Commuter with unattended charging, no LiPo for me?

[Taiden]

Sorry for asking a question that I'm sure has been asked a thousand times. I've spent the last couple of days reading here, and there are so many conflicting opinions, it's tough to weed out the real stuff.

It seems to me that if you had four 6s LiPo packs, and a four channel 6s balancing charger, your charging would be pretty much handled for you. Is it still irresponsible to unattended charge indoors? Am I way off the mark here?

 

[Schlafmutze]

No lipo for you.

 

[999zip999]

What controller you running yes amps at what voltage. Or just tell us the setup. Yes everthing. Not just a part question for a full answer. But a plug and play battery with bms that's rated for your needs. What are your needs ??? All your info first or you will buy a second battery too soon.
Plus where do you live...?

 

[dogman dan]

A good charger will eliminate 10% of the risk of using lipo. Still up to you to not overdischarge them, or ding them.

I have taken to saying, charge your RC packs in a place you'd build a fire. I do charge indoors, attended, in my fireplace.

 

[Taiden]

OK. I have decided to stick with LiFePo4 for my commuter. Thanks all.

 

[Ohbse]

Depends on your charging method. I charge using the Adaptto and integrated BMS with lipo packs unattended every day and don't worry about it.

I have also charged using my Powerlab8 semi-attended and it was in the back of my mind.

I would not charge a big duct tape mashup of non-hardcase lipo with a shitty charger (most of them) unattended. Quality of the equipment makes a big difference to both peace of mind and real risk.

 

[dogman dan]

Wrecked cells can still go up, no matter how good your charger or bms is. In case I didn't make it clear.

What's "attended"? I sure as hell don't pull up a chair and stare at my packs charging all day. I take all reasonable precautions to avoid dinging my packs, or over discharging them.

Then, charging in a place I'd build a fire, with smoke detector close by, I go about my business. But I don't leave the house, or go to sleep.

So having set it up as safe as possible, that's my version of "attended charging". If the worst should happen, I have a shovel nearby to try to fling that flaming thing out the door. 500wh is the biggest section, so I won't have 2kw blow into fire on me.

 

[riba2233]

OK. I have decided to stick with LiFePo4 for my commuter. Thanks all.

There's also the third option, 18650 limn cells. Smaller and lighter even than lipo, and as safe as lifepo4 There are cells from 1C to 10C, so something for everyone.

 

[Taiden]

I want to be able to park it at a friends house, work, etc, and plug it in without fear. I'd really only need a 10 mile range if I could do that, otherwise 20-25 mile range would be minimum. I'd also like to put about 80 amps through it.

 

[dogman dan]

IMO, 80 amps puts you right back to RC lico/lipo. You are just going to have to bring an extension cord, and charge it outside when you are at somebodies house.

At home, something like a place you'd build a fire to charge and store. If you live in an apartment, yer screwed.

And btw, 80 amps with lico doesn't mean 10 ah of 20c stuff. Cut the discharge rate by 3/4. 10 ah of 20c hobby king packs can do 50 amps ok. So you need more, or higher c rate packs.

 

[riba2233]

IMO, 80 amps puts you right back to RC lico/lipo. You are just going to have to bring an extension cord, and charge it outside when you are at somebodies house.

At home, something like a place you'd build a fire to charge and store. If you live in an apartment, yer screwed.

And btw, 80 amps with lico doesn't mean 10 ah of 20c stuff. Cut the discharge rate by 3/4. 10 ah of 20c hobby king packs can do 50 amps ok. So you need more, or higher c rate packs.

But why?

http://endless-sphere.com/forums/viewtopic.php?f=14&t=57291

Lipo can be justified only I you really need more than 10C. For deathbike or something like that.

 

[dogman dan]

Well, for most of us, there's the cost.

I didn't mean to say nothing exists for 80 amps. But after you pay a fine price for those great cells, you don't want to use them at the maximum rate in their specs either. If you go with the ol cut the c rate spec in half trick, 20 ah for an 80 amps controller.

So that means a fairly large pack, of damn expensive cells. If 72v, that will be a bit pricy. 48v not so bad. VS carry enough cheap ass HK cells to make it back home. Either way it's going to be a large pack, which may eliminate the real need for unattended charging.

In that thread they talked about buying them from Alibaba on page one, and I didn't read the entire thread. Can you get this from EM3ev yet? If so, there's your source, but not exactly cheap. I wouldn't trust every vendor in china to have the battery inside match the label outside.

 

[riba2233]

Yes, em3ev has samsung 20r, which are high c rate, and he will have 25r soon. He is expensive. If you want to buy bare cells and build your own packs, there is alibaba and the price is ok.

 

[dogman dan]

I'm just too chicken to buy stuff from alibaba. And too broke to afford EM3ev, for the pack size I need for my cargo bike.

For long rides, I need 25-35 ah. About $1800 including shipping for two 15 ah packs? So I keep choosing to buy more HK packs every year, since I can keep the annual cost at about $300. I'm not using HK lico packs for high amps, I limit to 30 amps, which an EM3ev pack can handle. As soon as I can afford $700-900 or so in my annual late winter battery buy, I'll be going after something safer than HK lico. A 15 ah 10c cell pack would be a nice addition to my range, and I could leave it in the bag on the bike when the garage is less than 80F.

 

[Taiden]

In case anyone is curious, I just got a quote on INR18650-25R from Shenzhen Evva Technology Co., Limited

$3.40 a cell @ qty 100
$88 shipping to USA
-----------------------
$428 for 72v12ah 100a battery pack.
3 hour standard charge, 50 min rapid charge
9.9 lbs total cell weight


http://evva.en.alibaba.com/product/1353007208-210510209/Samsung_INR18650_25R_High_Power_battery_for_power_tools.html?edm_src=sys&edm_type=fdbk&edm_grp=0&edm_cta=read_msg&edm_time=realtime&edm_ver=e

 

[docnjoj]

In case anyone is curious, I just got a quote on INR18650-25R from Shenzhen Evva Technology Co., Limited

$3.40 a cell @ qty 100
$88 shipping to USA
-----------------------
$428 for 72v12ah 100a battery pack.
3 hour standard charge, 50 min rapid charge
9.9 lbs total cell weight


http://evva.en.alibaba.com/product/1353007208-210510209/Samsung_INR18650_25R_High_Power_battery_for_power_tools.html?edm_src=sys&edm_type=fdbk&edm_grp=0&edm_cta=read_msg&edm_time=realtime&edm_ver=e

If they could only weld them 10P and leave tabs I would do it. Too much work otherwise.
otherDoc

 

[Taiden]

Got a reply, they spot weld for $0.10 a cell. So cheap.

 

[docnjoj]

Got a reply, they spot weld for $0.10 a cell. So cheap.

Hmmmmm.........that is reasonable. Now if I could just get the new Sony cells at about $2 each............
otherDoc

 

[Taiden]

$438 shipped for 10 qty 10p packs of 25R. What does a BMS run? I had a lot of fun building my last pack. Having new cells and having them already welded up would be pretty awesome. I'd rather have access to a welder though, be able to make some crazy layouts that way.