Medics...wondering if anyone would know if these can be used with my headway cells...if I buy 5 of them I can easily hook them up enough and not only will it read out the individual voltages but it has a balance function as well.. apparently they function as a balancer without charging..they will dissapate the voltages of the 6 attached cells equal to the lowest one in the pack using 450 Ma.
Heres the million dollar question; if all the cells are within 0.04 volts for example, would they be able to do this with these 15 Ah cells?

Thanks

John

 

[BVH]

The rumored soon-to-be-released higher Voltage Satiator looks to have a max Voltage of 103. It's still a 360 max Watts charger so it would give about 3.5 Amps at 103 Volts termination.

 

[johnnyz]

The rumored soon-to-be-released higher Voltage Satiator looks to have a max Voltage of 103. It's still a 360 max Watts charger so it would give about 3.5 Amps at 103 Volts termination.

I talked to Justin via email and thats just not enough of a charge for 15 ah headway cell..

John

 

[dmwahl]

The rumored soon-to-be-released higher Voltage Satiator looks to have a max Voltage of 103. It's still a 360 max Watts charger so it would give about 3.5 Amps at 103 Volts termination.

I talked to Justin via email and thats just not enough of a charge for 15 ah headway cell..

John

3.5A is plenty to charge a 15Ah cell, it would take ~5 hours to charge if fully drained. I charge a 20Ah headway pack (8S2P 10Ah cells) with a 24V lawn mower charger that only puts out about 750mA. It takes about 16 hours to charge, but I only mow once/week so it's fine. Why did he say it's not enough?

I ordered a greentime charger (here) for a 15Ah 24S LiFePO4 pack, 4A output. You definitely don't want to go over the recommended charge rate, but there's no reason not to charge slower than recommended.

 

[johnnyz]

The rumored soon-to-be-released higher Voltage Satiator looks to have a max Voltage of 103. It's still a 360 max Watts charger so it would give about 3.5 Amps at 103 Volts termination.

I talked to Justin via email and thats just not enough of a charge for 15 ah headway cell..

John

3.5A is plenty to charge a 15Ah cell, it would take ~5 hours to charge if fully drained. I charge a 20Ah headway pack (8S2P 10Ah cells) with a 24V lawn mower charger that only puts out about 750mA. It takes about 16 hours to charge, but I only mow once/week so it's fine. Why did he say it's not enough?

I ordered a greentime charger (here) for a 15Ah 24S LiFePO4 pack, 4A output. You definitely don't want to go over the recommended charge rate, but there's no reason not to charge slower than recommended.

It might be plenty for some but not for me..headways can easily take 10 amps...and why wait when you dont have to?...In fact 1C is optimal and that is 15 amps!....so 3.5 amps is too weak a charge in my opinion. I think that once I bottom balance these babies, and get the Satiator, Ill split the pack into 2 48 V units, charge each and then quick connect...done..

John

 

[dmwahl]

It might be plenty for some but not for me..headways can easily take 10 amps...and why wait when you dont have to?...In fact 1C is optimal and that is 15 amps!....so 3.5 amps is too weak a charge in my opinion. I think that once I bottom balance these babies, and get the Satiator, Ill split the pack into 2 48 V units, charge each and then quick connect...done..

John

Your post made it sound like he said 3.5A was somehow not enough to charge them, I was just pointing out that there's no reason (other than wanting it faster) that you can't charge at ~0.2C. Fixing your charger might be faster, especially if it's just a blown transistor or something simple to replace. Dnmun knows a lot about chargers, I'd try to get his attention. Just don't mention the bottom balance part

If you really want fast charging you should look at some electric car chargers. There are plenty in the voltage range you want, and the headway spec for 15Ah cells says 30A max charge current so a 1.5-2kW charger should work nicely for your ~100V pack, although you may age them faster than normal. Elcon makes some that might work for you: http://www.elconchargers.com/catalog/item/7344653/7638003.htm

 

[johnnyz]

I appreciate all the feedback from my initial question. I just got the satiator and cant wait untill the cells are all BOTTOM balanced to try it out. Why did you mention not to mention this ?...If you dont have a BMS and I dont, then bottom balancing makes the most logical sense. I am going to try this and when all the cells are at aprox 2.7 volts, I will give them all 7 amps of charge wired serially through the satiator. When the first cell hits 3.7 volts I will stop the charge noting the total voltage at that point. I will reduce this by 1/2 volt (total voltage) and set the charger for this amount of charge. I suspect that most will be around 3.39-3.5 volts. I also suspect that total voltage should be around 95-96 volts which compared to total full charge of all cells should be 102 volts is just about 6% loss in total capacity which is not bad. The good thing is that theoretically all the cells should drop the same in voltage and so when the total voltage hits around 84 volts (or an average of 3 volts per cell) I can stop the discharge. In this way, I know that I wont have any cells falling off the cliff so to speak, however I will verify this before assuming anything. I will keep this post monitored of my progress.

