bike performance 10ah vursus 20ah

[justlooking]

right to start with , i have a bike with only front suspension and im using the GNG V1 mid motor with the stock controller, the battery im using is a 48v 10ah,
now my question is, if i double the 10ah upto 20ah will i see any better performance apart from being able to go further per charge, ie will the bike have more torq. or even a bit more speed ,, will 20ah help better than 10ah in going uphills ??

i went up grapes hill in norwich uk yesterday and i noticed that the led light guage went down to one light out of the four lights that it have, im concerned that going up the hill might be trying to take to much out of the battery in one go just to get to the top of the hill, once i got to the top, then all lights came back on ,,

any advice welcome ..

 

[drebikes]

The reason the lights go out when you climb is because you pull so much current from the battery that the voltage sags and looks like it would be emptying, even though it's not (or not as fast).

In most cases upping the battery capacity (Ah) does increase performance. At equivalent cells (say 3C max continuous discharge): for 10Ah you have max 30Amps and 20Ah you have 60Amps.
Assuming the controller can control that many amps you may as mush as double current capability, thus power.
Max speed won't be touched in any way, in order to increase speed you need to increase voltage.

Do you have some links for the controller, batteries 10Ah and 20Ah? I don't know those kits and can't search now because @work.

 

[justlooking]

hi ,, there is this thread about the GNG MID MOUNT MOTOR ,, the batterys i have are bottle batteries, all lithium,
i have 2 24v and one 48v ,, all three are 10ah each. at the moment im only useing the 48v one ,,
im not realy bothered on going faster, but i was concerned when i saw the lights go down to only one out of the 4 ,, and wondered if i might be trying to take to many amps out of the battery in one go than what is good for it , i dont want to kill a £300 battery and if it needs it i will use the other 2 24v ones along side the 48v, even if it will make the bike heavier

i would be interested in upping the volts to 60v but would it use/need less amps going up the same hill on 60v, thus saving the weight of one bottle battery which is over 5kg

 

[drebikes]

I think you may be overworking the battery, that kind of voltage sag usually means either old/eol or overcharged; others may chime in though with their 2 cents

If you have further 2x24V batteries, I don't really know but supposing the 2x24V when charged are the same voltage as the 48V (usually a charged Lifepo 48V is 58.5V, 24V don't know) than you may put the 2x 24V in series with the 48V in parallel. Any imbalance in voltages though may create eddy currents between the batteries with bad effects (say overcharging the branch in parallel with lower Vmax). It needs testing, but it could work.

Another way to solve the sagging issue is to reprogram the controller and limit the max DC current. This way you'd have less assistance, but also you'll keep the battery healthy.

 

[bowlofsalad]

Do you have both a multimeter and a watt meter such as a cycleanalyst? If not, you should acquire both.

Saying 'all lithium' doesn't mean anything when talking about batteries. I might guess the chemistry of your battery is LiFePO4. C stands for capacity, if your pack is 3c, it this means your pack has a rating of 3 times capacity. To find capacity, multiply voltage by amp hours. That information is useless without a watt meter though, so get one.

10ah vs 20ah will double your capacity, so in short, it will help protect the battery from excessive draw and give you further range. The story I read repeatedly is that bottle batteries are often low C and very far from ideal in hilly regions.

 

[justlooking]

I think you may be overworking the battery, that kind of voltage sag usually means either old/eol or overcharged; others may chime in though with their 2 cents

If you have further 2x24V batteries, I don't really know but supposing the 2x24V when charged are the same voltage as the 48V (usually a charged Lifepo 48V is 58.5V, 24V don't know) than you may put the 2x 24V in series with the 48V in parallel. Any imbalance in voltages though may create eddy currents between the batteries with bad effects (say overcharging the branch in parallel with lower Vmax). It needs testing, but it could work.

Another way to solve the sagging issue is to reprogram the controller and limit the max DC current. This way you'd have less assistance, but also you'll keep the battery healthy.

thanks, i never thought about the combined voltages of the 2 24v compared to the 48v, i will connect the 2 24v together and check that before i go any further.

 

[justlooking]

Do you have both a multimeter and a watt meter such as a cycleanalyst? If not, you should acquire both.

Saying 'all lithium' doesn't mean anything when talking about batteries. I might guess the chemistry of your battery is LiFePO4. C stands for capacity, if your pack is 3c, it this means your pack has a rating of 3 times capacity. To find capacity, multiply voltage by amp hours. That information is useless without a watt meter though, so get one.

10ah vs 20ah will double your capacity, so in short, it will help protect the battery from excessive draw and give you further range. The story I read repeatedly is that bottle batteries are often low C and very far from ideal in hilly regions.

i know that one of the 24v and the 48v are the same cemestry but i dont think that the other 24v is the same as there is a bit difference in weight compared to the other 24v even though they have the same case.

i might buy another 48v to match the one i have,

 

[999zip999]

Most bottle batteries don't have the strongest cells inside. That could be the reason for the sag. Plus controller demands. The 24v must have the same voltage so check. And is only has ah of the lowest battery so be careful and don't kill one pack.

