CAPACITOR POWAH!

[Enki]

I think the video pretty much says it all. Language slightly NSFW.

Charging configuration:
To start, I used a regular car battery charger connected directly to the cap bank, which all together, had .3 volts at the time. It turns out this was a very bad idea (as I figured it would be) since an empty capacitor will move as much current as a shorted circuit, and the battery charger scared the shit out of my dad (he actually left the shed) because it was humming like a city substation despite being set to 2 amp trickle charge.

Trying to remove the connection with the charger still running was also a bad idea, and resulted in this:



So, I gave everything a few minutes to cool down and then I redid the charging circuit by including a charging ballast (in this case, one of the original headlights from the Falcon that this test is for). It took several hours to trickle charge up to ~8 volts, which is when I set the charger to run on a 15-40 cycle until 10 volts, which is when the ballast was removed. It charged pretty rapidly after that, and at about 12.5 volts is when it was moved out to the test vehicle. Also, every 2 volts of charge I disconnected everything and manually checked the balance on each cell; nothing was out of the ordinary, and final 14v charge (fresh off the test vehicle) saw a variance of only ~.1 volts per cap maximum; two caps held a charge of 2.39, and one had a charge of 2.3 while the rest had a charge of around 2.33-2.36. Considering cell max is 2.7, maybe 2.8 volts, this is well within spec and is unlikely to implicitly require a balancing circuit, even though I will be running one in the final product.

Incidentally, the caps never got warmer than ambient during any part of testing, though the terminal straps did pick up about 5 degrees or so, probably due to shitty connection which I'll fix later.

[BlckMs3]

[udntknw]

Originally Posted by BlckMs3

Couldn't have said it better myself... Unless I was black too. :/

Just tapa it in.

[Enki]

The power of supercaps:

Just ONE of my caps (all 2.7 volts of raw fury of it):

Ultracapacitor - Burning Up Stuff - YouTube

Ultracapacitor - Burning Up Stuff - YouTube

A bank exactly like mine:

6x Boostcap 3000 Farad Capacitors - Speaker Death 2 - YouTube

6x Boostcap 3000 Farad Capacitors - Speaker Death 2 - YouTube

A bank of 8x 2.5 volt 2600 F caps (about 1600 amps potential less than my bank):

Arc cutting with super capacitor - YouTube

Arc cutting with super capacitor - YouTube

Understand now?

[johnnyboy05gt]

Now all I need is 1.21 jiggawatts.

Sent from my SPH-L710 using Tapatalk

[madspd6]

Marty wait!

Can't you just skip this Shit and get a Mr. Fusion?

[Enki]

Bank has leaked down to 12.63 volts in 19 hours; at the 24 hour mark I'll recharge it to 14 and run the test again, and this time I'll document cell voltages too.

[Enki]

Bank leaked down another .01 volts in the 5 hours since prior post.

It's been charged back up to 14.42 volts at the bank and all individual cell voltages have been documented both pre and post charge up.

More to follow tomorrow.

[madspd6]

sorry for my ignorance but what is the end goal of this project?

[Enki]

To not require a lead acid battery in my project car.

[SofaKingAwesome]

Nice work James.

[udntknw]

Well this put more strain on the charging system when trying charge the capacitors?

Just tapa it in.

[Enki]

Yes it will. The caps will eat whatever amps they can get, but as the voltage increases, the draw eases.

[Enki]

Learned some interesting shit today.

First off, here's the as of yet unfinished math from the full recharge:



I also did some math (which may be wrong) and found that the 3k farad cap bank probably won't be enough to sustain the Mazda when shut down for very long. If the drain on the Mazda battery when off is accurate, (and it could be off, I'm not sure yet due to shitty test), then there's only enough amp hours in the 6x3000 farad bank to sustain the ECU for about 7 hours; this is at a roughly measured rate of 250 mA and does not include the losses from regular seepage that the caps will experience.

Here is some math to go with the above:




As a side note, this is the battery I'm currently using in the Mazda:
Braille Battery USA      Lighter ? Stronger ? Faster -

And this is why I kill one of them roughly every year/year and a half:

Braille B2317 Mazda Start - YouTube

Braille B2317 Mazda Start - YouTube

Yes, the battery managed to hit 9.49 volts during start.

