remote Lithium battery and standard VR in alternator possible?

[Mattias Andolfsson]

Hello
Thank you for letting me post here for my first time. I'm a car enthusiast and always interested in optimizing my builds. Now, my latest build, an Alfa Romeo Gt 1300 Junior from 1969 being prepped for race and road.

So, what is my problem;
§. Small lithium battery with 20A max charge amps
§. The battery is placed with ca 2m longer wires from the alternator than original
§. The alternator is a new Denso Nippon type of 45A

Q:
1. Will the regulator on the alternator "sense" the voltage of the battery correctly, even though there are sufficiently longer wires to it (ie voltage drop due to resistance in the wire)? I don't want to bulky wires too, everything is weight optimized.
2. Is it possible to "move" the regulating part of the alternator closer to the battery, and therefor get a correct charge on/off -effect?
3. Will the charging voltage still be too low, regarding to the longer cable / higher resistance with my new location of the battery?
4. Will my alternator blow my battery when charging with <45A, when the battery claims it only manages 20A? Can I put some thyristor or diode to maximize the charge load to 20A?

Thanks for your time.

 

[alec_t]

Welcome to ETO.
Whoa! What you are proposing to do is VERY DANGEROUS !!
The original alternator and voltage regulator are designed for use with a lead-acid battery, which is a completely different animal from a lithium battery. Lithium batteries will catch fire or EXPLODE if not charged and discharged correctly. You will need to use a dedicated lithium battery management system.
I suggest you have a read of the info at Battery University.

 

[Mattias Andolfsson]

thank you for your reply!
Is there any module to use in conjuction with the alternators regulator? I googled the lithium battery difference, and all I remember finding is tat the lithium charge should be (almost) ripple free, wich I think a newer alternator is.

 

[MikeMl]

Any automotive alternator (new or old) has identically the same ripple (six phase full-wave rectified, no filtering). It relies on the car's battery to "filter" it.

You have a lot of reading to do about LiPo batteries, how lead-acid battery charging systems work, and why one is incompatible with the other....

 

[Mattias Andolfsson]

there is lithium car batteries with built in electronics to solve that. How about my other Q?

 

[alec_t]

How about my other Q?

Q1) No.
Q2) No.
Q3) Depends what the lithium battery spec is.
Q4(a) Yes. Q4(b) No.
Post #3) You would need an entirely different regulator.

 

[Mickster]

If you have any doubts about how dangerous lithium batteries can be if not charged/discharged/handled properly, please look up "lithium battery fire" on Youtube.
Your safety, and that of anyone else for that matter, is much more important than the cost involved in repairing your vehicle, should you get this wrong.
Please carefully heed the above warnings.

 

[audioguru]

What will the new Lithium battery be used for? The car's starter motor has such a high current that the Lithium battery will explode.
You do not have a charging management system for a Lithium battery, instead you have one for a lead-acid battery that is completely different.
If the Lithium battery is discharged too low then it will be damaged and you try to charge it then it will explode or catch on fire.