12v to 36v 30a converter?
- Thread starter sangesf
- Start date
edcastrovalley
1 kW
Here's a nice American made one. A little pricey at $395 but it looks like a good one. It would around 90 to 92% efficient.
http://www.zahninc.com/DCDC6350.html
They have a smaller, less expensive one too but it falls short of the 20 amps output you need. You must be mounting a large 12 volt battery on an ebike?
http://www.zahninc.com/DCDC6350.html
They have a smaller, less expensive one too but it falls short of the 20 amps output you need. You must be mounting a large 12 volt battery on an ebike?
jonescg
100 MW
Well think about how easy the BMS would need to be! Only one cell at 3.3 volts nominal, 500 Ah. Buck it up to 400 V to run an AC motor :lol:
It would work, but is really an odd solution to an easy problem.
Whats the big deal with running a battery system with the voltage and capacity you want? Do you already have parts on hand you want to use? I just don't see any advantage to doing it that way.
Whats the big deal with running a battery system with the voltage and capacity you want? Do you already have parts on hand you want to use? I just don't see any advantage to doing it that way.
ZOMGVTEK said:
Let say, for arguments sake, that I happened upon a 12v 600AH Lifepo4 battery, that fully works and a 4000w inverter (both for free) and I want to use that setup on a 36v 30AH battery (While its in use and has a controller that pulls 20a max) using an 11a charger connected to (and charging) said battery.
Would there be any big problems?
P.S. This was a hypothetical question posed to me by a friend.
Edited for mathematical reasons.
There would be no problems at all with that setup, electrically.
You would obviously need to be aware of your power draw, since you would be charging at a lower rate than your peak discharge. So long as your average discharge is below the 11A charge rate, it will work until the 12V 600AH battery voltage falls low enough so that the inverter turns off, and then the 36V 30AH battery depletes. It would be a very simple setup to make, but somewhat costly, LARGE, and relatively inefficient. Even if the inverter was 92% efficient, you are loosing 8% of the power in the inverter alone, a few more percent in the 11A charger, and a touch more in the wires. It would probably be closer to 80-85% total charge system efficiency, meaning you loose 60-90AH out of your main 600AH battery to heat. Some batteries may not like charging while being discharged. That would be battery dependent. Anything without a BMS won't care, and most BMS's should be OK with it, but thats not a guarantee.
The SOLE advantage is if you have a HUGE 12V battery, inverter, and charger laying around. On a car, it might be OK to just throw this stuff in the trunk. But on a bike, even a 1000W inverter would take up quite a bit of space. Obviously you need to have the battery to go anywhere, and more battery means more capacity. However, the inverter and charger are both unnecessary for the system, and only required since you want to run a higher voltage than your battery supplies natively. The best solution would be to get a 36V 200AH battery, which would be equivalent capacity to the 12V 600AH one, but not require the inverter or charger.
You would obviously need to be aware of your power draw, since you would be charging at a lower rate than your peak discharge. So long as your average discharge is below the 11A charge rate, it will work until the 12V 600AH battery voltage falls low enough so that the inverter turns off, and then the 36V 30AH battery depletes. It would be a very simple setup to make, but somewhat costly, LARGE, and relatively inefficient. Even if the inverter was 92% efficient, you are loosing 8% of the power in the inverter alone, a few more percent in the 11A charger, and a touch more in the wires. It would probably be closer to 80-85% total charge system efficiency, meaning you loose 60-90AH out of your main 600AH battery to heat. Some batteries may not like charging while being discharged. That would be battery dependent. Anything without a BMS won't care, and most BMS's should be OK with it, but thats not a guarantee.
The SOLE advantage is if you have a HUGE 12V battery, inverter, and charger laying around. On a car, it might be OK to just throw this stuff in the trunk. But on a bike, even a 1000W inverter would take up quite a bit of space. Obviously you need to have the battery to go anywhere, and more battery means more capacity. However, the inverter and charger are both unnecessary for the system, and only required since you want to run a higher voltage than your battery supplies natively. The best solution would be to get a 36V 200AH battery, which would be equivalent capacity to the 12V 600AH one, but not require the inverter or charger.
Ok, now scale that down...
