How to choose: LiIon, LiPo, LiFePO4, Wet Cell, AGM, .....

[bm_cricket]

I've been sleuthing specialty forums, watching engineering lectures, reading hobby forums... But Burning Man is a special kind of place. What does everyone think of current, modern battery technology and what would you use if you could? All of these technologies have drawbacks but what do you think about them? A short summary so far:

Wet Cell batteries are cheap, messy, and come in various qualities from deep cycle to high cranking and voltages are typically either 2v, 6v or 12v per pack. Charging them is reasonably simple. They are heavy because they are full of lead. The quality can range from $30 lawn mower batteries that can't handle any deep discharge, up through dual use marine/cranking batteries that cost $500 or more per pack. I like my nice deep cycle battery but it weighs a ton, it has the potential of being very messy, and I think I will avoid it going forward.

AGM or Absorbed Glass Mat batteries are basically just less messy versions of wet cells. They cost more but they come in cheap, crappy forms for ATVs up through high end batteries for semi trucks. They are more expensive than wet cells but they also require less maintenance. This is what I put in my cars, trucks, etc, etc. They are great for specific purposes but are big and heavy. If you get a nice one then it will last for years if you use it the way it was designed to be used....

LiIon or Lithium Ion batteries come in many chemical compositions but are generally smaller and lighter than AGM or wet cells and have a higher energy density too... They also cost an arm and a leg more. They need a special charger. All my old laptops used these. They worked pretty well but they aren't very good at high amperage output or high amp hours. They need special charging hardware too.

LiPo or Lithium Polymer batteries sound great at first. They are super light weight, very high energy output, and are the cool new thing. They are also super sensitive and have a funny habit of exploding if you discharge them too much or damage them. They require very special chargers and special in-built voltage regulators. I have a few of these from crappy Chinese manufacturers and they terrify me. I used them last year at the burn and they worked but ALL of them are now bulging and ready to explode. My newer laptop uses this, as do most new phones. This is the cool new technology for low amperage electronics. Some electric cars use these but from what I can tell, they aren't really well suited for high amp applications.

LiFePO4 or Lithium Iron Phosphate are another type of battery used in higher amperage electronics like electric cars. It's expensive. I don't think I have anything that uses this type of battery.

Many, many other types. I could make a battery array out of potatoes or lemons if I wanted to... But I don't.

So, for all you tech heads out there, what do you use at Burning Man, at work, on your RV, ...? BTW, I plan to do a few things with my new found battery knowledge. 1) I will use it to power a few 24v 10A electric motors for my art car next year. 2) I will use it for a battery array for my camp and/or RV and/or trailer next year. 3) I will use it on my bicycles to power 12v LEDs THIS YEAR. 4) I will use it for my 5v wearable art for my costumes THIS YEAR.

Right now my plan is for 12v AGM batteries on my bicycle and 7.4v (down-stepped to 5v) Li-Ion on my wearable art. I probably don't have time right now to change the plan.

[bm_cricket]

It goes without saying that you need to keep everything charged. I'll be charging this stuff from a generator when I'm on the playa. I mostly just want batteries for when I'm not in camp or when I don't want to run a generator but I still want lights, or even the ability to run some blenders from battery powered inverters.

[Captain Goddammit]

I find old-school wet cells the most cost efficient when weight isn't the prime concern.
They tolerate all sorts of abuse, you can charge 'em at 50 amps if you want, and they're not really messy unless you let the terminals corrode.
I have an AGM in one of my cars. It's about half the size of a normal car battery and costs damn near twice as much. But the last one lasted about ten years!
As far as I can tell, the other newer high-tech batteries are cost prohibitive for anything but very low-power use.
There's an awesome 200-aH lithium car/boat/RV battery on the market but it's $2400!!

[bm_cricket]

I find old-school wet cells the most cost efficient when weight isn't the prime concern.
They tolerate all sorts of abuse, you can charge 'em at 50 amps if you want, and they're not really messy unless you let the terminals corrode.
I have an AGM in one of my cars. It's about half the size of a normal car battery and costs damn near twice as much. But the last one lasted about ten years!
As far as I can tell, the other newer high-tech batteries are cost prohibitive for anything but very low-power use.
There's an awesome 200-aH lithium car/boat/RV battery on the market but it's $2400!!

