Discharger Experiment.

[785boats]

I thought I'd try one of these 24V 300w heater/demister units as a load bank for discharging 6s & 4s packs.
It worked well enough. It didn't use the full 300watts. But it was still faster than using my iCharger or my little 150watt discharger with the three 50w lamps.
And it was certainly cheap enough.

https://www.ebay.com.au/itm/24V-Heater-Fan-Car-Heating-Cooling-Dual-Function-Portable-Defroster-Demister-M2/132405341677?hash=item1ed3f92ded:g:Ee4AAOSwi0xaIhKi

So here are some figures.

I set up a wattmeter in line with the load & plugged an alarm module into the balance leads.
I jotted down a few values during the discharge.

6s 5000mah Revolectrix pack.

Start at 25.2v
Initial draw.
9A----24.8v----230watts

then quickly settled to.
7.9A----24v----190watts


Midway through discharge.
7.8A----23.5v----185watts.

End of discharge at 3.8v alarm. 49% capacity remaining
7.98A----22.83v----182watts.

Time----16 minutes

Resting capacity after a few minutes was 53%




4s 6000mah HRB pack.
Start at 16.8v
Initial draw.
8A----16.44v----140watts

Midway through the discharge.
8.5A----16.2v----136watts

End of discharge at 3.8V alarm. 50% capacity remaining.
7.5A----15.2v----114watts

Time----12 minutes.

Resting capacity after a few minutes was 54%

I think it is successful enough.
I quickly tried a 2s & a 3s pack. But the low voltage caused the 24v fan to spin too slowly. I think the heater bank resistor would burn out, or the plastic casing would melt.
I would have no worries about connecting two 3s packs in series for 6s or two 2s packs in series for 4s.
I have an extra alarm module for the second pack.

But 12V car versions are available for single 2s or 3s packs. They are only 150watts, but they might work well for the lower voltages.

Just thought I'd share.

Inside the unit showing the heater bank & the fan.
001.jpg

The setup.
005.jpg

A pic of the meter & alarm module during the discharge.
006.jpg

[fweasel]

Nice work

[ray schrauwen]

Cool. I'm building a discharger like those sold by RL Power systems. I bought fans off eBay and resistors. The resistors never showed up and I just got my refund. I'm going to reorder some from a better seller.

[785boats]

Nice work

Thanks. It doesn't come much more simple than that for a discharger.

Ray.
Shame about the seller of the resistors. I hope you have better luck with the new seller.

[CraigP]

You can get any resistor you need at a reasonable price at Mouser.com

[785boats]

Well, I just tried a pair of 2s packs & a pair of 3s packs in series.
The results were pretty much the same as the single 4s & 6s packs. As would be expected. So that's encouraging.

[785boats]

Well I bought one of the 12V versions for the 2s, 3s, & 4s packs. They were just too slow on the 24V version.

Eg
A 2s 6000mah pack on the 24v unit was only pulling 20 watts at 2.4A
On the 12v version it is pulling 48 watts at 6.3A

A 3s 6000mah pack on the 24V unit was only pulling 57 Watts at 4.7A
On the 12V version is pulling 140 watts at 12A

A 4s 6000mah pack on the 24V unit is only pulling 136 watts at 8.5A
On the 12v version it is pulling 210 watts at 13.5A

All those measurements were at around halfway through the discharge.

I must add that all those readings are higher than discharge rates on the 150w balancer/discharger unit with the three halogen lamps too.
Which were.
2s pack was 27 watts at 3.3A.
3s pack was 47 watts at 4.05A
4s pack was 62watts at 4.3A
6s pack was 100 watts at 5A

So there's lots of options now.
6s packs on the 24V unit.
4s packs on the 12V unit.
3s packs on the 12V unit. Or in series on the 24V unit.
2s packs individualy on the 12V unit . Or in series on the 12v unit.

[ray schrauwen]

This should be here soon. 300 watts!

https://www.ebay.com/itm/1x-Portable-12V-300W-Car-Vehicle-Heating-Heater-Hot-Fan-Defroster-Demister/142971907370?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

[Mike W]

What about 2 12v heaters in series discharging 6S?

[Speedfreek]

What about 2 12v heaters in series discharging 6S?

24v 400w for 6S it discharges at 18.5 amps , thats what i use.
Make sure you have a good C rating LIPO for this

[ray schrauwen]

This should be here soon. 300 watts!
https://www.ebay.com/itm/1x-Portable...53.m2749.l2649

I have discharged 6S packs on this without any issues. Draws about 25 amps and decreases as voltage drops. Just make sure the fan is moving and you put a cage on it like I did. It needs airflow or else...

I did have to do some soldering inside it when I got it because the crimp connections were an accident waiting to happen.

[pescador]

I?ve got one of the larger ISDT 25 amp dischargers ordered to check out but it hasn?t arrived yet. I?ve been using their smaller 6 amp units quite a bit to put unused packs back to storage. They?ve pretty much replaced my light bulb dischargers now. I?ve given them a good workout the last couple years.


Sent from my iPhone using Tapatalk

[785boats]

I have discharged 6S packs on this without any issues. Draws about 25 amps and decreases as voltage drops. Just make sure the fan is moving and you put a cage on it like I did. It needs airflow or else...

I did have to do some soldering inside it when I got it because the crimp connections were an accident waiting to happen.

Hi Ray.
I bought one of these after you posted it here. I used it for the first time yesterday. Works great, even on 6s as you proved.

https://www.ebay.com/itm/1x-Portable...53.m2749.l2649

[Ben79]

Wow awesome! Just ordered the 24v unit for my 6s packs.. Thanks for the info 785boats

[785boats]

No worries.
Just make sure you plug in an alarm module that you can set to 3.75 - 3.8 volts. Don't want to overdischarge the packs.