At this point, I'm probably going to order a set of 650 caps and integrate them in with the existing Braille battery with the hope that I stop killing one every year or so, since the cap bank will do all the amp dumping and the Braille will basically keep the caps topped up.

[Enki]

Cap bank currently sitting at 13.245 volts. I'm pretty impressed; maybe with some actual voltage balancing the leakdown will be even better.

[Enki]

Here's some cold start logs from the AP with battery voltage listed. It's no wonder my car eats one of these things every year; voltage dropping to 9.3v on multi-day wait before cold starts, and it only gets a little better over time.

Mostly, I'm posting these for comparison data for when the 650 caps are installed (which arrived today). Hopefully I'll be able to get another 2 years out of this battery before it shits the bed completely this way.

Also, tomorrow I'll be testing the voltage across every cell in the big bank to see what the final leakdown numbers are after a 5 day wait. I also need to finish making my 2.3 volt minimum balancer, which I'm hoping will allow for more current to pass than the one that I got with the kit originally (hopefully around 10x faster balancing).

More to follow.

[udntknw]

I think it also has a lot to do with the fact the I rarely see the alternator charge over 13.7 volts. I would like to see at least 14.1ish out of the alternator.

Just tapa it in.

[Enki]

Sorry for the wait; taken at 2:00 PM today, but delayed due to whatever version of aids has infected my upper respiritory tract.

Bank: 13.08v
1: 2.23v
2: 2.22v
3: 2.145v
4: 2.19v
5: 2.14v
6: 2.125v

[bioevolve]

I'm a newb at this.
What would be the major difference between 2.7v 3000f vs 2.5v 350f setups in regards to cranking amps? if there is.
I know both should work between -40f to 140f.
Reason for asking, to fit the small tray lol, 51 size.

[Enki]

The only difference would be the rate at which the voltage on the cap bank drops.

Caps are different from batteries wherein as you draw amps from a battery the voltage drops in proportion to the actual load, not the charge level like on caps.

It would basically look like this (bullshit numbers pulled from my ass):
Battery:
12 v @ no load
9.5 volt @ peak drain
11.9 volts @ no load (with no alternator)

Capacitor:
12v @ no load
linear voltage drop during drain
10v @ no load (with no alternator)


The thing about batteries is that to pull a ton of amps from them, the battery has to get physically larger/heavier/more complex to supply more amperage, where as a capacitor will dump ALL of its amps if given the chance. The rating on each of these 3kf caps is 210 amps continuous (thermal maximum 40C), with 6300 amps short circuit current, with the 650s I've got now are rated at 88 amp continuous, 3400 amps short circuit (again 40C).

Thus, the 350 caps will most likely be able to supply any cranking amps you can ask of them, but that would be at the cost of thermal shock/cycles/lifetime depending on their characteristics.

As a side note, if you're really worried about size, a set of 650 caps in conjunction with an LFE battery pack in the 4 cell range (12.8 volts; 10-20 amp hours) with charge balancer/limiter to avoid burning up the battery would probably be extremely small and very lightweight. I'm still not sure that the 3k farad bank will be enough to start the Mazda after several days of idle sitting, but I'm going to be testing that, and I'll post up pictures at some point comparing the two banks with the Braille and a regular car battery.

[bioevolve]

Thanks for the info!
Flexible roll-up 15w solar panel on the dash with a charge controller should keep it charged up.

[Enki]

I live in AZ, so I'd much rather have the sun shade up in the window vs a solar panel, which won't work when I travel for work as I park underground.

[eppopipe]

Ive built a few hybrid supercap/batt setups for weight loss in racecars. Ive managed to get the whole thing under 15 pounds and about a quarter the size of the stock battery. They are also useful in car audio.

[Enki]

Care to detail one of your racecar setups?

[eppopipe]

Sure its just one of these
WILD SCORPION Replacement 14.8V 4200mAh Battery for R/C Boat Toy - Black + Silver - Free Shipping - DealExtreme

6 or 7 of these (why 7? read up on balancing series banks)
BCAP0350-E270-T11 [BCAP0350-E270-T11] - $10.75 : Tecate Group Ultracapacitors and Supercapacitors, The power of the future. Today.

Then zip tie em all together and build a little wood or abs or whatever you got around box and you've got a lightweight battery. Im sure there is room for improvement of course. Maybe some pcb control board or something of the sorts.

