What batteries are you running?

[sikbrik]

I'm not sure if this is the right board to discuss the specifics of certain battery types vs others but I'm curious what everyone is running.

I've seen a lot of smaller SLA (lawn equipment sized), a few large SLA (Optima), a couple lipo or other lithium technology packs (but very few.)

I keep my eyes on some of the EV and electrical hobby sites and I've been corresponding with Quinc on using lipo hobby packs but I'm just so up in the air on what's "best" for a kart application in 2019.

Lithium saves space and weight, which is typically an advantage in a kart. Of course there's lithium polymer, lifepo4, liion, and more...and purpose-built high voltage packs or smaller packs in series - that's a topic by itself, and then charging all of them...my head hurts.

SLA saves money and adds some level of safety, understanding there's danger in anything if you're not careful. But the weight and space penalty is high, especially when trying to draw enough amperage to move anything over 1200w.

Can anyone share what they're currently running in what application, why, and how it's working out for you?

Disclaimer: I'm trying to use this info to help make a decision on what to power our 60v 2kw BOMA kart with, knowing we'll go to a larger 3kw or 5kw motor down the road (when this motor burns up) and I'd like to not completely re-power at that time, if it's avoidable.

Thanks!

 

[itsid]

Functional Artist mentioned used Chevy Volt packs a couple of weeks ago
(used but in good enough state for a reasonable price)
you'll find that thread I'm sure.

That IMHO is a good starting point for space/weight saving yet affordable batteries..
bonus: IIRC they're 60V packs

personally I'd avoid stacking (cheap) hobby packs...
expensive and well made hobby packs okay,
but then you could already buy new car packs
without spending any additional funds ..

the only EV I currently move around is a complete pre-made (allegedly) 1600W skateboard kit
that came with it's own batpack of course (LG 18650s) and it being on it's third charge as of now
I wouldn't dare to call it anything but good so far.
(for my taste it could've used a spark arresting connector... scary to hook it up at times)

frankly I've not even tried to run it at full speed yet
only had cheap bearings for my wheels handy, and since I fell off a few weeks ago
I'm not exactly rushing myself buying new ones

aaanyways.. no long term experience yet..
not even tested the motor power properly
(claimed 2x 800W.. but it's essentially RC outrunners soooo ...yeah *shrugs*)

'sid

 

[Quinc]

From what I have seen/read leaf battery pack is probably the all around best for: ease of use/cost/reliability/kwh

I went with lipo r/c packs and this has been my experience so far.

PROS:
50v 20ah with a 25C-35C rating (500amp continues) weighs less than 10lbs, and can be fully recharged in about an hour for only 226$. Other pro is they are modular so you can easily re-arrange for different volts and aH.

CONS: Lack of BMS. However, with a programmable controller you can adjust the battery cut off voltage and when you recharge them make sure to "balance" charge. Other con is you have to buy a decent charger and power supply.

To do that with SLA's you would need roughly 4x 40ah batteries that would cost around 250$ and take hours to recharge, plus voltage sag etc

If you need help justifying getting away from SLA look at the cost to battery life cycle and the better battery technologies win. Other benefit is you can make a small self contained battery box that you can move from kart to kart.

Lipo4 packs I have looked at are a no go because the max amperage output is usually under 50amps. Which is fine for most ebikes.

 

[itsid]

I wonder why you need 40Ah in SLA to compete with a 20Ah LiPo pack
I hope it's discharge current (I doubt it is tbh or you're looking at the wrong SLAs )
since capacity wise the SLAs win in that config (by a factor of two *cough*)

'sid

 

[sikbrik]

One place I've been encountering difficulty with SLA is discharge current, now that itsid mentioned it. A good quality AGM SLA battery spec indicates discharge at 1 to 2c, so if I need 40amps continuous, I need at least 20ah batteries and ideally something closer to 30 or 40ah. That gets pretty big/heavy for a kart when I get to 60 or 72v.

Has anyone had a different experience with trying to draw more than 2c (basically double the ah, as I understand it, which I may not) from SLA while still maintaining a decent life-span?

 

[Quinc]

One place I've been encountering difficulty with SLA is discharge current, now that itsid mentioned it. A good quality AGM SLA battery spec indicates discharge at 1 to 2c, so if I need 40amps continuous, I need at least 20ah batteries and ideally something closer to 30 or 40ah. That gets pretty big/heavy for a kart when I get to 60 or 72v.

