Battery fusing

[Andy-Mat]

I have a trike which I purchased with a 250w motor. Last year I bought a 1000w kit and upgraded. The controller is 36v/ 48v and for nearly a year I used the 36v 15 ah battery, that came with the original bike, without issue. I have recently bought 2 36v 25ah batteries hoping to get a little more range. One of the batteries is fine, the other however fuses if I go up a hill. I have spoken with the vendor who tells me I need a bigger battery., but one works absolutely fine. Am I being fobbed off?

What was the maximum current you set up in the controller?
To me it sounds as though that is simply set a bit too high, and its on the knife edge for both batteries, one above one below....
I would suggest setting it to say 18 amps max, which may also give a bit more range as well..
Replacing a fuse with a larger value is normally not recommended at all. As the next "fuse" in line might burn the wiring and cause a dangerous battery fire. Li-ion batteries catching fire are simply horrific.....The whole bike will be ruined as you will not be able to get near it, or put the fire out, unless you can throw it in water deeper that the bike is high, when lying on its side.....
A hose pipe, if available, may keep it from spreading, and slow it down, but most unlikely to actually put it out!
This guy seems to be "playing with" two batteries, and look where it gets him:-

You can hear as individual cells explosed, in spite of the water!!
You may find that the two batteries are built possibly with different cells, possibly from two different cell vendors, or two different cell types from the same vendor.
Also, there are various types of fuse, with the same amp-age, but one is HRC and the other not, or one is slow blow and the other not!
I tend to think that HRC/Slowblow is better in this situation and a max current of under 20 amps be best.
Regards
Andy

 

[Nealh]

Selling your existing ones will likely mean you take quite a hit on them of 50% or more.

 

[Nealh]

Problem with D/D is it will be gutless at 18a, that's why they like higher current otherwise a 250w geared hub will trump it all day long.

Debbie should try the old 250w again if it was hub and set the controller to 18 - 22a and try again with the new batteries.
Being dual voltage is the controller a KT model ?

Can you show us a pic or link to batteries you bought as this will be getting expensive for you just throwing money at a high power D/D set up.

 

[Debbie Lomax]

What was the maximum current you set up in the controller?
To me it sounds as though that is simply set a bit too high, and its on the knife edge for both batteries, one above one below....
I would suggest setting it to say 18 amps max, which may also give a bit more range as well..
Replacing a fuse with a larger value is normally not recommended at all. As the next "fuse" in line might burn the wiring and cause a dangerous battery fire. Li-ion batteries catching fire are simply horrific.....The whole bike will be ruined as you will not be able to get near it, or put the fire out, unless you can throw it in water deeper that the bike is high, when lying on its side.....
A hose pipe, if available, may keep it from spreading, and slow it down, but most unlikely to actually put it out!
This guy seems to be "playing with" two batteries, and look where it gets him:-

You can hear as individual cells explosed, in spite of the water!!
You may find that the two batteries are built possibly with different cells, possibly from two different cell vendors, or two different cell types from the same vendor.
Also, there are various types of fuse, with the same amp-age, but one is HRC and the other not, or one is slow blow and the other not!
I tend to think that HRC/Slowblow is better in this situation and a max current of under 20 amps be best.
Regards
Andy

 

[Debbie Lomax]

I don't know how to set the current on the controller.

 

[Debbie Lomax]

Problem with D/D is it will be gutless at 18a, that's why they like higher current otherwise a 250w geared hub will trump it all day long.

Debbie should try the old 250w again if it was hub and set the controller to 18 - 22a and try again with the new batteries.
Being dual voltage is the controller a KT model ?

Can you show us a pic or link to batteries you bought as this will be getting expensive for you just throwing money at a high power D/D set up.

Here is a pic of controller. The battery is a silver fish style, the pic I have provided is of the only txt on it. I bought the 1000w for power, not speed, as the trike is quite heavy and I live on the pennines.

 

[Nealh]

Can you show us a full pic of the battery, I can't believe for one minute that 25a /900wh can fit inside a standard silverfish case. The most capacity for 36v I have seen for one is 17.25 ah using 3500mah cells.

The controller is KT you can adjust the current setting by using parameter C5 in the advanced settings, if you have the KT lcd3 or above.

 

[Debbie Lomax]

Can you show us a full pic of the battery, I can't believe for one minute that 25a /900wh can fit inside a standard silverfish case. The most capacity for 36v I have seen for one is 17.25 ah using 3500mah cells.

The controller is KT you can adjust the current setting by using parameter C5 in the advanced settings, if you have the KT lcd3 or above.

Oh right, I will drop it to 8 and try that.

 

[Nealh]

The length is deceiving in your pics, how many cm tall is it.
If C5 #8 doesn't help go lower, it depends how the C5 function works on your LCD my one's decrease amps by 0.5% for each digit decrease newer ones's by percentage.

 

[Debbie Lomax]

The length is deceiving in your pics, how many cm tall is it.
If C5 #8 doesn't help go lower, it depends how the C5 function works on your LCD my one's decrease amps by 0.5% for each digit decrease newer ones's by percentage.

The battery is 38. 5 cm high, and yes I will play around with the C5 function till I hopefully get it right.

 

[Nealh]

I would be very surprised if the batteries are 25ah/900wh , it would mean there are 70 cells in side.
How much does it weigh ?

 

[Debbie Lomax]

I would be very surprised if the batteries are 25ah/900wh , it would mean there are 70 cells in side.
How much does it weigh ?

4.7 kg

 

[Nealh]

4.8kg seems about right for 70 cells.
A 50 cell 15ah one is about 3.65kg so adding another 20 cells and interconnectors will add 1kg ,my guess is that Samsung 35E cells are being used inside.
You will certainly need to lower the C5 amps.

 

[Debbie Lomax]

4.8kg seems about right for 70 cells.
A 50 cell 15ah one is about 3.65kg so adding another 20 cells and interconnectors will add 1kg ,my guess is that Samsung 35E cells are being used inside.
You will certainly need to lower the C5 amps.

Thankyou so much for all the advice , it is very much appreciated .

 

[Nealh]

Let us know how you get on with making the current changes.

 

[Debbie Lomax]

Will do .

 

[Deleted member 25121]

Debbie Lomax - you mentioned you'd replaced a fuse, was that in the battery pack or elsewhere?

 

[Debbie Lomax]

Debbie Lomax - you mentioned you'd replaced a fuse, was that in the battery pack or elsewhere?

In the battery pack .

 

[Deleted member 25121]

In the battery pack .

Ah, as I suspected, so the original battery was probably able to provide the 30A without the risk of blowing any fuses. That had been puzzling me.

As Nealh has said, the motor will feel gutless at 18a, partly because it's direct drive (no gears) and partly because it will be delivering less than half it's capacity when running off 18A rather than 30A.

Still, it's worth trying to reduce the current down to 18A and see what happens but don't hold out too much hope that the bike will feel good...

 

[wheeliepete]

It might be worth you considering refitting your old 250w hub motor, assuming it's a geared brushless one and it has the same connections as your present motor. It will run fine at 18/20 amps and will perform much better on hills than the DD you have. It should also increase your range by a fair amount.