[Enki]

6 for higher farad capacity, peak voltage of 16.2.
7 for lower per cap voltage; voltage of 2.0285 peak per cap (makes it easier to balance with 2.3 volt diodes/LEDs.

[eppopipe]

You got it

[Enki]

Minor update:

After almost three weeks, the cap bank voltage has not dropped below 12.5 volts. As it stands, it's currently sitting at 12.58 volts, whereas my brand new, never before used Braille is sitting at 12.44 volts.

Since I'm feeling a bit better, I've charged the bank back up to 14.31 volts and will be doing a leakdown test while attached to the Mazda today at some point. I'll also pull start up voltage logs with the AP, which makes using the multimeter less useful.

Edit:
If all goes well from this test and it looks like the voltage will remain above 10v for at least a week, I'll probably forgo the battery pack and just build the cap bank case with balancing circuit instead.

[Enki]

MAJOR UPDATE:

OK well the results are in, and there was a couple surprises.

First off, a description of the log files that were taken (via AP):
Braille Cold Start.csv: First start of the day using the lead/acid Braille battery

Braille Hot Start.csv: Second start using the Braille battery; ECT ~188 deg F, EOT ~162 deg F

Cap Bank All In One.csv: This is the master cap bank log, with all of the following but Cap Bank Test 2 within it.

Cap Bank Hot Start.csv: Initial start using the cap bank (door open)

Cap Bank Live Drain.csv: This was engine off, door open, key on (gauges lit), radio on (volume 30)

Cap Bank Low Volt Start.csv: Post live drain test, hot start with 12.2 volts.

Cap Bank Test 2.csv: Another standalone hot start at high voltage (>13.5)


So the first surprise was how many amps it takes to start these things (based off of farad ratings):
Cap Bank Hot Start: 559.16 amps
Cap Bank Low Volt Start: 562.21 amps
Cap Bank Test 2: 553.76 amps

That is quite a bit of juice.


The second surprise was that these cars pull retarded amounts of power (greater than 250 MA) while off, so the initial estimate of 7 hours was being very, very forgiving; while I don't know if this draw drops off over time, I'm sure it's partially to blame for killing the FUCK out of my batteries since I normally only drive it every 2-3 days or so.

Car off, voltage at the terminals and cap bank connections/configuration during testing:


5 minutes after shutdown:


15 minutes after shutdown:


30 minutes after shutdown:



So, that all said and done, I'm not sure the 650 caps will be enough; six of them total up to ~108 farads effective capacitance, meaning they will probably drop about 5.2 volts (when started only from the bank) before the car has started. The 3k farad bank drops by about 1.1 volts, and a bank of 1500 farad caps would probably drop roughly 2.25 volts which seems like a reasonable compromise between raw capacitance and size.

With a battery in tow, it very well could be halved depending on the voltage drop the battery sees; I'm honestly not exactly sure how to do the math on that.

What does everyone think? I'd be willing to pick up a set of 1500's to test this further, as I'd really like to have my Brailles last longer; plus my battery box needs a redesign anyways.

NOTE:
The volt meter did read differently compared to what the AP saw, so there might be some step down regulation going on or just a poorly designed circuit somewhere, which could be partially to blame for my shitty draw on the cap bank.

EDIT:
As a side note, the Braille dropped between 2.76 volts during a cold start and 2.49 volts during a hot start, compared to the cap banks 1.1 volts during a hot start; that gives it roughly 2.5 times the cranking amperage per volt compared to the Braille's rated 1100 cold cranking amps. Food for thought.

[DSIT995]

Any ideas on what is causing such a high drain when the car is off?

[Enki]

Honestly, it's probably normal. I can leave the car off for about a week solid before starting becomes an issue. A normal car battery would probably last a lot longer.

Also I noticed that the ECU will command a 14 volt surge charge for about 15-20 seconds on a cold start, then level off at around 13.5 volts (you can see this in some of the logs, actually). This should be enough for the Braille, but I'm beginning to wonder if the Braille won't charge past a certain point without a 14 volt charge.

Something to research, anyways.

[udntknw]

Originally Posted by Enki Honestly, it's probably normal. I can leave the car off for about a week solid before starting becomes an issue. A normal car battery would probably last a lot longer. Also I noticed that the ECU will command a 14 volt surge charge for about 15-20 seconds on a cold start, then level off at around 13.5 volts (you can see this in some of the logs, actually). This should be enough for the Braille, but I'm beginning to wonder if the Braille won't charge past a certain point without a 14 volt charge. Something to research, anyways.

