30 mile range at 20 MPH for $150 no balancing

[Boyntonstu]

My 48 V pack of 2 parallel pairs of 6s HK Multistar 5200mAh in series (4 batteries) has about 550 miles on them.

https://hobbyking.com/en_us/multistar-high-capacity-6s-5200mah-multi-rotor-lipo-pack.html

I bought them on sale for $27 each.

For about 200 miles I charged them to 4.15 V per cell average.

After reading a few ES threads I lowered the charge Voltage to 4.0 per cell.

12 cells in series makes a constant 48 V charger easy to use and to measure,

I PA in the 20-24 mph speed range after learning how to handle the longer 6 Day bike at speed.

The discharge curves seems pretty linear,

A 6 mile ride takes the 4V down to 3.9, another 6 miles to 3.8, another 6 miles to 3.7.V. 18 miles and lots of pep left.

I have not taken them down to 3.6 V, but I am confident that there would not be a problem.

That would give the bike a 24 mile range starting at 4.0 V.

According to most LiPo charts 4.0V is about 80%.

Thus, if I charged the pack to 100% at 4.15 V I would get another 6 miles, for 30 miles.

Quite amazing!

I use the bike every day and I have not seen any reason to balance because the 48 V charger gives it 48 V.

I measured individual cells once and they matched,

A rotary balancing switch has been wired up and ready to go should the need arise.

This group has given be great advice and I appreciate it a lot.

 

[motomech]

I have been using LiPoly for 6 years and MultiStars for over a year and while I'm a big Fan of LiPoly in general and MultiStars in particular, I have some problems with your post.

I bought them on sale for $27 each

First off, when did you buy the 6S/52000 mAh's? I always follow the MS prices and I have never seen the 6S/5200mAh's for half price. Did I miss that? At any rate, with HK's new price structuring, they will never be that low again and to list them for that price, without an explanation is misleading.

12 cells in series makes a constant 48 V charger easy to use and to measure,

This is incorrect and dangerous advice. A Lithium Ion charger for example, has a top charge Voltage of over 54 Volts! A bulk charger needs to have an adjustable top Voltage(if i9t's not right from the factory) and a constant Current/constant Voltage function.

Thus, if I charged the pack to 100% at 4.15 V I would get another 6 miles, for 30 miles.
Quite amazing!

Yes, quite.
I sure many here would have a problem w/ determining range based on dis-charged Voltage values, but as you mentioned, the dis-charge rate of LiPoly is very linear and I myself am guilty of determining range this way, but by pack Voltage, not cell Voltage. But only on the sense of watching the Voltmeter for when I reach "halfway" and know it's time to turn around and head for home. Given the top Volt "burns off" fairly fast, I consider my starting Voltage @ 49V and my LVC is 42V., so 45.5V is the halfway mark.
But I know what the range of my 12S/10,4000 mAh MultiStar pack to be and yes, I can get almost 30 miles out of it. But that's pedaling along @ 15 mph on the bike path. That bike won't go faster than 20 mph, but my other bike will do 23 mph and @ those speeds the range drops off dramaticly. More like 15 to 20 miles on the same size pack. Are you saying you are getting 30 miles on a 10 Ah pack at 20 to 25 mph?

I use the bike every day and I have not seen any reason to balance because the 48 V charger give 48 V.

I measured individual cells once and they matched,

I really don't know what to say to this, but I would caution anyone reading this to not take this statement seriously.
While I am not a LiPoly alarmist, and think much of hand-wringing over it's danger is overblown, I do not think the time and care it requires is. If anything, I think it's more time consuming than folks realize. Just because the cell Voltages hadn't strayed one time, never ck'ing them is akin to playing Russian Roulette. At the least, I think they should be ck.ed every other cycle and anytime they are dis-charged below 3.8 V/cell.
And then there is the whole procedure of maintaining them @ storage Voltage and "top charging" just before riding. Something the OP has omitted. LiPoly is certainly NOT a "plug and play" battery.
Yes, LiPoly is an amazing performer, but it doesn't need to have it's downsides glossed over, or it's performance enhanced.

 

[Boyntonstu]

I have been using LiPoly for 6 years and MultiStars for over a year and while I'm a big Fan of LiPoly in general and MultiStars in particular, I have some problems with your post.

I bought them on sale for $27 each

First off, when did you buy the 6S/52000 mAh's?

From Hobby King on sale. At first they were not available, and shock and surprise, they came on at $27.