My friend already has these things... And ZERO CASH.... Hehe
1.) 36v 20ah lifepo4 battery with or without BMS. (doesn't matter which).
2.) 12v 100ah lifepo4 battery (no BMS).
3.) 400w DC-AC converter.
4.) 36v 5a Lifepo4 charger.
5.) 12v 25ah Lifepo4 charger
6.) 36v 17a max controller.
7.) More than enough space for all of the above.
He hooks it all up.
He's gonna ride for 2 hours and stop for an hour...
So let's see.... (or say)
1.) After 2 hours he's gone 30 miles....
(average 8 amps and/or 16ah usage - he has "4ah" left.)
2.) BUT he's charged 10ah worth
(or let's say only 9ah - he's back up to 13ah)
3.) It's sitting there for an hour and charges another 5ah worth.
(or let's say 4ah - he's back up to 17ah!)
4.) He's pulled 540wh from the 12v 100ah (1200wh) battery. (Down to 660wh).
(540wh * 80% efficiency of the system = 432wh or 15AHs worth of charging.)
He starts off again..
1.) Another 30 miles / 16ah usage.
(Down to 1AH - but not really because of #2)
2.) But, during his ride, he has also charged up 9ah.
(Up to 10AH)
3.) After an hour he's added another 4AH
(Up to 14AH!)
4.) He's pulled another 540wh off of the 12v Lifepo4 battery.
(Down to 120wh left on battery, so he disconnects it).
He can now go another 12AH worth of riding or 22.5 Miles - (1.5 more hours of riding.)
(Leaving 2Ah "safety margin")
He's now gone 82.5 miles and not having to find a 120v outlet or plug in even once!
(He's at home now [or at a friends house or wherever] and charges the two batteries back to full in only 4 hours.)
Just using his 36v 20ah battery he could only get 37.5 miles... But with the added 12v 100ah battery he has achieved 82.5! And still has a 2AH in reserve.. Heh
That's nice!
Yeah I know if he had a 36v 33ah battery as well he could get 95.5 miles and still have 2ah left total.
Ok.. Here's the deal..
Would you rather...
1.) Run the above charging scheme (36v 20ah and 12v 100ah) for NO additional cost...
OR
2.) Shell out money for an additional 36v 25ah battery (which would net the same distance capability)
or
An additional 36v 33ah battery (same as 12v 100ah in terms of WHs) to get the extra 13 miles capable?!?
For me, it's a no brainer...
My friend already has these things... And ZERO CASH.... Hehe
1.) 36v 20ah lifepo4 battery with or without BMS. (doesn't matter which).
2.) 12v 100ah lifepo4 battery (no BMS).
3.) 400w DC-AC converter.
4.) 36v 5a Lifepo4 charger.
5.) 12v 25ah Lifepo4 charger
6.) 36v 17a max controller.
7.) More than enough space for all of the above.
He hooks it all up.
He's gonna ride for 2 hours and stop for an hour...
So let's see.... (or say)
1.) After 2 hours he's gone 30 miles....
(average 8 amps and/or 16ah usage - he has "4ah" left.)
2.) BUT he's charged 10ah worth
(or let's say only 9ah - he's back up to 13ah)
3.) It's sitting there for an hour and charges another 5ah worth.
(or let's say 4ah - he's back up to 17ah!)
4.) He's pulled 540wh from the 12v 100ah (1200wh) battery. (Down to 660wh).
(540wh * 80% efficiency of the system = 432wh or 15AHs worth of charging.)
He starts off again..
1.) Another 30 miles / 16ah usage.
(Down to 1AH - but not really because of #2)
2.) But, during his ride, he has also charged up 9ah.
(Up to 10AH)
3.) After an hour he's added another 4AH
(Up to 14AH!)
4.) He's pulled another 540wh off of the 12v Lifepo4 battery.
(Down to 120wh left on battery, so he disconnects it).
He can now go another 12AH worth of riding or 22.5 Miles - (1.5 more hours of riding.)
(Leaving 2Ah "safety margin")
He's now gone 82.5 miles and not having to find a 120v outlet or plug in even once!
(He's at home now [or at a friends house or wherever] and charges the two batteries back to full in only 4 hours.)
Just using his 36v 20ah battery he could only get 37.5 miles... But with the added 12v 100ah battery he has achieved 82.5! And still has a 2AH in reserve.. Heh
That's nice!
