Campervan DIY battery build HUGE POWER!

today i'm going to go over the battery build i did for my truck a little while ago i basically built a battery out of a bunch of these cells they're relatively new chemistry they're called lithium titanium oxide and i think it's the best chemistry for an rv application uh the reasons for that are the the highest safety level of all the lithium chemistries and they've got a very long life it's going to be a big video i'm just going to try and include lots of information so hang in there they're normally used in high power cast euros due to their huge power output so they're considered the safest of all lithium chemistry this is a puncture test of a battery so i've got here a brand new penetrator 1000 an ncr18650b this was a panasonic design battery it's a lithium nickel cobalt aluminium quite often they're used in laptops and tesla have used them extensively for all your home battery cylindrical puncture testing i recommend holding them in a vise because it's nearly impossible to get a good clean hit and have them not spin around on you when they're sitting on the concrete oh so imagine if i had nearly a thousand of these stacked together similar results can happen from overcharging over discharging then recharging defects overheating so it's really nice to have the added safety of the lto chemistry so batteries have two types of electrical ratings first is the actual capacity and that's the amount they can hold it's sort of self-explanatory basically it's how long you can run an electrical load for and the second is the power output so it's basically how much power you can drain from the battery before you cause it some damage so if you look at this reenergy 100 amp hour lithium-ion phosphate battery you can see it's limited to 100 amps which is just over a thousand watts take into account the wiring and inverter losses so if you want to power something like an induction hob this battery isn't going to do it by itself each of these cells is rated for a 400 amp discharge which is roughly about 900 watts i've got 99 of these cells in my battery pack so that gives me about a 90 kva output just as an example this transformer on the side of the road here is 100 kva so the output of my whole battery is going to be just under the power rating of that transformer which will mean i can power 45 induction hobs additionally these can be up to around 10 times cheaper than an agm battery and i'll go into that later in the video so they'll also run quite happily down to minus 30 degrees celsius which you can't do with normal lithium batteries you need a battery heater otherwise they'll just died through dendrite formation so another thing they've got super long life rated for 20 000 cycles and up to 25 year calendar life which is you know just miles ahead of anything else so in this video we'll go over my design process my build we'll get into specs and lifespans of batteries i'll tell you how to prolong the life of your batteries you've currently got and obviously go into hindsights and things i do differently at the end so i'm going to link my part files down below in the description for you to copy if you decide you want to make something similar but before you do that it's important i tell you my qualifications and experience so you can decide whether it's a good idea or not i dropped out of high school i've got no trade qualifications most people are shocked to find out i'm not an electrician after i've wired something up and i've never built a big battery pack before on the surface nothing seems too complex about them so i'm hoping i can just build it up with a bit of common sense and it'll work out fine so electrically these seem to be about the most robust lithium chemistry batteries available however they're mechanically quite fragile some of the builds i see on the internet make me feel a little bit uncomfortable they've got a hard box which goes hard up against the surface this is only a thin aluminium cannon here can be quite easy to damage and dent another thing people quite often do is they'll tie two cells like this together with a bus bar where the cells have got the ability to flex like that which will put a big load on these studs and potentially crack and damage the battery so my design i'm going to support the cell itself on its studs i'm not going to allow any of that flexing to occur my battery itself is going to be 11 in series so they're all going to be end to end like this 9 in parallel with 99 batteries which will give around about 9 and a half kilowatt hours i think kilowatt hours is the proper measurement for battery capacity i know most people use amp hours and if you are stuck in the amp power mindset change it but it probably comes out to around 750 amp hour equivalent on a 12-volt system so with this battery build i'm using this 4040 section which i really like it's uh it's pretty solid things clamp together pretty easily so you can just put a like a coach bolt in the end there and then slide it on there crank it up that's going to be my foot i've made these little nylon brackets um coach bolts in in there and then these brackets can just slide into position and get cranked up along the rail so one of the advantages of building a battery like this is you can build it in a form factor you like so i'm going to build it in a space that fits underneath the kickspace of the kitchen bench so it's going to be slim but quite big so my bus bars i'm making around a four and a half millimeter thick aluminium i'm doing that so they've got a little bit of flex these batteries aren't all going to be an identical length and i've never seen anyone take this into account but i think if the bus bars are constraining their length because the bus bar is too rigid again you could put too much stress on individual batteries and cause them to fail prematurely so this bus bar has got a flexural stiffness of about one newton per 10 microns so one of the problems you get when you stack batteries together like this is you have to be aware of the expansion when they get hot they'll grow i chucked one on the freezer and the oven measured the length and it came out about 23 parts per million per degree which is exactly the same as aluminium so the rail and the battery pack is going to expand at the same rate with ambient temperature but say for example the interior of the truck is say zero degrees and i decided to put a 50 000 watt load on it and the batteries heat up to say 50 degrees celsius the batteries are now 50 degrees hotter than the rails that are supporting them and that means there'll be a millimeter either end the batteries will expand further than the rails are long so what i'm doing to allow for that there's 12 of these bus bar holders 12 bus bars all the way along four at either end i'm holding loose so that any expansion the rails and the bus bars can actually slide in these rails the center four i'm bolting tight so they're going to hold the battery rigid those four bus bars will have enough flex to take up any movement that they'll get so i'm fusing the battery for 400 amps which works out to be about 10 kilowatt which it's not heaps but it's going to be enough for me so the cells themselves are actually rated in that configuration for about 3600 amps let's get into the build i uh i drove up north to nice little beach town and built the battery up there so let's go [Music] [Music] [Music] [Music] [Music] [Music] [Music] okay so it's together and pretty much functioning um you'll have to excuse the background noise this is where i stayed last night pretty