Goped ESR750 LiPo 7S longevity / dependability build

[cujo67]

Hey all! New to the Lipo scene, over a year ago I installed the Headway LiFEPO4 cells with Chargery DB8 into my scooter. All was well for a couple months, then I went on vacation and all the cells had settle below the safe voltage threshold and I had tried reviving them but failed. So for the past year, I've had an e-scooter sitting in front of my TV to remind me to get this eyesore fixed, and only recently had Dragonfire on GPN informed me of the lipo 7s setup and how it's ideal for these scooters with their controllers, I'm willing to take a chance!

But before I do I would love to run my thoughts on this setup by the rest of you guys with all your experience. I probably only got about 30-40 cycles out of the LiFEPO4 setup, and do not want to drop that much cash into a similar setup. Looking to get a minimum of 300 cycles, if not more .

Plan is to purchase 4x ZIPPY Compact 5000mAh 7S 25C Lipo Packs

Discharge check, trying to get 1/4 of the discharge rating of the pack to extend cell life.
5000 x 25C = 125A constant draw
125A x 4 packs = 500A constant draw
500A x .25 = 125A continuous draw from all 4 packs.
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Now comes the tricky part. I've heard that it's possible to charge the batteries using the stock controller, but can't verify this since GPN's forum database won't connect for the past few days so it's still a mystery to me whether this is doable.

One thought I had was to purchase 4 of http://hobbyking.com/hobbyking/store/__7523__Turnigy_Accucel_8_150W_7A_Balancer_Charger.html to leave in the scooter and keep each one balanced 4 toggle switches on the outside to shut them off when not charging, to stop them from draining cells when not in use.

But I have (2) Chargery DB8's (pretty sure both work, know one works anyway) that I was thinking of running both inside the battery pan, parallel connections 2 packs per DB8 bms.

I've got an external charger, think it's a 7A if I remember correctly (at work sorry!) that I was thinking of using in conjunction with the DB8(s).
I'd love to somehow incorporate a LVC so that when the pack drains to say 30%, the pack cuts the power, or at minimum sends out a loud audible buzzer. I've got an old CellLog 8s that would be sweet to use for this, but other ideas would be welcome as well. Cutting power to the pack now that I think about it would be a bad thing, since the other 3 packs would have to take up the load, decreasing their C-rating by 1/4. Argh.

So the questions that nag now are the following:

1.) Is it true that with the Zippy packs you should halve the C-rating? If that's the case I'd have to double this setup and get x8 packs right?
2.) Would it be better for the batteries to be charged using the main leads or the balancing leads sending the power through a balancer?
3.) Is it better to balance the 4 packs individually or parallel them up to balance as one group?
4.) Are you better off charging all 4 packs through their main leads all connected together, or splitting the charger into the two DB8(s) directly?
5.) Would a Fire-Safe Bag per pack insulate the heat, effectively reducing the packs overall life?
6.) For the LVC would I need to send 4 sets of balance leads up the handlebars with 4 individual CellLog 8s displays? Or is there a better solution available?

Any input would be greatly appreciated, been researching hard for the past few days but can't seem to find the answers I seek. Unfortunately being a perfectionist at heart doesn't make matters any better hah! Cheers .

 

[silviasol]

Just curious, what did you end up doing with your ped? Seems almost noone here on ES has a goped. I have one and have built my own packs from single cells. I am currently finishing a 40ah pack with the cells linked below. If you haven't yet I would recommend the turnigy cells over the zippy, I hear they sag alot and the c rating is no where near what it is stated at. I have made two 10ah packs of these cells so far, the same I would assume used in all 5ah turnigy rc packs. I have ran one 10ah pack until it was just under 3.6v a cell and I got 7 miles in turbo which is extremely good, I figure probably 8-9 if I ran it dry. I get 4-5 run dry from a 8ah stock goped lipo pack with only about 150 cycles.

http://hobbyking.com/hobbyking/store/__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html

Your questions
1. yes I have heard zippy's are poor c rating. I doubt 8 packs are going to fit in the pan.
2. Two packs at once with a balance splitter would be dangerous. Each of those small cables will transfer power balancing the oposite cell, balance lead wires are not going to be a good size for that and the connectors are just small pins so that makes it even worse. This is just a big red flag for me, I wouldn't mess with that. I would recommend no db8 or balancing and some alarms for each pack then balance charge each pack individually with the accucel-8.
3. Charging 4 separate packs balancing all at once is possible with a balance splitter(if they make one with 4x 7s inputs) but I have never tried it, may lead to issue's. Probably best to charge them one by one or find a dual/quad charger. BTW I would never recommend using the on-board charger, I stopped using it when I noticed my pack was at 4.25v each cell and the bms was burning hot from it continuously balancing the cells, the charger would not shut off on it's own!
4. Again two db8's would work but you are back to a balance splitter. Charging with a 4x 7s splitter would be the same as using the db8. The db8 is really only good for a low voltage shut off which the alarms will replace.
5. If a fire starts it is because the cells became unbalanced and run a single or multiple cells under 2.75. This is why I recommend the alarms only. If you are going with rc packs to be safe multiple chargers or a multi charger is the safest option, don't want to mess around with lipo, mistakes will happen with you are not using a pack with a bms/pcb.
6. again 4 alarms is best, if any cells get under the 3.3v or whatever you set it at the alarm goes off and you know to shut it off.

