300 amp power supply

Where is the 14.5V/300A going?

If this is to charge the Lithium batteries... RUN away as quickly as you can >:-} ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Im not charging directly the battteries. They have a module between my unit and their battery bank.

My question is. Can I do without an inductor or transformer? Because every configuration i know about .. Sepic. Buck .. Cuk.. All contains an inductor.. K

You keep dodging the question... SHOW us the configuration.

You can _possibly_ do it without an inductor, but you must show us a schematic/diagram first. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

I dont have a diagram. You want a diagram of the whole system.

What is the input to your "voltage dropping device" and what is the load? Just saying a "module" tells me nothing. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

I sometimes wonder about Cuk converters at high powers as carrying such high power through a capacitor seems to me less usual. Capacitors rated for 300Amp at 10s/100s kHz are hard to buy off-the-shelf and hard to make oneself but any fool can wind copper on a core. Not saying multi-kilo watt Cuk can't be done but it just seems less common than all-magnetic topologies (at least in my very limited experience at these power levels)?

piglet

Jim, spoke with my client. There is an alternator dedicated for charging the batteries. The alternator should give anywhere between 14.5v to 16v but a max of 18v should be confi gured, then shuts down if more then 18v. The converter we are ask to do is to take that power and charge lithium ba tteries directly at a stable 14.5v. Our client said he will . You must understand that this is a big project out client has and our devic e will fit in somewhere in the chain. Their system will take of shutting do wn the device if batteries are charged. I've been told that the alternator does not turn on unless there is a charge on the batteries. K

[snip]

So we have a hybrid vehicle?

If this alternator is "dedicated" to charging the batteries at 14.5V, then my original statement applies... build a better regulator for the alternator... that will save you a lot of grief and dissipation.

If the alternator can definitely provide a minimum of 14.5V but varies up to 18V, then their regulator sucks >:-}

See my patents... at one point in time in the mid '60's _every_ American-made car (except American Motors) had an alternator regulator designed by me. The hilarity is that every one of them had a different idea about the TC curve for lead-acid ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

There are very specific charging specifications for lithium batteries, and the voltages and currents depend on the chemistry. LiFePO4, which is safer and more forgiving, has a nominal voltage of 3.3V per cell, which is 13.2 VDC for four in series, and maximum charging voltage is about 3.6 Vpc, or

14.4V. Lithium-Ion, or LiPo, have a nominal voltage of 3.6 to 3.7 Vpc, and can charge at up to 4.2 Vpc. But a proper charger uses a constant current of 1C to 10C (or more), until a target voltage is reached, and then throttles back to about C/10 or C/20 to finish the charge. Lithium cells do not do well on long term CV float charge.

With multiple cells in series, it is vitally important to install some sort of Battery Management System, or BMS, to monitor individual cell voltages. Lithium cells can be damaged by even a small amount of overvoltage, and the result can range from reduced lifetime and capacity, to shorted cells and violent explosion and fire. You will be applying close to 1000 watts per cell and a 300 A-h cell holds a lot of energy which can be catastrophically converted to heat and flame and rupture of the enclosure.

I would suggest discussing this project with members of the DIYelectricCar forum, who have had a lot of direct experience with lithium cells and EVs. The chargers I am working on are designed for high power lithium battery packs, but generally much higher voltage (48V-300V) and lower current (20-50A).

Good luck, and be safe...

Paul

It's good to see haw careful management is, in dealing with new lithium battery product development.

I think this whole thread is a crock.

RL

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Like I said, I'm only involved in a small section of a big project. There m ust be a reason why they want this but I'm not told. As far as the charging goes, I know lithium batteries are complex, but again , I'm not involved i nto that and they have something to control that which is beyond my reach . So back to square one !

K

OK, just for fun - yes you can;

RL

On Wed, 23 Sep 2015 15:00:13 -0700 (PDT), captoro Gave us:

Jim spoke with your client?

My guess would be that even if you could, you wouldn't want to.

I think the theoretical inductor-free solution would be to charge up a bunch of 5-capacitor series strings, then reconfigure them into a bunch of 4-capactor series strings and discharge them into your load.

That's 20 capacitors and at least 40 switches so it doesn't sound all too practical. The capacitors have to be closely matched, which isn't all that easy.

--
Bill Sloman, Sydney

Gave us:

I meant... Jim, (comma) I spoke with my client. (period) :)

HI bill,

This is what my client wants. I cannot changes anything else in the project, that is the alternator or other components. the size is the issue, very small unit for that much current. Other wise doable with an big inductor and more traditional methods.

K

Slowman == Clueless Noise source ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

If I remember rightly, I've admitted that I don't know much about the area.

You claim to have more experience. I think that my claim that a SEPIC inductive regulator would need a bigger inductor than a CUK-style transformer-based regulator happens to be valid.

I've been brooding about how such a CUK-style transformer based circuit might work and might even eventually get to something I could model in LTSpice.

Would you care to produce your own version of such a circuit? It would demonstrate a slightly tighter grasp of reality than the above.

This is a formal challenge - .asc files at ten thousand miles.

You could chicken out and eat dust ....

--
Bill Sloman, Sydney