Yeah I know if he had a 36v 33ah battery as well he could get 95.5 miles and still have 2ah left total.
Ok.. Here's the deal..
Would you rather...
1.) Run the above charging scheme (36v 20ah and 12v 100ah) for NO additional cost...
OR
2.) Shell out money for an additional 36v 25ah battery (which would net the same distance capability)
or
An additional 36v 33ah battery (same as 12v 100ah in terms of WHs) to get the extra 13 miles capable?!?
For me, it's a no brainer...
Your logic is sound, and it would work fine. Generally you should never expect 20AH out of a 20AH battery. It can be as low as 14-15AH, not usually higher than about 18-19AH. Of course this will depend on the cell type, construction, LVC, HVC, temp, discharge rate... Regardless, shallow discharges tend to be best. Try to avoid discharging the last little bit when possible.
A 1200W battery is large enough to have a substantial impact on range. It's more capacity than most carry around. You will run into some losses using it, since its 12V. Unfortunately the most cost effective solution would probably be converting the 12VDC to 120VAC, then the 120VAC down to 36VDC. It's a bit more lossy than a 12-36V step up, but cheap and easy. If you have the parts laying around, go for it and see what it will do. So long as the charger isn't too smart and gets mad at the occasional voltage drop, I don't foresee any major issues. Most of those brick style chargers shouldn't mind a nasty modified sine wave input, and a fluctuating voltage output.
A 1200W battery is large enough to have a substantial impact on range. It's more capacity than most carry around. You will run into some losses using it, since its 12V. Unfortunately the most cost effective solution would probably be converting the 12VDC to 120VAC, then the 120VAC down to 36VDC. It's a bit more lossy than a 12-36V step up, but cheap and easy. If you have the parts laying around, go for it and see what it will do. So long as the charger isn't too smart and gets mad at the occasional voltage drop, I don't foresee any major issues. Most of those brick style chargers shouldn't mind a nasty modified sine wave input, and a fluctuating voltage output.
I'm intrigued by this whole idea...
I personally don't have any of that kind of stuff...
BUT.. I DO have this...
1.) 12v 60AH LiFePo4. (4s Thundersky 60AH cells)
2.) 36v "true" 10ah Lifepo4. (Tested to 9.5ah on a 10a avg load)
3.) 36v 3a "brick" charger.
4.) 200w inverter..
5.) 36v 15a max controller. (Allows 48v and still only pulls 15a max).
I'll hook up the Inverter to the TSs, the Charger to the Inverter, and the Battery into the Charger and if the "charging system" works on a quick 2a load test, then..
I will run the motor/controller for an hour at 5a average (180wh - Using watt meter) and then remove the "charging system" and see how much "farther" I get...
That should give me a baseline as for my friends idea..
I prolly won't be able to do it for a while, but I'll see when I get the chance..
If anyone else can do it before me, I'd appreciate it!
Hehe.
I personally don't have any of that kind of stuff...
BUT.. I DO have this...
1.) 12v 60AH LiFePo4. (4s Thundersky 60AH cells)
2.) 36v "true" 10ah Lifepo4. (Tested to 9.5ah on a 10a avg load)
3.) 36v 3a "brick" charger.
4.) 200w inverter..
5.) 36v 15a max controller. (Allows 48v and still only pulls 15a max).
I'll hook up the Inverter to the TSs, the Charger to the Inverter, and the Battery into the Charger and if the "charging system" works on a quick 2a load test, then..
I will run the motor/controller for an hour at 5a average (180wh - Using watt meter) and then remove the "charging system" and see how much "farther" I get...
That should give me a baseline as for my friends idea..
I prolly won't be able to do it for a while, but I'll see when I get the chance..
If anyone else can do it before me, I'd appreciate it!
Hehe.
So, as I said, here are the results of what happened..
Yeah, the (60ah) TS cells I have been using, kept quite within reach of each other..
They stay at ~ 3.3xV from 0-20ah and at ~ 3.2xV from 20-40ah and at ~ 3.1xV from 40-52ah or so...
Once they get below 3.1v, I stop using 'em and recharge...
