48V 20AH battery for sale on ebay in USA any good?

Lifepo4 is fully charged to 100% when it reaches 3.6+ volts, but removed from the charger they settle down to 3.3v or so ( still fully charged ) .. completely drained at 2.0v ... most of the discharge cycle will happen between 3.2 and 2.8v ( depends on C rate of cells and the load )... from 2.8 to 2.0 it drops like a rock..
 
How the charger interacts with the battery and the bms is important for keeping cell groups at balanced states of charge.

For example: I've been suspicious about my (4amp) charger's ability to engage with the bms in order to balance cells.

Last night I plugged it in, and it charges the battery pack up by about 450watthrs. A full charge cause I used about 435watthrs yesterday.

But! This morning, I see that the battery pack is sitting there at ~54volts, and I know my charger when it first comes on it reads 56.4v unplugged from the battery.

When I unpluged the charger from the battery (leaving it attached to the wattmeter) i see the voltage drift on down toward zero even though the charger was plugged into the wall. It reminded me of this post which recently resurfaced: { http://endless-sphere.com/forums/viewtopic.php?f=14&t=11718&p=178138#p178138 } where certain chargers were getting confused and not properly engaging with the bms and allowing it to do it's balancing function.

Now, 54volts is a full charge capacity wise (3.375v/cell for the 16s). But I'm thinking, 'huh did the bms get a chance to do any balancing last night before the charger decided to slack off?'

So I plug in my ping charger (60.2v) and go do animals and kids, and a half-hour later the wattmeter sez 60volts, 6 watts still going into the battery, bms at the top is warm to the touch (hence the 6watts) and the bms must have been doing something.

Now, I Unplug the ping charger from the wattmeter (which is still connected to the battery) and the voltage stays there at 60v (which is an _average_ surface charge voltage of 3.75v/cell) and walk off and get us (three) all ready to load up on the longtail. And 15 minutes later the battery is sitting there at 56v (average 3.5v/cell).

So in my case when I was relying on the supplied charger, my batteries were getting way out of balance to the point where I needed to open up the pack and manually charge cell groups to get it back into a balanced condition. Now I use my ping charger, but I don't let it sit there and cook all night at 60.2v. The 4 amp charger that John supplied with my battery wasnt' the one he normally supplies with the 16s15ahr battery. I love it for a faster charge rate, but don't rely on it to properly engage with the bms for balancing.
 
Good stuff in this post, glad to see all the information on this newer battery. I haven't had the opportunity to do any real testing as the battery was purchased and is being used by the customer, however, he has not had any trouble with it and has been very pleased thus far.

I will let you all know if I hear different, but looks like a good product so far.

RVD, I wonder if maybe you got the wrong battery? Maybe it was supposed to be a 16S 3P battery, and the factory sent the wrong one?
 
I asked John about this battery because I was also suspicious and he replied saying that I received the correct battery.
 
ok enough is enough. i emailed john and asked him for either a replacement with a battery that really does charge up to at least 57v (says 60-61v on their ebay ads) or give me a refund. we'll see what happens...
 
They have agreed that this battery is 1 cell short. They have agreed to replace this battery if I send it back to them so I will try that and see what I get.

I will reserve future judgement until I get a new battery from them.
 
The replacement battery arrived last night. It's much better.

It is around 57v hot off the charger and settles down to about 54v. Once I ride for awhile it settled down to around 52v (down to around 50 with sag). Overall, it's about what I expected and is better than the old battery. This one clearly has 1 more cell than the old battery did so it's about 3.7v or so higher.

Overall, I would recommend this company. They stand by their product and they were good to make things right when I was not happy. It is cheaper than Ping and you will have your battery within 1 week of ordering instead of 3 weeks from China so if you're in a time crunch, these guys are a great option.

As for the quality of the battery, I think they are comparable. This battery doesn't have all of the lights on it like Ping but the BMS is internal and seems to work well.
 
Good to here your warranty was honoured and your happy with the battery.

I would not be surprised after a few cycles and a few overnight charges it charges up a few more volts. My 48v 20ah Vpower pack charges to 60v and holds at 60 when the charger is unplugged then its slowly tapers down to 57 or 56 overnight.

When in use the battery it quickly burns off the surface charge and runs in the 52 53v range when it starts to dip down under 50v I've used 13 + ah at that point. lvc is at 46.5 v and its around 17.5 17.9ah.

When the battery was new it would charge to 60v but drop down to 56v when the charger was unplugged but after a few cycles and then i forgot to unplug it for three days. it holds the same volts as the charger output. 60v.

