Testing Lithium 36v 10ah battery

robert1976

Pedelecer
Aug 18, 2015
144
4
47
Does anyone know how these can be tested at home.
I found i can ship it for testing at £20+p&p really dont wanna do this
I found a shop near me but they say ive got to book it in and that the test takes 48hrs and £15 (Fare on price???) ??? really dont want to do that.
I found tester on-line £200 Really not doing that.
Surely there is a way with basic equipment ???
 

KirstinS

Esteemed Pedelecer
Apr 5, 2011
3,224
899
Brighton
The above may sound trite

Not my intention

Do you mean to test

Capacity ?
C rate?
Bms output?
Bms function?
Internal resistance?
Something else?
 

robert1976

Pedelecer
Aug 18, 2015
144
4
47
Condition off battery. most of what said has been said above means nothing to me. I just want to know if its putting out enough amps and lasting as long as it should. I can see volts are fine.
What i typed is truth. people on ebay offer testing. my local mobility store said about the 48hrs. Found tester after scowering net. Did ask on here if anyone ne ar me could test but no reply.
 

Alan Quay

Esteemed Pedelecer
Dec 4, 2012
2,351
1,076
Devon
Condition off battery. most of what said has been said above means nothing to me. I just want to know if its putting out enough amps and lasting as long as it should. I can see volts are fine.
What i typed is truth. people on ebay offer testing. my local mobility store said about the 48hrs. Found tester after scowering net. Did ask on here if anyone ne ar me could test but no reply.
Whit basic equipment and a little knowledge. You need to be able to measure current, and voltage at the same time (two meters, or a watt meter), then stick a large load on it so that you can draw around 10 amps. I have used a few electric heaters in parallel before now, but a single element cut short (crock clip half way along) should work.

However, (and I don't mean this to be offensive) your lack of knowledge makes me think you would be better paying someone else to do it. The guys who said 48 hours will not be testing it correctly, as it needs to be tested at a much higher rate.

How old is it, what chemistry and how many volts are you getting?

Why not put it on the bike and ride it around until it stops?
 
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JuicyBike

Trade Member
Jan 26, 2009
1,671
527
Derbyshire
Condition off battery. most of what said has been said above means nothing to me. I just want to know if its putting out enough amps and lasting as long as it should. I can see volts are fine.
What i typed is truth. people on ebay offer testing. my local mobility store said about the 48hrs. Found tester after scowering net. Did ask on here if anyone ne ar me could test but no reply.
Where are you ?
 

robert1976

Pedelecer
Aug 18, 2015
144
4
47
Whit basic equipment and a little knowledge. You need to be able to measure current, and voltage at the same time (two meters, or a watt meter), then stick a large load on it so that you can draw around 10 amps. I have used a few electric heaters in parallel before now, but a single element cut short (crock clip half way along) should work.

However, (and I don't mean this to be offensive) your lack of knowledge makes me think you would be better paying someone else to do it. The guys who said 48 hours will not be testing it correctly, as it needs to be tested at a much higher rate.

How old is it, what chemistry and how many volts are you getting?

Why not put it on the bike and ride it around until it stops?
i dont see how riding till stops will help fully charged is 41.7 volts droping to 39.5 under throttle. drops to 33.4 lowest ive seen. shorly i need something that will measure the amps current ? Lol
 

flecc

Member
Oct 25, 2006
52,761
30,348
i dont see how riding till stops will help fully charged is 41.7 volts droping to 39.5 under throttle. drops to 33.4 lowest ive seen. shorly i need something that will measure the amps current ? Lol
Riding until empty will help since it will show whether the battery performs as it should. Surely that's all you need?

Alan has already told you how to check the current at a high discharge rate, you need to rig an appropriate load as he described. Obviously you need to know what you are doing. There is no low cost ready made equipment that could do this for you.

Riding until empty is the cheapest and simplest way to see if the battery is ok.

Meanwhile your voltages are ok, but that's no indication of whether the current discharge rate is adequate.
.
 

robert1976

Pedelecer
Aug 18, 2015
144
4
47
Riding until empty will help since it will show whether the battery performs as it should. Surely that's all you need?

