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Razor mx500 (mildly modded)
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Discussion Starter · #1 ·
Alright so already my 3 12v 18ah batteries are quickly losing their longevity of run time sooooo I'm looking into overvolting the system with this...


My current set up is the mx500, speed limiter bypass in the stock speed controller and an 800w motor. One of the things I've noticed is this particular pack has 30A discharge current, which if im not mistaken is around the same range of discharge current of the 36v set up i currently run and seems compatible with the rating of my stock speed controller... am i right? If i am that means what for performance and reliability since ill still be overvolting the system with 48v... should I be looking for a higher discharge rate or is 30A right where I need to be without upgrading speed controllers/motor?

Another question I have is ride time... I've never used lithium ion batteries in anything rideable and have no idea how long a 20ah 48v pack would go for between charges. While I'm aware rider weight and conditions play a huge factor I'm curious... would 20ah be enough for say... 10 mile range on flat asphalt with my 185lbs on it riding full throttle with minimal stop and go? I'm really looking for range and reliability over anything else as it's currently my only means of transportation... but I only have like 300 bucks to sink into a battery replacement at this time and money will be tight as I've just had another baby.

Any info, insight and advice would be awesome here
 

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You will get about 30 minutes of run time out of it if it truly is a 20ah battery but you won't know that until you charge it from a dead state with a RC car charger or a lab grade charger that tells you how many ah you put into the battery.

If it is a decent pack and the discharge rate is 30 amps continuous ( not some BS 30 amps max ) then you will be fine and I will reiterate that if it's some Chinese crap rated for 30 amps Max and the only reason it got that rating is because some Chinese guy got it to do 30 amp draw for a tenth of a second before blowing it up then you will not be fine and your pack will go nuclear like a 99$ Christmas hoverboard...

A lot of times when I charge the Chinese batteries and packs for my friends and stuff I only end up putting in about half of the amount of energy that the battery is rated for part of the reason why I recommend building A custom pack yourself out of quality 18650 cells obviously it's going to be more expensive because it's going to be rated for it says...
16232015761901619335022649446590.jpg
 

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What's your poison? Mine is 40:1
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I personally helped build a few mx500 and mx650's, 24v 500w motor, one has a 36 volt 1000 watt fast scooters controller, the other one has a stock 36 volt controller. One is running a 36 volt 10 amp hour battery pack for an e-bike. It's not one of the blue ones but it is made in China. The other one has a 12 amp hour. Both will last an hour with mixed riding conditions.
One thing you got to know with overvolting is you have to stop every 10 to 15 minutes if you're consistently going Full Throttle. The motor is getting very hot. You could run 30 minutes but they are really hot at that point. But like I said they are China packs with a regular lithium-ion charger. All of my RC Chargers are only up to 6s and all of these lithium packs are 10s or bigger. A typical RC charger is not going to cut it.
Some huge expensive aftermarket charger would probably do it but these lithium-ion Chargers that come with the battery packs are fine and will charge the battery pack in about 4 to 5 hours. Best investment both those bikes have gotten will be fine. (Best investment over the lead acid)
Especially since you need to do something quick and decently cheap. Building your own pack is always the way to go but I have never ever built one and always bought the premades and have never had a problem.
 

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Another thing is you need a readout of the voltage. These two bikes have one. One is on the throttle and the other one is just a digital readout on the gas tank. Because once the pack gets down to about 36 volts standing, under load it'll get down about 31 and you do not want it to get below 30. So you have to be easy on the throttle and you can always keep it above 30. And these packs standing voltage has been taken down to about 35.8 and then charged up in about 4 to 5 hours back to 42. The highest I've actually seen was about 41.8.
 

