Are These "Smart Batteries" Smart Enough NOT to Overheat and/or Burn?

[FantomPwr]

I'm an audio guy, and I'm looking for an external DC power system for my F8n field recorder.  Since the field is littered with various styles & types of Lithium-Ion batteries, my first concern is "How do I pick one that minimize the inherent risk of the battery overheating, or worse yet, going up in flames?"  I'm thinking of all the videos I've seen that show someone's cell phone igniting the cup-holder in the owner's brand new Lexus, or the flight attendant's failing attempts to stamp out a laptop fire in the aisle of a packed airliner.  All in the name of the Lithium-Ion battery.

 

So, enter the "Smart" Batteries: the Deity S-95, and the Remote Audio HiQ 98 are good examples.  These two have additional built-in circuits that allow attached devices to show telemetry data (on compatible devices, of course).  But is this info used to automatically protect the battery, or is it the user's responsibility to read the info and act accordingly to save the battery?  If it's the former, then that would justify the higher price, IMO.

 

I guess I've got a lot to learn about "Smart" Batteries".....

 

[fieldsound]

These batteries were originally designed for medical applications and as such can be considered to be quite reliable. One of several elements of telemetry you can monitor in real time while using these cells is temperature. Additionally, certain smart battery chargers will display the amount of power cycles on each battery. This data is useful to determine the health and performance of a battery.
 

As far as I know, all lithium ion battery systems have some risk of overheating, swelling or in rare cases exploding. However, as an operator you can practice due diligence by monitoring battery health as well as examining them for any physical deviations or defects before use. Additionally, care should be taken when transporting batteries. 
 

For what it’s worth, I’ve used smart battery systems for 7 years and have experienced no battery failures or questionable situations whatsoever. However, I would never go into a production without several backups in case one of them failed. My view is that they are worth the purchase price. 

[OB1]

I'll counter that by adding that I have been using IDX batteries exclusively since...well...as far as i can remember in my sound mixing career - let's say decades. I haven't used anything else. Obviously my BDS has changed from basic spliced cables and multipliers, to newer BDS designed for "smart" batteries but only using them for capacity telemetry and not the bells and whistles it offers. I've never had an IDX NP style battery fail me, ever. Sure, some have lost their charge but that is an expected outcome to constant use. I have had issues with V-mounts, but most here don't use that especially if you air travel.

 

Take that with a grain of salt. Smart batteries are great, I see how they have a place in our workflow.

[Derek H]

I second IDX lithium batteries. They’re very high quality, have many safety features built in and have never let me down. Not a smart battery but just change it out before the voltage dives too low and you’ll be smart enough. 

[igomarsound]

I used many solutions, from NP1 to sony LP,USB powerbanks, V lock, 18650, even motorcycle batteries (sometimes you gotta find a solution...). with more or less safety.

 

being able to read the temperature in your battery makes it very useful to avoid the kind of problems mentioned IMHO. As for safety circuits, im not sure but Antoine Malnati from Audioroot or @Andrew From Deity  could surely answer this. 

 

I use esmart batteries since audioroot 1st gen and would never change to any other system now. I flewn all over the world with it and the weight/space/effiency ratio is unbeatable, 

 

would love seeing a 50wH semi battery from deity tho...

 

as for powering a bigger workflow cart based, i'm eying the AC powerstations such as ecoflow

[DHB]

As external DC power supplies, I run my F8 on either an 'Alphasun' 26,800mAh/99Wh slimline external powerbank - I think I bought it on a crowdfunding website - which just goes on and on (its display shows its internal temperature as well as DC voltage, and whether its AC output is switched on or off), or I use an 'omnicharge' 'Omni Ultimate' (ditto pretty much everything above) with a 38,400mAh 142Wh output. It's a bit bigger, and about twice as heavy as the 'Alphasun'. Apparently, although 38,400mAh, it's acceptable on planes as it's TSA Approved.

 

The 'Alphasun' has three outputs (1 slow USB-A, 1 fast USB-A and one USB-C), and you can choose pretty much whatever voltage you want to get out of them, from 3.6v to 21v at up to 3.5amps. The 'omnicharge' offers 5v to 20v at up to 3amps. Either will run my F8 for days. The 'Alphasun' also has an integral 5v 1amp wireless charging pad ..for phones, for example.

