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Discussion Starter · #1 · (Edited)
I'm thinking about using one of those 58 farad supercapacitors from Maxwell, or the 65 farad equivalent from Eaton. Just wondering if anyone has had any negative experiences with them? I've haven't read anything bad yet...

Secondly, is the unit sealed underneath the removable bottom cover? I'm hoping to mount it to the radiator support just-in-case-of, and being rated IP54, it should be ok, but ...
 

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are you thinking to mount the caps in the engine compartment of a vehicle? i believe they are not rated/designed for that application, wrt to vibe & temperature

i would think you would want IP69 or IP67 in the engine bay area for sealing, and design to handle engine vibration requirements.

i think these would fall in the "industrial" grade parts, not commercial. industrial grade = machines in warehouses & stationary outside applications. i think you would want to target mounting the caps in interior compartment of vehicle.
 

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Discussion Starter · #3 ·
It's somewhat ironic. My beater, which by definition I don't really care about, has great spots to mount it under the hood, while my pride and joy does not, so I may just have to bite the bullet on that one. Here's the model I'm thinking about getting. I said commercial to differentiate them from the self-assembled versions, but they market them for industrial purposes.


It has a higher temperature rating than a flooded lead-acid battery... IP54 is the definitely my minimum for this application, I just wonder how conservative it is given the exposed terminals versus what we're used to dealing with...
 

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are you using the caps for audio system support?

why not just mount the caps close to the amp if you are?
i believe that's the best performance location.
so that you could provide high current quickly with low resistance path to the amp, such that you offload the stress on alternator & starting battery.

underhood temp range is -40C to 125C for electronics from my life experience. -40C to 85C for interior electronics.
 

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Discussion Starter · #5 ·
Just me being stubborn mostly... Definitely agree that closer to the amp is best for pretty much all use cases; I've just seen enough from the other side of things to be a bit leery of adding yet another fire hazard to my vehicle. Really only thinking about adding one to reduce headlight dimming and to some extent to abuse the alternator a bit less; not really worried about audio performance. But the realization that I have few good choices in my pride and joy to mount one other than in the cab makes accepting doing so in my beater all the easier.
 

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Here’s a data sheet from Eaton.

Supercap application guide

there’s a diagram that shows life expectancy is linearly correlated with temp, every 10C cuts life in half. Max of 70C, so use in an engine compartment is probably a bad idea. I don’t think caps are a fire hazard but if they get too hot they vent, which would be messy.

If you used 8+ cells you could run at 85C.
 

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I ran the maxwell supercap bank you need mentioned under my hood for 2 years with no issues at all. It could start my VW CC all by itself somehow!
That corresponds to about 17 thousand hours installed. Assuming your car is a typical persons car and not a long haul vehicle that spends most it's time on the road, a large portion of that time your car is cooling off and not sitting at worst case engine bay temps. Per that eaton data sheet, 3000 hours worst case lifespan in 70c would correspond to over 4 hours per day at 70c for two years. Also per that data sheet, you'd exceed 20,000 hours of life holding the caps at 50c all year round.

So that tracks.
 

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i think it's pretty cool that some of you have had success with mounting some caps underhood ..... @Selkec why did you remove the caps from the underhood area?

it still goes to say that it's not the intended application/environment. the guaranteed water intrusion, dirt intrusion, vibration and occasional temp extremes will likely be detrimental to life of the enclosure, terminals, caps and the circuit board and the internal connections in the module/unit. it's simply not designed for that application/environment. this guy is talking about mounting caps to a radiator (or very near radiator bracket).... i don't think i would go any further to encourage that mounting setup.

you can contact Eaton tech support/sales and ask them what they think about attaching their cap module to a car's radiator.... see if they will recommend that/warranty it or give any indication that it would last as long as it should.

i dunno man, if you have the option for interior mount, just do it there. not trying to be a dick, just trying to be the voice of reason. this idea just seems out there.

🤷‍♂️ 🤦‍♂️ 😊
 

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Discussion Starter · #11 ·
Thank you all for your feedback; much appreciated... I'm very much relieved that we're discussing my bad choices more than the product; my poor choices can be changed...

Thank you very much JohnnyOhh for towing the line of reason; reason is always welcome around me. Not saying I'll always listen to it, I am very stubborn after all, but it's always welcome. And thank you SQ_Bronco for pointing out that I'm overestimating the fire risk these capacitors pose. I've never dealt with capacitors much and for some reason I was assuming they'd have a higher safety risk, like a Li-Ion battery, but that was just foolish on my part.

In defense of my foolishness, so-called Cold Air Intakes put their cone filter in pretty much the same location as I'd be putting the capacitor. The capacitor would sit at the bottom of that cavity behind the headlights, pretty much the lowest point in the engine bay. It's also on the opposite side from the exhaust manifold, so honestly, I wasn't overly concerned with the heat aspect of it. My biggest concern was water intrusion when I take 'er water skiing with the crappy drainage the country roads have around here.

If there's minimal fire risk from the capacitor itself, then I'll just put it in the cab... Is that pretty much the extent of the risk with these things? Nasty crap leaking out? That I can deal with...
 

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I ended up getting a good deal on several Maxwell 500 farad supercap banks and I switched to running two of them and a double bank of Lishen lithium lto cells. I did decide to use them again when I got another car but I was an idiot and they had sat for a while and when I recharged them I did it reversed polarity and ruined them and they wouldn’t hold a charge after that
 
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