Is that an enquiry to buy one?
for now, this is just my DIY project, as you can notice from the (rather long) thread 
Are these strips highlighted in yellow mainly there to connect the balance wires for monitoring each parallel row? I guess they would also carry current between each cell in parallel to keep them at the same voltage in the event that they donāt discharge at the same rate? In a perfect world (perfectly identical cells) these wouldnāt be needed. Of course they will never be perfect which is why we need a BMS in the first place. Am I understanding this correctly?
Edit: Do you really need the thick bus bars since there are so many parallel connections already that would help distribute the load? Just trying to visualize where the bulk of the current flow would be in a pack like this. I think without the yellow highlighted strips it would make it a 15P13S.
The way we connect the bonkas I think is technicaly 2P12S (not 12S2P) because the series connections occur first. This makes it harder to connect a BMS because I would need to connect it to all 24 cells instead of to 12 pairs.
This H-Type of nickel strip is used for the parallel connections, and for the balancing.
I canāt give you a precise reason why itās done like that (I probably forgot), but this is how it is usually done.
before I ādesignedā this battery, I read that book DIY Lithium Batteries from Micah Toll (you can get it as an ebook on amazon, I am sure I posted a link above somewhere).
The bus bars probably donāt need to be as large/thick, but they are still as important as the the four cables, as they carry the full load in the end - they are, together with the four 8 AWG cables the bottleneck of the battery pack.
Have you flown more with your battery or is it -40Ā° like it is in Canada? Did you remove the rubber insulation and build a box that breaths? Curious how it does with heat build up now.
today was a beautiful day, perfect for flying - but I was tied up at work, unfortunately. +16Ā° C and sunny!
Havenāt flown since, as I need a case for the battery first. I have something in the making and will report back once I have news.
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That is one thing I dont want to happen - work hindering good flight weather.
I work form 7am to 3pm, no real pressing things pop up in my computer repair too often - leaving me good time to get home, grab stuff and head out. Dont want to to leave stuff in car all day so the path from work to home is only a tiny divergence to the flight area. 20min extra to go home, load and back on the road to the point I would turn to get back on the path to flight area. Wind conditions are are still coming down by then anyway so I am in no rush unless it is a really calm day.
Cheers
Last week I ordered a 14s22p li-ion pack from Veconcepts.
Battery Specs:
14S Samsung cells
55Ah
350A Peak
200A Continous
On/Off low voltage switch built into BMS
Battery Power LCD Screen.
Battery wrapped in blue heat shrink for waterproof/protection.
Anderson Plug
Fireproof storage/charging bag.
Dimensions 310x350x100mm
Battery $1750 USD
Charger $75
Shipping $265
Takes about 15 days to produce then air mail 8-10 days
I got 160kv motors with my kit instead of the 180 for the higher voltage pack. Will post pictures when it arrives.
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They cut you a bit of a deal. Looks like they lowered your charger cost and raised the battery but still cut you some slack.
They dont give much specs - what is the weight?
Looking forward to your flight time on this!
Cheers
Awesome! I wasnāt aware that VeConcepts is already providing a battery solution compatible with OpenPPG. Did I miss the announcement somewhere?
I look forward to seeing the pictures!
I donāt have the battery weight as it hasnāt been built yet and they probably donāt know what itāll be until itās done. But Iām guessing itāll be around 35lbs based on how many cells there are and they weigh 45grams per cell.
No official battery announcement Iāve been working with Chris to get this first battery made. Iāll be the guinny pig for others to benefit from any changes that might need to happen before more are produced. Iām sure if you really wanted the battery now though that they would make it for you now if you donāt want to wait to hear how it works from me. Also donāt hold these prices for what you might pay, I just wanted to share what I paid but as like anything the price could change on the next one, Iām all for transparency. Innitially I was quoted about $1500 for a 45ah pack that had 300 amp max discharge and 120 continuous. The 55ah pack has much better specs for this paramotor, hoping itāll stay nice and cool and can run full throttle for decent amount of time.
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I donāt want to critizise here, but based on my first 9 minute flight, with the battery overheating, Iād be cautious.
I have ordered another 65 cells which I will add to the already existing 195 cells, so this will be a 13S20P Setup, and the high load is spread over 5 more parallel group.
The Lithium Ion was a good choice, in my opinion, but this cell chemistry has one big disadvantage over the LiPo pouch cells: the lower discharge rate (Amp draw).
Regarding the veconcepts solution:
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which cell is used? there are not that many that have high discharge (the LG HG2 that I use has 3000 mA with 20C, so my 15P setup is the minimum required for a 300A continuous discharge. Full throttle apparently goes up to 360A on the 13S/48 Volt battery
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a proper BMS is a Must for charging, and is advisable for discharging. Is one included?
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so the ācaseā is a shrinkwrap only? ā¦ I am not so sure about this. I did not only use shrinkwrap, but that foamed rubber additionally (which added not only extra protection, but a bit of thermal insulation). But that setup overheated on 80% throttle right after 9 minutes, and that on a cold day!
I have ordered an aluminum case now with vent holes and three strong fans to pull lots of air through in between cells for cooling.
Hi etienne,
I fully support the scrutiny and appreciate your comments. This is the only way we can improve our battery systems.
So this is a 14s 55ah battery pack using Samsung 25r cells. Letās divide 55 by 2.5ah per cell, giving us 22. So this is a 14s22p pack. Take 22x14=308 cells total. Each cell rated for 20 amp continuous. So 22cellsx20amp=440amp max continuous. So they are being generous with the 350 amp number.
The battery will come with a bms that supports 350amp continuous output power, as well will charge the pack. Chris says this pack will stay cool but testing will confirm this.
Your pack most likely is a little too small plus the insulation didnāt help. Iāll most likely build something to protect the cells, possibly an open ended case out of plexiglass.
Iām interested in this case you ordered can you share where you got it, did you custom design it?
Since you are using 160 Kv motors for the 14s configuration, doesnāt this also imply that the Amp draw will be lower as well?
I think I might see slightly less amp draw. Lower kv motors have thinner wire for higher voltages and less amp draw so in theory I would think I should see a slight decrease.
Actually, to use 14S instead of 12S the motor that would give equivalent power would be 150 KV. With the 160 KV he may have to lower the prop pitch to prevent from drawing too many amps at full throttle. Then he will have higher volts and lower amps at the ESC and motors and wires with the same power as the standard 12S system.
As for the battery itself the only way to reduce the amps per cell is to have more cells. No matter how you arrange the cells in series vs parallel each cell still does the same amount of work for a given load and a given cell count.
Good point. If I am drawing too many amps at full throttle Iāll have to try the 22x8 props
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I used SchaefferĀ AG GehƤuse - they originally started with a front-plate designer (for custom housings) but in the meantime they extended to build complete custom cases.
You can download a software from them where you enter the three lengths, and a script creates a case out of it, where you can place holes and such.
They also have a USA based partner/daughter: http://www.frontpanelexpress.com/
warning: itās not cheap ā¦ but to get a quick and functioning solution I decided to go for it.
Please post pics and your thoughts on the case when you receive it. How long does it take to get? Can you share cost paid?
Darryl, just posted a couple of pictures and information.
I did put it into a new thread though:
When you charge your battery up with this bms, how are you doing it, just using one of the two battery + - leads? Or did you make a Y cable so that power is going through all four battery leads? Curious what amperage charger your using and how long it takes to charge? I ordered this 10amp one. https://www.amazon.ca/gp/product/B078MYP68W/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1