A better alternator delete

[Daox]

I am not sure exactly what configuration they will end up in. I do not think I will need the whole 120 cells for this project. The first pack I will be making is probably going to use about 40 cells. 5S8P is what I am thinking. I'll use a 300W dc-dc converter to charge the lead acid battery at just over what the alternator puts out.

The next step now is figuring out how to charge them. I have my doubts that my power supplies are isolated as Teoman mentioned. So I may have to come up with something else.

[UFO]

Originally Posted by Daox

I am not sure exactly what configuration they will end up in. I do not think I will need the whole 120 cells for this project. The first pack I will be making is probably going to use about 40 cells. 5S8P is what I am thinking. I'll use a 300W dc-dc converter to charge the lead acid battery at just over what the alternator puts out.

The next step now is figuring out how to charge them. I have my doubts that my power supplies are isolated as Teoman mentioned. So I may have to come up with something else.

Check them for sure, but typically off-line supplies (AC to DC) are required by law to have isolated outputs, so you should be able to charge individual cells in the stack.

[Daox]

Thats good news. I'll have to crack one open and double check. The cases seem mostly empty. I imagine they could have been much smaller.

[Daox]

It looks like it is isolated to me. The big yellow taped up thingy's part number is a transformer when you google it.

[teoman]

Those connectors look like laptop connectors. The laptop batteries have internal temp semsors and balance circuits...

If those are indeed the packs you have why not try to source the other half of the connector?

[teoman]

If i were you, i would try to source a connector and 3d print something to make the cells pluggable.

Wish they were in 4S format.


They communicate over I2C (if they are similar to laptop packs).

The chip that manages them was made by Texas Instruments (last time I had a look) and was able to pump out all kinds of usefull data like Wh remaining.

An arduino project would be an interesting endeavor.



OR you could say enough with high tech cr*p!

In that case, I would form the cells as parallel chains that are balanced capacity wise. (There was a website for that that jhurgia recommended).

Find a good connector that connects the strings in series. This connector would also double as your charging port. So depending on what you connect to this connector you can get 4S output or all cells parallel output. Then you can have single power supply charging without the need for balancing.

I Hope I was able to make myself clear.

[Piotrsko]

If the yellow transformer is across the AC plug, they are isolated, that is why the transformer is there. It's cheaper to build a buck power supply that is transformer less but not isolated. The diodes are getting hot because you are running max current the device was designed for, ditto on the capacitors because they are supplying current during the "off" portion of the cycle. I wouldn't run more than half the rated current without having heat sinks if you want any longevity or "surprise" oops events.

I would also be inclined to use the modules as is with the bms on top if they allowed charge to 4.2 @ cell. Which gives you 12.6v

[Stubby79]

I'm interested to see what creative methods you end up using, as well as feedback on those cells (they're a good price, so if they live up to what they are sold as, I'd want to pick up some).

You'll need more than 20A to keep everything running, unless you've modified the snot out of your car to minimize the load. (I needed 30a to keep my car running without putting any extra loads, like the wipers, or the parking lights). Of course if this isn't your intention, then you can ignore this.

I really ought to get back on to this (similar) project.

[Daox]

Originally Posted by teoman

Those connectors look like laptop connectors. The laptop batteries have internal temp semsors and balance circuits...

If those are indeed the packs you have why not try to source the other half of the connector?

They are modem batteries I believe. Printing something up so I don't have to disassemble them sounds like a great idea. I'm not sure I can make that work, but I will definitely look into it.

Originally Posted by Piotrsko

If the yellow transformer is across the AC plug, they are isolated, that is why the transformer is there. It's cheaper to build a buck power supply that is transformer less but not isolated.

I also tested for continuity and there was none.

The diodes are getting hot because you are running max current the device was designed for, ditto on the capacitors because they are supplying current during the "off" portion of the cycle. I wouldn't run more than half the rated current without having heat sinks if you want any longevity or "surprise" oops events.

They are rated for 5A, and I have them running at 4A. I figured 80% wasn't too much to ask, but perhaps it is. 3A would still be fine for these purposes I think.

I would also be inclined to use the modules as is with the bms on top if they allowed charge to 4.2 @ cell. Which gives you 12.6v

If that is possible, I could look into using a boost converter.

[Xist]

I think it is funny you are attempting to murder your alternator and MetroMPG is trying to bring his back from the dead.