 

[EdlB]

Hi guys

I have a 32 AH LiIon ESR 750. Looking to up battery power and voltage.

Anyone have any ideas?

 

[silviasol]

I have a 40ah pack made with turnigy cells I am just about finished with. The picture below is a 10ah pack, the pan fits 4 of them with the stock bms/pcm. Unfortunately you can not go higher then the 7s packs since the controller will not power on with more then 7s voltage. After I am finished with this pack I have a spare controller that I am going to try to modify it to bypass the high voltage shut off. I believe I found the resistor that reads the voltage to the cpu, I was told if I raise the value of that resistor it will offset the reading so you can put as much voltage as you want.

http://s928.photobucket.com/user/chips2482/media/IMG_0465-1.jpg.html

A word of advice for your esr.
I bought a non working 32ah esr750, probably the 2009-2010 model. It came to me with puffed packs and several popped cells that read 0v. I THINK, not sure though, the entire reason they puffed is because there is not enough room from the deck to the batteries so when you run over bumps or whatever you are putting pressure on the pack. I just could not believe it when I put in my good stock lipo pack and the deck would basically be torqued onto the battery! Not at all safe! Not sure what is going on with goped doing that but I took the deck spacer and deck from my other sla version and ran it with that on. This way there is about 1/2" of space between the batteries and the deck. If you have the single deck I would buy one of the spacers, it will keep your batteries running a whole lot longer not having pressure from your weight sitting on top of them. AND PREVENT ANY FIRES FROM HAPPENING

 

[duster]

Has anyone used a BCP Go-Cruise on their electric goped esr?

It seems like adding a freewheel would give you more distance per charge regardless of what batteries you choose.

http://www.davesmotors.com/gg520gocruisefreewheeladapter.html

Also this spacer might help with your spacing needs.

http://www.davesmotors.com/s.nl/it.A/id.2835/.f

 

[cujo67]

Geez where to begin! First off, sorry for the year before a reply! For the past year I've been checking GPN whenever it comes to mind to try and get back into the database and wealth of info that it provided, but seems after multiple emails sent to Goped that I'd love to host the forum, the lack of a reply speaks for itself. And as for a status update for the ESR750, it's still that eyesore in front of my TV in the living room, with the dead batteries connected like spaghetti sitting above it on the TV stand lol. Ugh.

Honestly thought my post went into the bin of oblivion, as I hadn't gotten a notification in the email or anything figured it was still orphaned within ES. Thanks for the replies! I've been working on researching it tonight after reading the posts, and have rethinked how to make this build happen.

First off thanks for the reply silviasol, my experience with soldering packs together is < 0 so unless I can figure out how to order the correct guage wires / connectors and solder the tabs without burning down my apartment and the flat above me, I may or may not attempt building my own packs. I have soldering irons and the know-how of general soldering (also learned tonight about zinc flux for those tabs that don't like to be soldered!), my minds getting cloudy here with 13 tabs in Firefox open it's a bit overwhelming haha. So here's what I was thinking to try and get it organized a bit....*cue the list*...

