12s bulk charging

[rborger73]

Just because the PSU can't supply the charger's maximum rating means nothing. (But in this case he is actually OK in the ratings; he could go even less power if wanted)

The only thing that will happen is that the charger will not be able to put out it's maximum rated charge wattage since the source is too low. BUT that's only IF his PSU were underrated, which it is NOT.

That was my thought as well. As long as it meets the minimum for what the chargers needs at a reasonable charge rate should be fine. I'd understand if charging for 30 minutes made the thing too hot to touch. It is barely warm enough to feel nice on cold hands. lol Doesn't seem wise to me to over power the specs of the charger by much. Already am over by a bit by the specs.

 

[rborger73]

Lets me put a 12s charger in my backpack without hardly knowing its there

A backpack will not experience as sharp a jolt as having a charger on the bike frame, however, several builders have carried their charger with them so they can charge at work, (or where-ever "opportunity" charging presents itself). Every time someone has strapped a conventional charger to a bike frame, the charger died (presumably from pothole jolts and constant vibration).

There was a thread a while back about using a fully potted LED power supply (or two in series) as a mobile charger for opportunity bulk charging to 80% full. No reports yet on how that worked out, but...sometimes storing a second charger at work is the cost-effective thing to do, rather than risk the survival of your main charger.

Best of luck with whatever you decide, and hopefully your results will be useful data for those who come after us.

Wouldn't be unless I'm planning on going 30 miles or more. I made a pvc shell to hold both the charger and psu tightly. They are double face taped into place on the bottom. Inside the backpack is a 5/8" thick pad and it gets strapped in tight so nothing moves. I won't be riding this rough at all. I could have a bag of loose eggs back there and probably bring them home crack free most of the time. Won't be a daily charger ride or anything. I won't be mounting it to the bike, but I am putting a hook on the back of the pvc shell so when charging I can hang the psu and charger on the side of the bike. So it will be rather secure 90% of the time.

I know using this lipo setup is a stepping stone for me as well. I see battery tech about to go nuts in the next 2 years. I want to double my Ah that fits in the same size as I have now at some point in the near future. This setup was a means to an end. Lower cost of the spectrum, easier learning curve etc. If we don't see a big difference in capacity by then (or sooner) I really want to fill the triangle better using 18650 cells. I plan on babying these batteries and getting the most out of them for the time being. At my current 48v setup they should do just fine. Even at 24s they will do just fine. Thanks for the advice on the subject at hand.

 

[Sad Planet]

I use that same charger on a 12s 3p setup using six 6s packs and a 220w PC PSU, and it charges at 1C(15amp) without any hassles. You can see the two harnesses I use in the third pic. They stay permanently connected and are the same for charging and discharging:

 

[RayGo]

I have the Thunder 1220 charger. It can be used to both bulk and balance charge your battery pack. The 1220 will "guess" the number of cells that it detects and you need to be sure it is the correct number or else you need to manually adjust it. My 1220 usually "sees" only 11 cells in my 12s pack, so I need to adjust the cell count.

The 1220 allows you to set the input wattage as high as 500 watts. However, it is also smart enough to limit the max charge amperage to the available wattage from the power supply. For example, my 120w PSU (13.5v @ 12.5a) will only charge at just over 3 amp even if I set it higher. I also have a 575w PSU but I have never charged my 12s pack using over 6amps. Your 350w PSU will work fine with the 1220.

I usually bulk charge my 12s1p 20AH Lifepo4 pack with no problems and the cells are closely balanced at 3.6v. Every now and then, I will perform a balance charge or just bulk charge at 1amp if I notice a cell getting slightly out of balance.

This info can all be found in the 1220 users manual. Hope this helps.

 

[rborger73]

Ya so far glad with what I got. Glad to hear more good reports about the charger. It also is green so it matches the highlights on my bike. Everything still sitting within about .03 from highest cell to lowest after sitting 48 hours off a bulk charge. I'm going to do another final balance charge tonight since looks like might be able to ride tomorrow. If it warms up earlier going to try to do two 15 mile runs and maybe swing by the LBS to have them take a look at the bike side of things and see if I can find someone that is able to move my mp3 in a 26" rim over to my 29er rim so I can finally get that all matching. Golden motors was out of the 700c rims and it would of taken an extra week or two to get at the time. Now I kind of wish I had just waited since finding proper spoke length and what I need to order is a pain. Bike came with nice heavy double walled rims so may as well use that rim and have the rims match.

 

[ddk]

I don't doubt the Thunder power supply would be right for the job of powering the 1220 charger, but I use what I use.
If you take the time to balance the cells after packaging them up, in my experience they will stay in balance unless you have cells with flaws.

Note: I've found NONE of these balance chargers to be good at balance charging. Takes somewhere between a very long time and forever.
I've started charging individual cell banks quite a while ago and achieve quicker, more accurate results that way.

