150w High Discharge "Battery Medics"

adrian_sm

1 MW
Joined
Feb 22, 2009
Messages
2,429
Location
Melbourne, Australia
I just stumbled across these. They appear to be a Battery Medic clones, with 3x 50w external bulbs to boost the discharge rate.
US$18.90 delivered

http://www.dealextreme.com/p/3-in-1-150w-li-po-li-fe-battery-balancer-voltage-tester-discharger-blue-2-6-lcd-127498?item=42

sku_127498_1.jpg

sku_127498_5.jpg


- Color: Blue
- Material: Plastic housing
- 2.6" LCD screen
- Suitable for Li-Po & Li-Fe battery (7.4V~22.2V)
- Features measure battery voltage, balance cell voltage in battery pack & discharge functions
- Balance Voltage Range: 2.0V~3.9V (pre-setting voltage: 3.3V)
- Discharging Voltage: 3.0~4.2V (pre-setting voltage: 3.9V)
- Discharging Current (4.0V/Cell): Approx 450mA
- Supports battery pack with JST / RX connector
- Accessories Include:
- 3 x 50W bulbs
- 1 x Connection kit
- 1 x English manual
 
And here is another model they stock with just a single exernal 50w bulb.

Weird thing is that they both say 450mA discharge current.

US$16.60
http://www.dealextreme.com/p/2-5-lcd-50w-li-polymer-li-fe-battery-voltage-meter-balancer-discharger-blue-127391?item=44

sku_127391_6.jpg

- Color: Blue
- Material: PVC
- 2.5" LCD display screen
- Measureable Battery Type and amount: Li-Polymer / Li-Fe: 2 - 6 Cell / 7.4V - 22.2V
- Measureable Battery Voltage: Receiver Battery / 1.2V - 8.5V
- Balance Voltage Setting Range (Lower Limit): 2V - 3.9V (pre-setting value 3.3V)
- Discharge Voltage Setting Range (Lower Limit): 3V - 4.2V (pre-setting value 3.9V)
- Discharging current: 450mA
- Supports common battery port, JST, RX port
- It makes sure battery pack keeping in excellent condition
- User could observe all cell voltage in whole battery pack at once
- It helps user to find out which cell is abnormal during charging or discharging process
- Package includes:
- 1 x 50W bulb
- 1 x Connection kit
- 1 x English manual
 
Looking at the picture, I think the external light bulb load might just be for pack level discharge, rather than cell level. Since it only has two wires going pack to the main unit, and an extra "deans" connector, which I assume connects to the main battery leads.

Pity. It would have been great for those bulk charging lipo if the high discharge was at the cell level.

- Adrian
 
The original version of these do cell level discharging, to balance the pack. Here is the hobbyking version:
http://www.hobbyking.com/hobbyking/store/__10328__Hobby_King_Battery_Medic_System_6S.html

I assume these new version do exactly the same, but I am not sure how the external bulb loads are used.
 
I bought one of these. It took a week to arrive.
there was no info concerning the dis-charge harness in the Spec/user sheet. I think it must be for a special RC one-cell battery that uses the mini Deans connector. Not very useful for our needs.
Otherwise, seems like the run-of-the-mill Battery Medic, just blue.
It's very accurate, matching my Celogg 8, Hyperion and meter.
 
iv got a whole bunch of regular battery medics, slow as discharge, but i paralleled like 4 together and gave it ago.

They just seem to unbalance my pack, they are useless

Anyone want 4 battery medics for $20 ? lol i payed 13 dollars each
 
motomech said:
I bought one of these. It took a week to arrive.
there was no info concerning the dis-charge harness in the Spec/user sheet. I think it must be for a special RC one-cell battery that uses the mini Deans connector. Not very useful for our needs.

adrian_sm said:
Weird thing is that they both say 450mA discharge current.

Yeah I don't think it would be a good idea to be discharging 150watts thru the LiPo's thin balance leads anyway.
 
nechaus said:
iv got a whole bunch of regular battery medics, slow as discharge, but i paralleled like 4 together and gave it ago.

They just seem to unbalance my pack, they are useless

Anyone want 4 battery medics for $20 ? lol i payed 13 dollars each
What I do is set them to discharge to 4.0 v then bring the whole pack up till the lowest cell is at 4v and hook these up to discharge to 4v and leve them on for ~8hr at a time. SO I will do a couple over night and a couple while at work the next day if my pack is to many cells for how many medics I have.

But if you want I will send you 20 for them!
 
I found these same units being sold on eBay by HKPowerstore for slightly cheaper. 8)
http://www.ebay.com/ctm/RC%20Lipo%20Battery%20Balancer%20LCD%20Voltage%20Meter%20Discharger?nfItemId=180692663771

They got 3 versions available:
- a 5w basic version w/o discharge bulb for $10.83,
- a 50w version with 1 discharge bulb for $12.93, and...
- a 150w version with 3 discharge bulbs for $17.98

I might order a few just to try them out. :mrgreen:

I also realized that the halogen bulbs they use look very similar to the 50w H-3 bulbs that I've used before on my car's driving lights and fog lights (only w/o the connector housing). If so then these bulbs get pretty darn hot and bright so you should be careful when using them. They do radiate a good amount of IR so keep them away from plastic things that can melt and ignite (like plastic grocery bags). :evil: And you can't just handle the bulbs with your bare hands because the oil from your fingers will stick to the glass surface and crack it when they get hot. :shock:
 
I don't think the bulbs can get that hot. For one thing, it has a sm. board with a chip and some resisters. An secondly, I think they are made to connect to one cell only via the mini Deans connector
But not being a RC guy, I'm not really sure what they are for, but you need to understand the dis-charge harness does not work "though" the B.M. the B.M. only displays info. via a 2-pin JST lead.
I really don't think it's useful for us. If I had a cell that was high enough that I felt I needed to pull it down, I would use a little adapter I made to dis-charge that cell with the dis-charge mode of my balance charger.
 