Here is the CRAZY setup.. (P.S. The 36v battery stays at 3.3v per cell throughout the whole test)
I have the 36v lifepo4 10ah battery that's seried with the 12v 60Ah battery AND the inverter is installed on the 12v to recharge the 36v battery at 3a (200w used per hour) WHILE I'm riding..
So that after an hour of riding, I've used 5Ah of the entire system and another 15Ah out of the 12v battery (inverter usage) for a total of 10 miles/20Ah used, 36v battery now has 3ah put back in.. So instead of at 5Ah left, it's at 8ah... (12v is still at 3.3xV per cell.).
So another hour of riding, same thing.. 20Ah used for ENTIRE system and another 10 miles..
36v at 6Ah (8Ah minus 5Ah used, plus 3Ah put back in)
12v at 3.2xV each (Total 40Ah used)
Then a 30 minute ride, same thing but half as much used/put in..
10Ah used for entire system and another 5 miles...
36v at 5Ah (6Ah minus 2.5Ah used, plus 1.5Ah put back in)
12v at 3.1xV each (Total 50Ah used)
(Time to turn of Inverter)
So I've gone 25 miles and 36v battery is still at 5Ah and 12v battery is still at 10Ah...
I usually run another 4 miles (re: 2Ah for the "48v part (36v+12v)"), so the 36v has 3Ah left and the 12v is at 52Ah used or 3.1v per cell.
If I run at night, I forgo the last 30min of inverter for my lighting system usage of the 12v battery. (Yeah, I use it for my lights too! - Heh.)
Basically, WITHOUT buying another battery, I get 30 miles out of my 36v 10Ah battery and still have 3Ah left and not one recharge! LOL!
P.S. (MOST I get out of the 36v 10Ah is 20 miles and that's to LVC, which I don't like to do... Also at 36v my top speed and power is a bit lower than the "48v setup")
I got the 4 TS 60Ah cells for $100 (Really lucky on an eBay auction), so for $100 I've effectively doubled the range of my 36v battery AND have higher top end and more torque!)
P.P.S. (I also have a switch setup in line of the series connection, so just in case, the 12v TSs get low, I can disconnect them for whatever reason.)
Yeah, the (60ah) TS cells I have been using, kept quite within reach of each other..
They stay at ~ 3.3xV from 0-20ah and at ~ 3.2xV from 20-40ah and at ~ 3.1xV from 40-52ah or so...
Once they get below 3.1v, I stop using 'em and recharge...
Here is the CRAZY setup.. (P.S. The 36v battery stays at 3.3v per cell throughout the whole test)
I have the 36v lifepo4 10ah battery that's seried with the 12v 60Ah battery AND the inverter is installed on the 12v to recharge the 36v battery at 3a (200w used per hour) WHILE I'm riding..
So that after an hour of riding, I've used 5Ah of the entire system and another 15Ah out of the 12v battery (inverter usage) for a total of 10 miles/20Ah used, 36v battery now has 3ah put back in.. So instead of at 5Ah left, it's at 8ah... (12v is still at 3.3xV per cell.).
So another hour of riding, same thing.. 20Ah used for ENTIRE system and another 10 miles..
36v at 6Ah (8Ah minus 5Ah used, plus 3Ah put back in)
12v at 3.2xV each (Total 40Ah used)
Then a 30 minute ride, same thing but half as much used/put in..
10Ah used for entire system and another 5 miles...
36v at 5Ah (6Ah minus 2.5Ah used, plus 1.5Ah put back in)
12v at 3.1xV each (Total 50Ah used)
(Time to turn of Inverter)
So I've gone 25 miles and 36v battery is still at 5Ah and 12v battery is still at 10Ah...
I usually run another 4 miles (re: 2Ah for the "48v part (36v+12v)"), so the 36v has 3Ah left and the 12v is at 52Ah used or 3.1v per cell.
If I run at night, I forgo the last 30min of inverter for my lighting system usage of the 12v battery. (Yeah, I use it for my lights too! - Heh.)
Basically, WITHOUT buying another battery, I get 30 miles out of my 36v 10Ah battery and still have 3Ah left and not one recharge! LOL!
