Battery DIY.

[awol]

Yea, that would probably be a better choise for my needs, but how are they regarding to shelf life? I'm probably not gonna use my bike every week, so shelflife is more important than recharge cycles. Link to a good cheap one which will give me 10-15min of full throttle on my 500w motor?

I've had some in my garage at storage volts for a couple years just cycled every 6 months or so (if that) and mine still appear ok.
Maybe a couple of these (not sure what country they are shipped from though)
https://hobbyking.com/en_us/turnigy-5000mah-6s-20c-lipo-pack.html
would give 12s in series with this
http://www.ebay.co.uk/itm/4MM-HXT-Harness-For-2-Lipo-Battery-In-Series-RC-Car-Plane-Boat-Connector-Cable-/330989322484?hash=item4d108040f4:g:JzMAAOSwNSxU7eDY
and one of these to charge.
https://hobbyking.com/en_us/imax-b6-dc-charger-5a-50w-copy.html
and a couple of these to tell you when they are empty.
https://hobbyking.com/en_us/hobbykingtm-lipoly-low-voltage-alarm-2s-6s.html

 

[anotherkiwi]

I would go with a more powerful charger so you can charge at 1C even if you decide you want to get some more/bigger capacity ones.

https://hobbyking.com/en_us/multistar-high-capacity-4s-5200mah-multi-rotor-lipo-pack.html

Three of those in series will give you about 4 Ah and as they are quite small and light (1.3 kg for the whole pack) you can make more modules and have 10.4 or 15.6 or 20.8 Ah at your disposal as you need it. Today that is a $60 battery plus 3 series wires so less that $80 with the alarms.

I have had batteries at storage voltage (3.85 V per cell) for months and they don't budge even by 0.01 V. Storage voltage is programmed into all the chargers.

PS I bought bigger 10 Ah ones but the 5.2 Ah is the most popular size because they charge fast and they fit in all sorts of frame bag shapes.

 

[Renax]

What are the alarms good for?

 

[D8ve]

What are the alarms good for?

Short answer safety.
Middle length one, Go find the battery university and look it up. You need some more education.

 

[Renax]

Short answer safety.
Middle length one, Go find the battery university and look it up. You need some more education.

Thank you for such informative answer. Anyone who can tell me what the alarm does?
I know nothing about lipo other than what happends if you hit them with an axe...

Edit: Reddit to the rescue, I now understand what the alarm does and that its useful. The voltage on my bike can be monitored by a voltmeter on the handlebar but its easyer to just have the alarm and it provides safeguards for uneven cell drain, witch could be a problem, at a couple £ per battery it seems well worth it.

 

[awol]

Lipo batteries need care when being used, I thought you were familiar with high power batteries so if your not familiar with lipo's then maybe for safety stick with li-ion cells but I still use those low voltage alarms on small li-ion packs I make up without BMS.
Back to your original question, if you chose a 22amp controller and as d8veh said that motor will be running inefficiently up hills so will be using about 1kwh so work it back to how many mins you will need it running at that for, 10mins about 170w plus a bit so about 220w is what the motor could use.

 

[Renax]

Yea, I didn't know how inefficient the motors are, now I know and my 13s1p plan fell apart.
I'm not familiar with LiPo but I'm familiar with learning new stuff. How is LiPo in use? The 5.2Ah @anotherkiwi linked, how much usable power do I get out of them before low voltage cutoff? will they be able to propel my bike full throttle for 10-15mins?
Cheap short power is what I'm after, so lipo's seems like a good plan. I don't want them to blow up in my face, so I will take the necessary precautions, I just need to know what they are, and why. I know they are quite violent when they go, I've seen that on my friends RC car, but I've never used them myself so I don't know why and when that happends or how to prevent it. I know I have a lot to learn, and thats why I'm trying to do.

Charger wise, I'm a little hesitant buying a charger only for lipo, is there some chargers I can use for lipo and other stuff? (Li-ion, even lead acid batteries?) I feel more comfortable spending more money on a charger I can use to charge anything from my vaping cells to my car in a pinch. If its not possible for some reason a good lipo charger will have room on my shelf, but I've been planning to buy a universal charger/power supply for a while...

