Increase Lipo battery fuse amps?

[jbs]

I have a 10Ah lipo battery with a 13A controller and what I believe is probably an MXUS 250w 36v hub motor, although it doesn't say MXUS anywhere I can see. The bike has a throttle as well as a pedal sensor.

Although at the cheaper end of things, in general I'm happy with the range and weight.

To help with a few long inclines on my 16 mile commute, I have been looking at options to slightly increase the power, and rather than buy new parts opted initially to increase the controller amps by soldering the shunt. Probably around 25% is soldered which was what I was aiming for.

All was good for a few days casual riding and power does indeed seem greater but yesterday using just throttle power (no pedalling) going slowly up a steep gravel drive the bike died. I have a spare battery which still works ok, and eventually traced the problem to a blown built in blade fuse in the battery itself, its on the main negative wire between the end battery terminal and the small circuit board (bms?) that is also in the battery pack.

My question for any technical expert is would it be safe to change the 15 amp fuse for something a bit larger such as 20 amp, or given the battery is lipo might that be asking for trouble / melting / fire?

Thanks!

 

[Deleted member 4366]

No problem. By lipo, I assume you mean lithium-ion, which will have a management system (BMS) to protect the cell-pack. 20A fuse should be OK. The management system will probably be around 20A, so you might get the odd cut-out, depending on how high you went on the controller, but it should cut back in by itself. There's another shunt in the BMS that you can add a bit of solder to to prevent that, but you mustn't go too high because it's there to protect the cells. If it didn't already cut-out before the fuse went, you should be OK with the BMS.

 

[jbs]

Thanks for the reply, I thought the battery might actually be lipo not lithium-ion, but I dont know for sure. It seems to be made up of 5 rectangular black pouch things, all wrapped in much shrink wrap plastic. Could that be lithium ion?

There are no circular batteries to be seen but there are two circuit boards joined together in the battery case.

Would it matter if it was lipo and I increased the fuse to 20A?

I can get a picture if it helps and would make a difference to your answer

 

[jbs]

I've taken the other battery pack apart and this one already has a 20 amp fuse where the first one had 15amp, otherwise it looks the same so I assume 20 is fine, Thanks for the feedback

 

[anotherkiwi]

Thanks for the reply, I thought the battery might actually be lipo not lithium-ion, but I dont know for sure. It seems to be made up of 5 rectangular black pouch things, all wrapped in much shrink wrap plastic. Could that be lithium ion?

There are no circular batteries to be seen but there are two circuit boards joined together in the battery case.

Would it matter if it was lipo and I increased the fuse to 20A?

I can get a picture if it helps and would make a difference to your answer

http://batteryuniversity.com/learn/archive/pouch_cell_small_but_not_trouble_free

http://www.epectec.com/batteries/prismatic-pouch-packs.html

 

[Deleted member 4366]

It's a normal Li-ion battery with 10 x 3.6v pouch cells (they must be in pairs) to make 36v. You won't see lipo in an OEM ebike battery, though sometimes it's written on the case.

All these things don't mean much. they're just names that people get mixed up with to say what's in the cells. In ebike speak, we use lipos to refer to the very volatile, high discharge rate pouch cells that the radio control guys use in their planes/helicopters. They're light and powerful, so made good home-built ebike batteries, but now there's better alternatives, so they've nearly died out in ebikes. That leaves two more main categories: Lithium iron phosphate (LiFePO4), which are heavy and last a long time; Li-ion, which is everything else.

Technically, they're all Li-ion batteries, but we differentiate them into LiFePO4, lipos and li-ion batteries rightly or wrongly.

I have a couple of lithium titanate ebike batteries. I'm not sure where they fit in! Anybody want them?