Homemade Battery Packs

DrkAngel · Nov 16, 2014

DrkAngel said:
I recently reviewed a video that indicated that one type of battery deterioration was directly related to time spent charging.
It seems that the graphite becomes plated with lithium during the charge cycle.
Reducing the time spent charging, increasing amps, reduces the degree of plating per Ah of charge.

So ...
I will upgrade my 25.9V 5A charger to 10A. (25.9V 25.92Ah battery)
and
I will upgrade my 36V 4.5A charger to 10-15A. (33.3V 31.2Ah battery)
Li-ion (Laptop LiCo) are variously recommended at .5C-.8C charge rate

Looking for a low current disconnect.

Much of the charging time is the low amperage "topping charge".
This, seems to be the most unproductive-damaging portion of the charge cycle.
By charging at 4.20V but disconnecting charger at 4.02V for my Sanyo 18650 packs and at 4.12V for my Lipo packs, I hope to more quickly attain optimal charged voltage while minimizing the reputably damaging, prolonged charge cycle.

By charging once to optimal voltage,
then applying 4.20V charge,
then noting charge amps ...
I can charge at 4.20V and disconnect when charging current diminishes to the predetermined amps.

Added Volt - Amp adjustment and meter to charger ...

This:
charges faster,
damages battery less-prolongs life
and if not disconnected at optimal time, still limits battery voltage to the "safe" oem recommended voltage!

A "switch" that disconnects charge power as current reduces to a determined amps would be ideal!
In the meantime I have begun manually disconnecting charger as amps reduce to predetermined point.

teslanv · Nov 16, 2014

DA, your work with Mean Wells is inspiring.

DrkAngel · Nov 16, 2014

teslanv said:
DA, your work with Mean Wells is inspiring.

I adapted S-150-xx Series into Lab type power supplies with metered voltage and amperage settings.

Mega-Mods
S-150-12 ~8 - 14V 0 - 20A Destroyed 1st prototype, waiting on replacement for pics and final results.
S-150-24 15 - 30V 0 - 10A
S-150-48 30 - 54V 0 - 5.4A

For precise charging or component power regulation.
Most useful when used in series for high wattage charging, will regulate amperage of larger switching power supply.
Genuine MeanWell S-150-xx in series with generic 350w power supply for 500w cv/cc charger

ridethelightning · Nov 17, 2014

cool charging tips DA!

ridethelightning · Nov 17, 2014

teslanv said:
Yes, as far as 18650 cells go, 3400 mAh is the largest you will find that is "authentic", and which is a High-capacity/Low C" rate Panasonic cell. The Ultrafire and other generic name cells, I would not believe any advertised capacity greater than around 2500 mAh.

samsung 25R,good price from EVVA technologies.
my friend just got about 600 cells from them.

http://evva.en.alibaba.com/product/1353 ... tools.html

Hillhater · Nov 17, 2014

You know, those "alibaba" page links never work !
You will have to give a screen shot or the direct supplier link.

ridethelightning · Nov 18, 2014

yeah your right.

try google evva technologies...or,

contact Eva Guo there:

eva@evva-tech.com

i think its under 4+usd percell for 25r

Allex · Nov 18, 2014

http://evva.en.alibaba.com/product/...0_25R_High_Power_battery_for_power_tools.html

If you have long links use "URL" button on top of the text windows when you type a new message and insert it there, between and

ipcalit · Nov 21, 2014

Anybody using SLA drop-in replacements with good results? There are many LiFePO4 packs from Dakota, Bienno, Stark power, K2, but no real reports of them in active use or comparisons with custom 18650 packs.

DrkAngel previously reported $360 for 4x Dakotas -- this is cheaper than the cells + BMS themselves (assuming their internal BMS is any good). Is it worth taking them apart and reusing the cells in other configurations? Perhaps packing more Wh in the available space or rigging them up in parallel for more Amps?

Drokz · Nov 29, 2014

hello ,

Ive bought new 80X Panasonic 18650PF cell.
they came yesterday with every cell 3.61V.

I have already 1 cell discharged, and charged first to 4.1 V but there was going 1780mah in, then further charged to 4 .2V, 245mah en charging ended.
so the cell are 2900mah, and 2750mah minimum. really weird that charged till 4.2V only 2025mah in.... :?

come this because they in really long storage time?

normaly i charge never till 4.2V.

the intention is to make a 18S4P pack. So 64.8 V 11.6 Amp
So iam making 3packs with 6S4p, because my chargers cant take more then 6S

With these 18650 brackets :

spinningmagnets · Dec 24, 2014

Some handy ideas about DIY soldering 18650's http://endless-sphere.com/forums/viewtopic.php?f=28&t=65094#p985797

Connections shown are with flux, pre-soldering...

Alan B · Dec 24, 2014

DrkAngel said:
...

Quality-voltage reduction of blocking\rectifier\bypass diode, varies widely, by manufacturer. ~.2V to 1V+.
I received a .3V drop, from a unknown brand diode, nice "fit" for my purpose.

