Home Life on the Road Bus Projects

We Built a Lithium Ion Battery Bank!

After another all-nighter lithium ion battery research session last Tuesday, we slept in on Wednesday and then made our way down the hill from Flagstaff into Phoenix. With every foot of elevation drop, the temperature increased and we were soon reminded of why we escaped to Flagstaff in the first place.

The long 6% grade descent into Phoenix.

The bus did incredibly well on the descent, and we learned the advantage of a jake brake – they not only sound cool, they’re very useful! After our first major drop in elevation, Chris exclaimed

‘If I ever meet Jake, I’m gonna kiss him!’.

In the 7000 foot elevation drop, Chris only had to briefly engage the regular bus brake once or twice, the rest the Jake handled with ease.

Unfortunately our late departure and stops at every rest stop, often of which involved more research and ordering parts that would be needed for the battery install – put us arriving in Phoenix too late to meet up with the supplier.

But never fear, we received an invitation inbound for bus parking, power and dinner with a fellow bus nut. Well actually, they’re the owners of one of the buses we looked at in our search, Bus’Osaurus. When our friends we rendezvoused with in Flagstaff walked into our bus, they decided they too needed a bus as their full time home.. and actually bought Bus’Osaurus this week!

We hadn’t realized how contagious this bus nut disease is, so caution to anyone who invites us over.

Battery Day

Thursday morning we arrived to Elite Power Solutions, who specializes in lithium iron phosphate (for the geeks amongst you, LiFeMnPO4 is the actual chemistry) batteries for electric cars, motorcycles and scooters. Our research into the state of lithium for RV use lead us to them as a reputable supplier of a non-combustable safer battery than previous versions of lithium ion.  When we reached out to their engineers they were happy to work with us to create our RV house battery solution. And they further offered us a great price on the batteries that sweetened the temptation to pioneer into the land of untested bright speculations.

We were anticipating when we arrived our time with them would be focused on getting the batteries installed into the bus and hooked up to the various other parts we had shipped to them – including our fancy new pure sine inverter, high end relay switches, fuses, and such.

Disassembling the 100ah Lithium Ion Packs

Little did we know that the batteries came in packs of 4 cells that make up 100ah at 12v. And to create our bank of 500ah, we’d have to manually disassemble 5 packs and re-assemble them into 4 packs of 500ah at 3.2v and hook them up in parallel. We soon learned how tedious of a process this is, which includes having to unscrew every jumper and all the assembly plates.

Re-assembling the packs into 5 cell, 500ah at 3.2v.

We then had to re-assemble the binding plates to support 5 cells each, and press the cells into the bands using a hydraulic jack.

It was actually quite exhilarating to physically build our own pack (and talk about the geeky DIY points we earned!) – but it’s time we hadn’t budgeted for. And this got complicated when the house generator in the bus overheated in the 110+ heat, threatening to roast poor Kiki with out air conditioning. We had to end Thursday early with a scramble to find a nearby RV park with power hook-ups and then rent a car. After making sure Kiki was ok, we ran some errands to obtain parts for the battery bank – and got our Fry’s Electronics fix (grin).

Wiring up our Lithium Ion battery pack. (Safety note: Bad idea to keep jewelry on while working on batteries - we'll be taking our commitment rings off in the future!)

On Friday morning we returned to Elite Power to finish building our bank and getting it all wired up – which involved tediously screwing in jumper bars in parallel, fuses and Elite’s EMS (Energy Management System).

Moving 500ah of Lithium Ion goodness into our rental car.

When we were done – we had a sweet looking 500ah battery bank that measures just 21″ x 14″ x 11″ and weighs just 140 lbs. And yes, a much more technical post is forthcoming for all you interested in more of the details.

We’re much further behind on the project than anticipated, but feel much more in tune with the system we’re building as a result of being so involved with its creation.

We’ll continue sharing the install as it progresses this coming week as we meander towards Reno, with the goal of having something workable by Burning Man.

Gates open in 9 days.

 

By the way, we should note – we are not trying to motivate anyone to follow us on this path. We are not selling these batteries, we are not affiliates with any battery dealer, we paid for all our components and nor do we have any financial stake in the technology beyond our own systems.  We are simply full time RVing technomads who are designing our own cutting edge home & office on wheels, and are sharing our research & project. Of course we’d love to have more folks out there pioneering and helping us take the arrows in our backs.  Right now, we do not consider this technology ready for the mainstream, and those contemplating this technology need to be a bit savvy with electrical and battery technology. 

Other Posts In this Series:

Promise of Lithium #1: Lead Acid Battery Downsides
Promise of Lithium #2: Lithium Ion Battery Advantages
All our Lithium Ion Battery Posts 

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17 Comments - Still Plenty of Room for Yours!

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  1. I was wondering if you all could help with this dilemma.
    I am trying to develop a renewable energy system with wind turbines and solar combined, with a battery bank of the following specifications:

    Option 1:
    48V system
    1,400Ah Battery Bank
    Option 2:
    24V system
    2,800 Ah Battery Bank
    Option 3:
    12V system
    4,800 Ah Battery Bank.

