waste of time. don't bother.

[hillzofvalp]

Good design. I tried to hide 14 A123 cells in standard water bottles to put on a road bike.. but thought the application would be dangerous (being a aluminum road bike with carbon fiber fork). I will try it again on a steel frame.. The ultimate stealth.

 

[Anonymous]

I am posting my project from some time ago, consisting of a 4series lipo unattended battery charger. I used it to recharge in series/parallel. I bought four of these, and they recharged a 20ah capacity within 10 hours.

involves two steps:

Red:charging

Green:charge completed

very useful if you bought the 4s hard case packs from hobbyking.com

at $16 a piece (actual price is around $11 this site's all I could at present find as a quick buy it now ).

http://www.aliexpress.com/product-fm/444100025-4S-14-8V-LED-Intelligence-LiPo-Battery-Charger-free-shipping-by-China-post-wholesalers.html

 

[cwah]

Magnificent! Almost exactly what I'm looking for. If the power supply was included into the charger that would be perfect.

Do you plug your lipo one after the other to charge them or do you have a balance harness?

And also, do you use 4 separate power supply? Where did you get it?

And lastly, what's the final voltage/cell at the end of charge? Would be great to limit that to 4.12V/cell for maximum longevity!

Thanks

 

[cwah]

I also found this one for 5s charging:

http://www.aliexpress.com/product-fm/553654196-3e-Model-Smart-Li-Polymer-Battery-Balance-Charger-wholesalers.html

 

[deVries]

Magnificent! Almost exactly what I'm looking for. If the power supply was included into the charger that would be perfect.

Do you plug your lipo one after the other to charge them or do you have a balance harness?

And also, do you use 4 separate power supply? Where did you get it?

And lastly, what's the final voltage/cell at the end of charge? Would be great to limit that to 4.12V/cell for maximum longevity!

Thanks

If you're going to charge w/2+ of these through the balance plugs AND leave the battery cells connected in series, then you do need to make certain each output is ISOLATED. Some balance chargers are not ISOLATED for each output, so if you use 2 non-isolated chargers in series... FAIL.

 

[cwah]

How do I know when an output is isolated?

 

[deVries]

How do I know when an output is isolated?

Specifications! ...or "test & fail" w/hopefully "test and not fail" :lol: or ask someone already using the chargers in series. You know Jeremy's works, since he's tested it successfully.

 

[Punx0r]

What is the rationale for leaving these chargers unattended?

 

[deVries]

What is the rationale for leaving these chargers unattended?

I don't think there is a good rational for doing this without using a fireproof charging area too. At a minimum use an AC timer that cuts power to the charger(s), and have a fire alarm positioned where it could sense smoke/heat easily. Also, only do this "unattended" if the setup is in a fireproof area that is vented too. Fireplace with flue open is ideal IF you don't have a better location outside. If you use HK RC type LiPo, then you definitely want to do this w/HVC cell-level cutoff protection too. A cell-level balance charger should do that, but any kind of bulk charge needs HVC cell-level protection, IMO. Fire-Extinguisher. BBQ Gloves.

 

[Punx0r]

Out of interest, what device offers HVC protection?

 

[Jeremy Harris]

Out of interest, what device offers HVC protection?

These simple balance port chargers do, as they are inherently voltage-limited at the outputs by their design (based on the ones I used). They can't go over-voltage, AFAICS, as each output is a fairly simple, well-regulated, low-voltage supply. These things have no intelligence at all, unlike a higher current RC type charger, they are simple analogue constant current/constant voltage cell level power supplies.

With a higher current RC type charger, where the charge current flows only through the pack + and - terminals, with the balance port only being used for sensing and cell discharge, there is certainly some risk of a cell going over-voltage if a fault develops and a cell over-voltage condition isn't properly detected by the ucontroller that runs the charger. This is primarily because if such a fault were to develop, then charge current could keep flowing through the string of cells in the pack, perhaps forcing the lowest capacity cell to a voltage above its safe maximum.

 

[Punx0r]

That's interesting to know, Jeremy

Is there any device that will offer HVC protection when bulk charging via an RC charger or PSU?

 

[Jeremy Harris]

That's interesting to know, Jeremy

Is there any device that will offer HVC protection when bulk charging via an RC charger or PSU?

Only really a shunt type BMS, with cell sensing. There have been several designs developed here, going back a few years now, probably the best known being the ones that Gary and Richard developed, together with Bob McCree. These detect any cell going over voltage and operate a charge cut-off, using opto-isolators. They are pretty effective, but AFAIK aren't available ready-built. I believe Gary is still working on these: http://endless-sphere.com/forums/viewtopic.php?f=14&t=26554#p383386

I've built a couple, plus I bought and assembled a kit from Gary a long time ago, and they've all worked pretty well. Coupled to the Meanwell mod that Richard came up with (http://endless-sphere.com/forums/viewtopic.php?f=31&t=36958) that turns a cheap power supply into a constant current source they make a pretty good charge system.

 

[cal3thousand]

That's interesting to know, Jeremy

Is there any device that will offer HVC protection when bulk charging via an RC charger or PSU?

Method's HVC Breaker

 

[deVries]

I believe Gary is still working on these: http://endless-sphere.com/forums/viewtopic.php?f=14&t=26554#p383386

Both Gary (& Fechter) have put further development "on hold" for now. Gary is probably out of pcb to make these kits too, he has not posted on ES in 2012, and his website was "down" with no active selling of his kits.