P.S. (MOST I get out of the 36v 10Ah is 20 miles and that's to LVC, which I don't like to do... Also at 36v my top speed and power is a bit lower than the "48v setup")
I got the 4 TS 60Ah cells for $100 (Really lucky on an eBay auction), so for $100 I've effectively doubled the range of my 36v battery AND have higher top end and more torque!)
P.P.S. (I also have a switch setup in line of the series connection, so just in case, the 12v TSs get low, I can disconnect them for whatever reason.)
ZOMGVTEK said:
In the morning, I'll take some pics...
Bike is charging (the 36v battery) and there's no lights near it and my iPhone (3G) has no light on the camera.
P.S. It don't look pretty, but it does work..
P.P.S. I'm in the middle of a "second run" for a nighttime/worse case scenario test on the 12v 60AH TSs.
(Using Motor/Inverter/Lights/Radio/Amp (set at 5a max draw)).
Used up 33.45Ah out of the 60Ah Thunderskys (Cells have stayed steady from 3.3xV to 3.2xV, from 2Ah - 33Ah so far, so good).
Avg 8a draw for motor, Avg 8a for lights/radio/amp and Avg 14a for inverter setup for a total Avg of 30amp (.5C) continuous draw (Conservative Estimates)
I've cycled the TSs 20 times before starting these tests.. Looking to see available AH on a .5C continuous draw and then will test with 60-120a (1-2C) loads.
dogman dan
1 PW
Whacky, but it works. Sure you lose some watts along the way, but it does work. It's actually a lot like carrying a generator to run a charger to charge a smallish 36v battery while you ride. Only when I did this with a generator, the generator weighed about 90 pounds. Bet the 12v 60 ah TS battery is a lot lighter than that!
Nice McGuyver! You wouldn't go buy everything specificly to do it that way, but it happens to be what you have, and it works.
Nice McGuyver! You wouldn't go buy everything specificly to do it that way, but it happens to be what you have, and it works.
dogman said:
It sure is McGuyver'd! It really is just a" proof of concept" test, because I have plenty of TS-60's to make whatever batteries I want, just checking to see if this works and if so, what the power drain is... (Really a test of these new cells too)...
With a large SLA, it Should work ok, but you would need it to be a HUGE one...
Pulling 33ah off of TSs with an average of 20 or so amps coninuous is a different story then pulling it from an SLA..
As promised.. The ugly setup works like this...
Pic of Batts/Inverter/charger..
P.S. In tas above photo, you can disregard the XLR connector, molex connector, and wires as those are for charging a totally different battery...(not shown in the pic and not "part" of the "system".)
And now pic of it coming out of box....
And now it running into the battery...
Ugly, massively inefficient, heavy, BUT it Works!
DAND214
10 MW
I'm so confused! Give me a minute to put my head on straight.
Wow that's a lot of work.
Wouldn't want to get caught in a downpour.
I'm sure you have it all waterpoofed.
Dan
Wow that's a lot of work.
Wouldn't want to get caught in a downpour.
I'm sure you have it all waterpoofed.
Dan
I have two of those Schwinn OCC electric chopper bikes, this one is my test bed for all my projects / testing...
(The other one will be completed after all my testing is done and I get my diamond plate aluminum boxes and everything on that one will be completely waterproofed. FWIW, the completed one will have two 48v motors/controllers (30a max) running off of one 48v 60Ah battery, I should be able to maintain a 25mph speed and get approx 150-200 miles out of it without the need for a recharge! - Yeah it's gonna be heavy as crap, but it's a true cruiser, with ALL the amenities, I could EVER want.)
I DO ride this one daily, BUT if it's raining, I don't ride it. One of the controllers (front) is NOT waterproofed (Although the batteries / connections are) and the rear box holds the other batteries / inverter / chargers / etc and is basically water proof.. Currently I just put plastic bags (that I always keep on me), over the radio and front controller if it starts to rain and that keeps them dry.
I also, as well, carry TP [cause ya never know when there'll be a "zombie apocalypse" LOL].
P.S. I have various other threads showing this bike with pics, videos, tests, quandries, queries, etc.
(The other one will be completed after all my testing is done and I get my diamond plate aluminum boxes and everything on that one will be completely waterproofed. FWIW, the completed one will have two 48v motors/controllers (30a max) running off of one 48v 60Ah battery, I should be able to maintain a 25mph speed and get approx 150-200 miles out of it without the need for a recharge! - Yeah it's gonna be heavy as crap, but it's a true cruiser, with ALL the amenities, I could EVER want.)
