You know future man
I think these dudes made a board that could actually be really good for your purposes…
I’m impressed with the Overlander
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I mostly agree with you, for an off the shelf product it does look pretty cool. But there are several things i don’t like about it for my needs…
- Gear drive - no thanks. I want belts for both obtainability and ease of replacement parts
- Suspension - no thanks. More parts, more problems. I’d rather have flex in the deck to absorb harsh bumps, although i do have my doubts about the ability of the Phantom enclosure to be able to flex properly without cracking.
- Trucks - no thanks. They look horrendous and difficult to design things to mount on them like lights/fenders/bull bars
- Replacement parts in general - i have no idea how that thing is built and what level of difficulty would be involved in replacing parts. A core design tenet of my build is that everything should be reasonably quick and easy to replace.
- Finally… DIY - i miss it! I wanna build my own monster!
I think it looks like a great board and i think i’d really enjoy it, but there’s too many boxes that it doesn’t tick for me 
In other news… tracking for my wheels doesn’t work and Lorentz said it could take up to 30 days from the shipping date. Because the tracking doesn’t work at all, i don’t really know when they were shipped, so i have no idea when they are coming, but hopefully not too long now 
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Could always preempt the problem by cutting the segments and taping them back together, then a whole bunch of butyl to seal each segment. Just an idea!
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Yeah very similar thoughts have crossed my mind and will continue to cross my mind until i do some science and determine how much the deck will flex on it’s own vs how much the enclosure will flex on its own…
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Yeeeewwwwww! Received confirmation from @Tony_Stark that we’re good to go with Radium electronics and motors, so this board is very much DECIDED now.
The only thing left to commit to is which cell I will be using, but that’s inconsequential at this point as it’s gonna be a while before i can afford 300 bees knees cells anyway.
Still UNTITLED, but that will work itself out in good time!
FUCK YEAH!
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There are new teaser 6.0ah power cells.
https://www.alibaba.com/product-detail/Genuine-Great-Power-INR21700-6000Q-3_1601898533473.html
The GreatPower 50Q is a good performer, up there with the top performing 5.0ah power cells, so hopefully the 60Q is also a top performer among the 6000mah nominal cells
There is a decent chance this cell is the same as the Trydan Tech 6000t which has been tested.
Here is the 6000T compared to the Reliance RS50 at 25 amps continuous:
It delivers 16.96wh compared to the RS50’s 15.47wh down to 3.0v, and stays a bit cooler.
Edit: Added the BAK65E too.
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How about “I’m quitting DIY… LOL JK”
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Hmmmm one of my favourite bands at the moment The Skinner Brothers have a song called NO JK… but they also have a more appropriately named song… XL BULLY… Goddammit Benji you’ve done it!
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Dude they’re soooo good. Been banging Mark of the Beast for weeks
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Hell yeah dude, i ‘ve had them on solid rotation for the last year, their EP with Ren is a fuckin banger
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After hearing about @Flyboy recent issues here Homebuilt, Overengineered, Next-generation Drag And Cannonball Racing Vehicle - #95 by Flyboy , i am slightly concerned about running my trailer battery directly to my ESCs, mostly because I do not understand enough about inductance and capacitors to feel confident risking thousands of dollars of parts.
I had a conversation with the AI machine last night around that and several other options and I was pretty amazed at just how much it confidently got completely wrong. I understand your disdain @BenjaminF.
Pretty much everything it said to me triggered my bullshit alarms, and then when i questioned it, it was very apologetic abd told me it was wrong. This went on for literally hours, it leading me down rabbit holes, me calling it out and eventually, me deciding that I am going to be far more vigilant with any use of AI in the future.
All that said though, I think it did pointme in one direction that I might like to explore. Rather than directly connecting the batteries in parallel and risking potentially devastating voltage spikes to the escs, I wat to consider using the trailer battery to charge the board battery.
Given the batteries will be identical, i won’t be able to use a boost converter, it’ll have to be a buck or potentially an MPPT device? I did start looking into some Victron MPPTs but nothing that I found could output 75.6v.
Similarly with the buck converters, I couldn’t really find anything that would be anywhere near powerful enough. I think i’d realistically like to be able to charge and ride at about 1kw, so i’d like something rated around 2kw because all the ratings on those things seem pretty unrealistic in my previous experience with them.
Any thoughts from the brain trust?
I think you should find a DC to AC inverter and run a normal lithium charger off of that, no? Maybe I’m misunderstanding how you’re intending to set up the system, but the mppt charger should charge the trailer battery off of the solar panel, and the lithium battery wall charger should run off an inverter connected to the trailer battery, and those two charging systems should be able to operate independently.
