36v 500w vs 52v 1500w

[Tim Goffin]

Now this may seem like a silly question to some! But, I'm currently running a 52/48v system with 1500w and 35amp controller... I went out this morning with the 52v 17ah battery full charge and done 17miles... hardly any throttle, mostly in PAS 1/2.

When I got home I put my fluke meter on battery and it was 51.8v...so from my understanding I only had about 4volts left to play with.. I wouldn't mind if I had been in PAS 5 the while time but I was really trying to conserve my battery..

So.. I would like a better set up for range...I have the 52v and a 20ah 48v battery and don't want to fork out for a 36v so I'm thinking
350-500w rear geared hub motor, with a 15amp controller...

Being as so many peeps on here have such good knowledge do any of you think the lower power set Will show me a night & day difference?.. I don't go much over 23-24mph and have no want to...just want good low end torque and the best range possible from one charge..

Any suggestions very much appreciated....

 

[Woosh]

if you have a 48V system, the range of voltage is 42V (empty) to 52V (full).
There is nothing wrong with your kit, you still have 90%+ in the tank.
Few geared motors can take 35A @ 52V.

 

[wheeliepete]

If you are running a 52v battery (58.8v fully charged), then your LVC is going to be around 43v, so you should get around 38-40 miles range.

 

[Tim Goffin]

Hmmm don't know why I thought it was 47v cut off...jimmy told me my bms is set to shut off battery when cells get to 2.8 per cell...I suppose if I run my bike untill bms kicks in, see how many miles I've done then take 8miles off that figure I will have a safe average to work from

 

[Woosh]

So.. I would like a better set up for range...I have the 52v and a 20ah 48v battery and don't want to fork out for a 36v so I'm thinking
350-500w rear geared hub motor, with a 15amp controller...

hi Tim,
if you want more range then you have to lower your speed.
At 25mph you burn 30WH/mile, at 20mph, you burn 17WH/mile.
pedaling hard does not count for much at that sort of burn rate (at best you reduce consumption by 6W/mile, average pedaling contributes 3-4W/mile),

 

[Tim Goffin]

Thank you whoosh I will set my limit to 20mph and see what difference that makes....just thinking I really didn't need a 1500w system now lol...

 

[Woosh]

for commuting, if you ride derestricted, 20mph is a good compromise, 15WH/mile to 17WH/mile on a 600WH battery system gives you 45-50 good miles. A motor like SWX02 is perfect for that, it climbs well and it's not too heavy.. The Aikema 128SX is also a good candidate, same power and little lighter.

 

[wheeliepete]

.just thinking I really didn't need a 1500w system now lol...

Don't worry, your not aloneI started 3 years ago thinking I wanted POWER!! every bike I've built since has less and less of it. Still got the bike with the power though!!

 

[Woosh]

every bike I've built since has less and less of it.

I am betting on the 48V TSDZ2 kit as the right compromise: 80NM for climbing, 44T/46T for speed, 3.6kgs for weight.

 

[wheeliepete]

I am betting on the 48V TSDZ2 kit as the right compromise: 80NM for climbing, 44T/46T for speed, 3.6kgs for weight.

Don't tempt me, 4 bikes is enough.........or is it?

 

[Woosh]

Don't tempt me, 4 bikes is enough.........or is it?

nah.. I have to have a new bikes every 4-5 months. It's a health condition so I tell myself.

 

[wheeliepete]

nah.. I have to have a new bikes every 4-5 months. It's a health condition so I tell myself.

It's OK for you, you build and sell the things and can afford the therapy

 

[Tim Goffin]

LoL...I hope I have not started something here...do u sell the kit you mentioned whoosh?... I'm thinking sell the high power and go for a more all rounder...I have spent £1020 on batterys from jimmy so the hard bit is done

 

[Woosh]

no, not yet but you can get it on amazon, pswpower.com.
They are making a road legal high torque version for me at the moment.

 

[Tim Goffin]

Great, will look into it...

 

[Nealh]

2,8v is quite a deep discharge = 39.2v for 14s/52v, to be kinder to the cells and a longer life cycle look at 3.3/3.4v = 46.2/47.6 end voltage.

 

[Tim Goffin]

2,8v is quite a deep discharge = 39.2v for 14s/52v, to be kinder to the cells and a longer life cycle look at 3.3/3.4v = 46.2/47.6 end voltage.

Ok...also maybe silly question..should I stop when my bike is drawing the battery below 47.6v? Or when it is at rest at that voltage?..

 

[anotherkiwi]

No, but you are not lengthening the life of your battery. My LiPo cells are charged to 4.15v and discharged to 3.65v (per cell) and despite using them for quite some time now (over 2 years for the multistar) show no sign of degradation. You can treat your Li-Ion cells the same way and they will last for a very long time, ask Tesla. OK so a battery does go on fire in a Tesla now and then...

 

[Tim Goffin]

Went on a ride to the bootfair this morning, swapped over to my 48v 21ah when my 52v got to 50v... bikes abit heavy with both but hopefully I will get a good few years outta them if inuse them in this way...

There was a group on TT bikes so I did go into PAS 5 so I could fly past sitting nice and upright haha....

 

[Nealh]

Ok...also maybe silly question..should I stop when my bike is drawing the battery below 47.6v? Or when it is at rest at that voltage?..

In use the you will see battery sag so it will dip lower then 47.6 underload once voltage has decreased but once load is reduced it will bounce back, I use rest V's.
Once it sags below reduce load applied and use lower assist to mollycoddle the cells instead of stressing them.
For 48v I use to 44v resting or 3.4v per cell approx. max dod.

On 50 -70+/ 80 - 110km + rides I take two 14.5ah batteries and usually swap over once I see 3.7v per cell underload on pas 2. If second battery is used to 3.4v per cell ( needs an even longer ride) I know I have good reserve in first battery if ever needed., mostly on return home both are 3.7 - 3.85v per cell.