nice to wake up to this morning i've got this little battery management system links up with bluetooth and you know you can monitor everything you can set all uh the different parameters of the battery i've actually got that on a burner phone because i don't really trust chinese software that much so that was the build and i'm i'm pretty happy with it it's been working well so one of the the many problems with china is the suppliers and the legitimacy of batteries i found a bunch of people buying 40 amp hour batteries but only getting 17 amp hours 20 amp hours things like that so yeah i did a lot of research to find legit suppliers i'll link down below also just leave a comment if you're interested in buying some especially if you're in new zealand i've got a few left over so there are two main manufacturers of lti batteries there's yin long and toshiba i probably would have bought toshiba in preference but living in new zealand it can be difficult to get exactly what you want so i've been testing all my batteries and they've been coming out you know well above spec which is great so i've been using this thing as a battery load i don't recommend it at all the user interface is the worst of any user interface i've ever used of anything and it has a tendency to crash it has a tendency to lock up the software this fan is software powered when it gets up to 41 degrees it turns on but if the software locks up the fan never turns on and you overheat and cook this thing maybe burn your place down so don't buy one of these so due to the newness and low volume of these batteries there's not a lot of good information around about them i just about didn't buy them actually because i watched a video by will prouse on youtube uh he's a solo sort of battery guy it's generally okay generally got some pretty good information but he didn't recommend them at all he said they're only 80 80 85 efficient and uh you know which is not great when you're you know it means you need 20 more solar panels than you would ordinarily need but i had to think about it and it didn't sit right with me because if these batteries can charge ridiculously fast so these have got a charge rate you can charge them from zero percent to 100 in just 10 minutes and you can discharge them in six minutes you know the huge drains if that was case if they are only 80 efficient then the rest of that that 20 would be disappearing in heat and the battery would just get too hot if it was that inefficient i did some more research i found some papers showing 99 efficiency i also did my own test i put 41.85 amp hours into the battery and then the battery delivered 41.4 amp house which again works out to 99 efficient so wheel press was i think completely wrong in that video so the specified voltage range of these cells is 1.8 to 2.8 volts now looking at this discharge curve i made for my testing it shows no benefit taking below 2 volts or above 2.6 the only reason you'd have it above 2.6 would be for balancing okay so i'm going to cost your batteries so a lot of people consider the cost of the battery basically the cost versus the capacity of the battery the amp hours will well they should consider kilowatt hour rating so i don't consider that to be an accurate indicator of the battery cost every time you put power in or take power out of a battery it degrades a little bit and so that's what i consider the cost to be agm batteries always appear significantly cheaper than lithium cells but due to their low cycle life and low calorie life they can be quite a lot more expensive first off to keep agm having a reasonable lifespan you shouldn't discharge them really below 50 so that means you're only getting half the battery paid for anyway and potentially a third because of their inefficiencies so if we take for example this renergie 200 amp hour agm it's four hundred dollars um fifty percent deep the discharge we're only getting 100 amp hours it's 400 dollars divided by 1.2 kilowatt hours at 700 cycle life that works out at 48 cents per kilowatt hour which is they're perfectly expensive we'll take this renergie lithium ion phosphate battery nine hundred dollars eighty percent depth of discharge is rated for so it's 900 divided by 1.024 kilowatt hours divided by its rating of 4 000 cycles so that works out at 22 cents per kilowatt hour which is still expensive it's it's um i i rate that it's still being expensive so then we get onto these things so you should be able to pick these things up for around 50 to 55 they're about 92 watt hours per cell so that works out at 20 000 cycles to be cents per kilowatt hour out of one of these which is would say eight times cheaper than the lithium-ion phosphate and 17 times cheaper than the agm this might be a bit generous to these though because no one's going to be putting that amount of power in and out of the batteries so you know it might be closer to 10 cents per kilowatt hour but still a lot cheaper than anything else so we're going to battery life and extending battery life with agms you have to try and keep them as close to 100 as you can this reduces sulfation on the plates and extends their life a lot of people would think that lilium's the same you know if they keep keep their battery up around 100 it's happy but that's actually not the case you should try and keep it just below half especially if you're storing it here's a couple of charts of more conventional lithium-ion battery chemistry top chart shows the battery decay storing the batteries charged to 100 and the bottom shows it stored at 40 charge each of them show the various temperatures so if you have some new lithium batteries and you want to extend the battery life for them as much as possible and you can handle a little bit of power loss maybe set your charge controller to 80 rather than 100 so you're not holding them at a 100 and with all batteries try and keep them in as cool as space as possible to extend their life so that's why i keep batteries i can fit in the fridge in the fridge okay so hindsights and things i do a bit differently the battery's about six months old now and i haven't had to do anything to it it's worked pretty flawlessly so i'm generally pretty happy with it but if i was to build it again i'd make it 48 volts instead of 24. the i wanted to make it 24 because it matches the trucks voltage it's just easier to link the two systems together so 48 volt system would have been half as much to build for the the wire and inverter side of it um 48 volt inverter systems are really popular because they're used in a lot of off-grid situations they're you know they're pretty much the standard for off-grid instead of using loctite on the threads next time i'd probably use something like a polyurethane sealant adhesive just because i think the loctite might hold the threads too tight and if i have to undo them and take cells out in the future i risk damaging the studs because those studs are quite fragile i would have also used flange nuts instead of the star washers that i used so uh yeah sorry that was a long video but thanks for watching i appreciate you hanging in to the end i'm going to be doing other battery builds in the future i'll probably use other chemistries and i have a lot of other information about wiring and fusing there's a lot of misinformation especially on youtube around rvs that's all for now thanks for watching catch you next time

Channel: Brendon Tait

Views: 636,403

Rating: 4.8951144 out of 5

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Id: kYx097cVR48

Length: 16min 55sec (1015 seconds)

Published: Sat Sep 05 2020