That's about the same conclusion I'm coming to as well. My applications, however, are all mobile so wet cell is a little risky. If I can handle/tolerate using AGM, that's my sweet spot for power output/density/cost/and simplicity.... unless someone on here suggests otherwise. For the bicycles this year I'm also going to use AGM because the cheap, crappy lithium polymer cells were such a bust last year.

[ShreddinPB]

I use a LOT of lifepo4 batteries, all headway cels.
I use them to power my tricycle and the huge boom box on the back of it.

I have 2 36v 12Ah packs
1 24V 60Ah pack
2 12V 10Ah packs

I love the cels, 38120's, 38140, and then 40152s
The two 36V and 2 12V packs have been to the last 2 burns and been totally fine

[bm_cricket]

I use a LOT of lifepo4 batteries, all headway cels.
I use them to power my tricycle and the huge boom box on the back of it.

I have 2 36v 12Ah packs
1 24V 60Ah pack
2 12V 10Ah packs

I love the cels, 38120's, 38140, and then 40152s
The two 36V and 2 12V packs have been to the last 2 burns and been totally fine

I just checked those out. COOL! I'll be sure to check those out for next year.

[mozburrn]

I use a LOT of lifepo4 batteries, all headway cels.
I use them to power my tricycle and the huge boom box on the back of it.

I have 2 36v 12Ah packs
1 24V 60Ah pack
2 12V 10Ah packs

I love the cels, 38120's, 38140, and then 40152s
The two 36V and 2 12V packs have been to the last 2 burns and been totally fine

Can you recommend a source for LiFePo? What do you use to control charging?

To answer the OP's question, the various flavors of lead acid battery probably remain the most practical battery type due to ease of use and cost.

[bm_cricket]

To answer the OP's question, the various flavors of lead acid battery probably remain the most practical battery type due to ease of use and cost.

As a follow up to everyone, I went with two 12v AGM 3AH batteries for this year. They worked great. The only real downside was that they were GOD AWFUL HEAVY. This year they were strapped to a bicycle to run the LEDs and they were annoying but they worked, they didn't explode (unlike the stupid LiPo things from China), and they were really easy to charge.

I also got a LiFePO4 battery for work. I'm a geologist so I build tools sometimes. This time I built something and the LiFePO4 battery fit the technical design requirements better than anything else. Yay! A new toy! So far the battery voltage hasn't even dipped low enough to detect during regular use.. The battery is actually performing according to the design specs that the seller claims! I look forward to seeing how it performs over the next year of regular use. I'll try to remember to come back to tell everyone.

BTW, for cost comparisons, the LiFePO4 battery was $250 for a 25AH, 12V battery pack from what I'm considering a "reputable seller". The alternative AGM cell would cost a little over $100 but would probably handle deep discharge 50 or 100 times, and regular 20-30% discharges a few hundred. The LiFePO4 that I got should handle more than that.

[maladroit]

I needed 12V for LEDs on my bike too (spinning disco light projectors that turned the playa around my bike into a party). I just used a pack of D cells and didn't need to replace the batteries all week. Budgeting some alkaline cell usage can be worthwhile for something you use once a year, and they still have the best power density. Cost me $8 for the week, would have been hard to work up a LiPoly system for less. I did figure out, as a backup, my lithium packs from cordless drill were usable and I could just stick spade terminals in the power contacts.

[Canoe]

... Budgeting some alkaline cell usage can be worthwhile for something you use once a year,..

Big time.

Unless it's a lot more amp hours and/or a lot more voltage. Like an e-bike, but is likely for way more use than just the week of BM.

(But playing with Li cells, a BMS and choosing a package is so much fun!)

[bm_cricket]

High amp hours really demand batteries that either 1) take it on a single discharge cycle, or 2) can handle many discharge cycles. It's also a bummer that virtually all batteries drop voltage as you use them, some more than others.

AGM really is the sweet spot for most applications, especially at Burning Man. If something gets used at home then fancy batteries come into play. That fantastic (seeming) LiFePO4 25AH battery I mentioned for work will hopefully have a 1,000+ cycle life the way it will hopefully be used at work. That should put it at 5+ years and it will outlive the clunky deep cycle marine batteries we usually use. LiFePO4 also has the cool bonus that during battery discharge the voltage remains much higher than the marine batteries. LiFePO4 seems to hover between 13v -> 12v and the deep cycle battery goes from 12.6v down to 10v during a single day's use.... Our equipment starts to really clunk along by the time it gets to 10v.

