Simple low current LiPo charger

[deVries]

ps for devries: I have 2 meanwell and 2 hyperions but they are simply not plug and charge. I want something I can plug (one time) and go to bed. Hyperion are too noisy, you have to plug battery wires and balance wires, you have to provide setting to each hyperion, and it's also bulky. 2 meanwells and 2 hyperions are quite massive, and you can't bring it with you when necessary. Alternative is required

Yes, well now, this setup can not be traveled with. :lol:

For those interested... you can remotely connect to your Hyperion charger(s) through a (wireless, etc.) network if you can usb connect it to a computer directly or use wireless usb. Then you don't have to fool with tiny screen or reprogram, etc. This would allow your charge station setup to be close by -or- in a remote safe location, be quiet away from you, etc.

Also, you do not have to connect balance wires to bulk charge w/Hyperion.

Anyway, I'm glad you found a safe solution to charge in the meantime. You can build another ebike now that you have lots of chargers & 2 high-voltage complete batteries...

 

[deVries]

That's a nice and cheap idea for safe bulk charging!

Would that work if I get 8 of them to bulk charge a 24s pack, but with the connection in series still plugged in?
And use a single 12V 150W power supply on all the balance charger (via parallel connection)?

That would be a cheap, safe and plug and play power supply+charger combo I can use it to charge my pack overnight?

Unfortunately that wouldn't work, as each one of these chargers needs an independent, isolated, 12 V supply, so that the outputs can be fed to a series connected pack. It's why I ended up using three 12 V supplies to run three of these chargers.

If you wanted to charge a 24S pack, then you'd need 8 of these chargers and also 8 isolated 12 V power supplies to run them.

Some MW clones I have do have three +/- isolated 12v-15v (adjustable as one voltage setting) DC outputs but, obviously, just one AC plug. Are the three DC Isolated Outputs w/one AC plug PS ok to hook-up and power 3 of these chargers while also remaining in series connection too???

Thanks.

 

[Jeremy Harris]

Some MW clones I have do have three +/- isolated 12v-15v (adjustable as one voltage setting) DC outputs but, obviously, just one AC plug. Are the three DC Isolated Outputs w/one AC plug PS ok to hook-up and power 3 of these chargers while also remaining in series connection too???

Thanks.

Should be OK, I'd have thought. It's interesting that they make supplies like this, as having outputs that are isolated from each other is pretty useful. Were they ebay buys, or do you have a link to a supplier?

 

[deVries]

Some MW clones I have do have three +/- isolated 12v-15v (adjustable as one voltage setting) DC outputs but, obviously, just one AC plug. Are the three DC Isolated Outputs w/one AC plug PS ok to hook-up and power 3 of these chargers while also remaining in series connection too???

Thanks.

Should be OK, I'd have thought. It's interesting that they make supplies like this, as having outputs that are isolated from each other is pretty useful. Were they ebay buys, or do you have a link to a supplier?

These do have 3 separate DC outputs each for +/- on back of the unit, but maybe these are *not* isolated from each other? That was my memory going back a few years. There is a block diagram if you scroll down the detailed info, but I don't see that each of the three DC outputs are shown as isolated from each other.

I don't have the technical knowledge, but hopefully the info given is enough for you to know whether the three outputs are isolated or not from each other. Thanks for asking & checking this out...

http://www.ebay.com/itm/17055709020...X:IT&_trksid=p3984.m1438.l2649#ht_7420wt_1372

 

[miuan]

I hate to be trolling guys, but while it can be made to work, connecting so many low-cost and low-quality devices together is an almost guaranteed way to failure. These gadgets are so cheap you never know when they melt down or burn, leaving one bank empty while others are charging. You'd need to make all the indicators visible, and enforce the user to make sure all are lit before using the battery. Having to deal with all of this, you might already be better off going with an 8-cell RC charger like the Accucel8. Depends on the user, obviously, but at least the dreaded fail wouldn't unbalance the battery.