John

 

[dmwahl]

Bottom balancing assumes that once all cells are at the bottom of their state of charge then they won't move away from that point over repeated charge/discharge cycles, and therefore you can simply discharge to the corresponding pack voltage and similarly charge to a voltage below when the cell voltages start to move apart at the top of charge. While it works in theory, in practice cells drift apart slowly over time, regardless of whether they're balanced at the top or bottom.

The problem with bottom balancing is that it's much more difficult to achieve in operation than top balancing and proponents usually advise that individual cell voltage monitoring is not important. In a top-balanced pack, you simply bleed off energy from cells that are higher than others, and to prevent over-discharge, stop discharging once any cell hits 2.5V or so. In bottom balancing, the general recommendation is to charge to less than full SOC and stop discharge when the pack voltage is ~2.5V x # of cells. If the cells were all identical and things like peukert effect, heating due to internal resistance, etc are all identical, then bottom balancing would work just fine. Since no 2 cells are identical, they will drift apart over time. When you have no way of monitoring individual cell voltages, then you have no way of preventing damage due to cells moving outside of their operating range. A lot of people use some pretty bad logic to argue against top-balancing BMS systems, calling them "vampire bleeder boards" or "battery murdering systems" etc... In reality, every commercial lithium battery system I've ever seen (laptops, commercial EVs, power tool packs, etc) uses a top-balancing scheme. Some avoid charging to 100% every charge cycle, but they still balance at the top of charge. Bottom balancing can work, but requires more effort on the part of the user and that's just not something the average consumer is willing to deal with.

Hopefully that makes sense. I'm not going to try and tell you not to bottom balance, but it's definitely more work than top-balancing with a BMS and having cell level LVC cutoff. If you don't want to use the full pack capacity, then you can probably get away with either manual top or bottom balancing with periodic manual balancing. Plenty of people do it, I just don't think it's worth it myself.

 

[johnnyz]

Bottom balancing assumes that once all cells are at the bottom of their state of charge then they won't move away from that point over repeated charge/discharge cycles, and therefore you can simply discharge to the corresponding pack voltage and similarly charge to a voltage below when the cell voltages start to move apart at the top of charge. While it works in theory, in practice cells drift apart slowly over time, regardless of whether they're balanced at the top or bottom.

The problem with bottom balancing is that it's much more difficult to achieve in operation than top balancing and proponents usually advise that individual cell voltage monitoring is not important. In a top-balanced pack, you simply bleed off energy from cells that are higher than others, and to prevent over-discharge, stop discharging once any cell hits 2.5V or so. In bottom balancing, the general recommendation is to charge to less than full SOC and stop discharge when the pack voltage is ~2.5V x # of cells. If the cells were all identical and things like peukert effect, heating due to internal resistance, etc are all identical, then bottom balancing would work just fine. Since no 2 cells are identical, they will drift apart over time. When you have no way of monitoring individual cell voltages, then you have no way of preventing damage due to cells moving outside of their operating range. A lot of people use some pretty bad logic to argue against top-balancing BMS systems, calling them "vampire bleeder boards" or "battery murdering systems" etc... In reality, every commercial lithium battery system I've ever seen (laptops, commercial EVs, power tool packs, etc) uses a top-balancing scheme. Some avoid charging to 100% every charge cycle, but they still balance at the top of charge. Bottom balancing can work, but requires more effort on the part of the user and that's just not something the average consumer is willing to deal with.

Hopefully that makes sense. I'm not going to try and tell you not to bottom balance, but it's definitely more work than top-balancing with a BMS and having cell level LVC cutoff. If you don't want to use the full pack capacity, then you can probably get away with either manual top or bottom balancing with periodic manual balancing. Plenty of people do it, I just don't think it's worth it myself.

Well Ive finally got them all to about 2.75 volts give or take .05 volt. The thing with these cells is that I bled them all down to 2.5 volts. They then would bounce up..some of them to almost 3 volts, so one more hit using around 7 amps and down to 2.5 volts..they would then settle to about 2.75 volts.
I have had to split my pack up in 2 parts making each a 48 volt pack. Using the Satiator, I started the charge at .02 amps untill I got to 42 volts, then 7 amps...so far none are varing more than .05 volts....stay tuned....

 

[johnnyz]

I set the charge to go to 7 amps once the pack reached 42 volts. I set the total charge to 49 volts. If they all remain within .05 volts and so far they are (at 47 volts) then all should be close to 3.5 volts. My guess is that before or at this number they will all stay close or start to differ...we will see...The thing looks messy but wont be once its in the trike. The modules on top of the cells are individual modules i bought that supposedly shunt the cell once it reaches about 3.5 volts...but at only 450 mah...it wasnt enough and cells began to go past the safe upper limit....for now these are on there just to track the progress of this set up. So far temperature on the Satiator started at 30 C but has now risen to 58C...yup its def warm to hot to the touch!

 

[johnnyz]

At 47.6 cell differences have risen to .07...lowest at 3.33 and highest at 3.40....only 2 cells at this high number, most at between 3.33 and 3.36.....

Temps on the Satiator have risen to 60 C....

 

[johnnyz]

ok...at 48.1 the Satiator temps rose to 65C...I put a fan right in front of it and within 8 minutes temps fell to 53...mmm...I will have to talk to Justin and see what kind of temps they were getting or expecting from this unit charging at 7 amps...cell voltages have somehow closed up the difference..now biggest diff is .07...