 

[soundwave]

http://www.skyrc.com/index.php?route=product/product&path=20&product_id=217

will charge most batts but only up to 6s

 

[Danidl]

Yea, I didn't know how inefficient the motors are, now I know and my 13s1p plan fell apart.
I'm not familiar with LiPo but I'm familiar with learning new stuff. How is LiPo in use? The 5.2Ah @anotherkiwi linked, how much usable power do I get out of them before low voltage cutoff? will they be able to propel my bike full throttle for 10-15mins?
Cheap short power is what I'm after, so lipo's seems like a good plan. I don't want them to blow up in my face, so I will take the necessary precautions, I just need to know what they are, and why. I know they are quite violent when they go, I've seen that on my friends RC car, but I've never used them myself so I don't know why and when that happends or how to prevent it. I know I have a lot to learn, and thats why I'm trying to do.

Charger wise, I'm a little hesitant buying a charger only for lipo, is there some chargers I can use for lipo and other stuff? (Li-ion, even lead acid batteries?) I feel more comfortable spending more money on a charger I can use to charge anything from my vaping cells to my car in a pinch. If its not possible for some reason a good lipo charger will have room on my shelf, but I've been planning to buy a universal charger/power supply for a while...

Any good electronic lab power supply will have, adjustable voltage and adjustable current limits. They are readily available on second hand sites from time to time. New ones can be pretty expensive. Key parameters will be maximum voltage ... Most top out at 60v. And maximum current rating.
The alternative is to roll your own. Making a DC supply, particularly when the regulation need not be tight is easy and there are plenty of sources on the net. Hint ... Obsolete PSUs from defunct pcs give plenty of current at 5 and 12 volt increments as a starting point.

 

[Renax]

http://www.skyrc.com/index.php?route=product/product&path=20&product_id=217

will charge most batts but only up to 6s

That one looks good, would like one that could supply higher voltages for charging big li-ion packs but its not a huge deal..

Any good electronic lab power supply will have, adjustable voltage and adjustable current limits.

Yea, but how safe is it to charge lipo's with just limited volt and current, isn't there some sorcery involved in charging lipos? (again, I don't know but assumed there was because lipo chargers are so much more advanced than a standard li-ion charger?)

A power supply that could supply 60v 5A and had some buttons to push for charging different kinds of batteries would be perfect, but I can feel my wallet going into hiding only writing this down, so I'll leave it at that.

 

[soundwave]

i have the sky rc mini and got it off ebay for 15 quid i think. all the cells i get are tested with it and if they dont have the mha stated then they go back.

there are clones of them mind made in china and there a bit cheaper.

 

[D8ve]

That one looks good, would like one that could supply higher voltages for charging big li-ion packs but its not a huge deal..


Yea, but how safe is it to charge lipo's with just limited volt and current, isn't there some sorcery involved in charging lipos? (again, I don't know but assumed there was because lipo chargers are so much more advanced than a standard li-ion charger?)

A power supply that could supply 60v 5A and had some buttons to push for charging different kinds of batteries would be perfect, but I can feel my wallet going into hiding only writing this down, so I'll leave it at that.

Battery university, hint hint.

 

[Renax]

there are clones of them mind made in china and there a bit cheaper.

Yea, I buy a lot of cloned versions for different things, but somehow for batteries and chargers I always find the money to buy good quality instead, a house fire somehow doesn't seem so attractive, so I try to avoid it.

Battery university, hint hint.

Send me a good relevant document less than 10-15 pages long and I'll read it, I don't have time for a year at a university to be able to use a battery..

 

[Danidl]

That one looks good, would like one that could supply higher voltages for charging big li-ion packs but its not a huge deal..


Yea, but how safe is it to charge lipo's with just limited volt and current, isn't there some sorcery involved in charging lipos? (again, I don't know but assumed there was because lipo chargers are so much more advanced than a standard li-ion charger?)

A power supply that could supply 60v 5A and had some buttons to push for charging different kinds of batteries would be perfect, but I can feel my wallet going into hiding only writing this down, so I'll leave it at that.

There is no sorcery involved. Simple science ... The cell will accept voltages of up to 4.2v, ... So 10 in series 42v max etc. Voltages in excess of this willl cause highly undesirable consequences. The lower the charging current the better for longer life and total charge deposit ed but since forever is a long time,we compromise and we use larger currents for the earlier part of the charging cycle and then slowly ramp up to the final voltage. Expensive chargers can have programmed cycles included. A simple lab supply will be more adaptable but will need human intervention. These cells also do not like being discharged below specific limits ... The chemical composition of the components changes and bad things also happen,.... Of which shorted lifetime is the least significant.
They also do not like I being heated either internally by excess discharge currents or by ambient temperature above 60 Celsius, again due to formation of rogue compounds.

