18650 10S4P Battery Design

[Ianhill]

I've just built a 10s9p pack I picked individual fuses added to each cells instead of digitally protecting the battery as bms can fail and cause a fire, with a couple of lithium's in parallel the current is so high that it can melt the fuse wire nearly instantly if one cell fails, I then use low voltage alarms on a 10s balance lead split into 2 5s jst connectors and a 300w 10s I charger, i feel its safer charging more accurate balancing, only downside each fused cell adds more resistance but as your paralleling them up the resistance of the pack will be low and provide high peak power. There's a big argument to BMS or not and I choose not too with my 10s9p pack on a scooter I've covered many miles with no issue running a 36v 500watt unite motor and pulls well over 1000watt uphill I climbed a 1000ft mountain the pack was barely warm to touch , I think a single cell pack needs a BMS as the current can't reach the heights of a multi parralel pack, Tesla cars packs are fused in series and parallel configuration I believe as they use so many cells faluire current would be in the kilo amp range but obviously they will have a very safisticated BMS along side.

 

[Ianhill]

I've stood the cells upright in a 10*9 config its to big for a board bit fits a razor e300 scooter perfect, I've used surpless Samsung cells I found 2a 3c , like u mentioned the key is getting the rating correct or the fuse is useless do your homework and you will be very happy with the results, my next project is adding a 5s booster circuit to get a 60v output around 30mph and around 20 miles range without stressing the old girl

 

[magiced]

This looks cool! I'd like to do something similar as the ground clearance on my board is abysmal.

What BMS are you thinking of using?

 

[Ianhill]

IMO a BMS of that quality will only be a fragile fail point the whole pack can be fried and I was only just reading about a ebike fire in a garage due to poor BMS, spend the extra money and get a decent rc charger u can check the resistance of the pack capacity and voltage much easier and more regular so u know your battery's health and when not in use can be completely isolated as u don't want to burn your house down, It would take up less room to just having balance leads and can charge the cells at the correct C rating as the BMS cannot choose it highest charge rate its preset.

 

[Ianhill]

Because your by bypassing for discharge the under voltage protection won't be used and it doesn't state its charge current each cell likes to be charged at .5c to 3c range depending on the cell this board doesn't state its charge current so can't work out charge time or if its in correct parameter's, U could easily over discharge the pack by bypassing for discharge, give it a go u maybe lucky but at the very least with this you will need a way of monitoring voltage under load if bypassed im not trying to be a pain but iam a electrician with a bit of Rc knowledge.

 

[Ianhill]

Double up the balance leads then split one set into a 2* 5s jst connector and use 2 lilo low voltage alarms along side the board, personally scrap the BMS board charge with the balance leads and direct feed then use a xt90 connector to mate the pack to the board when charged and plug in the low voltage alarms same space plus u have a rc hobbie charger then to charge other packs etc. The beauty of an intelligent charge is you set the charge rate and voltages can check pack health see resistances much better option if you are electrical savvy if not stick to the route you are on.

 

[Ianhill]

I know that I know nothing about boards and trucks etc but with a battery its best to be safe than sorry, I hope your board turns out to be a beast, I get some laughs when they see a scooter first thing they say is it petrol lol

 

[Ianhill]

I take it your having them professionally spot welded, I think you will be very pleased with a 4p yoy should get a good 40mins I would have thought.

 

[Ianhill]

Iam glad I was of assistance, It took me 2 months to design and build my pack I conditioned each cell charge and discharged singulary first to make sure they were a reasonable match and in good health then I built it, I would love to turn a hobbie into a living building packs but the price of lithium cells in UK means not much demand. My next pack will be built of 40152s headway cells much easier to work with and change config at a later date and imensive discharge capabilities and long lasting.

 

[Gatwod]

Yes they are being made by a battery manufacturer who specializes in custom packs. When they arrive to me they should be ready to go already shrink wrapped with connectors and balance leads etc. It actually ended up being very cost effective to have them custom made from a manufacturer instead of building them myself which I also considered.

I gotta ask brotha...what's the going rate on a 10s custom battery pack? I've also considered making my own vs. S.P.A.C.E Cell vs customs packs...so many options! I need more juice!!!

 

[zool774]

wow great news!!!!!!!!! I was looking for a custom lipo battery, and Im really interested to buy one asap, someting like around 8S 10000/12000mAh.
Please let me know if is doable and cost range, please.
thanks

 

[jamesonotc]

I ended up picking up a pack from Subcreative in 10s4p just the same as him.

The quality and craftsmanship you can tell whomever built it has done this quite a few times before, Im now just waiting too for my charger to arrive and I will be finalizing my build.
I might just need pyscotiller to make me an enclosure specifically for this package.

 

[rmrf]

I wonder how batteries are connected with each other (series connection)? With wires or metal strips?

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