This was the receipt on 9/15:

Shipment: UPS Express DG $31.40
Discount: Discount code: 8EDB1F03-8F35-4F44-90A $0.00
Taxes: $0.00
Total: $143.36 (For 4 6s 5,200 Multistars)

I always follow the MS prices and I have never seen the 6S/5200mAh's for half price. Did I miss that? At any rate, with HK's new price structuring, they will never be that low again and to list them for that price, without an explanation is misleading.

12 cells in series makes a constant 48 V charger easy to use and to measure,

This is incorrect and dangerous advice. A Lithium Ion charger for example, has a top charge Voltage of over 54 Volts! A bulk charger needs to have an adjustable top Voltage(if i9t's not right from the factory) and a constant Current/constant Voltage function.

am using a commercial 4 Amp max output charger that can be set to exactly 48.0 Volts.

With 2 strings in parallel, the current divides to 2 A per string. No possibility of overcharging.
I use a timer set for 2-1/2 hr.

Thus, if I charged the pack to 100% at 4.15 V I would get another 6 miles, for 30 miles.
Quite amazing!

Yes, quite.
I sure many here would have a problem w/ determining range based on dis-charged Voltage values, but as you mentioned, the dis-charge rate of LiPoly is very linear and I myself am guilty of determining range this way, but by pack Voltage, not cell Voltage. But only on the sense of watching the Voltmeter for when I reach "halfway" and know it's time to turn around and head for home. Given the top Volt "burns off" fairly fast, I consider my starting Voltage @ 49V and my LVC is 42V., so 45.5V is the halfway mark.
But I know what the range of my 12S/10,4000 mAh MultiStar pack to be and yes, I can get almost 30 miles out of it. But that's pedaling along @ 15 mph on the bike path. That bike won't go faster than 20 mph, but my other bike will do 23 mph and @ those speeds the range drops off dramaticly. More like 15 to 20 miles on the same size pack.

Are you saying you are getting 30 miles on a 10 Ah pack at 20 to 25 mph? I am saying that I am getting 18 miles at 20-25 MPH,
The extra 12 miles would come from charging to 4.15 and discharging to 3.6 V.

I will be 78 next week, and I am using an 11 tooth rear with fairly hard but doable pedaling.
I have never gone full throttle, but I have had it up to 27 MPH.
The semi-recumbent feet forward long wheelbase rolls very well,

I use the bike every day and I have not seen any reason to balance because the 48 V charger give 48 V.

My routine is to ride 12 miles and never discharged the pack below 45.5V (3.79V).

I have one of these LED throttles on order: http://www.ebay.com/itm/172387463329?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

I measured individual cells once and they matched,

I really don't know what to say to this, but I would caution anyone reading this to not take this statement seriously.
While I am not a LiPoly alarmist, and think much of hand-wringing over it's danger is overblown, I do not think the time and care it requires is. If anything, I think it's more time consuming than folks realize. Just because the cell Voltages hadn't strayed one time, never ck'ing them is akin to playing Russian Roulette. At the least, I think they should be ck.ed every other cycle and anytime they are dis-charged below 3.8 V/cell.
And then there is the whole procedure of maintaining them @ storage Voltage and "top charging" just before riding. Something the OP has omitted. LiPoly is certainly NOT a "plug and play" battery.
Yes, LiPoly is an amazing performer, but it doesn't need to have it's downsides glossed over, or it's performance enhanced.

 

[dogman dan]

CHECK OFTEN.

But the way he uses them,, they should stay balanced for months at a time. Low c rate, and typically stops before they go off the cliff.

But ya still have to check em.. In this case, charging to 4v per cell gives him up to .3v per cell of wiggle room at the top, for safe bulk charging. That's a HELL OF A LOT of wiggle room.

As always with RC lipo packs, Never store or charge them in a place you would not build a fire. With any naked pouch pack, the risk of physical damage is very high, and a dinged pack can go off.

 

[Ykick]

Good old Stu can’t be bothered with power meter and thus some legit/useful battery data. Instead, he publishes this nonsense gibberish which helps nobody and may lead somebody down a dangerous RC Lipo path.

 

[dogman dan]

I think he does have a way to quickly check each cells voltage. All he really needs. Once he knows his range, you don't really even need a pack voltage display.

But I won't ride without a CA anymore, much. I've seen murphys law in effect that many times with batteries.

 

[Ykick]

I don't care much about voltages either. The critique goes back to original “walmart jumper battery” thread spewing a bunch of “range” and capacity data which contained no legit power measurement.

Can’t be bothered to use $20 power meter, really? 'Seems like a waste to not fill in the picture of battery and system performance picture for those who might follow?