Has anyone had a different experience with trying to draw more than 2c (basically double the ah, as I understand it, which I may not) from SLA while still maintaining a decent life-span?

From what I have read AGM batteries have a higher C rating. Calculator you can use to determine how many aH of lead acid you need.
https://www.batterystuff.com/kb/tools/calculator-sizing-a-battery-to-a-load.html


You can use up to 80% of a lipo and only 50% of Lead acid. Tons of info online from the ebike crowds comparing aH range between Lead and Lithium.

 

[Functional Artist]

How long do you want to ride or how long do you usually ride at a time?

A long time ago, I was told "ya gotta use big batteries or your wastin' your time".

My first batteries were 12V 35AH SLA solar batteries from Harbor Freight (~$70.00 ea & ~20 lbs. ea.)
Double Trouble https://www.youtube.com/watch?v=TRIKLdvGlTA&t=10s

I also used them on El Dingo https://www.youtube.com/watch?v=AV0BQPm5JFo&t=18s
...but, it was soooo heavy that the maneuverability was awful
…& the steering was worse (it was more like a suggestion than a command)

When I made the first kart for my kids I just used them small 12V 12AH SLA's. (~25.00 & ~8 lbs. ea.) & they rode ~45 min

So, I gave 'em a try on bigger karts & have done several now using them (12V 12AH SLA's) & I get ~30-45 min of run time (everytime)

* Them little 12V 12AH SLA can pack quite a punch

Example, here are some amp tests I did last summer
@12V I saw ~50A draw
@ 24V I saw ~64A draw
@36V I saw ~75A draw
@ 48V I saw ~80A draw

https://www.youtube.com/watch?v=aVip7AKtHZg

** There are other options available. I used (4) 12V 15AH SLA's in the Torsk kart (~$30.00 & ~10 lbs. ea.)
https://www.youtube.com/watch?v=wztjU3Uy4vg

…& (4) 12V 17AH SLA's on El Dingo II (~$30.00 & 12 lbs. ea.)
https://www.youtube.com/watch?v=zYWuGJTC0jQ&t=176s

*** It took me a few years before I even thought about goin' lithium & I'm still hesitant (added cost, added danger & added complications)

**** The Atom kart I'm building will use (5) 12V 15AH SLA's
5 x $30.00 = 150.00 + ~$25.00 for a 60V charger = ~$175.00 rolling out the door

 

[Quinc]

**** The Atom kart I'm building will use (5) 12V 15AH SLA's
5 x $30.00 = 150.00 + ~$25.00 for a 60V charger = ~$175.00 rolling out the door

Love your kart collection every time I see your videos!

 

[sikbrik]

Good info...the amp draw tests are interesting. Thanks for sharing that!
I still worry about battery life at such a high amp draw on lead and the charging complexity is what has kept me from pulling the trigger on lipo but FA and Quinc continually give me good reasons to consider both.

In the end, it's a kid kart and there's 4 of them (kids) so it'll get new motors and new batteries continuously so I guess I can change my mind later. Oh, the kart weighs <80 lbs without batteries and the kid is about 85 so I'm looking at the difference between a 180lb and 220-ish lbs total weight.

We'd hope he can ride for at least 30 minutes, mix of grass and road but pretty flat. 2000w 60v boma. It's tough coming off the dinosaur juice, where you can ride all day.

A purpose-built ebike pack still intrigues me at between $350 and $550...more expensive but simpler to maintain, light and small, etc.

 

[Quinc]

Keep checking hobbyking (not sure if anywhere else has sales?) and when the price is right give them a shot.

 

[itsid]

You can use up to 80% of a lipo and only 50% of Lead acid. Tons of info online from the ebike crowds comparing aH range between Lead and Lithium.

That sounds like a voltage mistake again tbh..
12V Lead acid cells must not be discharged to less than ~10.5V or they will not be rechargeable any longer (fully charged they provide ~13.5 Volts)
[exceptions are deep cycle cells wich can be discharged to just below ten volts or something.. didn't bother to look that up]

Lithium cells are typically nominal 3.3 Volts (fully charged ~4.2 fully discharged 2 Volts or less IIRC)

That makes ~80% of left over voltage potential in the lead acid and ~50% left over voltage potential in the LiPo
The main reason why same capacity Lithium bateries are lighter btw.
they have less 'dead charge'

could be coincidental.. but smells like a misinformation, no?