[Canoe]

...LiFePO4 also has the cool bonus that during battery discharge the voltage remains much higher than the marine batteries.
LiFePO4 seems to hover between 13v -> 12v and the deep cycle battery goes from 12.6v down to 10v during a single day's use.... Our equipment starts to really clunk along by the time it gets to 10v.

What you are likely observing is a lower internal resistance in the LiFePO4. Much nicer for electronics, for the reasons you observed, and voltage stays higher for the useful charge. If you've still got that much voltage showing, you're nowhere near to using the capacity of that battery. But in case you do start to use a larger portion of the available charge, do find out if the pack uses per-pack or per-cell under/over voltage monitoring in its BMS. If it's not per-cell, you could find the pack bricks when you least expect it as a single cell drops below its minimum voltage. You can replace that cell, but if you're in the field...
More expensive packs use matched cells, so you get to use more of the nominal AH instead of having a weak cell shut the BMS down (or brick if it's not per-cell monitored). Some will use matched cells and a per-pack BMS, but that's still a much higher risk than per-cell BMS.

[bm_cricket]

More expensive packs use matched cells, so you get to use more of the nominal AH instead of having a weak cell shut the BMS down (or brick if it's not per-cell monitored). Some will use matched cells and a per-pack BMS, but that's still a much higher risk than per-cell BMS.

You got me wondering... So I looked into it a little. They don't mention per cell monitoring but I can only assume that they would if they did. I'll make a phone call tomorrow to check it out. Thanks!

[Canoe]

Specifically, the danger is that one cell in the pack can go below the cell minimum voltage, which 99 44/100 % of the time means that cell is a brick, taking out the pack. This can happen while the other cells are well charged, hence showing lots of voltage, so even as you approach the minimum voltage on one cell, if there's no BMS or the BMS is only monitoring the overall pack voltage, it can be saying 'this is the total voltage: it's well above the Vmin per cell x the number of cells, so we're good'.

Also, instead of having to let the pack rest after charging to equalize the charge between cells (assuming it even does that), the BMSs that monitor the voltage per cell during discharge may also control the charge voltage per-cell so all cells are charged to their max, with none being overcharged. As with discharging, a low cell in the pack can fool the charger/BMS that's controlling by pack voltage into over-charging. So with per-cell voltage control for charging, the charge rate can be higher too, as you're not worried about blowing over any cells, nor do you have to under charge the pack to ensure you don't over charge individual cells.

And a good BMS should have current limiting, if not short protection, as the instantaneous current a Li pack can delivery is astounding. You do not want to drop a tool across the contacts. I had a short blow a hole through a heavy-duty bus bar is less time than it took to type 'bus bar'.

With your typical expensive Li cordless power tool's battery, one low cell causes the majority of their failures. Replace the one cell, and it's good to go.

With your ~12 VDC pack, you're reporting 13 VDC, so its voltage is likely derived from four 3.2 VDC cells in series, with more in parallel to get your AH. Your Vpack-min would be around 2.0 VDC x 4 cells, for 8 VDC. So with your pack ranging from ~13 to ~12 VDC, you're likely going no where near Vcell-min on any of the cells - unless you've got one or more cells that is grossly mis-matched and should have gone into the low quality bin. Which is why gurus making custom packs test individual cells for their voltage curve and match them; but they want to know that their pack has a usable capacity of 25.1 AH vs. 24.6 AH, vs. a grossly mismatched cell that could reduce the usable pack capacity to 22.8 AH. They're fun to listen to - once or twice. And if you ever build your own pack, don't tell them that you didn't test & match your cells, if you have pity on their blood pressure and heart.

[usurpedus]

id like to purchase a secondary(backup) 36V li ion battery for my electric bike for the playa this year. i can't seem to find much online.. can anyone recommend a resource?

thanks

[Popeye]

id like to purchase a secondary(backup) 36V li ion battery for my electric bike for the playa this year. i can't seem to find much online.. can anyone recommend a resource?

thanks

You couldn't find anything on line? Here let me help you.

https://www.google.com/search?q=36V+li+ ... 8&oe=utf-8 About 435,000 results (0.32 seconds

batterie bosch 36v li ion 36v lithium ... mh battery

[gaminwench]

I unplug for the duration.

It is liberating, and it can be done.

[100 Proof]

As an update to this post; it was last responded to in 2015. MUCH has transpired in the battery world since then.

In this day and age (2024), I would heartily recommend LifePo4 batteries. They have come way down in price and perform well on playa. I've been using them on playa and everywhere else since 2017 and would never go back to any lead-acid or AGM technology.