 

[Jeremy Harris]

I hate to be trolling guys, but while it can be made to work, connecting so many low-cost and low-quality devices together is an almost guaranteed way to failure. These gadgets are so cheap you never know when they melt down or burn, leaving one bank empty while others are charging. You'd need to make all the indicators visible, and enforce the user to make sure all are lit before using the battery. Having to deal with all of this, you might already be better off going with an 8-cell RC charger like the Accucel8. Depends on the user, obviously, but at least the dreaded fail wouldn't unbalance the battery.

All I can say is it's been working faultlessly for a fair time now, and is being used by a partially sighted person in her late 70's who simply could not use a conventional RC type charger. When you look at these things internally, they are very simple, with little to go wrong. Reliability generally relates to the number of components (and a few other factors) and being so simple I'd suggest this set up is probably more reliable than a far more complex, µcontroller based, charger.

It's not a universal solution for everyone, it was a very specific solution for someone who would have been unable to use anything other than a plug-and-play charger. For other reasons I needed to keep the bike weight down (it's an alloy ladies bike with a Bafang rear hub), and needed a small battery that she could easily take on and off the bike if needed, and which gave enough range to be useful. All told it's been a great success, providing enhanced mobility for someone who cannot drive a car any more.

Don't knock it until you've tried and tested it for a year or so, as I have!

 

[Jeremy Harris]

These do have 3 separate DC outputs each for +/- on back of the unit, but maybe these are *not* isolated from each other? That was my memory going back a few years. There is a block diagram if you scroll down the detailed info, but I don't see that each of the three DC outputs are shown as isolated from each other.

I don't have the technical knowledge, but hopefully the info given is enough for you to know whether the three outputs are isolated or not from each other. Thanks for asking & checking this out...

http://www.ebay.com/itm/17055709020...X:IT&_trksid=p3984.m1438.l2649#ht_7420wt_1372

Unfortunately these are the same as a couple I have. The output terminals are just paralleled on that block, so aren't isolated. Pity, would have been a good find otherwise!

 

[miuan]

Don't knock it until you've tried and tested it for a year or so, as I have!

Not meant to understate your efforts at all, Jeremy.
At the very least, you need some automated way to check all the devices are working properly to avoid imbalance as any of the device may fail without warning - I've had some cheap PSUs and chargers do that.

 

[Jeremy Harris]

Not meant to understate your efforts at all, Jeremy.
At the very least, you need some automated way to check all the devices are working properly to avoid imbalance as any of the device may fail without warning - I've had some cheap PSUs and chargers do that.

These chargers have LEDs for each channel, so you get an indication of power and whether or not they are charging. AFAICS, the LEDs are triggered by the charger going from constant current mode to constant voltage mode at the end of charge. I just fitted the original LEDs to the case I made, so it's easy to check whether or not all is well. The LEDs should all come on when charging starts, and go out as charging completes, pretty foolproof and reasonably safe given that these are just simple single channel chargers.

 

[mistercrash]

I like the plug and play approach.

Another way of achieving something similar would be with 7 x single cell chargers.

For example, you can get 7 of these 4.2V / 1A chargers for 5.95$ each, free shipping:

http://www.dealextreme.com/details.dx/sku.5837

The advantage is that they each have their own AC Power supply. Also being single cell chargers, there is no balancing algorithm to go wrong.

You could take the plastic casing and AC cords out and rewire all AC inputs to a single cord. For the outputs, just make your own 8 pins connector that regroups the outputs of the 7 chargers and matches what you have on your 7s pack.

I'm sorry if you feel I'm highjacking your thread Jeremy and I'm sorry if this has been asked before. I didn't read the whole thread even though it is short. Can I take 14 of those and do what El_Steak suggested to charge cells individually on my 14S pack? I'm thinking that some Aluminum or ABS project box of the right size could house all of those little boards with the LEDs showing through little holes in the project box. A Multipin connector to group all the wires in one connector and I'm guessing those LEDs are red when charging and turn green when fully charged. All green is good to go, real simple and easy. The only problem I see is that it charges at 1 amp. On a 24 amp pack, that's a long time charging. Is there a way to make them charge at a higher rate?

