Overview and Testing of the BigBattery 24V 100Ah Lithium Batteries, Plug-and-Play!

Taking a look at the pre-built 24V 100Ah lithium battery modules by BigBattery. These modules are built with new Model 3 (Panasonic 21700) cells. I opened one up to see what was inside, then connected two of them in series for a 51.8V configuration. Stress testing was done at 100A with a thermal camera.

*WARNING:* Lithium batteries are dangerous and can result in fire! This video is NOT intended to be instructional or a "how-to" lesson. I am not a professional. Do not attempt anything you see here without first contacting a certified and/or licensed professional.

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► I receive a small commission on purchases made using my affiliated links shared the video description and comments section. The views and opinions expressed here are my own, unbiased, and not influenced by this commission in any way.
► My videos are in no way intended to be instructional "how-to" lessons. I am simply documenting my project for informational purposes. Property damage, personal injury, or death may result, even when following manufacturer's instructions. I cannot be held liable for such damage or injury. It is YOUR OBLIGATION to ensure that you are complying with any local and federal laws as well as code and permit requirements.

[LithiumSolar]

Hey guys, I'm happy to let you know that I have spoken with BigBattery this evening regarding the problem(s) I have experienced. We are all in agreement that the problem is not the way the breaker is wired, but rather the torque of the bolts and the quality of the breaker overall. They have had many internal discussions since the posting of these two videos, and will no longer be using these breakers going forward. For them, it's a matter of reducing the potential points of failure. They will be redesigning the product to feature a user-serviceable fuse with an on-off switch rather than a breaker. Despite my disappointment in having experienced this problem, I strongly appreciate knowing BigBattery is willing to listen to customer feedback and make changes for the better of everyone.

[dkd]

This channel is one of the most technically informative resources I've seen on YouTube. Thanks!

[HBPowerwall]

Would love to see how balanced those batteries were at the bottom - perhaps over charge a little so you can see the heat sink heating while balancing.. Also be good to know the temp inside as it doesn't look like there is any vents for heat to escape - that could shorten the life of the cells..

[kleetus]

You can parallel breakers and other components and get good current sharing, you just need to be geometric in your assembly. Meaning your power connections to and from the breaker need to look like a tuning fork, not a bar connection with the power lead at one end, it needs to be centered between the two input terminals.

We do this all the time with high power rectifiers and SCR bridges for medium voltage motor control.

Sometimes you can't get parts in the form factor you're looking for in the ampacity you need. 63A is as big a mini circuit breaker as you're going to find by any manufacturer.

[EnriqueReyes]

Great review. I've been looking at these batteries. A video suggestion would be to upgrade the few things on this battery box to your better design.

[ShaoyangJia]

Nice review.

The Anderson Powerpole connectors are the best mass-produced DC connectors. The their spec sheet, there are detailed test results on the temperature raise at the rated load.

The reason why the DC breakers gets warm is that the breaker actually relies on the raising temperature to cause deformation in a bi-metal spring to trip. When the current is near the rated capacity of the breaker, the temperature is expected to be high.

[HolgerNestmann]

Thank you for the thorough review and all the great information you put in your videos. It has been a great resource so far - the fuse video was super nice and in the reviews your views on pro and cons are really educative. This breaker was an interesting design for instance as I was always curious how well current splits up if one say doubles the wiring.

[AveRage_Joe]

Awesome Review! Been wondering how well these packs work!

[marcoa.rosado]

Very nice test, at 2 in series, if you were to wire 2 in series with 3 in parallel then the load distribution to each pack would allow the batteries to run cooler. Glad to see your big Aim inverter in use. Mine is still kicking away.

[realfutbol]

Nice video. Did you touch the BMS heat sink by any chance? FLIR cameras are unreliable for measuring shiny metal: often the temp looks like whatever is being reflected by the metal- so whenever a heat sink looks like room temp, that should raise alarms - it might be showing you the wall or ceiling or enclosure temperature.
FLIR cams have a setting for type of material (helps a bit, not perfect). They also can automatically jump to the highest-temp spot in a photo though I'm not sure about video- that should help you find the hottest hotspot faster.

Finally, since they have visible and IR cameras, the stencil outline and lepton maps are often misaligned especially at close range- there's an offset function to compensate for this, but it doesn't adjust based on distance so might not be super helpful.

[geraldhenrickson]

The batteries revealed several issues and some are attributed to the test procedure? Should not another test been performed? Also...did you say at the end of the video that if the circuit breakers were upgraded this battery might achieve the specs listed right on the case? Do I understand you correctly? This video was fun to watch and these seem like a great battery yet what have we really learned here?

[heartPahoa]

Great insight, thank you for taking the time to put this review together.

[johnsavage]

Nice vid.
At first I thought these were a tremendous value,
then I realized they are Li-ion not LFP.

[danielnjenga]

Nice review, they should add a cooling fan though

[miket]

Cool video! $855 is steep for what you get though. For 100 amps they should’ve used an absolute minimum of 4awg internally, preferably 2awg. 8 and 6 “gauge” are not adequate for that load over that distance. You can see on the thermal camera that the internal cables were getting extremely hot—this is indicative of insufficient wire size for the current being drawn through it. Wouldn’t need 200c temperature rated wire if they had used the proper size wire in the first place. I’d be curious to see the results after changing all those 8 and 6 gauge wires out for true 4awg or, better yet, 2awg tinned OFC. My theory is better thermal readings and less voltage sag.

[I]

If you did replace the breaker with a 100 amp single pole.

Do you think it would exacerbate the heating issue.? And is there another configuration which might alleviate it.?

[re]

I would like your opinion on purchasing either 2 of these 24v units or 4 of the 12v and series either of them to run a 48v electric outboard. I am currently running that 48v outboard with 4 AGM 110 AH batteries in series. Please let me know your thoughts. Thank you - Ro

[johnfriesen]

Excellent teardown...thanks for doing this. You say "used cells" but I see "NEW" cells on their website for this battery...which is it?

[casalino]

Great information, Being recycled cells, do they test to their stated rate? If so can you calculate the degree of degradation, meaning what would the power actually be if the total cells were new? Side note; they do offer the parallel or series version of these connectors. Thank you.

[GREATDANE]

I just bought a Big Battery Hawk 24 Volt 3.8watt hour battery and awaiting Delivery now for My Victron Phoenix 24/1200 Inverter and 150/35 Smart Solar Charge Controller and 600 Watts o Eco Flow BiFacial Solar Panels