 

[Renax]

Yea, I don't quite fancy sitting for hrs looking at a display to know when to swich from constant current to constant voltage. Can I charge with constant voltage from the start, (as is it will only take longer time?) I have loads of time, as I've previously stated I don't think Ill be riding my bike every week..
Nevertheless, the charger soundwave linked me to looks good and will cater all my current needs, I just like to buy something that I won't have to upgrade because I get a new hobby in a couple years, And I actually need a good car battery charger, that a cheap simple unit in it self but if I can have it integrated in another charger thats great, the car battery doesn't need charging every week either...

 

[Danidl]

Yea, I don't quite fancy sitting for hrs looking at a display to know when to swich from constant current to constant voltage. Can I charge with constant voltage from the start, (as is it will only take longer time?) I have loads of time, as I've previously stated I don't think Ill be riding my bike every week..
Nevertheless, the charger soundwave linked me to looks good and will cater all my current needs, I just like to buy something that I won't have to upgrade because I get a new hobby in a couple years, And I actually need a good car battery charger, that a cheap simple unit in it self but if I can have it integrated in another charger thats great, the car battery doesn't need charging every week either...

No. Certainly not! constant voltage means larger currents . The internal resistance of these cells is very small, so a high power constant voltage will drive Hugh current into the cells . Say you had set the constant voltage at 42v and the pack was at 36 V , and the resistance of the pack was 100milliohm ( a larger value than the norm), then the power supply will be driving 60 amps into the battery. ... not a good outcome.
In a constant current mode, the voltage ramps up and down in order to keep the current stable at a set value irrespective of the resistance of the load. Constant current with max voltage set is the best combination.

 

[Alan Quay]

Yea, I don't quite fancy sitting for hrs looking at a display to know when to swich from constant current to constant voltage. Can I charge with constant voltage from the start, (as is it will only take longer time?) I have loads of time, as I've previously stated I don't think Ill be riding my bike every week..
Nevertheless, the charger soundwave linked me to looks good and will cater all my current needs, I just like to buy something that I won't have to upgrade because I get a new hobby in a couple years, And I actually need a good car battery charger, that a cheap simple unit in it self but if I can have it integrated in another charger thats great, the car battery doesn't need charging every week either...

The IMAX b6 will charge just about everything, including lipo, li-ion, SLA, ni-mh, ni-cad.

I have a clone one, its been really good.

It will also discharge, so you can test capacity.

Sent from my HTC 10 using Tapatalk

 

[cyclebuddy]

The IMAX b6 will charge just about everything, including lipo, li-ion, SLA, ni-mh, ni-cad.

I have a clone one, its been really good.

It will also discharge, so you can test capacity.

Sent from my HTC 10 using Tapatalk

I broadly agree (I have an original and a clone)... some B6 clones are reported to have issues with resistor tolerance meaning individual cell balancing can be a little wayward, whereas the Sky-made original is spot on. The other limitation (for both versions) is charge limit is for 6 lithium cells in series (where that's needed), and the discharge limit is a quite slow 1-amp (being convection cooled, whereas fan cooled multi-.chargers are a lot higher/faster). Overall though I'd agree it's a very useful multi-purpose charger.

 

[Renax]

No. Certainly not! constant voltage means larger currents

ofc, don't know what I was thinking.
A lab power supply can then easily be used to charge a lipo battery, but there will be no cutoff switch, so if I forget about it it will still be charging (altho at constant voltage and very low amp) a long time after a dedicated charger have shut off?

The IMAX b6 will charge just about everything, including lipo, li-ion, SLA, ni-mh, ni-cad.

Yea, it looks good for most uses, but can't be used for my 48V Li-ion pac for example.. not that I need it to, but I might in the future want to buy a similar battery, and if i now buy a charger that can charge such a battery I can save my future self both money and shelf space. that being said who knows what kind of battery my future self will actually buy, so at this point in time the B6AC seems like a reasonable compromise...

 

[Deleted member 4366]

A lab power supply can then easily be used to charge a lipo battery, but there will be no cutoff switch, so if I forget about it it will still be charging (altho at constant voltage and very low amp) a long time after a dedicated charger have shut off?



Yea, it looks good for most uses, but can't be used for my 48V Li-ion pac for example.. not that I need it to, but I might in the future want to buy a similar battery, and if i now buy a charger that can charge such a battery I can save my future self both money and shelf space. that being said who knows what kind of battery my future self will actually buy, so at this point in time the B6AC seems like a reasonable compromise...

You can't use a lab power supplies to charge a lipo pack. You need a balance charger to balance the cells. Without balancing, the lab power supply can make the pack explode.