Larger-large capacity, blocking diodes, require an electrically isolated heatsink!

Note that diodes do not have constant voltage drops. The actual forward voltage drop of a diode is a function of current, temperature and junction type/materials. As the charge current drops at the end of charge, the voltage drop across the diode will fall also. At very low currents the voltage drop is diminishingly small (square law). Depending on a diode for a constant voltage drop requires constant current and temperature conditions which are not present in the end-of-charge scenario. Schottky diodes can have 0.1V drops at considerable currents, the commonly quoted 0.7V drop is for silicon diodes at moderate currents. It is not a "Quality" issue.

DrkAngel · Dec 25, 2014

Drokz said:
hello ,

Ive bought new 80X Panasonic 18650PF cell.
they came yesterday with every cell 3.61V.

I have already 1 cell discharged, and charged first to 4.1 V but there was going 1780mah in, then further charged to 4 .2V, 245mah en charging ended.
so the cell are 2900mah, and 2750mah minimum. really weird that charged till 4.2V only 2025mah in.... :?

come this because they in really long storage time?

normaly i charge never till 4.2V.

Recommend you charge 1st.
Do not discharge 1st.
Do not deeply discharge!
1st charge - discharge cycles are critical for "breaking-in" new cells!
"New cells are very impressionable" - susceptible to damage

≤ .5C charges and ≤ 1C discharges recommended for initial cycles.
Recommend >3.5V - <4.2V for preliminary test cycles

DrkAngel · Dec 25, 2014

ipcalit said:
Anybody using SLA drop-in replacements with good results? There are many LiFePO4 packs from Dakota, Bienno, Stark power, K2, but no real reports of them in active use or comparisons with custom 18650 packs.

DrkAngel previously reported $360 for 4x Dakotas -- this is cheaper than the cells + BMS themselves (assuming their internal BMS is any good). Is it worth taking them apart and reusing the cells in other configurations? Perhaps packing more Wh in the available space or rigging them up in parallel for more Amps?

See - Dakota drop-in replacement for eZip
Dakota - Amazon Reviews
Clean Republic eBay feedback = 99.7% positive

Cashew · Dec 31, 2014

Many things are to easy and wrong in this text sorry. I tryed to explane it better in this thread:
Spot Welding Battery Packs.

I found something interesting, on the german pedelec-forum.
Is this new in this forum?
Looks easy, and I think it is, but keep in mind they are working with a few hundreds(thousand?) Amps, “only 2-3 ms” enough for some serious damage of your eyes fingers...
So don't do it. !!! DANGER !
I do not recumment it !!
If you do:
Wear safety glasses and gloves.
Do not try to “modify” something.
For example if you try thin electrodes 2mm /wires they will explode, with liquid metal flying around.
Wrong polarity on the capacitor explosion?
I am not an expert.
The idea is to charge an big capacitor 1F, to about 10-16V, and use this energy to make spot welding points with Hiluminband.
Cables from the capacitor are? look at the video. Electrodes are 10mm copper!!!(because of resistance heat)

This is one of their plans.
http://www.pedelecforum.de/forum/index.php?attachments/psg_einfach-jpg.54403/

Video.
https://www.youtube.com/watch?feature=player_embedded&v=hg2YMafJDYA

This example seams to work good.
He ended up with an 2F capacitor, 8 IRF1404, and adjust the welding power by adjusting the charging voltage from 0-16V.

riba2233 · Dec 31, 2014

This isn't new, use search next time:

http://endless-sphere.com/forums/viewtopic.php?f=14&t=59383

Cashew · Dec 31, 2014

Thank you. I poste it there again with more informations. I think they like it it.

kje · Jan 2, 2015

DrkAngel said:
Deans (T Plugs) are reputed to be 100A capable.

100A continuous?

Alan B · Jan 2, 2015

How much airflow is required for that rating? RC ratings often require 100 mph or some considerable airflow.

Does this rating continue after dozens to hundreds of insertion cycles?

kje · Jan 8, 2015

Is it safe to use Deans plug on 55A continuous?

Allex · Jan 8, 2015

Who uses Deans today? Use bullet type connectors, like xt60, t90 or xt150 and you don't have to worry about current.

madin88 · Jan 8, 2015

i also would prefer slotted bullet connectors (not lamella types). the original deans have silver coated contacts and they corrode pretty quick..
the current handling depends also on wire gauge.

kje · Jan 8, 2015

Okey. Will EC5 Connectors be fine with 55A continuous?

I had some problems with my Anderson Power Poles 45A. They actually melted...

Alan B · Jan 8, 2015

Another option is to use two Anderson PowerPoles per circuit, 25A is okay for one circuit but 45A is a bit much. The contacts must be free to move and properly align or hotspots can be created.

Allex · Jan 8, 2015

In high power applications I would not trust that much on bullets with lamell springs attaches to their core, like EC5. Go for something more heavy duty.
XT connectors make a direct contact, that is why they are the one and only for hig power drain, like big Helis or ebikes.

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