Attachments

  • SAM_0760.JPG
    SAM_0760.JPG
    46.7 KB · Views: 2,519
Thanks for that . But no I understood the bulbs are for discharging the whole pack voltage and not for individual cell voltage (balancing). I balance-charge with Hyperion 1420i chargers so I don't need these for myself.

I was only planning on getting the just basic 5w units (which do discharge-balance at the cell level) for my brother who only bulk charges. At $10.83 they're as cheap as I've seen them so I figure it's a good time to get him some to balance his LiPo's.
 
Nope, I made a quick and dirty adapter and hooked it up to a 6S brick,...it promptly blew the bulbs :roll:
Maybe up to 3 cells > 13.8V.
 
motomech said:
Nope, I made a quick and dirty adapter and hooked it up to a 6S brick,...it promptly blew the bulbs :roll:
Maybe up to 3 cells > 13.8V.
Sorry to hear that. :cry:
But doesn't it work like a regular Battery Medic and balance the cells without the bulbs?
Cause that's really why I'm buying them for.
 
It works fine as a BM[cause that is what it is].
Mines's very accurate, right down to the .001.
Has the Red board, but we all know that doesn't mean anything :lol:
 
OK here's the low down :)
I meant to post about these months back when I first came across them but got side tracked with other projects (namely the isolated balance chargers which kinda made these a bit redundant)

OK, so they're essentially a standard battery medic with an additonal port that connects up to this external board that has either 1,2 or 3 50w 12v halogen globes connected. One might logically assume that they discharge at 150w with these connected but infact they discharge much higher than that - like 250w. They're an interesting circuit actually, you can hear a high pitch whine as they power up and the bulbs get brighter and brighter. I assume it's high frequency pulsing the power to the globes to get the higher power output without popping them. As stated they can't balance discharge, only bulk discharge. The internal circuitry continues to slowly leech away at the individual cells (as per a normal battery medic) while this external circuit connected up to the main discharge leads pulls bulk amps. And when I say bulk amps I mean around 10a. Which is quite a bit for a little unit like this.
So it whacks this heavy lead onto the discharge leads while still keeping an eye on the individual cell levels and trivially bleeding them down in addition with the SMD resistors. When any cell level gets close to the target discharge voltage the circuit dials the power back, dropping the brightness of one bulb first, then switching it off leaving just 2 running, then switching those off as well until all globes are off and just the internal SMD resistors are left sipping away at each cell. As is usually the case which ever is the runt cell will cut out first and in the case of the bulk discharge when that cell hits the programmed LVC off go the lights. If this is at say 3.3v many of the others are still around 3.5v or what ever and the medic will keep trying to pull those down to the same level.
So in short they're good for rapidly discharging or cycling packs but not for fast balancing as such. I was using them to cycle new packs with a watts up meter in series with the battery. With a 10a discharge on single 5ah packs (ie 2C) you could get a close to a real world discharge for lipo packs in ebike use.

motomech said:
I don't think the bulbs can get that hot.
WRONG! these get stupidly hot - like 160c (I measured with my IR thermometre). Within seconds of powering up they were burning into my MDF work bench top. They're also very bright - think of a 200w flood light laying on your bench top. I tried putting them in a biscuit tin but after a minute or so the tin was at close to 100C and started smoking. I'll post pics of my modified set up with these when I get home, but yes these do get VERY hot.


motomech said:
Nope, I made a quick and dirty adapter and hooked it up to a 6S brick,...it promptly blew the bulbs :roll:
Maybe up to 3 cells > 13.8V.

Yep, they're 12v globes and connecting up 24v+ will pop them instantly. You'll need to run 2 in series on a 6S pack.
 
This is my makeshift charging setup to prevent the bulbs just laying around as they come. Even standing vertical on their ceramic bases you can see just how much heat they radiate - scorching the timber block I have them mounted on. If I was serious about it I'd get half a brick and mount them in the holes. This acheives several goals - prevents scorching surroundings, prevents blinding you and prevents burns if you bump it. The radiated heat from these is not to be underestimate - if powered up as they are the heat causes the LCD on the medic and the wattsup meter to be blackened (like leaving in the hot sun). At first I thought it'd permanantly damaged it but they came good when it cooled down.

Oh, and yeah the accuracy of these blue ones seems to be fairly good, unlike the russian roulette of the last lot I got from various sources (different ebay vendors and hobbyking)

150w medic.jpg
 
Guys,

Has anyone tried putting a different external load on these devices in place of the light bulb?
A simple calculation shows that if its 50W @ 12V, the resistance is 2.88 ohm with each bulb drawing 4A.
Used on a 2S pack, this means that only 2.5A will be drawn off per bulb.
If I swap out the bulb for a 1 ohm resistor (100W rated or thereabouts), at 7.4V the draw will be 6.75 per resistor, x 3 resistors will give me a draw of about 20A.
My biggest question is around the circuit that the bulbs connect to (the one with the Deans plug that connects to the battery). I can't quite see what the little ICs are. My concern is that while they can clearly handle 50W of power, I'm not sure if they can handle the jump from 4.1A (12V, 50W) to 6.75A (7.4V, 50W). If I pop these then the device becomes useless.

Does anyone have any insights on this?

Thanks.
 
Back
Top