Thundersky 36v20AH batteries 120 mile review

[morph999]

*bought them from elitepowersolutions.com
*you buy the batteries up front...then she sends you another bill in your e-mail for the shipping cost...shipping wasn't too bad..only about $20
*paid about $380 for them but they are on sale now for $104 per pack I think

This is my 2nd e-bike. My 1st one still runs, though. I bought the bike used.

* I have a 5303 hub motor with a 36v - 72v 35amp controller.
* I now have 48v on the bike. Was using 36v20AH thundersky for 3 months and then decided to buy another thundersky 12v pack to make it 48v.
* I weigh about 267 lbs.
* I've had the Thundersky's since january of 2010
* most AH that I've used is around 10 (50 % of the pack)

So far so good. I pull about 2C out of these batteries.

EDIT:
GET A BMS FOR THESE CELLS. IF THEY DROP BELOW 2.5V EVEN ON VOLTAGE SAG. YOU CAN DAMAGE THEM.

I'm happy with them. I've charged them about 5 or 6 times now without balancing (topping them off) and they are still pretty well balanced. I was balancing them about every time. I've heard that the 36v 6amp charger that comes with them from elitepowersolutions.com is not very good, though. The people that are having trouble balancing your batteries; I don't really understand how it is that your batteries get so out of wack. Maybe mine are all from the same batch or something. I recommend using a 12v black and decker charger with a 2/6/10 amp setting on these because it tapers the current as the battery gets full and does not damage the batteries.

EDIT:
GET A BMS FOR THESE CELLS. IF THEY DROP BELOW 2.5V EVEN ON VOLTAGE SAG. YOU CAN DAMAGE THEM.

In the beginning, they did get a bit out of wack at first but I think once you cycle them they seem to all behave the same way and nearly same voltage. I charged them at first and one was about .1v or .15v off but that doesn't even happen anymore now that I have about 25 cycles on them.

 

[Russell]

Morph,

Are you checking each of the four individual cells within the silver boxes to see if they are balanced? What is the most Amp-hours you've used so far.

-R

 

[icecube57]

I have a 60v 20Ah 20s 1P Thundersky pack. They are assembled in 4 5s bricks. I currently use them at 2.5C on my 45A controller. I have done 6 cycles. I have gone 208 miles. I have discharged 98AH. I charge the cells to 3.7v a cell. I put a 6pn JST-XH balance connector on every 5s pack. I balance my packs with two hobby city battery medics.Each medic balances two 5s packs. I charge ins a 10s 2p configuration with my MeanWell power supply. I have it set at 37v. It charges at 10.4-10.5A With peaks up to 11A when that damn fan cycles on and off. On a freshly charged pack the voltage sag is around 2.85-2.90v a cell. I sit at 66.6v resting. I sit at 57-58v under a 45A load. Ive done two full DOD. They both gave me 19.4 AH before hitting 2.5v a cell. At around 17-18AH the cells can barely hold 1-2C load without sagging down to or below 2.5v a cell. They were hard to balance the first cycle or two. After full DOD I have trouble out of 4 cells... 1 in each of my 5s packs. They get fully charged before the rest of the cell in the strings. This causes them to sit very high sometimes in the balancing phase of charging. Near 3.9-4.1v.( Apparently still within cell specs) The balancer struggles to get these cells down. Eventually within the hour all cells rest at 3.7v on the battery medic. When the cells are shallow less than 80% DOD they balance very quickly within 30 min with the strong cells reaching 3.8v a cell max. The medic can easily pull this down allowing the other cells to top off.

My plans for the future is to buy two more medics so that 1 medic isnt trying to balance a 5s-40AH pack. I will have a total of 4 medics. Each pack having its own dedicated balancer. I also plan to buy pack analyzers to give me current cell voltage... lowest cell voltage ... and have an alarm for when a cell reaches 2.5v lvc during a ride.
Here is a link to my build thread. This is a link to the section where I posted pictures of my packs.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=8807&start=165#p247014

 

[morph999]

Morph,

Are you checking each of the four individual cells within the silver boxes to see if they are balanced? What is the most Amp-hours you've used so far.

-R

Most AH used is about 10. I still get about 19 miles out of it. Yep, I take the top off to check the cells every now and then. That's why the corners are cut off. For the first 15 cycles, I tried to take it as easy on them as possible. I heard that doing that can prolong the life.

