quick check before I buy, and charger advice please

[knighty]

hi

sorry for the noob post, I'm not used to being a noob

I'm now to ebikes but have been doing a lot of reading...

I'm thinking of buying....

ebay rear wheel kit, 48v 1000watts

72v 1500watt controller

8x Turnigy 14.8v 5000mAh
(parallel two lots of 4 in series..... if that sounds ok?)

and then mob the controller for a lower cut off voltage

it's 5 miles to work, I'd like to bike it to work, charge it there all day, then bike it back... so it would be a massive bonus if I could charge the pack as one, or at least be able to just have one plug to plug in and no messing with the packs etc...

any recommendations for a charger / how to charge ? there's so much information here it's hard to follow it all
(I'm dyslexic, all the acronyms throw me)


thanks

Alan

 

[MD.]

I've been using a similar motor combo for my commute to work without the hua tong controller. The stock controller is precnfigured for a max of 25a. I've been running it with 6 of those same batteries. I run it at 48v by wiring two sets of three in series. That configuration gives me 12s, 48v, 10000 mah. It works great. I get around 25mph on flats with a 26" rim. I average about 1 mile per 1000mah for a total of 10 miles on that battery config. My commute to work is exactly 10 miles round trip. I peddle and have been only using 80% of my battery for several days. I have huge hills here in San Diego CA

Here's the combo I'm using.
http://www.ebay.com/itm/Electric-Bike-Conversion-Kit-Rear-Hub-Motor-with-26-Rim-and-Speed-Controller-/110950272355?pt=Cycling_Parts_Accessories&hash=item19d526cd63

I've been looking at the Hyperion 1420i charger. It will charge up to 14s. Since I like to balance I would charge each parallel 12s one at a time. That would mean I have to charge twice or buy two of the Hyperion chargers..

 

[dogman dan]

Well, not a bad plan, the motor kit looks fine. Appears to be a 9c clone such as a muxus.

Can't really go wrong with the hyperion, however that's a 14s charger, and you are planning on 16s sooo,,,,.

14 cells in series, 4 x 4s packs. One solution would be to use a hyperion charger, but run only three of the packs in series. 12s, so the 14s hyperion charger could just plug in and charge. This plan has the advantage of not needing a new controller.

The other approach is to use three 5s packs. Charge them to 4.1v per cell and get very close to the same voltage as 16s. But again, you don't need the new controller. By just slightly undercharging the packs, which is recomended for longer lifespan, you stay under the limit of the 48v controllers 63v max. Again though, cant charge 15s with the hyperion 14s charger unless you break up the pack some.

I don't see enough advantage to bother with, to run 16s rather than 15s, to make it worth a new controller. If you get the 72v controller, just run 18s. Or maybe just stick with "48v" but get a controller with more amps. That way instead of lots more top speed, you just get faster off the stop light to the same 25 mph or so top speed.

Look at Icecube 57's harness for sale thread in for sale new here. He's got the elegant solutiong to charging RC lipo with a one plug harness that switches from paralell to series. With this harness, all you need is a reasonably fast 6s or 8s charger.

The other solution is bulk charging with the complete lipo protection system. Methods sells that at his Methtek website. You can read about it also in the for sale new area.

 

[pdf]

First of all, I am going to tell you what I do, but note that your mileage may vary, etc. etc.

I have a 6.5 mile one way, pretty hilly route each day. You have 70% more watt-hours in that pack than I have. I never recharge at work. Note, I am usually between 22 and 18 mph so I am not burning the watt-hours wastefully. For me, charging at work is possible but not trivial. I'd get a bigger pack before I would bother for that distance. My opinion, etc. etc.

I have 3x 6s 5000mAh Turnigy LiPO wired as 18s (I have a high turn count motor so need the volts). I started by using a cheap hobby charger, bought a parallel charging cord and made a series harness for putting on the bike. It was a pain to take the pack apart each time but on the upside, I could monitor the cells at a more individual level (well, at least as three cells in parallel). I could also balance charge but the pack never got out of balance so I only seldom checked (perhaps a bad idea). Got tired of the charging dance so I bought a 75.5V charger from BMSbattery. I have only just started using it so I have no data yet on reliability (NOTE: some people have some real problems with BMSBattery. At a minimum, the shipping is going to be high and will take a while. So mentally factor shipping into the cost and delivery time). My plan is to check the balance every 10 or so bulk charges.

As Dogman pointed out, there are several people on the forum that sell "automatic" battery management systems, that make sure that the cells stay balanced during charging and that you don't run the voltage of the pack or a cell too low. I did consider these options. There are very good reasons to invest in these, not the least of which is potentially avoiding a cell that gets wildly out of balance and causes a more serious problem, such as a battery fire.

I don't use an automatic BMS which is another way of saying I am the BMS. I am probably going to invest in the little gizmos that plug into the balance plug that looks at each cell. That way, I will probably see problem cells before they get too far out of whack. They would probably last longer if I had a BMS but on the other hand, LiPO is pretty cheap so payback on a BMS system could be long. My theory is that decent LiPO probably stays balanced until near end-of-life anyway. Of course, one LiPO fire might shoot that theory to heck.

Complacency isn't a problem until it is, so I can't defend my behavior so I don't try.

 

[dnmun]

i don't think it is the being unbalanced that has caused the lipo fires i have seen reported. most often it is from overcharging one cell for long enuff for it to go into thermal runaway. or to short it out or to reverse it against another bigger battery higher voltage battery that i have seen as fires. luke has destroyed a bunch to make them burn up too.

the difference i have seen between lipo and the lifepo4 is when i overcharge the headways, it just goes open circuit. dead battery so i can live with that 1kWh of lifepo4 charging in the front room all night. in fact this is now the third day of trying to get it to balance under the ping v1 BMS or two actually i have hacked up for the 22S. this pack was from two different packs and one side was fully charged and the other side almost discharged so it has been a long time balancing it. burned up my 5ohm power resistor and finally it is cycling on the high cells, beginning to warm up a few resistors.