Using RC Pack Nimh for pack instead of SLA

[chopper_elec]

Hey all,
I have come across a set of 10x 3000mah rc battery packs that I was quite familiar with as I used to do rc car racing.

The packs come as 6 cells, each 1.2v.

For their weight I think they are much lighter for power output then sla batteries.

All up I would have the equilant of 72v at 3ah, or if I run 1/2 of them in parallel so I would have 36v at 6ah which would be about the same capacity/volt as a set of 3x 12v 12ah sla batteries.

Would also allow me to fast charge the cells at around 3ah (or if I do them seperately it would be about 5ah)

The packs are very cheap, and i'd struggle to find an equivilant pack for the same price.

I was thinking about grabbing this charger too:
http://www.amazon.com/Tenergy-Charger-NiMH-Battery-Cells/dp/B003U51PT2

My only worry is that there is no balancing for all 60 cells. The only way to really balance them would be to seperate the cables and charge them seperately (not particularly hard just a bit more time consuming.

 

[nechaus]

Why not save your money and look for some second hand lithium cells?
there was also those cheapish a123 20ah Pouch cells, grey market/black market reject cells,
They might be another option as i remember the price was pretty cheap but quality was not the best..

 

[nechaus]

I have a 48volt 10 ah Headway pack with BMS + ac charger, Was intended to be used for my gf bike, I paid $550 for it, Id sell you it for $500
Never used, Never charged, All good voltage. 3 months old

If it was me using it, Id prob get rid of the bms as its limited to 35 amps and peak of 40 or 50 i cant remember


It came in a kit and needs to be wired up
Headways are the nicest looking cells i reckon, they can be used to make the bike look pretty awesome, like a piece of art



72 volt @ 3ah is so little, iv tried it with some junk cells before

 

[Hillhater]

I have come across a set of 10x 3000mah rc battery packs .....
....The packs are very cheap,.... .

There is more to consider than just price and weight
How cheap ? ..
What is their "C" rating ( how many amps can they discharge continuous) ?
What voltage sag do they experience.

Note: ..36v 6Ahr of 20C LiPo could be had for $100.

 

[nechaus]

They are one of the Better Lifep04 battery types...

They have better discharge rates than thunderskys, which can be great without a bms, but discharging them to fast will shorten the life for sure.


They say 10c , but good for 5 c continuous in my experience, Pulse @ 10 c for a short time, they do have voltage sag but nothing compared to SLA..
Maybe you should google them, they are pretty well known, The brand is headway, they are 10 ah cells The blue ones not the red... ( they come with the orange connectors to)
There is 16 cells in total

and a pic of some other guys large pack...


But anyway, 10ah is the smallest id wanna go on a ebike battery, certainly on 48 volts as well, i like 72/74 volts 10/16/24 ah for my ebikes

 

[nechaus]

in saying that, for $500 you can buy rc Lipo
x8 5s 5ah cells $36 each $300 with the shipping and then you could buy a bc-168 balance charger from hyena, they are such a good easy charger, they charge the cells by the battery leads
so for $400 you would have lipo + balance charger, and then you will need a 300 watt power supply for $50


20s /74 volt @ 10 amp hours capacity close to 700 watt hours, its a good amount

 

[chopper_elec]

Thanks for all the comments, i've always had a thing against lipo batteries from previous experiences with RC racing. I find them just a bit too voltage particular.


WIth the setup i'm planning, the 48v battery pack in 6 ah would be around $50. I sold my last 48v 16ah battery a few weeks ago, that I got for around $400+ shipping. Thanks for the offer on the lifepo4, but I would struggle to find that sort of money.

My budget is rather limited at the moment, even if I can test it out around the block with a 3ah battery it would be fun. I have so far not been able to test it out and its getting to me

I'd have a budget of around $100 at the moment, I know thats nothing but I am battling through with loan repayments and supporting my gf at the moment on the one income. The big budget items are a bit difficult to afford at the moment. Maybe I should hold off for a decent lifepo4 36v 10-15ah and be done with it.

 

[nechaus]

if thats the case,

Just get some SLA/nimh , they will be useful later im sure, and when you can afford it, upgrade the battery

 

[nechaus]

Perhaps some motorbike wreckers would have some cheap 12 volt sla's

 

[chopper_elec]

Perhaps some motorbike wreckers would have some cheap 12 volt sla's

Oh thats a good point actually, would most motorbikes run 6v or 12v I wonder?