    I believe Lithium batteries will be the best way to go, for weight purposes.
    Weight is important, as this will be incorporated onto a vehicle.

    Do you have any thoughts?
    -Roger

    • Hi Roger..

      Didn’t really see a dilemma question posed here to respond to. All of the positives of Lithium Ion are outlined in this blog series, but there are also risks and high upfront costs. Only you can determine if you are up for them.

      If you have specific questions, feel free to pose them.

    • The advantage of higher voltages is that you can transmit the same amounts of power over much smaller battery cables. So if you can go with a higher voltage system, do it. We couldn’t since we wanted to be able to tie into our buses 12V alternator.

  2. I find your posts about your lithium battery install very interesting, however I am confused about your need to disassemble the GBS-LFMP 100ah/12v battery packs and reassemble them to 500ah/3.2v battery packs. Are the new battery packs taller or longer? How do the 3.2v packs help? How did you go from 100ah per pack to 500ah?

    • Hi Michael –

      If we had wired the separate 100ah battery packs in parallel to make a 500ah bank, the EMS probes would not be able to monitor the individual battery cells properly. To be monitored correctly, each 3.2v “cell” needs to be in parallel.

      We accomplished this by turning the 100ah 12.8v battery packs made up of 4 cells wired in series into 500ah 3.2v battery packs made up of five cells wired in parallel.

      It was a lot of work, but the only practical way to put the system together and still monitor it with the EMS.

      – Chris

      • Chris,
        Good Work , so you now have 500 ah capacity pack by reconfiguring a 5 (cell banks) , what is the new voltage output now ? Im just curious ?

      • While in use, our batteries read between 13.4V (100% full – no load) to 12.8V (25% remaining, no load) to 12.5V (15% remaining, no load).

        As you can see, the voltage drain curve is extremely flat – with less than 1V difference between full and near empty.

  3. I’m interested in knowing more about the batteries you built, too, especially cost.
    Please email me when you share more information. Happy trails.

    Thank you,

    Doug

    • Hi Doug, thanks for stopping by – we’ll be doing a series of posts on the lithium ion batteries starting this week. You can subscribe to the blog on RSS via reader or e-mail (just click on the orange RSS icon on the top right hand corner of the blog, and follow Google’s instructions), or just keep checking back, or follow us on Facebook or Twitter.

      I’m sorry, we can’t possibly remember to individually e-mail folks when we post new content about a certain topic, thus why we offer all these ways for folks to choose how to subscribe to our tales.

  4. Very intrigued by this mod. Can’t wait for the details of how and how they perform. Also, costs would be nice to know, if you don’t mind revealing them.

  5. WOW! We just bought 540 Amp Hrs of AGM Batteries for the “K-SVERT Mobile Broadcast Trailer” at Burning Man and they only weigh… 400+ lbs! Heh! Way to keep it light. We paid $1 per pound though. I’m thinking you may have come in somewhere north of that number?!?!

    See you at Burning Man!

    Tom and Schelby

    • Wow.. where did you get AGM for less than $1 per AH??? That’s an incredible price! We were finding them for about $2-3/AH.

      Aside from size & weight, one of the drawbacks of AGM is that you really shouldn’t discharge them below 50% if you want to extend their life – so 540 AH is really only 270AH of usable capacity. Of course, if you’re planning to rock them out for just BM, no problem 🙂

      The Lithium, in theory, should be able to be discharge far deeper without much loss of life to them. So our 500AH is pretty close to the usable capacity, and again in theory, should have a lifespan much greater than AGM. We shall see about this theory thing, that’s all part of the new territory we’re exploring.

      • It gets even better! I said a buck a pound. We actually paid .75 per amp hr! Living in Silicon Valley still has perks. A friend of a friend owns a battery sales company. He installed 1000+ of these AGM’s in a companies server farm about a year ago, 6 months later the company went belly up and he sold them back to the original seller for a SUBSTANTIAL loss. He knows for a fact that they were NEVER discharged! He gave us a 6 month warranty too. Pretty sweet…

        After the burn, they are going in the “Love Trailer” as we hit the the road for some Fall and Winter Camping.

  6. Nice battery!

    Older Techs often keep their wedding rings in their pockets on a keychain when they work around power like that. Dog Tags on neck chains are another hazzard to beware.

    Having once dropped a aluminium pan between a starter terminal and a steel brake line I appreciate what can happen with only 12 volts.. The brake line flashed white and was gone..

    Will enough cooling air get to the center batteries during heavy charge or discharge rates?

    Enjoy your Blog.

    Harry

    • Yup… we’ve already been reminded to take the commitment jewelry (not wedding rings – we’re very intentionally unmarried) off, and will be doing so in the future when working with the bank.

      Check Elite’s webpage for their description of how the battery cell cases are constructed to allow air flow throughout the bank. Pretty clever.

    • BTW – one of the many nice traits of lithium banks is the incredibly low internal resistance, so theoretically the batteries do not heat up much at all while being charged.

      We will be taking careful measurements to see how theory matches reality. The EMS will give us a temperature readout of each cell so we can track the temperature.

      – Chris

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