Backfire 2017 G2 battery pack recommendations

[galvatron1]

Looking for something to replace my 10s2p pack, what is the safest & lasts the longest in terms of cycles & range?

The only 2 options I know of are going with:

Backfire’s vtc6, which I don’t know the how many cycles, safety or how well the battery pack is manufactured

Or

Meepo’s 40 T which I don’t know the how many cycles, safety, how well the battery pack is manufactured or if it will fit in the enclosure and if the connector is compatible

I’d like to know if you guys know which cells are currently the best for my application and ideally where to purchase such pack already pre-built to plug and play, with the same safeguards as an em3ev pack? Thanks!

 

[Hillhater]

I’d like to know if you guys know which cells are currently the best for my application.... Thanks!

But, you dont say what your “application” is ?

 

[galvatron1]

Using it for food delivery, 8 hour day. Don’t need to go faster than 12-15 mph, thanks!

Found out since, the meepo pack won’t fit my enclosure. So the questions remain for the vtc6.

 

[amberwolf]

Using it for food delivery, 8 hour day. Don’t need to go faster than 12-15 mph, thanks!

8 hours of continuous riding (presumably lots of stop/start traffic riding) at 15mph is going to be one huge battery, even if it's all completley flat roads with zero wind of any kind.

15mph (assuming no kick power for simplicity of calculation) in stop/start traffic with around 200-250lbs of board, rider, and payload (guesstimate since no data given) is likely to take around 16wh/mile or more. This simulation is a guess of your configuration; you can play with it to make a closer estimate.
https://www.ebikes.ca/tools/simulator.html?hp=0&frame=fat&wheel=90mm&motor=MSkate90mmX2&autothrot=true&axis=mph&throt=47.2

At 15mph, times 8 hours, that's 120 miles, times 16wh/mile, is about 2000wh, or 2kwh.

My 2kwh battery is about 35lbs, and the size of a good stack of hardback books.

And that doesn't account for any hills or even slopes, or any headwinds, which will dramatically increase your power usage and shorten your range, or require a potentially significantly larger battery pack to get the same range.

So I think you will want to use swappable battery packs, and have a charger setup at your central location, with multiple smaller packs (a few hundred wh, perhaps--something bigger than the very longest possible trip you'd make would ever require).


For which pack is better, I don't know, but you want something that can easily handle the continous current draw of the board, without much voltage sag or heating of the cells. If all you hae room for is 2p, thats probably a high current draw per cell, which is hard on the cells, and decreases their lifespan and performance.

 

[galvatron1]

Even 8-12 mph max, is what I do working, realistically. Will slow speeds put less strain on the battery, while heavy stop and go traffic regen a few more miles? Are light electric skateboards twice as efficient as 60+ lb. ebikes, due to their lighter weight & harder durometer urethane wheels?

With a 36v 4.4aH 10s2p battery pack, I was eeking out 2.5 - 3 hours of work, because of hypermiling. Keep in mind, some of that 3 hours is waiting for orders to be ready or going in buildings to drop off food, not continuously riding all through out. I do enjoy the fact my board is only 14 lbs..having the world’s lightest EV has advantages. Carrying it with me, gives me peace of mind = priceless.

May have to consider carrying an extra board or use a board with an easier swappable pack like the Revel Kit, though. Thanks for the suggestion!

 

[amberwolf]

Even 8-12 mph max, is what I do working, realistically. Will slow speeds put less strain on the battery, while heavy stop and go traffic regen a few more miles?

Slow speeds will be slower. Whether they put less strain on anything depends on the system and the conditions. Most likely they will increase runtime, but probably not by all that much. Regen--usually this is a few percent at best, on bicycles--I expect similar on boards. You'd have to have a wattmeter that can read current flow in both directions to measure this and test whether it makes much difference or not.

So if you got say, 10mph average, and had two hours out of the three actually riding, you went 20 miles. Let's be generous and say you get 5% regen, you'd get one extra mile's worth of power back.

Are light electric skateboards twice as efficient as 60+ lb. ebikes, due to their lighter weight & harder durometer urethane wheels?

No, because you still have your weight to get started, which is the majority of the weight in any of these small systems, and your body's wind resistance, which is the majority of the wind resistance, too.

Startups from a stop may be more efficient with the smaller wheels and the slightly less weight, you can compare this on the simulator I linked above. If you install a wattmeter on the board you can actually measure what you use under various conditions, and directly compare it to other people's reported wh/mile here on ES and elsewhere, for the same usage conditions.

 

[galvatron1]

I went with the vtc6 pack from backfire last night. I also upgraded the ESC, they claim 15% greater efficiencies, but not sure how to test that.

I just saw on their IG post from a while back, they discovered a flaw in their suppliers bms, halted shipping to return them to supplier & offered replacements battery packs to anyone with the 2 serial numbers affected. That shows Randy cares, and puts my fears & doubts to rest about Backfire’s safety as a company. My biggest fear was that my $400 budget board from China would catch fire in my house, but I feel safer now. Great to see a budget company from China that does the right thing by their customers for safety.

My only problem now is what to do with the old ESC & battery pack?

 

[amberwolf]

I went with the vtc6 pack from backfire last night. I also upgraded the ESC, they claim 15% greater efficiencies, but not sure how to test that.

That's unlikely--the ESC by itself isn't going to noticeably change system efficiency, unless the old one was radically inefficient vs a new one that is incredibly efficient.

Marketing departments at work, helping people spend money they don't need to.

It is your usage vs the equipment vs the conditions that changes efficiency most.

My only problem now is what to do with the old ESC & battery pack?

Build another board?

 

[galvatron1]

This guy on YouTube connects the batteries in parallel. Is it safe to do? Someone in the comments mentioned it’s unsafe because it doesn’t have a limiter. The guy making the video retorted he’s done 1,000 miles, it’s not a problem. Who’s correct?

Here’s how he connects the 2nd battery:

[youtube] https://youtu.be/QfYvA-OaAds[/youtube]

 

[amberwolf]

This guy on YouTube connects the batteries in parallel. Is it safe to do?

Depends on usage, and actual batteries/condition, and which connector is used.

You do not want to connect one battery into the charge port of the other one, only directly connect both of the discharge ports to the board's battery input.

If they are identical batteries, and fully charged (or otherwise at same state of charge/voltage), then they are safe to parallel at the discharge ports, especially if they have no BMSes.

BUT: If the BMS on the batteries has separate charge and discharge ports, then you want to disconnect the charge ports when discharging, and disconnect he discharge ports when charging, so the BMSes can properly manage and protect the cells in each mode.

IF the BMSes both have just one port each, and charge/discharge is done thru that, then it's safe to parallel them and leave them that way for both charge and discharge.


If the packs are not the same number of series cells and the same chemistry, then they will be different full and empty voltages, so while they can be used in parallel, they can only be charged as full as the limit of the lower voltage pack, and only discharged as low as the limit of the higher voltage pack, so you can't use the full capacity of either one.


If you want an extra layer of protection, you can add a fuse on each pack's output (either positive or negative, shouldn't matter), with a rating higher than what the board needs to operate at peak; it's just there to cut off the pack from the board and the other pack in the unlikely case of a dead short anywhere.

 

[galvatron1]

Any ideas what do with the dead battery pack?