Keep in mind, these cars seem to like to charge around 13.6-8. Very rarely have I seen it charge over 14.

Just tapa it in.

[Enki]

Yeah I've only seen it hit 14 on cold starts, and even then only for a short period of time.

[bladerunner10121]

Originally Posted by Enki Yeah I've only seen it hit 14 on cold starts, and even then only for a short period of time.

Very interesting stuff. Its amazing how relatively low tech all this seems. I don't know, I work in the IT industry and it just does not seem like battery technology is keeping up with everything else. That is starting to change however.

On another note, you seem to know what you are doing so I would appreciate some advice. My girlfriend has an old Schwinn S180 Electric Scooter that I am in the process of upgrading. it is originally a 12v motor with 2 12v batteries. I am trying to retrofit it with a 48v motor and need help with the batteries. There is just not enough room for me to fit enough lead acid batteries to get 48V with a descent enough capacity. I also have the option of running it at 36V but lead acid would still not work due to the same reason.

What's the best approach to juicing this thing up? Any advice is appreciated. Thanks.

[Enki]

Motorcycle batteries maybe? What is the amp/wattage draw on the motor? That is probably the most important thing to consider; if the initial hit is large but sustained is low, you can get away with higher voltage/lower amp hours, but if the sustained is large, you're probably going to need more amp hours/reserve capacity.

Edit:
You could always build a larger amp hour x volt pack using Lithium Iron (LFE) cells; they are about 3.2 volts each, so should scale well (4 = 12.8v which is nearly ideal for cars); they have the added bonus of not randomly catching on fire.

[bladerunner10121]

Originally Posted by Enki Motorcycle batteries maybe? What is the amp/wattage draw on the motor? That is probably the most important thing to consider; if the initial hit is large but sustained is low, you can get away with higher voltage/lower amp hours, but if the sustained is large, you're probably going to need more amp hours/reserve capacity.

I just looked up the motor and its actually only 36V at 1000w. Not sure the current draw. My electrical knowledge does not extend beyond the V=IR I learned in high school physics.

As far as batteries. The stock ones are about the size of motorcycle batteries. Like the ones from bigger UPS's. They are rated 10Ah. I would need at least 6 of these to give it enough juice and run it for any reasonable amount of time and that's just too much weight and not enough room.

[Enki]

Amps = Watts / Volts = 27 Amps
Volts = Watts / Amps
Watts = Amps * Volts

A 30 amp hour battery (or pack) should last an hour at that level of draw; note that putting 3 10 amp hour batteries in series still only gets you 10 amp hours at 3x the voltage, while the overall wattage of the pack is additive; this works because the voltage is multiplied with the amp hours staying static.

[Enki]

LFE batteries are still kinda expensive, but 12 of these would probably work:

High Power LFP Polymer Cell: 3.2V 20Ah (100122200-2C, 64Wh, 40A rate) UN Approved (DGR)

12 in a pack would be 38.4 volts, 20 amp hours, and measure 8" by 5" by 6" (without case). The price, though, would be close to a grand after factoring in a balancing charger, but it would charge a shitload faster than the lead acid batteries.

[bladerunner10121]

Originally Posted by Enki Amps = Watts / Volts = 27 Amps Volts = Watts / Amps Watts = Amps * Volts A 30 amp hour battery (or pack) should last an hour at that level of draw; note that putting 3 10 amp hour batteries in series still only gets you 10 amp hours at 3x the voltage, while the overall wattage of the pack is additive; this works because the voltage is multiplied with the amp hours staying static.

Thank you. The LiFePO4 looks to be the best option. It looks like I may be able to build a 10Ah battery back with the LiFePO4 for around 300bucks which should get me about 20 minutes at full load. I got some reading to do.

Also where is the best place to buy this kind of stuff from. I was looking at All-battery.com. Ill stop cluttering up your thread now. Thank you for your help.

Edit: never mind I just saw your post above. Thanks.

[Enki]

Be mindful of the recommended draw rate (usually in amps) on those cells; if you exceed it, the life cycle goes down pretty quickly depending on how far over you are.

As for where, well I'm not entirely sure. Batteryspace was the first place I found that had what I was looking for, so I didn't look further, but I'm sure its possible to find stuff like this on Ebay (risky) or Amazon or the like.