battery charging

[billyboya]

I have a 48V 30Ah battery on my electric moped. and when its fully charged moped top speed is about 27 to 28KM/h thats when battery says 54.9 v which is fully charged But the battery is now at 47v and top speed says about 22 to 23KM/h which seems a bit slow to me. I think people can run past me faster LOL. will it do harm if I keep charging it up when its low as 47v as like i said its a bit slow at 22 to 23KM/h

I feel like Mr Bean in his movie he made Mr Beans Holiday lol

 

[sjpt]

There shouldn't be any problem charging it up regularly. If you aren't going to ride for a few days its best not to keep it fully charged; charge it to maybe 50v and then top up to full just before the next ride.

 

[billyboya]

There shouldn't be any problem charging it up regularly. If you aren't going to ride for a few days its best not to keep it fully charged; charge it to maybe 50v and then top up to full just before the next ride.

Ok will do, as like I said at 22 to 23KM/h its a bit slow. I would prefer 26 to 28KM/h I do get a few annoyed cars behind me LOL But sod them, the more they pip there horns the slower i will go.

 

[Nealh]

47v is about 40% it equates to 3.61v per cell group. The low speed is likely due to the cheapness of the battery cells, so yes charge it up.

 

[billyboya]

47v is about 40% it equates to 3.61v per cell group. The low speed is likely due to the cheapness of the battery cells, so yes charge it up.

thanks Nealh. I let the battery get low as 47v. As that seems to make top speed approx 22 to 23 KM/h. But on full charge it’s approx 26 to 28KM/h

 

[sjpt]

It does sound as if they aren't that high quality cells. Using the full speed when fully charged may be draining them faster than they really like, which could significantly reduce battery life. I suspect the moped isn't that efficient, and I seem to remember that you are using full assist and not providing anything yourself?

You mentioned it is a 30Ah battery, but haven't (on this thread anyway) said what continuous current it is rated for (sometimes not that easy to find out).

 

[Nealh]

Don't forget as you are only using throttle and sheer electric power then the hub speed is proportionate to voltage the higher the voltage the then the higher the terminal speed is, as seen in your case as the voltage decreases as does speed.
So your answer going fwd's is a larger capacity battery that can hold the voltage higher longer or another wired in parallel. Both options have there draw backs, one will take ages to charge and the other one has to keep an eye on two charging.

 

[billyboya]

It does sound as if they aren't that high quality cells. Using the full speed when fully charged may be draining them faster than they really like, which could significantly reduce battery life. I suspect the moped isn't that efficient, and I seem to remember that you are using full assist and not providing anything yourself?

You mentioned it is a 30Ah battery, but haven't (on this thread anyway) said what continuous current it is rated for (sometimes not that easy to find out).

Battery Model	48v 30ah
Nominal Voltage (V)	48v
Nominal Capacity (AH)	30ah
Source Resistance (mΩ)	about 40
Cell Specification	3.7V 5ah
Cell Combination	6-parallel 13-series
Cell Size	21700
Cell Quantity (parallel*series)	78pcs
Discharge Cutoff Voltage (V)	36.4+/- 1V
Charge Cutoff Voltage (V)	54.6v
Rated Discharge Current (A)	30A
instantaneous Maximum Discharge Current (A)	60A
Maximum Continuous Discharge Current (A)	30A
Maximum Continuous Charge Current (A)	2A
Charge Mode	CC-CV
Standard Charge Current (A)	2A
Charge Time under Standard Charge Current	10hours
Fast Charge Current (A)	5A
Charge Time under Fast Charge Current	4hours
Charge Temperature Range	-20-55°C
Cell Size (L*W*T )	295*130*75mm
Battery Weight	About 5.5KG
Battery Power	1500W

 

[billyboya]

Don't forget as you are only using throttle and sheer electric power then the hub speed is proportionate to voltage the higher the voltage the then the higher the terminal speed is, as seen in your case as the voltage decreases as does speed.
So your answer going fwd's is a larger capacity battery that can hold the voltage higher longer or another wired in parallel. Both options have there draw backs, one will take ages to charge and the other one has to keep an eye on two charging.

26 to 28KM/h is fast enough for me LOL . But thanks to your help moped is going great

 

[Nealh]

Very pleased you are happy with the result of all the hard work, so battery wise simply charge it after or just before the next use.

 

[sjpt]

Looks as if the battery discharge is enough (30 amp continuous at 48v) not to worry about top speed, though I don't know the controller details.

Enjoy, glad it was ready for spring and summer.

 

[billyboya]

Very pleased you are happy with the result of all the hard work, so battery wise simply charge it after or just before the next use.

Well I like to have 26 to 28KM/h so will keep charging it after every use. As like I said earlier 22 to 23 KM/h. Is ok but a bit slow for me

yes it’s took 4 months in all so I’m grateful to you and MatthewSlack as I was totally clueless about this moped but learnt loads now