Thanks for everyones comments

 

[nechaus]

my old motorbike had 12 volts.

 

[Hillhater]

you just know that any battery you get from a breakers is a waste of money !
..And even new SLA will die on you within months.
At $50, the NimHi is a better bet...if it can supply enough amps

 

[nechaus]

An sla wont die within months, my friend used some for about 12 months of heavy use, just have to baby them more than lipo, feather the throttle


yeah wrecker batteries are prob crap, iv had some larger 100 ah ones that delivered close to 40 ah @ incredibly slow discharge, less than an amp an hour
Which i though was good for the SLA, it looked new the battery at the time

 

[amberwolf]

All up I would have the equilant of 72v at 3ah, or if I run 1/2 of them in parallel so I would have 36v at 6ah which would be about the same capacity/volt as a set of 3x 12v 12ah sla batteries.

You may want to search up the previous several discussions of NiMH in parallel before you attempt that, as there are good reasons not to do that, and precautions you should take if you do, unless you like fires.

There may be copies or links in the ES Wiki.

Would also allow me to fast charge the cells at around 3ah (or if I do them seperately it would be about 5ah)

Just so you don't get confused or confuse other people, you can't charge anything at an "Ah" rate, only an "A" rate. The former is ONLY a capacity, never a speed or rate.

The packs are very cheap, and i'd struggle to find an equivilant pack for the same price.

See the many "cheap NiMH" threads for why they're often so cheap.

My only worry is that there is no balancing for all 60 cells. The only way to really balance them would be to seperate the cables and charge them seperately (not particularly hard just a bit more time consuming.

See those NiMH threads for how balancing works with NiMH--it's not like you might think.

 

[Hillhater]

An sla wont die within months, my friend used some for about 12 months of heavy use, just have to baby them more than lipo, feather the throttle...

??? ..so what is the point ?..feather the throttle because the sag is huge !
Baby them because if you dont ,..you kill them !
their capacity /performance drops off after only a few dozen cycles and before you have 150 ( gentle) cycles on them, they are just boat anchors.

so how much would 36v, 6 ahr ( useable ) of SLA cost ??.. $75 - $100.. ??
As i said before you can get 6Ahr 36v, Lipo for similar money.

how many times do we have to go back over this battery choice discussion

..i've always had a thing against lipo batteries from previous experiences with RC racing....

This isnt RC racing ..maybe you need to re evaluate your prejudice !

 

[chopper_elec]

An sla wont die within months, my friend used some for about 12 months of heavy use, just have to baby them more than lipo, feather the throttle...

??? ..so what is the point ?..feather the throttle because the sag is huge !
Baby them because if you dont ,..you kill them !
their capacity /performance drops off after only a few dozen cycles and before you have 150 ( gentle) cycles on them, they are just boat anchors.

so how much would 36v, 6 ahr ( useable ) of SLA cost ??.. $75 - $100.. ??
As i said before you can get 6Ahr 36v, Lipo for similar money.

how many times do we have to go back over this battery choice discussion

..i've always had a thing against lipo batteries from previous experiences with RC racing....

This isnt RC racing ..maybe you need to re evaluate your prejudice !

Yeah there are less chances for them to crash, I just don't trust leaving lipos inside the house charging, and can't stand having to be around them so close maintaining them. Even with the best chargers you need to keep an eye on them. Not to say that you don't with any other battery choice but i'd just be more comfortable with nimh and lifepo4, unfortunately lifepo4 is not available in my price range.

I've been considering this charger, but it will not be able to balance the cells, they would need to be maintained. I wonder if I can use a bms on a nimh pack?

http://www.all-battery.com/48vsmartuniversalchargerfor40-cellbatterypack1a.aspxy.

 

[amberwolf]

I've been considering this charger, but it will not be able to balance the cells, they would need to be maintained. I wonder if I can use a bms on a nimh pack?

http://www.endless-sphere.com/forums/viewtopic.php?p=647895#p647895

My only worry is that there is no balancing for all 60 cells. The only way to really balance them would be to seperate the cables and charge them seperately (not particularly hard just a bit more time consuming.

See those NiMH threads for how balancing works with NiMH--it's not like you might think.