The same thing happened after storing it for the winter, a few cycles and 48 hours on the charger all cells balanced and works the same after 100+ cycles 2500+ km
 
Guy's, can we here your trial's on these batteries?,I want to pull the trigger on a 48v15ah,48v20ah battery, I'm not getting the answer's I need from various suppliers! I don't want to build my next battery box until i get the next one. thanks, Randel.
 
Well, I have played around with both the 48v 15ah battery and the 48v 20ah battery. I received 1 battery that was 1 cell short so the company did take it back and send me another with with the correct number of cells.

The batteries appear to be in good condition and made well.

The charger seems to be good.

I have also purchased Ping batteries in the past. Unlike Ping, these batteries don't have leds that light up on the BMS so you can see when the batteries are fully charged and balanced.

Voltage sag appears to be normal for these types of batteries.

Hot off the charger, my batteries are around 57v. They die down to about 54v pretty quickly and sag to down to about 52v or so with time. With sag you see 48-51v most of the time on the cycleanalyst.

I'm not sure what else to say...overall I think these batteries are a good alternative to Ping. You will get faster shipping in the US since you will probably have your batteries in hand within 1 week of paying for them.
 
My setup of using two 24v 10ah batteries has been working fine for almost 2000 miles now! To work and back every day (19 miles roundtrip) without a hiccup.
 
Does anyone know if these are still for sale? Their website don't give ordering info and I can no longer find them on ebay. I'd like to add another 24v battery to my bike. :) Need for speed! :D
 
I know this is an older thread but I thought I'd chime in since this is one of the threads that convinced me to purchase from Green Oasis. I just purchased a 48v 20ah battery and it's charging now, my ebike kit won't be here until next week. I'm quite the noob so I'm not sure I could offer any information at the moment as to its quality, bms type and other details, but I can say that I ordered it late Saturday night and it showed up Wednesday - much faster than what I was expecting! A 3a charger came with the pack and it looks as though the pack was fully charged by the time it got to me (this was confirmed by John). I plugged in the charger and it only charged for a couple of minutes before shutting off and LED going green. Again I'm a noob so I'm not sure when balancing if all chargers blink green / red until everything is fully charged and if mine was already balanced which is why my charger didn't seem to do any blinking. I'm definitely jazzed about finding a US dealer and the service and product have been good so far
 
mythprod said:
I know this is an older thread but I thought I'd chime in since this is one of the threads that convinced me to purchase from Green Oasis. I just purchased a 48v 20ah battery and it's charging now, my ebike kit won't be here until next week. I'm quite the noob so I'm not sure I could offer any information at the moment as to its quality, bms type and other details, but I can say that I ordered it late Saturday night and it showed up Wednesday - much faster than what I was expecting! A 3a charger came with the pack and it looks as though the pack was fully charged by the time it got to me (this was confirmed by John). I plugged in the charger and it only charged for a couple of minutes before shutting off and LED going green. Again I'm a noob so I'm not sure when balancing if all chargers blink green / red until everything is fully charged and if mine was already balanced which is why my charger didn't seem to do any blinking. I'm definitely jazzed about finding a US dealer and the service and product have been good so far
Click to expand...


the charging lights turn on and off when the charging mosfet on the BMS turns on and off.

the charging mosfet turns off when the voltage on any cell climbs over 3.9V. there will be one cell that is much higher than the others and it determines how rapidly the pack charges up, and if it is bulk charging then being unbalanced a lot means longer times on the charger.

balancing is done by the shunt transistor and is different from the charging mosfet and they do different things. the shunt transistor begins to turn on as the charging voltage climbs over 3.6V and that transistor then diverts the charging current around the cell to prevent the cell from overcharging. this is the primary function of the BMS.

you can determine if your BMS is balancing the pack by measuring the cell voltages while the pack is on the charger to see what voltages the BMS can fix as the final charging voltage.

then when you list the voltages, it will be apparent whether the pack is balancing or not. the ping leds do that visually for a lot of people. monitoring devices are used to visually monitor cell voltages too.
 
These are the batteries I was trying to remember as I recall they used the fairly large round cells that are easier to work with than pouch cells. I don't need a battery now but if in the future I do these are an alternative to Ping and easier to repair when cells go bad. I now think that the A123 20 ah pouches and agniusm's kits are the bees knees for this type and ah/hrs set up. This could change in a heartbeat if A123 become regularly availible in the USA> They would rule!
otherDoc
 
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