I DO ride this one daily, BUT if it's raining, I don't ride it. One of the controllers (front) is NOT waterproofed (Although the batteries / connections are) and the rear box holds the other batteries / inverter / chargers / etc and is basically water proof.. Currently I just put plastic bags (that I always keep on me), over the radio and front controller if it starts to rain and that keeps them dry.
I also, as well, carry TP [cause ya never know when there'll be a "zombie apocalypse" LOL].
P.S. I have various other threads showing this bike with pics, videos, tests, quandries, queries, etc.
dogman dan
1 PW
48v 60 ah is a lot of battery to pack, but if it's what you got, it's what you got.
dogman said:
True dat!
P.S. I tested that 12v 60Ah pack (made of LFMP60AHA) and received these results...
(Charged to 3.65v @15a(.25C), then charged to 4.0v @1.8a(.03C), they then all sat settled at 3.7v-3.71v after an hour - tested down to 2.8v under load - pulled load off and waited 5 min for "settled at" voltage.
1C test = 58.6Ah received at 2.8v
(settled at an average of 3.02v)
.5C test = 59.3Ah received at 2.8v
(settled at an average of 3.09v)
.2C test = 63.7Ah! received at 2.8v
(settled at an average of 3.11v)
Cell voltages were all within .09v(1C test) - .04v(.2C test) of each other at the ends of the tests.
(Very well matched cells)
neptronix said:
Yep... When I get a chance, I'll hook up an ammeter between the battery and the inverter (with the charger running) and see what the amp pull (wattage) is...
(The charger (nominally) puts out 45.6v at 3a. (136.8w) and the inverter is a 200w continuous (with a 250w shutoff)... If I had to hazard a guess, I'd agree with you and say the process is in the 68% - 70% efficiency range.)
Will let you know!
That setup is almost hilarious.
It works, and I suppose there is minimal advantage to increasing efficiency of the charger/inverter system. The 12V battery has massively more capacity than the 36V one. It would depend on how the bike is used, but practical range wouldn't really increase with a more efficient setup. My best guess at that systems charge efficiency would be around 82% I'd say high 70's at the worst.
At least now you can plug in a phone charger or some other low power device.
It works, and I suppose there is minimal advantage to increasing efficiency of the charger/inverter system. The 12V battery has massively more capacity than the 36V one. It would depend on how the bike is used, but practical range wouldn't really increase with a more efficient setup. My best guess at that systems charge efficiency would be around 82% I'd say high 70's at the worst.
At least now you can plug in a phone charger or some other low power device.
ZOMGVTEK said:
Actually, the 12v 60Ah system is 720wh and the 36v 10Ah is 360, so although it's not "Massively" more capacity it IS double.
. Even at 75% efficiency it is like having a 36v 15Ah battery. (Albeit for the price I paid for those specific 4 TSs (lucky me-$120 -about a 1/3 of the cost of a lifepo4) and I had all the other parts already, so for a proof of concept, it's just dandy!
(If not for anything, if anyone can get 4-60Ah+ TSs [for cheap] and already has the equipment like I did, then spending the money on another 36v battery might not be needed.. Also, the need for a BMS kinda goes out the window too..
)If you've seen ANY of my other threads, you know, I got soo much ability/crap on the bike to accomplish (just about) anything in terms of charging the motor's batteries/cell phones/laptops/etc, using the radio/amp/lights/etc, helping others (and myself) fix tires/controllers/throttles/tubes/electronics/etc, and many other Things.
Sunder
10 MW
Any reason why you didn't get like a cheap 12 -> 50v step up converter, then set it to the float voltage of the 36v battery?
It would weigh 50g, cost you about $20, convert at 92% efficiency. You couldn't use it to drive the bike, but you could use it to charge the battery at 1/2 C, even as you were using it.
You could even use 2 or three of them in parallel to get 10 or 15A.
It would weigh 50g, cost you about $20, convert at 92% efficiency. You couldn't use it to drive the bike, but you could use it to charge the battery at 1/2 C, even as you were using it.
You could even use 2 or three of them in parallel to get 10 or 15A.
Similar threads