 

[Jeremy Harris]

Yes, it should work fine. I did much the same using some RC type simple chargers, but I took mine out of their cases and mounted them in a project box, with the LEDs showing through drilled holes. I'd not recommend taking them out of their cases for these household supply driven ones, really just because of the risk of electric shock from the high voltage side. No reason not to fit them in a box complete with their cases, though, although you'll probably find that you need to arrange a bit of ventilation. I doubt you can increase the current of these, my guess is that they are pretty much fixed at 1 A.

Others here have done similar with the little Voltphreaks single cell chargers when charging LiFePO4 cells, it works very well, I believe.

Did you see the link that cwah gave earlier to this one: http://www.ebay.com/itm/Titan-B3-Balance-Charger-for-2-3Cell-2S-3S-7-4v-11-1v-RC-LiPo-Battery-Helicopter-/280857924238?pt=Battery_Chargers&hash=item41646fd28e#ht_4576wt_922 ?

It will charge three cells, so for your 14S pack you could use five of them (with one only charging two cells), rather than 14 of the Dealextreme ones.

 

[mistercrash]

Did you see the link that cwah gave earlier to this one: http://www.ebay.com/itm/Titan-B3-Balance-Charger-for-2-3Cell-2S-3S-7-4v-11-1v-RC-LiPo-Battery-Helicopter-/280857924238?pt=Battery_Chargers&hash=item41646fd28e#ht_4576wt_922 ?

Ok so you managed to make me go back and read the whole thread :lol: Yes I saw those but aren't they just like any other RC charger that starts off charging fast and then goes into balance mode and takes a very long time to finish up especially if cells were out of balance? That is what I would like to get out of. I presently use a Hyperion 1420i on my 14S16P konion battery pack. It works well but sometimes takes forever to balance the cells. I want a charger that charges all the cells individually, without having to make multiple connections every time.

 

[Jeremy Harris]

Did you see the link that cwah gave earlier to this one: http://www.ebay.com/itm/Titan-B3-Balance-Charger-for-2-3Cell-2S-3S-7-4v-11-1v-RC-LiPo-Battery-Helicopter-/280857924238?pt=Battery_Chargers&hash=item41646fd28e#ht_4576wt_922 ?

Ok so you managed to make me go back and read the whole thread :lol: Yes I saw those but aren't they just like any other RC charger that starts off charging fast and then goes into balance mode and takes a very long time to finish up especially if cells were out of balance? That is what I would like to get out of. I presently use a Hyperion 1420i on my 14S16P konion battery pack. It works well but sometimes takes forever to balance the cells. I want a charger that charges all the cells individually, without having to make multiple connections every time.

No, they seem to be similar to the ones I used, but with their own built in power supply. These are just three individual cell chargers in a single case, they don't have any µcontroller or clever stuff, they simply deliver a constant current until the cell voltage rises, then hold the cell at a constant voltage, then they shut off the individual charge channel when the cell has reached the cut off voltage. If they work the same as my ones (and I strongly suspect they do) then they pretty much guarantee that the pack will stay in balance, with no need to use an RC type bleed-off balancing charger that, as you say, takes a long time to get the pack balanced.

 

[mistercrash]

Thanks for clarifying Jeremy, this seems like a very good alternative for me.

 

[deVries]

Thanks for clarifying Jeremy, this seems like a very good alternative for me.

Those 3s chargers use balance type connections on the 3s charger Cwah found. That's not so easy to work with if you have 4s batteries. It only charges at very low 800mA per cell.

Here is an inexpensive 4s 1.5A per cell charger...

4s LiPo Cheap Charger for Series 12s, 16s, 20s, 24s, etc.

 

[mistercrash]

So I got a few of those

http://www.ebay.com/itm/31033990536...NX:IT&_trksid=p3984.m1439.l2649#ht_3951wt_954

I was hoping to make a slow balance charger out of them but after trying four of them I found out that they have a tendency to over charge the cells. I got four different 100% SOC from 4.24V up to 4.38V. Is there a simple way to make those little units more precise? I can provide pics of the boards if needed.