Simple 4s lifepo4 12v block management

Batteries, Chargers, and Battery Management Systems.
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juzamthai   10 µW

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Joined: Aug 18 2016 4:51am

Simple 4s lifepo4 12v block management

Post by juzamthai » Feb 14 2017 2:09pm

Hi

Living in an RV, battery system quality is biggest part of confort, for a geek like me.

So i decide to build up a little project.


I already found an easy way to convert 12v dc to 19v dc (for the laptop reloading)
Clear :)

So i dlike to go for a 4s lifepo4 pack.
Arround 100 A even more in 12v.

I'm thinking about winston or sinopoly or calb cells (all in 100A 3,2v)

These cells will discharge at max 3C
And for loading, 0.3c to 2c

What charger power size should i take for a 100ah 12v block.

And a kind of charger that can automaticaly cut off when the max treshold is reached.


I know that to optimise lifecycles, it's better to stop charging when reaching 3.65v /cell wich is enough and avoid all kind of "over-x" ^^

Also read that most of burst case happened because of defective bms.

And that it's safer to avoid using one.



So let me know your point of view about all this.

And if you have a automatic settable cutoff charger that will handle the 100A 12v as fast as possible.


Thank you for your help.

Regards.

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Sunder   100 MW

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Location: Sydney, Australia

Re: Simple 4s lifepo4 12v block management

Post by Sunder » Feb 14 2017 6:04pm

just get an adjustable switchmode psu set for 14.6v.

The faster you want to charge, the more of them you put in parallel. Easy.
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 on 36S
eCar: Mitsubishi Outlander PHEV... Waiting for warranty to expire
eHouse: 5.5kw On-grid solar with battery backup coming soon!

After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca

IBScootn   100 W

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Joined: Jan 30 2012 11:47pm
Location: Colorado, USA

Re: Simple 4s lifepo4 12v block management

Post by IBScootn » Feb 14 2017 9:59pm

Keep the charging current less than 1/3C. I had 60AH cells and wanted to charge them using level 2 chargers (30-32A), but distributors tech support said no more than 1/3C (or 20A in my case).
Motorcycles:
ZEV T7100, 84V, 60AH, 65+mph; Mods: TNC throttle, windshield, Cycle Analyst , Cell Log , and custom charger
Kymco GT300i - for long rides through the Rocky Mountains
Big EV Grin. :)

juzamthai   10 µW

10 µW
Posts: 5
Joined: Aug 18 2016 4:51am

Re: Simple 4s lifepo4 12v block management

Post by juzamthai » Feb 15 2017 1:12am

Ok

Got it for 1/3C reload (Or 33A in my case of 100 Ah

Means it will take between 2 and 3 hours to get fully charged.


For the PSU, do you have any ref to share, a 30 A modele that will automaticaly cutoff ?


Regards

juzamthai   10 µW

10 µW
Posts: 5
Joined: Aug 18 2016 4:51am

Re: Simple 4s lifepo4 12v block management

Post by juzamthai » Feb 15 2017 2:06am

hard to find a 12v 30 amp charger.

A 40 is really too much ?


Or can I use a 20 + a 10 at the same time in // ?
Or 3 x 10A ?

Or maybe I should go for 24v, I will find more big power charger model.

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Sunder   100 MW

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Joined: Sep 06 2011 11:24pm
Location: Sydney, Australia

Re: Simple 4s lifepo4 12v block management

Post by Sunder » Feb 15 2017 7:31am

You don't need an automatic cut off if the final voltage is below what the battery can take.

If power supply voltage = battery voltage, then no current flows.
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 on 36S
eCar: Mitsubishi Outlander PHEV... Waiting for warranty to expire
eHouse: 5.5kw On-grid solar with battery backup coming soon!

After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca

juzamthai   10 µW

10 µW
Posts: 5
Joined: Aug 18 2016 4:51am

Re: Simple 4s lifepo4 12v block management

Post by juzamthai » Feb 16 2017 10:46am

So this modele will be good for 100ah 12v pack ?

https://www.ev-power.eu/_d4816.html

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