 

[wesnewell]

Stu, Don't worry about any of the comments. Using the batteries the way you are is just fine and they should last 6-10 years this way. But, I'd spend $20 for a couple of battery medics to use while charging every now and then, I'd also invest in a simple $2 volt meter to use while riding just for peace of mind and use it as a fuel gauge.
https://www.youtube.com/watch?v=SDjgrVDnyrs
http://www.ebay.com/itm/BATTERY-MEDIC-SYSTEM-LCD-2-6S-LIPO-LIFE-VOLTAGE-CELL-CHECKER-BALANCE-DISCHARGE-/112118191222
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=120v+voltmeter&_sop=15

 

[Boyntonstu]

Stu, Don't worry about any of the comments. Using the batteries the way you are is just fine and they should last 6-10 years this way. But, I'd spend $20 for a couple of battery medics to use while charging every now and then, I'd also invest in a simple $2 volt meter to use while riding just for peace of mind and use it as a fuel gauge.
https://www.youtube.com/watch?v=SDjgrVDnyrs
http://www.ebay.com/itm/BATTERY-MEDIC-SYSTEM-LCD-2-6S-LIPO-LIFE-VOLTAGE-CELL-CHECKER-BALANCE-DISCHARGE-/112118191222
http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=120v+voltmeter&_sop=15

Thanks for your help. I follow success and since you have gone over 15,000 miles on LiPo's, I follow your advice.

How is this for a convenient fuel gauge and acceleration drain meter?

http://www.ebay.com/itm/172387463329?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

 

[wesnewell]

If you like twist throttles, looks like a good all in one setup if you run <100V. You can get it cheaper.
http://www.ebay.com/itm/24V-36V-48V-EBike-Electric-Scooter-Throttle-Grip-Handlebar-LED-Digital-Meter/131925770053
http://www.ebay.com/itm/12-90V-EBike-Electric-Scooter-Throttle-Grip-Handlebar-with-LED-Digital-Meter-/332042298492

 

[Boyntonstu]

If you like twist throttles, looks like a good all in one setup if you run <100V. You can get it cheaper.
http://www.ebay.com/itm/24V-36V-48V-EBike-Electric-Scooter-Throttle-Grip-Handlebar-LED-Digital-Meter/131925770053
http://www.ebay.com/itm/12-90V-EBike-Electric-Scooter-Throttle-Grip-Handlebar-with-LED-Digital-Meter-/332042298492

These throttles use a key as the on/off switch.

I prefer a push button for quick off safety.

BTW My long bike requires almost 2 meters of cable.

The throttles above have the required cable length.

I hate keys because I always manage to misplace them.

OTOH Keys add security, so I will probably order one of the 2 that you suggested,

 

[dogman dan]

If I was misunderstood, what you are doing is just fine.

Treat lipo nice, and it wont do any of the bad stuff, and it will last a long time. It's just when murphys law catches up that you get in trouble.

One of the times I had a parallel connection pop loose, I then discharged a 5s pack to 0v. It was actually dripping the shrink in my gloved hand, and OMG did it puff. I was very lucky no fire that time.

The lesson, tape up those plugs on the parallel connections. Don't let them pop loose. Then you won't end up with one pack full, and the other at 0v, instead of both packs at 3.75 per cell.

But had I been riding with a voltmeter display,, I would have immediately seen a problem developing. I would not have ridden till the melting shrink stink made me go Hmmmm,, wtf?

 

[Boyntonstu]

If I was misunderstood, what you are doing is just fine.

Treat lipo nice, and it wont do any of the bad stuff, and it will last a long time. It's just when murphys law catches up that you get in trouble.

One of the times I had a parallel connection pop loose, I then discharged a 5s pack to 0v. It was actually dripping the shrink in my gloved hand, and OMG did it puff. I was very lucky no fire that time.

The lesson, tape up those plugs on the parallel connections. Don't let them pop loose. Then you won't end up with one pack full, and the other at 0v, instead of both packs at 3.75 per cell.

But had I been riding with a voltmeter display,, I would have immediately seen a problem developing. I would not have ridden till the melting shrink stink made me go Hmmmm,, wtf?

No plug connections.

I use a soldered wire end loop and 1/4-20 screws that are torqued down.

[youtube]7vEBqjyOF5o[/youtube]

 

[dogman dan]

Looks solid.

For a while I was doing permanent crimps to connect two 5s packs. ( instead of the disconnect prone Anderson) Now I just use a better connector, the 4 or 5 mm bullets, to make reusable y connectors. Then with tape, they never disconnect one pack.

In any case, with a CA on the bike, I'll never ride till I smell it. Any good visibility pack voltage display will do.