AFter about 20 cycles, all the cells are usually within about .05v of each other.

 

[morph999]

They both gave me 19.4 AH before hitting 2.5v a cell. At around 17-18AH the cells can barely hold 1-2C load without sagging down to or below 2.5v a cell.

Is that typical with lithium? Do Ping's do that?

I use a 35 amp controller and with 36v on there, my sag is from 42v to around 38v and sometimes 37.5v. I've never seen a 36v reading yet, though.

I'm sure there are better lithium batteries out there but these are good enough for me. Much better than SLA. Much much better. I'm going 4x longer distance than with my SLA batteries. Just make sure you get a charger that babies these batteries. Preferably one that tapers off the current as it gets close to full.

 

[dnmun]

babies the batteries has nothing to do with whether they overcharge. where is the BMS for those cells inside the silver boxes? how do you balance those cells? someone just asked and you didn't answer.

 

[morph999]

babies the batteries has nothing to do with whether they overcharge. where is the BMS for those cells inside the silver boxes? how do you balance those cells? someone just asked and you didn't answer.

Most people know that I don't use a BMS. It's just a matter of choice. I charge them to about 98 % full and then I either go on a ride like that or I spend about another 2 hours balancing them. I haven't balanced them for about 2 weeks, though.

 

[morph999]

what most people don't realize is that if you have a charger that charges the cells to only 98 %, you don't need a BMS to prevent it from overcharging because it will never reach that point. That's essentially what I'm doing. Electricity flow through all the cells so they all reach the same point at about the same time. The only thing you need to worry about is going long periods without manually balancing them. Yes, I would damage them without a BMS if my charger were to charge them to 100 % because some would probably go over the high voltage level.

 

[Russell]

Most AH used is about 10. I still get about 19 miles out of it. Yep, I take the top off to check the cells every now and then. That's why the corners are cut off. For the first 15 cycles, I tried to take it as easy on them as possible. I heard that doing that can prolong the life.

AFter about 20 cycles, all the cells are usually within about .05v of each other.

I use a 35 amp controller and with 36v on there, my sag is from 42v to around 38v and sometimes 37.5v. I've never seen a 36v reading yet, though.

I'm sure there are better lithium batteries out there but these are good enough for me. Much better than SLA. Much much better. I'm going 4x longer distance than with my SLA batteries. Just make sure you get a charger that babies these batteries. Preferably one that tapers off the current as it gets close to full.

Did you initially charge each cell to the same point using a single-cell charger to make sure all of the cells started at the same voltage?

It sounds like the ThunderSky batteries are working great for you without a BMS. You're also no doubt having good results because the most you've used is half the battery's capacity. If you keep the DOD to 70 or even 80% you should have no problems at all.

I've been running my own generic pouch type LiFePO4 10Ah 2C max battery without a BMS for 14 cycles so far with most discharges in the 70-80% range with one ride at 87% DOD. I top-balanced mine initially then again after the 8th and 14th cycle mainly because it's easy for me to do by connecting up the old BMS while charging. On the first ride I used just 57% and the discharged cell voltages were grouped very tightly (0.01V) but even the spread at the deepest discharge wasn't great (0.05V). I wouldn't want to take the battery much past 90% because I have identified one cell that is below the others but so far so good.

I do think for a number of reasons most folks will want a BMS but for others it's unnecessary. I consider the T-S cells to be too heavy for my ebike but if I had an electric scooter I'd have no qualms about using them "naked".

Oh and regarding your last statement as long as the charger voltage isn't set way too high for the intended application current ramps down naturally as the cell fills up until it goes to zero when the battery voltage equals the charger voltage.

-R

 

[Russell]

what most people don't realize is that if you have a charger that charges the cells to only 98 %, you don't need a BMS to prevent it from overcharging because it will never reach that point.

Yes and no.

First that assumes all of the cells are within a couple of percent in actual capacity. Modern manufacturing should be able to produce cells to that tolerance but you never know about YOUR cells until you test them. If you have a cell that is substantially below the capacity of the others it will be very obvious when you run without a BMS where if you have a BMS it will cover up the deficiency. The low capacity cell will still limit the capacity of the pack with the BMS but the BMS will keep the cell voltage from going too high when charging or too low on discharge. In fact most people who have their BMS cutting out earlier than they expect probably have at least one cell which is significantly lower in capacity than the rest.