Now the point is: that says NOTHING about the capacity of the cells
the capacity is what charge fit's in between those two potentials.
At least around here.. the 20Ah on a lead acid pack do not include the remnants that you must not touch in order to keep the cell alive, the same holds true for LiPos in that regard..
Capacity ignores the left overs you aren't allowed to deplete.

The voltage drop is a sure indicator of a depleted battery,
that's why controllers check for 'undervoltage' and cut off to keep the battery safe.
unadjustable controllers always at lead acid levels btw..

So a LiPo pack will not be discharged to less than 48V on a 60V rated controller, just as a lead acid pack wouldn't.

you'll need a programmable controller to make use of a LiPo benefit.

And while it's true that you cannot (well SHOULD NOT)
draw more than ~2C from a 12V battery any length of time..
(usually 10% cycles are the minimum) so draw 40Amps from a 20Ah battery for 20 seconds and wait at least 200 seconds to try that again (within that 200 seconds you should stay below 20A[1C] )
to allow the battery to cool down again.
But the something similar holds true for Lithium cells...
they can overheat too (with more dramatic results btw )

The point is.. the max current is only drawn on any vehicle when accelerating from a dead stop..
or (if badly geared) climbing up a steep incline.
Most of the time in a properly geared vehicle the motors run at a much lower rate than max...

So constant current is far less than max current if you haven't made any mistake
and if you did.. the LiPo are far more dangerous than a lead acid cell..

That's why temp fuses are a must in LiPo packs
and cheap ones mostly lack such... the main reason I would stay away from those in EV applications.. cheap LiPos add another source of danger and the combo is terrifying.

LiPos are great but if you want to use them, you will need deep pockets or you risk catastrophic failure mode..
As a self aware adult you might be willing to take that risk.

but PLEASE do not allow kids near stressed cheap chinese lithium cells... that might end up badly.

'sid

 

[Functional Artist]

Good info...the amp draw tests are interesting. Thanks for sharing that!
I still worry about battery life at such a high amp draw on lead and the charging complexity is what has kept me from pulling the trigger on lipo but FA and Quinc continually give me good reasons to consider both.

In the end, it's a kid kart and there's 4 of them (kids) so it'll get new motors and new batteries continuously so I guess I can change my mind later. Oh, the kart weighs <80 lbs without batteries and the kid is about 85 so I'm looking at the difference between a 180lb and 220-ish lbs total weight.

We'd hope he can ride for at least 30 minutes, mix of grass and road but pretty flat. 2000w 60v boma. It's tough coming off the dinosaur juice, where you can ride all day.

A purpose-built ebike pack still intrigues me at between $350 and $550...more expensive but simpler to maintain, light and small, etc.

If ya haven't found it already, here is a lot of info on lithium batteries, in general & especially on the Chevy Volt battery packs
http://www.diygokarts.com/vb/showthread.php?t=38167


Looking on eBay it seems like they have went up ~$100.00 in the last year
I hear that they are getting popular with the home solar power folks.
Like putting ~200-400AH worth of Volt batteries in their garages or special built out buildings.
(enough to power their whole home)

Here is a 48V (45V nominal) 2kWh (~47AH) section of a Chevy Volt battery for ~$400.00
https://www.ebay.com/itm/2012-Chevy...p3:sc:FedExHomeDelivery!43607!US!-1:rk:1:pf:0

…& here is a Volt battery & charger combo ($750.00)
https://www.ebay.com/itm/48v-2kwh-4...=item33fd1b93bd:g:y3IAAOSwVCpcGTCi:rk:15:pf:0
(there is a lot of interesting info, in the ad, just scroll down)

…& there is also tons of info, on Chevy Volt batteries & on the proper monitoring & charging, in my ElMoto thread
http://www.diygokarts.com/vb/showthread.php?t=37062

 

[Quinc]

'sid

I read the aH comparison on multiple sites so maybe or maybe not. However, looking at other electric karts and ebikes people are getting longer ride times with a fraction of the aH.