Total of 4.75 Ah into the cells...these are rated for 15 ah..but I seriously have my doubts as to that claim...probably closer to 12-13 would be my guess..these cells have 2000 kms on them..

 

[johnnyz]

ok...1 hr 17 mins into the charge..all voltages within .07 volts...total of 48.5 volts , 9.2 Ah into the cells....highest cell is at 3.45 volts and lowest is at 3.38...

 

[johnnyz]

Well well...14.2 amps this 2000 km, 15 ah battery pack took...one cell was at 3.58 volts and the lowest was at 3.44...so they def spread the higher it went but this pack took 14 ahs!!....ok lets do the math....thats 94% of capacity...so up to this point, this is an excellent result. I will charge up the other bank tomorrow and then on sunday go for a long ride and see what the voltages are as they drop. I dont suspect that over the long run, and I dont really know what that means, but eventually the voltages will drift and bottom balancing would have to be done again...but so far so good!

The Satiator got up to a high of 68 c before once again I kicked on the fan bringing it down to 48 c

John

 

[johnnyz]

Ok...well after a long ride and using 13 amps out of the batteries and 1000 whs...I chose to come in and check things out...most of the cells were at 3.18 volts but some were 3.08 and 3.09, 3.12....etc. When I had used only 400 wh out of the pack the cell voltage were all around 3.3 give or take .01 volt. As the discharge continued though, it appears the spread between voltages widened...

From this little test i can conclude some things...in this specific case, it appears that so far, bottom balancing does not prohibit the cells from varying in their respective voltages as you discharge them and if i continued ( unlikely as voltage sag was tremendous) then some cells would have hit 2 volts before some others, thats a fact. Also, I noticed that using this method, it appeared that there was more voltage sag than the way I used to charge them...

I have ordered some battery medics and since the Cycle Satiator can be programmed to charge at whatever voltage I want and will then reduce the current to whatever rate I want it seems logical that the battery medics would be able to shunt the charge at the end of the charge cycle..I will try it out

Im charging them up again, be curious to see the extent of the voltage pattern...see if they will charge up to the same voltage I did when I bottom balanced them without one cell going over.

John

 

[dmwahl]

Keep in mind that bottom balancing won't keep cells from drifting over time, nor will this drift likely show up right away. It will be over lots of cycles, as well as over time. Charging as 2 separate blocks will exacerbate the issue. It's no different from top-balancing in that regard.

Perhaps I missed it, but why not use a BMS at least during charge?

 

[999zip999]

I Charge to 3.5v, but not less then 3.45v.
A bms and matching charger will take cells to 3.65v to 3.8v then bleed them down to 3.6v or so. Now after a little time it may settle to 3.40v or so with bms.
I have a 24s 20ah lifepo4 pack no bms. I charge as a split pack 12s 42volts ea with a 12.6v 550watt power supply and a meanwell from Teslanv. It bulk charges at 15 amps each12s pack. Plus I have 4-6s sense wires for cellog.
I don't have a cellog, but two hyperion 7s monitors. They are only so accurate they seem to be off on number 5 cell no matter what I checked with my fluke and they're all even. plus I have a mystery balancer , voltage and cell voltage plus bleed down balancer. It woks ok. I hooked up and it gave me 15amp. It ok for checking charge voltage but you can't keep in line during charge cycle. It doesn't like it. Plus it's just for 6s.
Just finish charging all cells 3.484v -3.524 v

 

[johnnyz]

I Charge to 3.5v, but less then 3.45v.
A bms and matching charger will take cells to 3.65v to 3.8v then bleed them down to 3.6v or so. Now after a little time it may settle to 3.40v or so with bms.
I have a 24s 20ah lifepo4 pack no bms. I charge as a split pack 12s 42volts ea with a 12.6v 550watt power supply and a meanwell from Teslanv. It bulk charges at 15 amps each12s pack. Plus I have 4-6s sense wires for cellog.
I don't have a cellog, but two hyperion 7s monitors. They are only so accurate they seem to be off on number 5 cell no matter what I checked with my fluke and they're all even. plus I have a mystery balancer , voltage and cell voltage plus bleed down balancer. It woks ok. I hooked up and it gave me 15amp. It ok for checking charge voltage but you can't keep in line during charge cycle. It doesn't like it. Plus it's just for 6s.
Just finish charging all cells 3.484v -3.524 v

You charge to 3.5 v but less than 3.45?...what??...

The Battery Medic arrived yesterday and I hooked it up to the first 6 cells. it is in accordance to my volt meter within .001 volts. I am going to be doing a little experiment and having the BM adjusted so that the voltage where it begins shunting voltage is at 3.6 volts and at that voltage I will have the charger ramp down the amps to about 400 ma and see how they work to limit the top voltages. So far after a couple of cycles, the voltages are really consistent up and down.



John

 

[999zip999]

Sorry I meant to say no less than 3.45v or trying for 3.5v

This works good without bms as it hits 3.6v the voltage will go up up and run away in seconds.