 

The 'Alphasun' came with its own mains-to 19v output plug-in-the-wall charger. The 'omnicharge' can be charged with any DC source of 5v to 32v with a circular coaxial plug on it.

 

I can't find the 'Alphasun' online anywhere, but 'omnicharge' seems to be still going strong at https://uk.omnicharge.co/collections/omnicharge-power-banks

The US store is at https://www.omnicharge.co/collections/omnicharge-power-banks

 

The 'omni ultimate+' is shown as £399.00 - or $399.00 in the US store - and appears to come with a 45w wall-plug charger.

 

I can recommend either, or both, of them. I haven't used any other 'powerbank' DC sources with my F8.

[The Documentary Sound Guy]

16 hours ago, FantomPwr said:

my first concern is "How do I pick one that minimize the inherent risk of the battery overheating, or worse yet, going up in flames?"

If this is your highest priority, going by brand or format probably isn't the best approach.  It's very difficult to assess that kind of risk accurately on the basis of brand, especially since the underlying cells tend to be sourced elsewhere anyway.  Even the with the worst brands, total meltdown is a rare, black-swan event, so there isn't really a good way of getting real data as a consumer.  Only the manufacturer or maybe the FCC would have enough data to make that judgement, and even then I would have my doubts.

 

I would start with:  Chemistry.  As you are aware, pretty much all lithium batteries have a risk of runaway heating if the battery gets above a certain internal temperature.  It's a gradual process, and there are different stages of runaway, but the risk starts around 80°C (ballpark, and apparently quite battery-specific).  The only sure way to eliminate that particular risk is to use a different chemistry.  This will mean a serious trade-off in capacity and weight, but non-lithium batteries generally do not have a thermal runaway point that is inherent to the chemistry.  Other chemistries are still explosive and flammable, and the non-cell components can still fail catastrophically, but the peculiar idiosyncrasy of lithium to overheat and catch fire can be avoided.  You *might* still find NiCd batteries in IDX / NP1 format if you look carefully, otherwise a lead-acid chemistry may be the easiest to get hold of.  I would try and find a NiMH chemistry if you can, but I've only seen this chemistry used in AA format, not larger, higher voltage battery packs.

 

Assuming you are willing to risk lithium chemistry in the first place, and you are just trying to minimize risk, the obvious precaution is to make sure if something short-circuits in your recorder, the battery is behind a fuse so it will never see an open circuit.  This basically means using a BDS system with an appropriate fuse.

 

Next, heat is proportionate to current, and current and voltage are inversely related.  If you have more voltage available, your recorder will draw less current to receive the same amount of power (wattage).  So, use a battery that is near the maximum input voltage your recorder can accept (16V for the F8n if I recall correctly).  In practice, the eSmart batteries (& IDX NP batteries) are nominally 14.7V, which is probably as close as you will get.  Also in practice, your recorder draws so little power that heating due to current is pretty minimal, but it is something to think about if you start piling up additional equipment in your bag.

 

External sources of heat are probably more realistic threats from a safety perspective.  So, don't leave the battery in direct sunlight (or a hot car), and don't keep the battery directly next to a source of heat (i.e. your recorder).  Find a way to ensure that the battery is vented so that heat that the battery creates internally while in use has somewhere to go (i.e., don't bury it in your bag and surround it with foam).  If the climate you live in is exceptionally hot, that increases the risk overall  Mainly, it reduces the headroom for additional heating before thermal runaway begins, so the battery can supply less power safely.  See the previous paragraph:  The amount of power your recorder draws on its own (and therefore the amount of heat it creates in the battery) is probably pretty low, therefore, even in a hot climate you are probably ok.

 

Lastly, mechanical failure can create internal shorts in the battery.  This is one place where brand / format / design *can* be assessed a bit more reliably.  You want a battery that is physically robust.  I'd say the eSmart and IDX NP batteries are both pretty good in this regard; I'd give the edge to IDX, but both are tougher than your average camera battery, and much better than some of the generic USB "power packs" that you see on Amazon.

 

All things considered, the eSmart / IDX formats that are commonly in use are both pretty good choices compared to a more DIY approach:  They are physically robust, have a voltage output that will keep current and temperature low, and they can be remoted away from the recorder as heat source via a BDS cable.  Make sure your BDS is adequately fused, and you've covered most of your bases.  There's probably people more paranoid than me that can think of some other modes failure to think about, but I think I've covered the big ones.