Second, you do need to make sure you charge each cell to the same point before putting the pack into service. If you don't do this the individual cells could be at any SOC and once in series the cells with the higher charge could go through the roof when the pack is bulk-charged. This was keenly demonstrated by a fellow forum member who bulk-charged a new "naked" Headway pack without initially balancing the cells. He had some cells go over 4.2V while others were still at 3.3V.

-R

 

[morph999]

Most AH used is about 10. I still get about 19 miles out of it. Yep, I take the top off to check the cells every now and then. That's why the corners are cut off. For the first 15 cycles, I tried to take it as easy on them as possible. I heard that doing that can prolong the life.

AFter about 20 cycles, all the cells are usually within about .05v of each other.

I use a 35 amp controller and with 36v on there, my sag is from 42v to around 38v and sometimes 37.5v. I've never seen a 36v reading yet, though.

I'm sure there are better lithium batteries out there but these are good enough for me. Much better than SLA. Much much better. I'm going 4x longer distance than with my SLA batteries. Just make sure you get a charger that babies these batteries. Preferably one that tapers off the current as it gets close to full.

Did you initially charge each cell to the same point using a single-cell charger to make sure all of the cells started at the same voltage?

It sounds like the ThunderSky batteries are working great for you without a BMS. You're also no doubt having good results because the most you've used is half the battery's capacity. If you keep the DOD to 70 or even 80% you should have no problems at all. -R

When I got the first 3 packs, I used the 12v black and decker on them but I was in there watching them the whole time with my multi-meter out so that none of them went over the limit. That was kind of half-hazard of me to do that, though and when I got the 4th pack, I used my 3.2v lifepo4 chargers to charge all the cells so I would get a good balance charge in before using the 12v charger. I was lucky in that whoever was charging the cells obviously charged all the cells to relatively the same capacity. Had they not done that, I could have had problems. I think my small charger was still being shipped when I got my lifepo4 packs. I should have waited for those before charging. The B&D gives me some room for error when charging. If they charged much higher than 14.8v per pack then I would probably have damaged a cell by now.

When I first got my packs, I did a little calculation on what the average cell charge would be when charging 4 cells at a time. So I knew, 14.8 / 4 = 3.7v . That's well below the 4.2v so the cells would have to be seriously out of wack to cause a problem in my opinion. I think if I would have bought a different charger, I probably would have damaged a cell. I think charging 4 cells at a time is preventing me from having major problems.

 

[evblazer]

Good to hear you haven't been having any problems with the batteries so far. I have a 24v pack that I have about 10 partial cycles on it. I am using them part time in my mower as it is 24v and was using its charger to charge the batteries. It only takes the pack up to 26.8 volts which probably didn't help the old lead acids survive or mow very far. :?
I did get my celllog8 hooked up today and mowed the lawn with it connected and before during and after using about 7ah out of the pack the voltages were all within .02 of each other which I thought was great.
I've got some other charger stuff in the work mainly because I want something to be able to charge the batteries with when I start riding to work. I've got a B&D 12v 2/4/6 but I'd rather something small and quiet for work.

 

[morph999]

Get a BMS. Make sure you put a BMS on these cells. If you take them below 2.5v at any time even on voltage sag, you can damage them. I think I damaged a cell from that. I'm not positive but just to be safe. Get a celllog 8s monitor and make sure your cells don't go below 2.5v .

 

[dogman dan]

At least some lvc alarms from hobby king would be good. Less than 4 bucks each, for $15 you could monitor all 16 cells in a 48v pack. Back off the throttle if they get much below 3v.

 

[maydaverave]

It looks like these batteries are going for 155.00 now with a bms.

 

[BLUESTREAK]

I am running 4 of these TS 20ah on my WIFE'S MERIDIAN trike using the balancers and thay seem to doing a good job.

 

[morph999]

my cells are fine. I killed one but I think it was from pushing it too hard. Anyway, there are risks to everything and nothing seems to be a perfect solution yet. I'm going without a BMS because I don't want the headaches. I use my bike just for recreation. It was either from pushing the bike too hard or it was just a quality problem with the cell. I don't know but my other cells are fine and that's all I care about. I know the limits now.

I went for a 15 mile ride today. No problems.

