Turnigy LiPo Upgrade for ESR-750

[Goped ESR750]

Hi... I am planning on upgrading my stock SLA set-up on my ESR 750 to give me a range of about 10-15miles in WOT Turbo.

I popped on the goped forum, who adviced it may be more informative if I drop a thread other here for advice. I have read through many threads in regard to LiPo and the safety aspects involve with that particular chemistry. With that information at hand I have selected the packs I would like, a balancing charger and also a 6s series cell monitor/low voltage alarm.

I am planning on using Turnigy LiPo packs, 6s 5ah. I intend to use four of these packs in parrallel to start with, giving me 20ah and maybe adding another couple later on to take it up to 30ah. Their is a link to the packs below. With these long packs I can fit them in without having an addition spacer for the board and greatly reducing the weight compared to stock SLA ex pack.

Battery Packs: http://www.hobbyking.com/hobbyking/stor ... duct=14323

Each battery pack I will accompany with a low voltage alarm set to 3.0v for each cell. My range should be well over what I need, this is to reduce deep cycling but would be nice to now the state of the batteries during a ride.

Low Voltage Alarm: http://www.hobbyking.com/hobbyking/stor ... oduct=7227

Last but not least the charger. I have selected a charger called a quattro. Is capable of balancing and charging four individual 6s packs in conjunction. My intention is to remove them all from the board to charge in some form of safe perhaps. Just incase the worst did happen, it wont damage my scooter.

Quattro Charger: http://www.hobbyking.com/hobbyking/stor ... duct=10327

Im pretty confident with this set-up after reading many threads, however being a noob to LiPo I would like any advice I can get or anyone to point out anything that might help me or anything I have missed.

Thanks in advanced!!!

[dogman]

If you paralell the packs, you can leave them paralelled to charge too. So you will only need one charger. 6s is only 25 volts, so you might have an issue with the lvc in your controller if it's set too high. No problem if your scoot will run on 18v. You definitely won't want to go lower than 3v per cell on the lipo, and ought to stop at around 3.5v. The cheapie lvc's start to flash at you at 3.75, and chrip at 3.5.

On the other hand, how high voltage can your scoot take? You could get some 8s packs if 34v won't smoke the controller.

[number1cruncher]

Welcome to Lipo!

First, when paralleling the packs, you want to parallel both the discharge wires AND the balance taps. So in essence, when 4-6 6s packs are in parallel, you should still only have 1 set of discharge wires and 1 balance tap. This setup will only require the use of 1 voltage alarm. I recommend the CellLog8, as they are highly versatile. Below is a link:

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=10952

Next the charger you chose is not necessary with your setup. You can charge all your packs at once in parallel, using a single charger, at a higher current. I recommend the one below:

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=12105

Make sure to get something to make up a parallel discharge harness and a balance tap harness. GGoodrum sells a great solution for paralleling the balance taps. The discharge harness can be a little more free form depending on your connector preference. I use Andresons. Some use Deans. Others continue using the bullets.

http://www.tppacks.com/products.asp?cat=26

Good luck!

[Goped ESR750]

Welcome to Lipo!

First, when paralleling the packs, you want to parallel both the discharge wires AND the balance taps. So in essence, when 4-6 6s packs are in parallel, you should still only have 1 set of discharge wires and 1 balance tap. This setup will only require the use of 1 voltage alarm. I recommend the CellLog8, as they are highly versatile. Below is a link:

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=10952

Next the charger you chose is not necessary with your setup. You can charge all your packs at once in parallel, using a single charger, at a higher current. I recommend the one below:

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=12105

Make sure to get something to make up a parallel discharge harness and a balance tap harness. GGoodrum sells a great solution for paralleling the balance taps. The discharge harness can be a little more free form depending on your connector preference. I use Andresons. Some use Deans. Others continue using the bullets.

http://www.tppacks.com/products.asp?cat=26

Good luck!

Ok interesting. So basically parrelling a cell makes it behave as one. I don't need to check the cells are balanced between the parrelells?

For example from what you are saying that to each balance wire there is actually going to be four individual cells parralleled. These cells are at no risk of inbalancing, because they are parralleled?

I am happy with that if thats the case, just wanted to clarify. So really I am treating the one big pack as a single 6s, because I have parralleled them.

Like the idea of the PCB having all the connections on it and inclusive of the low voltage meter. I was just planning on using crimps and anderson and what not but that looks a lot more tidier. Thanks for letting me now about that one.

[Goped ESR750]

If you paralell the packs, you can leave them paralelled to charge too. So you will only need one charger. 6s is only 25 volts, so you might have an issue with the lvc in your controller if it's set too high. No problem if your scoot will run on 18v. You definitely won't want to go lower than 3v per cell on the lipo, and ought to stop at around 3.5v. The cheapie lvc's start to flash at you at 3.75, and chrip at 3.5.

On the other hand, how high voltage can your scoot take? You could get some 8s packs if 34v won't smoke the controller.

Unfortunatly the controller is capped @ 30v on the stock unit. Is there anyway I may be able to reduce the voltage prior to the controller? I know some people who have upgraded to 36v kelly controller but this is also usually in conjuction with a motor upgrade. Im not sure how well the stock motor would hold up at 36v. The controller can deliver up to 200amps @ 24volts though so is pretty punchy. The SLA really suck when it comes to the high current draw, so am I expecting even with the slightly lower voltage to go faster because of the ability to hold voltage at higher amps.

[dogman]

I thought that might be the case. 24v controllers often use a 30v cap since sla's or nicads are usually not over 28v. 7s would get you spot on that voltage. I had a similar issue with a 24v lawnmower. Runs great on 8s, but the blade spins really fast, possibly dangerous fast at 33v.

But it gets awkward, since 7s packs aren't sold right now. So you'd have to use 3s packs and 4s packs, and complicate it. If the speed of 6s is fast enough for you, stick to that plan. Much easier to charge. You can always make changes to your voltage later if you decide to upgrade to 36v. One of the cool things about the lipo is the ability to run whatever voltage you want, by combining packs differently.

[number1cruncher]

Ok interesting. So basically parrelling a cell makes it behave as one. I don't need to check the cells are balanced between the parrelells?

For example from what you are saying that to each balance wire there is actually going to be four individual cells parralleled. These cells are at no risk of inbalancing, because they are parralleled?

I am happy with that if thats the case, just wanted to clarify. So really I am treating the one big pack as a single 6s, because I have parralleled them.

Like the idea of the PCB having all the connections on it and inclusive of the low voltage meter. I was just planning on using crimps and anderson and what not but that looks a lot more tidier. Thanks for letting me now about that one.

When you parallel the cells, they do behave as one cell. Before they are assembled in parallel, you will need to make sure they balanced to each other. The balance charger will do that for you. And yes, this will essentially be one big 6s pack.