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I was thinking of using the trailer battery as the input to the mppt, rather than a panel. I know @DerelictRobot has fucked with mppt devices for charging before, so it can’t be a TERRIBLE idea… can it? 
A dc to ac inverter to an ac to dc charger seems inefficient, and a 2kw inverter is gonna add some serious beef. I’d rather avoid that, but i’d accept a beefy dc to dc buck.
Ah, I misunderstood. So the mppt is just supposed to go DC to DC directly and avoid the need for any more components? I guess that makes sense.
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Maybe JKESC that is pretuned to specific motors might not have any issues? IDK.
I have an CC/CV booster that claims it can handle 40 input amps, and I have used it at continuous 38amps with ~12.5v input. That was a little over 400 watts output with Booster output set to 41.75v, and some 60 watts turned to heat at this low input voltage.
Say the trailer battery is Just a battery to power a CCCV booster. The battery could be built around the trailer dimensions and use high energy cells, and keep the power cells in the Esk8 itself.
So a 16S14P trailer battery with Amprius SA1126500mah or more budget friendly FEB21700G(6.5ah).Either is rated at 13 amps each, so Halve this and 91 amps continuous Should keep them under 55C, but the 40 amp CCCV booster is limited.
16S nominal is 57.6 x 40 CCCV booster amps is 2304 watts x 0.9 for Booster inefficiency is 2073 Watts charging potential at 73.8v 18S ( at 4.1vpcell)
That would be about 28 amps charging current if you were to dial up 40 input amps.
When You stop to charge, have one charger for 18S, one for 16S, and then no worries about hooking up batteries in parallel at slightly different voltages.
This is my ‘1800 watt’ booster that I have pushed as high as 36 amps input continuously. It has a Fan on a pretty big finned heatsink which cycles on and off with heat.
Print up an enclosure for it and move the fan to the side for lower profile and so it can blow over inductor too. Pot it. Design Push pull fans on either end if you are feeling fancy. Cheap enough to print two and carry a backup.
I really like my 7s2p150wh portable charger holding my 10s2p 360wh Esk8 battery at 41.5v for a few miles. Spicier throttle, more range, and when portacharger is depleted I can leave it on the deck between my feet or put it into backpack, or Fiona’s Chariot.
So consider designing your trailer around a wide flat High energy density pack designed solely as a portable charger, with a super low center of gravity, and pleny of storage. It Need not have the high $ power cells, save those for the Esk8 enclosure.
THE 1800 CC/CV booster fed 16S voltages outputting 18S voltages can exceed your 1000 watt charge and ride desire, and likely run far cooler and more efficiently than mine being fed 12.5v and outputting 41.75v.
You can also feed it 12S voltages from batteries you might already have, or even M18 power tool packs in an emergency.
I’m working around the design constraint of the trailer battery being identical to the board battery so in a worst case scenario, i have a backup board battery that i can pull out of the trailer and put it into the board, so I really am limited to a step down converter.
I have searched for high power buck converters in the past with no luck, the highest power one i have found is only 400w, but I refuse to believe that they don’t exist, they have to
I’ll keep searching for bucks and mppts that could suit my use case but is there any other way that I can use the trailer battery to charge or parallel with the board battery, while being isolated from the ESCs?
The output from escs to motors is not a concern to me, rather the long wire length from the trailer battery to the esc causing inductance and voltage spikes that could cook the escs
It increases part count for the same reason as inverter-charger, but you can put a boost converter between the trailer battery and the DC-DC charger in the same way.
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I’d really like to avoid daisy chaining components like that. If that was my only option i’d lean further towards a cap bank
I know, I’m just not aware of any chargers that can charge to a higher voltage than what they’re being supplied with. I’d love to be corrected cuz that would be cool
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It knows nothing, it has no ability to understand or apply knowledge, it is incapable of changing its programmed behavior which produces the bad outputs. No amount of “correcting” it or pointing out its mistakes will change its likelyhood of making a similar mistake in the immediate future. Every example of it being “right” is either a broken clock being right twice a day, or it actually being wrong but in a way that you didn’t catch.
It is, by design, a “plausible-sounding answers” machine. Or, put another way, it’s the worst apprentice you’ve ever met on the jobsite 
Yeah, an MPPT is the exact thing you’re looking for. Most are designed to boost and buck to suit varying input voltage (i.e. a solar panel as the sunlight changes, or in this case your trailer battery draining) and output voltage to directly charge a battery. Some even do the proper CC/CV liion charging curve, though that’s not super critical if you’re just using it to maintain the charge of your board battery while you ride.
You don’t need multiple devices in series, you don’t need an inverter or a separate boost converter. Just come to terms with the cost and size of a decent MPPT for your needs and go with that.
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