 

[alsmith]

Open a pack and see if the pack is marked with the battery ratings.
My first iteration of ebike used a small water-bottle type battery, I got a second for a little better range. They were claimed as 36V 6Ah and/or 8Ah depending on what you read, where you looked, or who you listened to (which wasn't much anyway) but opening showed one pack labelled as 4.8Ah and max discharge of 9.0A. The other battery didn't have pack markings and the cell markings gave no clue.
This format bike was bought to start off with the first planned upgrade being a 20Ah battery followed by better motor and controller.

 

[dogman dan]

You have a bike that drives through the gears. One common thing with those is riding up hills in too high a gear. So if not using the low gear on hills, it may help to gear down. That lets the motor spin faster, and stay in it's more efficient rpm range.

As for the battery, if you double your capacity, you half the discharge rate you are subjecting the battery to. This will be good. Batteries will sag under heavy load, so lessening the load lessens sag. The math is simple. Say you have a 10 ah battery and discharge at 20 amps. This is 2c discharge rate, and can cause many bike batteries to start dropping in voltage when the 2c rate is continuous. But if you double the size to 20 ah, a 20 amps discharge is now only 1c, and results in less voltage drop. If you carry 20 ah and only discharge at 10 amps, you have a very easy .5c rate.

Wattmeters are a great tool for learning how to ride in the right gear to keep your amps rate down. You quickly see what gear you should not climb that hill in.

Lessening the c rate of the discharge, generally milks more of the capacity from batteries. A 10 ah pack might provide a real world 9 ah or more at 1c, but only 8 ah at 2c.

Plus, you have twice as much to start with. So you can go a lot farther on 20 ah than on 10 ah.

 

[justlooking]

one more question ,, if the batteries are different chemistry , would this matter ?? i dont want to use them all together if it will/could cause problems with one or more of the others ,,

if there could be problems then what could that be ..


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in the 24v batteries i know that one has round cells (like a normal cell battery) and the other one has pouches, i can not get them out of the cases as they seem to be glued in place and i dont want to start banging them to get them out ,,

 

[justlooking]

You have a bike that drives through the gears. One common thing with those is riding up hills in too high a gear. So if not using the low gear on hills, it may help to gear down. That lets the motor spin faster, and stay in it's more efficient rpm range.

going up grapes hill i was in first gear, the hill gets steeper the higher that you go ,, i have no idea what the hills % is,
i think i need to up the amps at the battery,
lucky enough norwich in the uk dont have many hills and its not a real problem going round them ,, but it would be noce to know that i can go up them if i need to,

 

[drebikes]

one more question ,, if the batteries are different chemistry , would this matter ?? i dont want to use them all together if it will/could cause problems with one or more of the others ,,

if there could be problems then what could that be ..
///////////////////
in the 24v batteries i know that one has round cells (like a normal cell battery) and the other one has pouches, i can not get them out of the cases as they seem to be glued in place and i dont want to start banging them to get them out ,,

It is very important the batteries have the same voltage, which pretty much means same chemistry, but also same health level. Putting the 2x24V in series and then in parallel with the 48V could give problems if:
*full 2x24V voltage is different from full 48V voltage because imagine the 48V and one of the 24V have the full voltage of 58V and respectively 29V; if the second 24V has full voltage of 28V, this means the 48V pack is @58V and the 2x24 @57V - the 1V difference will mean the 48pack overcharges the 2x24 which is very risky, even 1V. So it is critical they start at the same voltage or as close as possible (0.1V probably won't hurt)
*one of the 24V has lower Ah than the second 24V; the assembly will have the minimum of the two packs; if this minimum is smaller than the 48V Ah, then the 2x24V will cut before the 48V does, so you'll be left again with only the 48V battery powering the bike, while carrying all the weight

If all batteries would be the same chemistry and the 24V ones would have precisely half the number of series cells as the 48V then this series/parallel setup has more chances of working. If they're not, you'll need a lot of luck for everything to fit together.

 

[justlooking]

one more question ,, if the batteries are different chemistry , would this matter ?? i dont want to use them all together if it will/could cause problems with one or more of the others ,,

if there could be problems then what could that be ..
///////////////////
in the 24v batteries i know that one has round cells (like a normal cell battery) and the other one has pouches, i can not get them out of the cases as they seem to be glued in place and i dont want to start banging them to get them out ,,

It is very important the batteries have the same voltage, which pretty much means same chemistry, but also same health level. Putting the 2x24V in series and then in parallel with the 48V could give problems if:
*full 2x24V voltage is different from full 48V voltage because imagine the 48V and one of the 24V have the full voltage of 58V and respectively 29V; if the second 24V has full voltage of 28V, this means the 48V pack is @58V and the 2x24 @57V - the 1V difference will mean the 48pack overcharges the 2x24 which is very risky, even 1V. So it is critical they start at the same voltage or as close as possible (0.1V probably won't hurt)
*one of the 24V has lower Ah than the second 24V; the assembly will have the minimum of the two packs; if this minimum is smaller than the 48V Ah, then the 2x24V will cut before the 48V does, so you'll be left again with only the 48V battery powering the bike, while carrying all the weight

If all batteries would be the same chemistry and the 24V ones would have precisely half the number of series cells as the 48V then this series/parallel setup has more chances of working. If they're not, you'll need a lot of luck for everything to fit together.

thanks m8 ,, i have decided that i wont use the 24v ones in parallel with the 48v, but will keep them as spare ones,

i will wait untill i upgrade my batteries and then use the hobbyking packs to make up a 20ah pack.