Been using a Thunder 1220 for about a year now.
99% of the time as a bulk charger.
No BMS (cepting me)
I use various flavors of HobbyKings' LiCo packs

I also own and use an iCharger 1010B+ and a couple of "less than expensive" rc chargers.The iCharger regularly needs reseting to operate. The cheap rc chargers have to have the balance cables connected (rarely gets used) and they do a very poor job of balancing anyways.
The Thunder 1220 hasbeen the most stable and reliable charger I've yet to own.
(knocks on wooden something)
I do check battery balance before charging about once a week; usually far, far less often, because the resting voltage of the battery packs would have to be seriously 'different' from my expectations to prompt me into checking the individual cells.
I have a few batteries that are noted for being easily unbalanced. But the other 240-some cells rarely need balancing. Most cells I haven't balance-charged for over a year because they didn't require balancing as all cells stay within 0.01V of each other.
I'm pretty sure they stay in balance so well because cells are paralleled to other like cells 3 to 4 times within each battery pack.

My power supplies are:
-solar panels charging AGM batteries fused for 1kW at my charging bench
-several (cheap) meanwell clone 12V power supplies that are rated for 350W out... and does it daily for about a year before failure.
-Real meanwell 12V 350w power supply that only sources 200W before it shuts down... so it should last longer lol. (just recently acquired this thing-not impressed)

 

[rborger73]

I don't doubt the Thunder power supply would be right for the job of powering the 1220 charger, but I use what I use.
If you take the time to balance the cells after packaging them up, in my experience they will stay in balance unless you have cells with flaws.

Note: I've found NONE of these balance chargers to be good at balance charging. Takes somewhere between a very long time and forever.
I've started charging individual cell banks quite a while ago and achieve quicker, more accurate results that way.

Been using a Thunder 1220 for about a year now.
99% of the time as a bulk charger.
No BMS (cepting me)
I use various flavors of HobbyKings' LiCo packs

I also own and use an iCharger 1010B+ and a couple of "less than expensive" rc chargers.The iCharger regularly needs reseting to operate. The cheap rc chargers have to have the balance cables connected (rarely gets used) and they do a very poor job of balancing anyways.
The Thunder 1220 hasbeen the most stable and reliable charger I've yet to own.
(knocks on wooden something)
I do check battery balance before charging about once a week; usually far, far less often, because the resting voltage of the battery packs would have to be seriously 'different' from my expectations to prompt me into checking the individual cells.
I have a few batteries that are noted for being easily unbalanced. But the other 240-some cells rarely need balancing. Most cells I haven't balance-charged for over a year because they didn't require balancing as all cells stay within 0.01V of each other.
I'm pretty sure they stay in balance so well because cells are paralleled to other like cells 3 to 4 times within each battery pack.

My power supplies are:
-solar panels charging AGM batteries fused for 1kW at my charging bench
-several (cheap) meanwell clone 12V power supplies that are rated for 350W out... and does it daily for about a year before failure.
-Real meanwell 12V 350w power supply that only sources 200W before it shuts down... so it should last longer lol. (just recently acquired this thing-not impressed)

Ya I did a top off and balance tonight. Bulk charged up to about 4.02 and then topped it off. Went up to 4.18 on all of them. Everything is awesomely balanced. Thought the weather was supposed be better tomorrow and planned on getting out first it is warm enough to ride. Might get a quick ride in. Trying to bulk charge a few times and see how close everything stays. The Thunder 1220 is working just awesomely as is the psu. Anyways I see a 62 and sunny for Monday so maybe I can see how many miles I can squeeze in.

 

[rborger73]

I had a pretty good laugh reading through some of the "doomsday" replies here today.. With nearly 32,000 miles with the original battery pack I built, same charger, same power supply. Charger and power supply have been on nearly every ride. There was a point I would leave them at home, but often I'd end up regretting not just bringing them as plans change.

Bulk charged pretty much every charge. Balance batteries maybe once every six months. The key here is building a large capacity battery that you aren't always running down to nothing. My average ride is 20 to 45 miles. Which might take me down to at the lowest 45.5v by the time I charge. But most rides are around 20 miles when I'm commuting. Which takes me to make 47.5 to 48.5 depending on wind conditions etc. I always just let the charger shut off when the battery is charged, and don't have it set to a lower level. Normally it ends up being 50.25 to 50.28 once the charger has finished, and I often run it again after it finishes the first time.

I am looking for a faster bulk charging solution now. I an only max out at around 6.30a, but normally I charge at around 3.5 to 5a. I'm still planning an 8,000 + ebike trip and I will have a newly built and broke in pack, and will be hopefully able to add another 20Ah to give me 70Ah of fresh 12s pack or the trip. Planning on bringing my current charger with me for night time slower charging, but want to build in to the bike a 12s bulk charger that can do up to 20A or more. I plan to have a lot of stops arranged at homes along the way, and should have 20a and some 30a AC 110v plugs to use, so I want a charger that can use some of that amperage to get me topped back up faster. I'll be adding additional fans and possible liquid cooling to the charger so there will be less worries of overheating. Looking for a smaller form factor of course as it will be on the bike.

But, ya... some of the replies here are pretty comical. The people burning down their houses most likely had way small packs, ran them way low, cheap cells, bad wiring, and poor judgment. Build a pack much larger than your needs, break it in checking often for the first few months. Most likely you'll be just fine. If you are trying to squeeze 25 miles out of a 10Ah chinese ebay pack, you will likely eventually have a bad time... I'll be researching to decide which new hard pack that is new on the market will give me better results than the ones I used for the first 31,750 miles..

Who else is in the 30k club these days?