 

[dogman dan]

When you charge that nimh, you can only do it 1s. So charging will be a hassle. But you'd at least be able to test you bike.

I think though, that for testing purposes, 2 ah of lipo would be a better investment. 2 6s packs of 2000 mph can't be so expensive? Wouldn't you rather have a small but good batttery than a nimh? Honestly, some cheap lead is still a better choice than the nimh.

 

[chopper_elec]

I know this sounds bad but I may end up getting started with a set of sla once and for all. If they last me 100 cycles, by that time i'll be able to well and truly afford a decent 48v pack. I would prefer some lag at the moment, it may be more gentle on my front forks lol.

Sorry all I know i've crapped on for so many threads, just a bit tricky finances wise and I want to make the most of the time. You have all recommended some fantastic options, I would love to go lipo, but I know it will just drive me crazy.

The rides around the block will be substantial enough to keep me going for the next few months of saving for sure.

I was going to grab a few of these. $76 posted for all of them is a fair compromise, I still have a 48v charger for sla here too
http://www.ebay.com.au/itm/ALARM-BATTERY-7AH-AMP-HOUR-SPOTLIGHT-AGM-SLA-UPS-12-VOLT-12V-/310468997129?pt=LH_DefaultDomain_15&hash=item484964f009

Wonder how many km I could get out of the 7ah sla at 48v on a 500w 24" front wheel.

 

[Jeremy Harris]

7Ah of SLA at 48V is a theoretical capacity of 336 Wh, but the practically achievable capacity will be around half this, maybe a little bit more, so perhaps around 170Wh. If you can keep the power down then you might get something like half a dozen miles from such a pack, but I suspect that, because of the very low cell capacity, the voltage sag will be such as to make this pack pretty much unusable at anything over 5 to 10 A discharge current. You'll probably find that the controller LVC would just kick in and kill the power pretty much every time you open the throttle (because of the sag), unless you set a really low current limit on the controller (like less than 10A).

 

[dogman dan]

Yeah, those will not get you very far. But bad as they will be, I'd say get them over the nimh. It would be different, if your nimh source was for 8 ah cells. But tiny nimh will be a real problem to charge.

Using those slas, it will help a ton if you do the ol pedal first thing. Pedal to 5-10 mph, then slowly open the throttle, and continue pedaling if the gear is high enough. Using that method, you should be able to reach 30 kph without using much more than 10 amps. Eliminating the big amp spike getting going will help extend the limited range of that battery.

Do some hunting around in your locality. Maybe you can scrounge up something to paralell with those 7 ah sla's, or like I was saying, get some tiny lipo packs later.

 

[chopper_elec]

Thanks for all the comments.

I have the original shop that I got my sla 12ah from, i'm tempted to grab a set of those instead, with nearly twice the capacity I should hopefully be able to get. Those will be $135 for 4x 12ah sla.

There would be around 14kg of weight (they should just fit in my panniers that i'm making) on the back wheel bracket which shouldn't be too bad (7kg per side).

If I was just to use the 7ah ones i'd be weighing in around 8kg which is more reasonable but I wouldn't get far at all.

Hmm its never easy, its a pity that these technologies are still quite expensive. Its amazing how cheap (and environmentally harmful) petrol setups are (not that i'd ever run one).

 

[amberwolf]

Have you tried the options i suggested in one of your other threads?

 

[chopper_elec]

Have you tried the options i suggested in one of your other threads?

Yeah mate there is no doubt your previous options are going to be the best long term, some money spent for a bit of fun instead of a bit more money a bit later on for a lot more fun will be much more worth it.

I think I should hold off for the battery first time round.

The ones i've been seeing on ebay again are 36v and 48v lifepo4 15ah and 20ah. I believe Vpower make up a 36v 15amp pack weighing in around 7.4kg which would mean they would use the spherical cells. I feel more comfortable with a cyndrical cell (more familiar) more than a pouch cell (reminds me of lipo lol)

There were a few other businesses on ebay that were selling 36v/48v in any size required, so I was thinking about getting one made up in a long row. This way I could mount it on the bottom bar so it will be quite slimline. I may even make a perspex box to keep it well protected.

 

[dnmun]

i think i have already warned you once not to buy a Vpower pack. you had an offer of a headway pack which is your best option if you are going heavy with a chopper anyway. do not use them without a BMS though because they always go outa balance. the headway BMS is good for 60A anyway.