Turnigy Accucel 8 vs Hobbyking eco 8

[CUDAcores89]

Long time broswer, but first time poster, here we go.

I am building an ebike on a budget. My budget for the entire thing is $600. Anyway so far I have built the battery for the ebike:



It is a 14s 14p 48v (true 51.8v) 28AH 1.45KWh battery pack I made form salvaged laptop 18650 cells. I plan to be using a 48v 1kw ebike hub motor for my bike so because of that I had to really overbuild the pack because laptop cells can't handle a discharge of over 1C. Anyway here is where the problem comes in, I need to charge the darn thing somehow.

The pack is designed so it can easily be split into a 7S 28p pack later on so I can charge the pack with a standard 8S hobby charger. There are a couple of chargers I am looking at. The first one is the Hobbyking eco-8 and I can get this charger for $30. The second one is the Turnigy Accucel-8 and that charger costs double the hobbyking charger at $60. I am not sure what charger I should buy and what experiences have you guys had with either of them?

 

[amberwolf]

Sorry I couldn't help.
I dont' know either of those chargers...but if you run the pack down to near empty, it's going to take a long time to charge the pack with either one, at 56Ah (when it's 7s). I'd guess that at most, you'll get about 5A charge rate when it starts out, which will taper off as it gets closer to full. So it could take 12-14 hours, or possibly much more (not including time for balancing).

I do have an Accucell 6, and it works ok...but I have a second one whose LCD screen only works on half of it. :/ Neither one has a fan that works right (sticks and starts/stops during charge; have to use an external fan on them so they dont' cook). 12V PSU on one of them died, the other one's connector broke off the PCB so I wired it straight in.

You can search the forums and google the web for the charger names and get much more info about them, too.



BTW, what are you going to use while riding to tell you when a cell group is low, so you don't keep going, overdischarge that group, and damage the battery pack?

 

[Overclocker]

i used to have the accucel-6 LiHV version. it sucked. was designed to prevent people from screwing up i.e. you're FORCED to plug in the balance wires. it simply wouldn't charge without the balance wires

you got a sizeable pack there. the 150w chargers would take a very long time. unfortunately there aren't very many low-cost 8s options out there. the next step up would probably be the turnigy reaktor 1000w and MEGAs

 

[parabellum]

I have 2 units of Hobbyking eco-8.
Both have inaccuracy in V measurement on some cell and you can not calibrate them. 1 came in with broken discharge function, so it will not balance nor discharge. You will also have to always connect balance wires for cooling fan to work, if not, they overheat and shut down in few minutes.

 

[dogman dan]

Since you are going to be discharging without a bms anyway,, you might as well just bulk charge the whole pack at 14s. Just get a lithuium charger set to 14s.

Then, use a cellog 8 to look at how balanced it is, and balance manually as needed. Manual balancing can be done with a crazy cheap RC charger, used as a one cell charger or discharger. If you treat your pack right, you only have to balance occasionally. Balancing manually can be quite a bit quicker than using RC chargers to do it. Just put more into the one or two low charged cell group.

Slightly undercharge, like to 4.15v per cell, so you have more headroom for unbalance before danger or damage happens.

Once you know your pack well, you know which cell group to watch with a voltmeter, the lowest capacity one, when you need to discharge to 100%.

This type charger will have the ability to adjust the voltage. So you can set your chargers voltage to your exact choice of end of charge voltage. http://www.ebay.com/itm/48v-4A-electric-bike-e-bike-Li-ion-Li-NiCoMn-Li-MnO2-Lithium-ion-battery-charger-/182232650394?hash=item2a6de9929a:g:V3kAAOSwARZXpRla

About 7-8 hours to fully charge, at 4 amps.