"how far does a 48V12AH battery go?

[dfmerrifield]

Sorry Bruno

That site did have a lot to do with what I was saying about it must have a bad cell in it causing my problems.

   Figure 2: Serial connection
with one faulty cell.
Faulty cell 3 lowers the overall voltage to 4.2V, causing the equipment to cut off prematurely.

   Figure 4: Parallel connection
with one faulty cell.
A weak cell will not affect the voltage but provide a low runtime. A shorted cell could cause excessive heat and create a fire hazard.

This is what I was talking about.  This is what has been happening to my battery and is just getting worse every time I use it.

Don

[GM Brazil]

Hello Don,

The 36V16Ah have, I guess, 4 parallel groups of 10 cells in series each. So the GM batteries have serial+parallel configuration and a dead cell in one of those groups will affect as your description. Do not try to open the batter case to discovery this because you will loose you warranty - send an e-mail to Tom or the dealer you bought to see how can you ask for a replacement!

If you have some friends who plays with electric R/C airplanes you can ask them a Watt meter to test the battery for a sure conclusion, but your described experience should be enough to claim. It happens sometimes, you got bad luck! 

Been on the charger for over 8 hours now and still trying to charge up.  The charger is so "HOT", I picked it up after feeling how warm it was and could not keep my hand on the bottom of it for more than 3 seconds.  It was way too hot to handle.  It's always been just a tad warm and only on one side and at about the 4 hour mark would shut down.  Now, over 8 hours and still going strong.   Gonna leave it on and see how long it takes to shut down if it does.
All I wanted was how far other people are going on one charge so I could use it for a reference to my batteries' properties.

This behavior should be because the BMS still trying to balance the cells and as you have a bad cell this never happens. My bike have a 12Ah battery and a 3A charger (check the output information at your charger) and this means 12Ah/3A=4 hours and generally is this time I got for a full charge, if your charger is 3A too, it should got 16Ah/3A= 5hours and 20 min

Besides the behavior you experienced, this long time for charging is another prof of a bad battery

Bruno

[dfmerrifield]

Hey Bruno

My battery is a 48v12ah with a 2 amp charger.  If the battery was totally dead it would take 6 hours to charge.  But seeing as the batteries don't go totally dead and cut out (as mine was doing) around 38 - 39 volts.  Depending on how low my battery was, it would usually take mine about 4 hours.

It has been 10.5 hours on the charger and the light just started to fade out.  Unplugged the charger and the light went full dim so, the charger was still giving a small charge even now.

Anyway, this thread was started for the sole purpose of trying to get Tom's attention.  I got a hold of my dealer and he can't do anything unless Tom OK's the replacement.  So, I started this thread and sent a copy of the original post to Tom as an email and so did my dealer and we are just waiting for some sort of contact from Tom at this time so we can get the OK and get me a new replacement.

Don
 

[GM Brazil]

Don,

Just for curiosity: I think I have a different charger, check those attached photos. Mine have two leds, one red for power on and the other is orange during charge and green when fully charged. And do not be worried, it takes time but when I was researching to be a GM dealer one thing that I did note is that they always solves warranty problems - you see several examples here and at other forums of these experiences.

Gary,

I'm worried about these warranty problems, it is really necessary to wait for Tom's answer for a sure warranty problem? Because sometimes GM take a lot of time to answer    Here in Brazil we have laws pertaining to the consumer that there are deadlines for solving these problems and not meeting them can result in severe fines. Can we, dealers, decide for ourselves while we wait for Tom's answer? How this works for you?

[dfmerrifield]

Hey Bruno

No Sir, not the same one at all!  Mine is a plain black rectangular box with no fan or nothing labeled on the top nor sides.  It's a Sans, model SSLC109V55.

I wish mine was of the quality yours is.

Don

[dfmerrifield]

  Well, I gave her a try again today, just for the hell of it, and got just under 11 mile out or my battery.  Had to try!  Just can't believe my luck as usual.  But, Hey, Not all mechanical things are made perfect and sh!t happens.  Just waiting for my replacement and all will be well.

  People!  Don't let this thread detour you from getting a Magic Pie or just a Hub Motor from Golden Motor.  The system is so cool, you will love it the first time you go for a ride on it.  The motor is so quiet, you can't tell if you are coasting or actually using the system.  I just happen to be one of the lucky ones' out of the many that get the luck of a bad cell and that's all.

  I am in love with my Magic Pie, TOTALLY!  Lots of fun and so nice to ride.   I get lots of people in cars slowing down to look at the bike, while passing and they seem just amazed at the thing.  Even the bikers, that live all around me, all check it out and all thumbs up from them too.  Give MP a try and you will love it.

Don

[GM Canada]

Gary,

I'm worried about these warranty problems, it is really necessary to wait for Tom's answer for a sure warranty problem? Because sometimes GM take a lot of time to answer   Here in Brazil we have laws pertaining to the consumer that there are deadlines for solving these problems and not meeting them can result in severe fines. Can we, dealers, decide for ourselves while we wait for Tom's answer? How this works for you?