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Yeah more than likely he will need a charger like this thing here and a good BMS it goes upto 72 volts at 18amps buttttttt yea $$$
16232097696886322402382489890427.jpg
 

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Razor mx500 (mildly modded)
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Discussion Starter · #6 ·
Thank you guys so much for the info! Definitely helpful. So honestly... knowing my set up of 800w motor and modded stock speed controller and with a budget of $300 what would you guys recommend for a lithium ion battery pack? Like I said my main priorities are distance and reliability as it's my daily transportation for a while but I certainly wouldn't hate having a little more torque or top end. With that said should i:

A. Overvolt to the 48v pack? There's also the 30ah option that's rated for 50a bit that seems a bit much for my mild build... and it's a little over my budget. Or I could go with the 20ah 30a max discharge 15a continuous discharge pack above and see what kind of performance and range I get (and hopefully not blow it up)

B. Stick with a 36v battery pack, shoot for a 30ah 30a max discharge 15a continuous discharge and worry less about cooking electronics but lose performance gains from overvolting... but maybe gain some range?

For the record I occasionally pull a kids 2 seater bicycle trailer thing (usually for hauling 2 kids with you) thats been converted to a utility trailer for grabbing groceries and hauling larger items that won't fit in a backpack. I usually only go about 2/3 a mile round trip with it max and will need to continue to do so (got 5 kids to feed lol)
 

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I would go with the bigger battery pack it will definitely last a lot longer if it doesn't have to work hard the smaller battery pack you will be maxing it out almost all the time one tip I can give you those high end E vape mod smoking batteries are ok 18650 cells the best are Samsung or Panasonic but you have to buy them from a reputable source you can spot the fake ones by weighing them!!!

Then think about this too eventually you're going to be forced to go with brushless especially with the distance that you want to travel Chinese brushes and commutators do not last long so if you have any kind of plan for a eventual upgrade you would want the bigger battery and then make sure that you're eventual upgrade does not pull more from the battery then what it's rated for how does the saying go spend $100 now to prevent spending hundreds later.
 

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I would honestly just by a decent e-bike battery pack, the to that I had used were 18650 cells. 30a max discharge with 20amp continuous. The one with the 36 volt thousand watt controller popped the 30 amp built in fuse after five or six rides. It was interesting, the 24 volt 500 watt motor pulled more than 30 amps it happened under Full Throttle from mid-range. Yeah remember these motors will pull all the amps that they can get.
Find a pack with a charger and you'll be happy of the distance and even if it dies after a year or two then you know what not to buy next time or company, excetera.
 

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And for right now I would stick with your stock 36 volts. Just me. But it should be the cheapest route for right now. That way you can see how it goes and figuring you will probably upgrade eventually.
 

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The packs that I helped you guys buy have a built-in BMS. That is one of the best things you can find in a 18650 pack
 

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Discussion Starter · #12 ·
Thanks again guys for the intel. So far both the 36 and 48v packs have the bms board and are rated at 30a max, 15a continuous. Will the 15a continuous be good enough or should I be looking for a higher continuous output? Also i do like the idea of the 48v battery lasting longer but im curious... by lasting longer do you mean run time or do you mean life expectancy? I could see it working in either scenario so I figured I'd ask.
 

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Discussion Starter · #13 ·
Oh yeah and from what I can tell both packs consist of the 18650 cells, but that also leads me to another question... why are the 18650s more desirable than the packs consisting of the flexible flat cells they use in laptops?
 

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18650s are what they use in Tesla cars as well. ( Thousands of them ).

And yes you're correct lipo ( lithium polymer ) is more desirable and 3 times more expensive the two battery packs it takes to run my RC truck is $350. If you have the $1,000 to sink into it 100% definitely go the lipo route!

I have found that most people on this forum are crying about trying to get the cheapest crap they possibly can get away with lol.
 

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Discussion Starter · #15 ·
18650s are what they use in Tesla cars as well. ( Thousands of them ).

And yes you're correct lipo ( lithium polymer ) is more desirable and 3 times more expensive the two battery packs it takes to run my RC truck is $350. If you have the $1,000 to sink into it 100% definitely go the lipo route!