1. Creating my own packs, perhaps using that foam double-stick tape, two pieces between the packs leaving an air gap to allow air flow to keep the packs cool.
2. Sticking to the 4p7s original plan, just because I'm afraid that altering the discharge rate may negatively affect the charge cycles. On a side note just wondering how the 10ah pack you setup is working? Is that the 20c cell pack? When I ran the figures in the post here I got 4x 25c made 120A max continuous draw, which is from what if I recall correctly (damn you GPN for being down!!) is the amp draw in turbo. Was thinking of going 40c cells, since it's only 4 bucks more a cell, times 28
3. Would love to know how you wired up those PCM boards (PCM-LI25.9V90A) and how I could incorperate that into this build. Now does this constantly trim down the volages 24/7? Just wondering if when storing the scooter you need to disconnect the board or not.
4. Rather than running multiple Cellog wires up to the handlebards to monitor cell health, eyeballing on Amazon the 1-8s Lipo Battery Low Voltage Buzzer Alarm. it's programmable for the voltage and from the reviews it's audiable even from flying RC airplanes, which should be sufficient for the battery pan. If not could modify it so the speaker is directed outside the pan perhaps.
5. Been trying to determine the best way to secure the packs within the pan. was thinking strong double-stick tape at the bottom, as well as gorilla tape on the sides like an L to keep it stationary on both sides going over the top, yet able to dissapate heat. Last thing I want is the glue to delaminate and burst into flames shooting down a hill lol.
6. Where did you order your supplies from? And what is that wrap that you wrapped the batteries up in called? Does it allow for expansion fi the cells swell?
7. Any idea of a method of switching packs on the charger without having to plug in each pack individually? Like some kind of 4 way switch? The MPA-XH-US http://www.usastore.revolectrix.com/Products_2/MPA_2/MPA-XH_2 looks interesting but not sure if it's doing the same thing as that PCM board you have setup on the packs.
8. Is there any reason to fuse the main connections between the packs? Ya know, flying fireballs and all.
9. Got a deck spacer that came with the upgraded batteries (extended range kit?) from the previous owner.
10. What have you learned now that you wish you had known when you put together the set of packs a year ago?

Oh and thanks for the tip duster, had no idea DDM carried a freewheel kit for it, so friggin sweet! That was a big disappointment when traveling downhill to work, was spinning the motor for no reason and actually governing the top speed hehe.

Thanks! And I'll be sure to check back a little sooner now lol.






Speaking of which, you had mentioned building your pack

 

[silviasol]

So the questions that nag now are the following:

1.) Is it true that with the Zippy packs you should halve the C-rating? If that's the case I'd have to double this setup and get x8 packs right?
2.) Would it be better for the batteries to be charged using the main leads or the balancing leads sending the power through a balancer?
3.) Is it better to balance the 4 packs individually or parallel them up to balance as one group?
4.) Are you better off charging all 4 packs through their main leads all connected together, or splitting the charger into the two DB8(s) directly?
5.) Would a Fire-Safe Bag per pack insulate the heat, effectively reducing the packs overall life?
6.) For the LVC would I need to send 4 sets of balance leads up the handlebars with 4 individual CellLog 8s displays? Or is there a better solution available?

Any input would be greatly appreciated, been researching hard for the past few days but can't seem to find the answers I seek. Unfortunately being a perfectionist at heart doesn't make matters any better hah! Cheers .

1.) I have built a 20ah pack with the zippy compact 5000mah, they fit perfectly in the pan side by side(about a half an inch less wide as the stock goped lipo but a bit longer), see the post link below. The actual size of the goped lipo is the same size as the pcm/bms board in the pictures, that is the stock pcm/bms they use.
http://endless-sphere.com/forums/viewtopic.php?f=35&t=59238&p=891041&hilit=iped+lipo#p891041
2.)I have no idea how the db8's are set up but with a bms/pcm board you have to wire it without the first negative and last positive wire on most boards and the main pos/neg wires are soldered to it. Lipo is different voltages then headways lifepo cells and I believe the db8 is for lifepo only but not sure.
3.)You can plug in all the packs to a board that will connect them as one and ride using it that way but the balance cells are only rated for a few amps so there could be issue's if the cells get out of balance while riding which would send amps from the higher voltage cells to the lower voltage cells. Worse case scenario would be a burnt wire, you could check after every ride to make sure the wires are cool to the touch.
4.)You would probably be fine with just one db8(if it works). Just connect all the packs in parallel and connect the balance connectors with whatever board/wiring if they make them.
5.)No idea but you normally don't use them while riding, just when charging. My 20ah pack does not get even warm to the touch on long runs, I would worry about engine overheating more then the pack overheating.
6.)You can use just one if you connect all the balance leads, or use one for each pack. It is best to keep a close eye on them, I had bought two of them and the first one failed after about 3 months probably from bouncing around in the battery pan.

 

[legend@gazeta.pl]

Hi All,
I know it's an old topic but I'm currently planning to build my own battery based on 18650 cells. I wonder, what's the max current being pulled by the scooter in turbo mode. 40A, 50A?
Thanks,
Kamil

 

[fechter]

Post above indicates 120A. I doubt it would stay that high for very long, but not a bad target.

 

[legend@gazeta.pl]

I'll see. I've ordered 45A BMS (180A max).
My current scooter pulls max 1kW (20A@48V) and I doubt that 120A...
(unless the brushed motor is far less efficient than my BLDC motor)

 

[fechter]

The brushed motor can take very high peak currents, so 120A would be possible on takeoff from a complete stop. It will depend on the controller more than the motor. If your controller is limited to 20A, you will have no problems. You could probably increase that and still be OK depending on motor heating.