As for being dangerous. Stick with name brand batteries with a higher C rating then you need.(If you need 100amps get batteries that can handle 200amps) I am more worried about losing money on the batteries going bad then I am with them lighting on fire.

Few steps I take to keep the batteries lasting as long as possible and not turning into a fireball:

• Do not go below 3.6v per cell
• Use a fuse
• Use cell checker/alarms on them while riding and check cell volts between rides. (also feel for heat)
• Charge them at .5C - 1C
• Balance charge every time
• If sitting for more then 2-3 days charge/discharge them to "storage" capacity.
• More for convenience then anything else but also makes them a bit more safe to keep them in some kind of container like an ammo box.

*List will likely change as I become more educated.

 

[Functional Artist]

...the only EV I currently move around is a complete pre-made (allegedly) 1600W skateboard kit
that came with it's own batpack of course (LG 18650s) and it being on it's third charge as of now
I wouldn't dare to call it anything but good so far.
(for my taste it could've used a spark arresting connector... scary to hook it up at times)

frankly I've not even tried to run it at full speed yet
only had cheap bearings for my wheels handy, and since I fell off a few weeks ago
I'm not exactly rushing myself buying new ones

aaanyways.. no long term experience yet..
not even tested the motor power properly
(claimed 2x 800W.. but it's essentially RC outrunners soooo ...yeah *shrugs*)

'sid

You gotta be careful.
How's your "wing" healing?

You gonna post some more pics? (the ones I saw were really kool!)

What voltage is your system?
...maybe a build thread? (we want more info)

 

[sikbrik]

I will probably do a set of four 4s lipo packs in series for 16s (for the 60v BOMA), with a parallel charging board and a balance charger.

I'll also likely house them in a fire retardant bag and either add a "firewall" between the seat and battery or inside a sealed metal box.

Now I just need to keep watching for sales on packs over 8000mah. The 10, 16, and 20ah packs are $$$ if purchased at full retail.

---------- Post added at 05:37 PM ---------- Previous post was at 05:36 PM ----------

And where do I find more details on the 1600w skateboard?!?! Sounds nuts!

 

[itsid]

You gotta be careful.
How's your "wing" healing?

You gonna post some more pics? (the ones I saw were really kool!)

What voltage is your system?
...maybe a build thread? (we want more info)

yeah that's what you get when you 'remove' the kicktail functionality with a third axis
and terrible tbh...
I'm afraid that'd be history within days 25 years ago..
but my meaty vessel shows signs of age or something
the shoulder is still not back to normal ...
got an appointment with my shaman early next year.

It's a low volt system.. 22.2 according to the website..
but since it's 18650 cells (3.6V nominally per cell) it's likely a 6S
with 21.6V really and a 24V max voltage.
that'd fit the 25.2V charger that came with it

I'll refurb the board and hardmount the driven axle to see how that goes.
(that missing kicktail is inconvenient to say the least)
And I still need to buy new bearings for the wheels

I doubt it'd justify a built thread really, but I might post a handfull of pics if you want me to.
but again.. it's a kit.. nothing I built just something I bought

'sid

 

[Quinc]

This looks like a decent deal on batteries.


Too bad no matter how I try and check out the price jumps to 110$ per battery.

---------- Post added at 05:24 PM ---------- Previous post was at 05:18 PM ----------

Also not a bad deal as long as you stay under the C rating. 12C on 5.2AH = 60amps max. So I would run it at least 10.4ah to be safe.

https://hobbyking.com/en_us/multistar-high-capacity-5200mah-4s-12c-multi-rotor-lipo-pack-w-xt60.html

 

[itsid]

well before I pay 90 bucks for shipping,
I'd pay 60 bucks for six more batpacks I guess and get free shipping..
Or what am I missing in that screenshot?

'sid

 

[Quinc]

well before I pay 90 bucks for shipping,
I'd pay 60 bucks for six more batpacks I guess and get free shipping..
Or what am I missing in that screenshot?

'sid

10$ per 10ah 6S(24v) lipo. Normal price is 120$ each. Also no free shipping over 100kwh.

---------- Post added at 05:45 PM ---------- Previous post was at 05:44 PM ----------

If those would have stayed as separate posts it would be more clear.

 

[itsid]

That's not my point at all..
my point IS.. I'd not buy 9 if I can have 15 for less from the very same website.

nevermind

'sid