If I had it to do over again, I would buy the Thundersky batteries again but I'd get probably a nine continent motor with a 20 amp controller so that I'm only pulling 1C from the batteries. The Thundersky's handle 1C discharge very nicely but don't seem to like 2C all that much but it's doable but don't expect to get a full 20AH from the cells. If you plan on using 2C from the 20AH Thundersky cells, plan on only using about 10AH (50 %) of the battery.

Considering that good SLA's are about $200. I spent about $360 on my 36v20AH thundersky. It's still a very good investment I think. These go way farther than my SLA's went and I'm sure my SLA batteries would have conked out by now. I'm going on over 200 miles so far and my SLA's only lasted about 150 miles if I remember right. I just need them to last about 2 or 3 yrs and I will be super happy. By then, hopefully some really good lifepo4 will be on the market.

 

[dumbass]

I am running 4 of these TS 20ah on my WIFE'S MERIDIAN trike using the balancers and thay seem to doing a good job.

What balancers are you running on them?

 

[BLUESTREAK]

The ones that are for sale on the (ELITEPOWERSOLUTIONS>COM) site I think thay are about $8.00 each.

 

[evblazer]

Hopefully I can get more then 10ah out of them with the celllog8 watching them and individual charging. 10ah out of a 20ah battery long term would be way too little. If they don't last a few hundred cycles I shoulda kept with lead
I ran my pack again this weekend two cycles at ~1.4C average 3c peek 15ah 1st cycle and 17ah 2nd and all seems well. Pack within .01 v when I stopped using them and when recharged. Hopefully when I get my new drive running I"ll be using them more but they'll at most be seeing 1/2c so should be good there.

 

[icecube57]

Again im going to say these dont start acting foolish until about 17-18AH. When you do DOD pas 80% you will see your cells become out of balance. I advise you to get the medics or something to top end balance. There is no way that no one is having issues with balancing.(ATLEAST CELL LOGS AND BATTERY MEDICS GIVE YOU ALL YOUR CELL VOLTAGES) The medics can actively balance while charging. Out of the 24 cells I have all of them need balancing after every charge even if its a shallow discharge of only 5AH. Although it balances quickly in about 30 min to 1hr. But what im saying is my cells have never came up together with each cell at the same voltage. NEVER!. When I get done balancing them they are all exactly 3.70v. For bulk charging they are all at the same level within .01v-.05v for the whole charging cycle up to about 85-90% charged but at the end of the charge the cells with the low IR tend to get the most voltage. If you dont have balancers to knock that charge off so it can be absorbed into the other lower cells you are have an issue with cells being under charged which tends to get them even more out of balance with each charge.

I recieved my packs and all cells had the same voltage. I put them on the charger one shot really high after about 20 min. 2 were low and one was right on the mark. The correct finished charge voltage was on the pack but the cells werent balance and the difference from high to low was .4v. This was a pack that was still in the plastic casing and pretty much virgin from EPS. Morph Im not sure how you are checking yours but you cant sit here and tell me that with the way you are charging that all your cells are balanced at the same level. They may appear to be since your are undercharging to 85-90% them but they probably not balanced.

Bluestreak is probably not having any issues cause his balancers are bleeding down when they hit 3.7v allowing the lower cells to catch up and charge.

 

[morph999]

These Thunderskys can handle 2C. At least they can for the first 350 miles or so which is a pretty good sample. That's how much I got so far. Been running 2C on them since January and blew up one cell but I think that was something else beyond my control. If you want to run Thundersky at 2C, only use 50 % and they'll be just fine. I've been using full throttle on it too and holding it down for long periods of time and no problems except for that one cell.

 

[morph999]

All my cells rest at 3.55 - 3.49v. What's the problem with that? They charge up to about 3.7v and then settle. I balance them every now and then but not every time.

I'll put in a balance charge today just to be sure. We'll see how out of balance they are.

Icecube, the only reason for balancing is to try to get all cells the same capacity. Voltage is not a pinpoint way of measuring capacity. Right now, there is not really accurate method of measuring capacity once you start cycling the battery. So a cell at about 3.49v might have the same capacity as one at 3.52v . I don't think being a few hundreds of voltage off is a big deal. Where am I wrong?

 

[morph999]

all my cells are still good minus that one long ago that had problems. It's been about 10 months now that I've had them.

 

[BLUESTREAK]

MORPH: it's good to see you back.