I have found that most people on this forum are crying about trying to get the cheapest crap they possibly can get away with lol.
I mean if it were up to me I'd have no expense spared on this build... but the whole dad thing is super expensive lol
 

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I have tested the lipos on a pr200 pocket bike. So cool. But like mrkitty said, expensive and the same for a charger to charge all of them. Plus the packs max out at 6s, tou need at least 4-6lipos to run the bigger bikes.
That said....
48v you get more power, range is dependent on your AH. Here's the pack I picked up for the 1 bike
Does very well in the overvolted (24v 500w motor, 36v 1000w controller) bike.
If you overvolt to 48v especially your 800w 36v motor, you will be pulling 1000 to 1200 watts. The 20ah would be better, also might need a 40amp max with20-25amp constant discharge. You could always run a smaller battery but you take a chance not having the power you're looking for. And trust me I don't have my science down perfect. Just the a bunch of stuff I had learned over the past four years
 

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Discussion Starter · #17 ·
I have tested the lipos on a pr200 pocket bike. So cool. But like mrkitty said, expensive and the same for a charger to charge all of them. Plus the packs max out at 6s, tou need at least 4-6lipos to run the bigger bikes.
That said....
48v you get more power, range is dependent on your AH. Here's the pack I picked up for the 1 bike
Does very well in the overvolted (24v 500w motor, 36v 1000w controller) bike.
If you overvolt to 48v especially your 800w 36v motor, you will be pulling 1000 to 1200 watts. The 20ah would be better, also might need a 40amp max with20-25amp constant discharge. You could always run a smaller battery but you take a chance not having the power you're looking for. And trust me I don't have my science down perfect. Just the a bunch of stuff I had learned over the past four years
Good to know! The 48v 20ah and the 36v 20ah packs im interested in only claim 15a continuous discharge, is that gonna be a problem?
 

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I haven't tried a 15 amp continuous discharge battery but it should be okay. Basically you just got to be a little later on the throttle. You'll get that 30 amp discharge at Max but then it'll switch to 15. When I rode my buddies, both of them. You just had ro be nice and easy on the throttle, take about 2 to 3 seconds to get up to full throttle. You won't be full speed but you'll be full throttle. If you just crack it off the line which you can do because you'll have 30 amp discharge Max but anywhere in the mid-range is where it seems to be touchy and you just got to make sure you're easy on the throttle from mid to Max. It's hard to explain but you'll figure it out once you get a pack in. All I have to say is you'll be thoroughly happy because the lithium's just last longer don't die as fast and charge faster. When I get my own mx500 to keep, I will do that immediately. I did splurge and buy my kid a mototec 36 volts 1000 watt with lithium pack electric dirt bike. It's maxed out at 18 but the thing tear me through the grass at 190 pounds. What I love about the mototec is fluid front shocks and a gas charge rear shock. The tires are thicker, rims are thicker, spokes are thicker. Just a Better Built bike. But unfortunately it's twice the price of a brand new razor. Luckily I know a guy that's local. Apparently they're not too easy to get online right now
 

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Good to know! The 48v 20ah and the 36v 20ah packs im interested in only claim 15a continuous discharge, is that gonna be a problem?
Yea I would consider onley having 15 amps continuous a major problem you need 20 amps at least you have 30 amps burst about 20 amps continuous with the stock SLA batteries I don't know use this calculator to figure it out it all depends on your setup

Now remember with these calculators they don't take into account efficiency of the speed control ( wasted energy in heat ) and you need a few amps to run the rest of the electronics the speed control itself the throttle controller and other random devices that you're going to be using to monitor your amp draw and battery levels.


You would need two of those packs to make it work the way you want it to!!!

Trust me on this when you whack it wide open throttle and the BMS says no you don't have enough amps and cuts your juice off I'll be here to reiterate that you need a 40 amp BMS minimum... ( If it were me I would build a custom pack with a 50 amp BMS )

Remember the Chinese rate their stuff at the absolute Max with the battery charged all the way up when the battery is half full you can cut your amp delivery down as well.

Also if you run these batteries at absolute Max you can cut your life expectancy down to almost nothing if you spend a little money now you will have a battery pack that lasts you years instead of months...

The good news is if it doesn't work out you can always just buy a second battery and run two packs 👍
 

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Discussion Starter · #20 ·
Alrighty then I guess I'll be looking for a higher continuous output pack! Thanks for the advice
 
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