Alan has already told you how to check the current at a high discharge rate, you need to rig an appropriate load as he described. Obviously you need to know what you are doing. There is no low cost ready made equipment that could do this for you.

Riding until empty is the cheapest and simplest way to see if the battery is ok.

Meanwhile your voltages are ok, but that's no indication of whether the current discharge rate is adequate.
.
Sorry was at work earlier when replied.

Sellers info "Range: up to 24 miles on full charge depending on speed/rider weight/terrain."
I get 10 miles and its really struggling.


Yesterday I bought a brand new 36v 10 ah lithium battery Its even crapper than the old one. my 10 mile journey totally killed it nearly. It was down to 32.7 volts very close to cutting out. Do Lithium need a few charges to wake them up to full power ?

Battery's are under warranty. I need evidence to supply to sellers to confirm/prove there faulty or wrongly advertised.
 

Alan Quay

Esteemed Pedelecer
Dec 4, 2012
2,351
1,076
Devon
Sorry was at work earlier when replied.

Sellers info "Range: up to 24 miles on full charge depending on speed/rider weight/terrain."
I get 10 miles and its really struggling.


Yesterday I bought a brand new 36v 10 ah lithium battery Its even crapper than the old one. my 10 mile journey totally killed it nearly. It was down to 32.7 volts very close to cutting out. Do Lithium need a few charges to wake them up to full power ?

Battery's are under warranty. I need evidence to supply to sellers to confirm/prove there faulty or wrongly advertised.
10ah should be good for about 20 miles if:

You weigh less than about 80 kilos
You put in a bit of effort yourself
You don't have massive hills/headwinds.
You have a 250w (15a) motor
 
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trex

Esteemed Pedelecer
May 15, 2011
7,703
2,671
Sorry could you advise me how you would test them please. Thanks
Power consumption varies with speed to the cube, hence very sensitive to headwinds. The next factor is motor type. Hub motors tend to give you more miles - about 30miles-33 miles for a 36V10AH battery, crank drives about 10%-20% less because most people with CD motors tend to ride 20% faster, direct drive motors are worst for consumption because of very low motor efficiency at low speed, frequent start/stop at traffic lights in town can easily half your miles. The next factor is the maximum continuous output of the battery. If this factor is low, your battery will sag heavily when climbing hills, reducing range due to Peukert effect.
Tell us what motor/controller you have, we can advise what is reasonable to expect.
How to test:
Your battery is at least functional, so the main reason for testing is to find out if the capacity is as advertised and if the cells are well balanced. The simplest method that you can do at home is to get yourself an energy meter, something like this:
http://www.ebay.co.uk/itm/Status-Plug-In-Energy-Meter-kWh-Electricity-Monitor-Consumption-Usage-Analyzer-/141833338442
Charge your battery to full, reset your trip meter.
Ride until the battery is pretty flat.
Let's say you ride 15 miles.
Plug your charger to the energy meter and plug the energy meter to the wall socket.
Charge up the battery to full.
Check the amount of electricity used.
On a good bike, one would expect to see 5AH used. The power consumption shown onyour meter should be about 200WH.
Now measure the voltage of your battery.
When it's 100% full, it should be 41.5V, when it's very flat, 31.5V, so you should expect to see 36V.
You get the idea.
 

robert1976

Pedelecer
Aug 18, 2015
144
4
47
10ah should be good for about 20 miles if:

You weigh less than about 80 kilos
You put in a bit of effort yourself
You don't have massive hills/headwinds.
You have a 250w (15a) motor
Bike is 38 kg im 10.7 stone and bag close ect prob about 8kg.
9.4 miles. 23 mins ascent time 20 mins descent time. elevation loss/gain 354 ft very little peddle assist. winds 10 mph but return journey, no real hills. 200 watt motor not shore of amps.
 

Alan Quay

Esteemed Pedelecer
Dec 4, 2012
2,351
1,076
Devon
Bike is 38 kg im 10.7 stone and bag close ect prob about 8kg.
9.4 miles. 23 mins ascent time 20 mins descent time. elevation loss/gain 354 ft very little peddle assist. winds 10 mph but return journey, no real hills. 200 watt motor not shore of amps.
Well you are light, but that bike is heavy. No pedalling will kill your range, but 10 Miles is pretty poor.

What bike is it?
 

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