Unfortunatly GM China makes the final desision on all warranty issues. If I just replace something from my stock, I risk paying for it myself. Any issue has had to go through the proper procedure of writing to Tom. He then trys suggesting a few tests and determines what the issue is. He reports to his manager and the decision is made. Last issue took 5 days, others have taken longer. GM has always come through for me, but its not like we are dealing with walmart. We are dealing with a factory on the exact opposite side of the planet (at least to me). Unfortunatly Tom does all the shipping, tracking, tech support and warranty issues and its the busiest time of year.

Do not worry though , Don and I have talked on the phone a few times and he knows I will not let him down.

Gary

[GM Canada]

For the 36V16Ah battery you have 576Wh of energy, so with a 750W full throttle and considering 78% of efficiency:

750W/0,78=961,54W of consuming power, so:

576Wh/961,54W=36 minutes or 0,6 hours of use.

Then you can multiply your max speed by those 0,6 hour and check if it fits your range if not, we need to change the efficiency value.

Since you are handy with these formulas, how far should I go?

As you probably already know, I'm running a 48v1000w setup on my bike with 2 48v12ah batterys in paralell.

I was studying the data on my CA during a ride today. At 20 kph im burning an average of 275w, at 32kph 550w. full throttle 38-40kph 1000-1100w. Even racing down a hill at over 54 kph still buning over 800 watts at full throttle. Add in any wind or wind gusts and you add at least an extra 100-200w of consumtion.

So what distance should I get at 20kph, 32 kph and flat out...

Gary

[dfmerrifield]

Gary

These are an easy way to get real close and are exactly what I was getting, with a single battery system on my MP, the first week on the road before the battery decided to go on me.

Single Battery System

(48 V X 12 Ah / 275 W) X 20 kph = 41.89 km or 26 mi
(48 V X 12 Ah / 550 W) X 32 kph = 33.51 km or 20.8 mi
(48 V X 12 Ah / 1000 W) X 40 kph = 23.04 km or 14.3 mi

Dual Battery System

(48 V X 24 Ah / 275 W) X 20 kph = 83.78 km or 52 mi
(48 V X 24 Ah / 550 W) X 32 kph = 67.03 km or 41.6 mi
(48 V X 24 Ah / 1000 W) X 40 kph = 46.08 km or 28.6 mi

Don

[dfmerrifield]

Hey Gary

  Actually, I got farther at the given kph.  I only weigh 88 kg (190 lbs) and I am not pulling the wattage you are at the same speed.  At 40+ kph, I was getting 18 to 21 miles, depending on the winds, but that's running on all flat roads with no stop and go either.  The ratting I gave above is realistic for a new battery with way under 1000 charges keeping your efficiency rating at the top level.  After your efficiency rating drops when you get closer to the 800 or so mark, these distances will drop accordingly.

  As you have seen with the difference between your wife's bike @ 36V16Ah and she only weighing at the 100 lb area and you using two 48V12Ah batteries giving you 24 Ah your in the #$% lb area.  Your wife, being so light, is pulling considerably less wattage than you so of coarse she is going to go farther with less power.  That is why I was getting good distance out of my MP because I don't weigh as much as you meaning I am only pulling around 600 or so watts at 40 kph.  The average person at about 160 lbs should in theory only pull 250 to 300 watts at 32 kph (20 mph) but this still depends on wind, uphill or downhill, total weight, type of tires used etc.

  "This part of the reply is only for new owners and potential owners to use as a reference as I know you know all about this weight and wattage draws as we have talked about this on the phone."

Don

[GM Brazil]

Do not worry though , Don and I have talked on the phone a few times and he knows I will not let him down.

Gary

I'm sure about this I just wanted to learn more about you experience with warranty issues! This will be very helpfull, thank you!

Bruno

[GM Canada]

Well written Don,

Now we just have to figure out at what point the BMS kicks out the batteries. The BMS does not let you drain the batteries completely. I believe the BMS only allows you to use about 75-80 percent of your power before kicking out to protect the battery. I beleive it works by voltage which I thought was around 38 volts but read somewhere it is at 42 volts. Anyone know what percentages or voltages the BMS kicks out at?

Gary

[muzza.au]

Well written Don,

Now we just have to figure out at what point the BMS kicks out the batteries. The BMS does not let you drain the batteries completely. I believe the BMS only allows you to use about 75-80 percent of your power before kicking out to protect the battery. I beleive it works by voltage which I thought was around 38 volts but read somewhere it is at 42 volts. Anyone know what percentages or voltages the BMS kicks out at?

Gary

I don't know what the voltage is, but it would be for the first individual cell to fall below a certain threshold, not the overall battery voltage. The bms is to protect all the cells. If just one falls below the lvc, the whole battery is turned off. My old GM battery didn't have a bms, so while the overall voltage may have been above overall lvc, some of the cells were pushed too far and they died, leaked and wrecked the whole battery.

Muzza.au

[GM Canada]

Sorry Gary

This reply was for Bruno from Brazil:

In the future Don, you can always go back and modify or delete any of your posts. I do that constantly as my typnig skils an speeling is perthetic.

Gary

[dfmerrifield]

Hey Gary

LMAO

In the future Don, you can always go back and modify or delete any of your posts. I do that constantly as my typnig skils an speeling is perthetic.

Don