Question for Jeremy:

Jeremy, as long as these low power chargers come with their own AC/DC power supply, whether it's 1s, 3s, 4s, 6s, or 8s, then these could be "stacked" in series to charge a larger sized battery too, for example, 16s or 24s safely without blowing "each other" out because of not being properly isolated from each other?

I know some of these "low power" chargers without their own power supply will "blow the magic smoke" if stacked in series. I don't know whether this is because someone tries to share the same PS for 2 or more of these in series, or whether it could also happen using a different PS for each charger in series too? Do you know the answer for this?

Thanks.

 

[Jeremy Harris]

Jeremy, as long as these low power chargers come with their own AC/DC power supply, whether it's 1s, 3s, 4s, 6s, or 8s, then these could be "stacked" in series to charge a larger sized battery too, for example, 16s or 24s safely without blowing "each other" out because of not being properly isolated from each other?

I know some of these "low power" chargers without their own power supply will "blow the magic smoke" if stacked in series. I don't know whether this is because someone tries to share the same PS for 2 or more of these in series, or whether it could also happen using a different PS for each charger in series too? Do you know the answer for this?

Thanks.

They should stack just fine, as the AC supplies that drive them will be isolated from the outputs. Certainly the DC input ones I've used stack OK when driven with separate, isolated, supplies for each. I've ordered some of these ones with the built in AC supply, so when they arrive I'll be able to tell for sure.

 

[dnmun]

most if not all these SMPS designs have isolated outputs. but i have seen little 12V adapters with a three prong plug have the ground tied to the negative output so it does happen.

if it has a three pronged plug you can check to see if the ground is connected to the negative charging lead with your dvm.

 

[Jeremy Harris]

The ones in question have a two pin plug, so "should" be double insulated and isolated.

In the other thread I made mention of a potential problem with the small PSUs I used that was similar to that you mention, in that the case design was such that it could just contact the -ve DC terminal on the PCB, if the solder resist wore through. The fix was to just bend back the PCB securing tab a bit and add some kapton tape to be sure.

 

[deVries]

I also found this one for 5s charging:

That 5s is expensive vs this 4s charger...

This guy says you can find these for $11 ea. For $66 you could do 24s. These come with the charger & power supply combo I've seen for $20, so you can buy 12V 5A PS with higher combo price. Also, he says he used in Series connections, so these are isolated too w/combo PS included for $20. Just connect through the balance leads w/battery cells remaining in series. (I'd just disconnect from controller before charging.)

I don't think you can beat $66. :lol: See if you can find the $11 price for these... Update: I found these for $10 with free shipping or for $20 with PS.

Magnificent! Almost exactly what I'm looking for. If the power supply was included into the charger that would be perfect.

 

[cwah]

No, you have to buy separate power supply for each of them so it's quite expensive.

Cheapest solution remains this one:
http://www.ebay.com/itm/Titan-B3-Balance-Charger-for-2-3Cell-2S-3S-7-4v-11-1v-RC-LiPo-Battery-Helicopter-/140717849170?pt=Battery_Chargers&hash=item20c36ffa52

Balance charger and power supply in one. At an unbeatable price. Only issue: you can't limit the end voltage to 4.12V (but I'm sure Jeremy will find a way once he'll receive them)

 

[deVries]

And lastly, what's the final voltage/cell at the end of charge? Would be great to limit that to 4.12V/cell for maximum longevity!

Only issue: you can't limit the end voltage to 4.12V (but I'm sure Jeremy will find a way once he'll receive them)

Just use longer "smaller standard" balance wires to adjust voltage downward... to your "mark" of 4.12v or whatever you choose.

 

[deVries]

Cheapest solution remains this one:
http://www.ebay.com/itm/Titan-B3-Ba...y_Chargers&hash=item20c36ffa52#ht_3137wt_1399

The OP charger, subject of this thread, will charge each cell at 1.5A up to 4s. This charger you reference will charge each cell at 800mA but only up to 3s, so it is only 1/2 as powerful & you need more of these to buy at only 3s. 16s battery would need 6 of these 3s chargers but only 4 needed for this 4s charger.

Plus, many of us use 4s batteries, so the connectors are "ready made", rather than having to make special adapter plugs for the 3s to charge beyond that limited 3s size. It's a hassle to deal w/3s vs 4s, imo.

I prefer to pay more for easier 4s connections and 1.5A charge per cell. Overall, it's a better value, IMO.

4 x $10 w/your own PS = 16s

6 x $10 w/your own PS = 24s

I bet you can find a decent PS at surplus 12v-18v 5A-6A+ for under $10 if you look. I found a 15v 5A for $7.45 on Amazon with free shipping, so it can be done really cheap. Spend a few dollars more for a 6A 15v or 5A 18v for even less stress on the PS.

 

[Anonymous]

This, is by far the easiest way to never worry about 12" spokes again.

I am thinking of a 72T on one of these, linked by 415 chain to a D132 lynch motor.

I wonder what the stress integral factor formula is on those spokes.. does anyone know more about these? are they aluminium?

 

[Jeremy Harris]

I don't know what those are made from, but I rode a bike with CF disc wheels a fair time ago and it was diabolical. OK on a billiard table smooth surface, but as rough as hell on normal roads. I couldn't believe how much cushioning and suspension a spoked wheel gives, just from the slight flex in the spokes and rim, whereas the solid wheels transmitted every small bump right through the frame. Thoroughly nasty for a road bike running high pressure tyres.

 

[chisixer6]

I have 6 of these wheels, they are made of carbon fiber, from Milford Michigan. They supported me on my Kestrel, mountain bike and recumbents since 1992, when I was close 300#. Still true.