Fitting bigger capacity battery to a Swytch gen2 kit

[halfpenny]

This is what I did to deal with a failing battery. I am 71 and happy with the Swytch kit, which used to give me over 25 miles assistance at level 1, but lately not reliable above 20 miles. The Swytch battery is 36v,5Ah capacity. I bought a Yose36v, 13Ah for frame fitting. The Swytch battery and motor controller is removed from the bag, and the battery unplugged by pulling out the yellow connector. I kept the bag in place for tool storage. The motor controller went back into the bag, and a stiff insert in the bag lid to support the control pad. Red and black wires were attached to the corresponding wires from the motor controller, and passed through a hole in the bottom of the bag - I used a choc block electrical connector for convenience, and you will need 500mm of wire at least of the gauge coming from the new battery. I found the Yose battery frame did not fit where I wanted it, so I fitted 3 additional 5mm rivnuts in the cycle frame to suit, leaving clearance for the battery to be removed ( I wanted to keep a bottlecage on the seat tube). Then I fitted automotive crimp connectors to the free wire ends - these mate with the Yose output connectors That's it. The weight penalty is about 1 Kg.
The Swytch motor controller doesn't know the battery has a larger capacity, and works as before. Now, at the end of a 25 mile ride the Swytch pad still shows 4 bars capacity (out of 5), so I have a huge reserve which will help as the new battery inevitably degrades over time. I doubt I shall need more than 35 miles range. More usefully, the old battery would give progressively less assistance as it reached end of range, whereas the replacement does not behave this way because capacity is so much greater.
A very successful adaptation in my opinion , and good value for my needs.

 

[saneagle]

This is what I did to deal with a failing battery. I am 71 and happy with the Swytch kit, which used to give me over 25 miles assistance at level 1, but lately not reliable above 20 miles. The Swytch battery is 36v,5Ah capacity. I bought a Yose36v, 13Ah for frame fitting. The Swytch battery and motor controller is removed from the bag, and the battery unplugged by pulling out the yellow connector. I kept the bag in place for tool storage. The motor controller went back into the bag, and a stiff insert in the bag lid to support the control pad. Red and black wires were attached to the corresponding wires from the motor controller, and passed through a hole in the bottom of the bag - I used a choc block electrical connector for convenience, and you will need 500mm of wire at least of the gauge coming from the new battery. I found the Yose battery frame did not fit where I wanted it, so I fitted 3 additional 5mm rivnuts in the cycle frame to suit, leaving clearance for the battery to be removed ( I wanted to keep a bottlecage on the seat tube). Then I fitted automotive crimp connectors to the free wire ends - these mate with the Yose output connectors That's it. The weight penalty is about 1 Kg.
The Swytch motor controller doesn't know the battery has a larger capacity, and works as before. Now, at the end of a 25 mile ride the Swytch pad still shows 4 bars capacity (out of 5), so I have a huge reserve which will help as the new battery inevitably degrades over time. I doubt I shall need more than 35 miles range. More usefully, the old battery would give progressively less assistance as it reached end of range, whereas the replacement does not behave this way because capacity is so much greater.
A very successful adaptation in my opinion , and good value for my needs.

A good result; however, you shouldn't use chocolate box connectors anywhere on an ebike, least of all on any wires carrying 36v, and even worse on anything carrying high current. It'll be fine at first, so you trust it, but bare copper oxidises continuously in air until there's a compromised connection, which will cause the bike to stop working if you're lucky, otherwise it'll heat up and cause a fire due to the relatively large current. You can make it better by soldering the wires before you put them in the connector, but if you're going to do that, you might as well solder the wires together and have a lot more reliable and less lossy connection.

 

[halfpenny]

Actually I used bootlace terminal ends in the choc blocks, but will likely switch to automotive bullet connectors to match the battery. Choc blocks are of course fine for 240v, 13A in an appropriate setting.

 

[saneagle]

Actually I used bootlace terminal ends in the choc blocks, but will likely switch to automotive bullet connectors to match the battery. Choc blocks are of course fine for 240v, 13A in an appropriate setting.

Don't waste time with connectors. You don't need them because the battery is removeable using its own connection system. It's quicker, less work, cheaper, more reliable and more efficient (contact resistance) to solder the wires to each other.

Chocolate box connectors might be OK for a 1 amp table lamp, but they have no place on an ebike.

We've seen bullet connectors overheat and burn the pvc wires many times. If a battery has short tails and those bullets, like you get on many of the downtube battery holders, you should cut them off immediately. It's best not to have any connectors on the battery wires, but if you must, only use them at the controller end and only if it's away from the battery.

The same applies to bullet connectors on the motor wires: Don't let them anywhere near a battery.

 

[halfpenny]

Good advice I'm sure. Swytch use plug connectors as standard, as do high current automotive installations; I'm happy that my installation and standard of work is safe, bearing in mind the low current my motor draws and the waterproof enclosure. Poorly made connections carrying a high current may of course fail catastrophically.
As I said, this is what I did - you may do differently.

 

[saneagle]

Good advice I'm sure. Swytch use plug connectors as standard, as do high current automotive installations; I'm happy that my installation and standard of work is safe, bearing in mind the low current my motor draws and the waterproof enclosure. Poorly made connections carrying a high current may of course fail catastrophically.
As I said, this is what I did - you may do differently.

I don't think you understand the failure mode. When you wiggle the bullets in, it can stretch the barrels to the extent that they're making contact but there's no holding pressure. The plastic sleeve is tight around them, so you get the impression that they're in tight. When you demand high power, like when you go up any steep hill, the contact resistance heats them up to the point that the plastic shroud melts, then the metal parts touch and you get catastrophic failure, like thermal runaway in the battery if it's the battery wires or blown MOSFETs in the controller if it's the motor wires, and once any MOSFET blows, there's a direct short from the battery to the motor coils, which can burn them or cause wires to burn and more consequential damage.

As I have said, we've seen the burnt connectors and wires very many times, but, thankfully, in those cases, there wasn't much consequential damage, but logic says that if the consequence was that the whole bike caught fire, we'd only see it in the 47 pages of the thread below without knowing the cause, not some guy showing his burnt wires. You can start on page 4.

Battery Fires

This might help with understanding. His summary seems to be that it's individual cell quality that leads to fires, though I only skipped through it so far:

www.pedelecs.co.uk

 

[halfpenny]

May I suggest you post a guide to your best practice on upgrading a battery and, if you have the knowledge, particularly for a gen 2 Swytch. Better this than a keyboard warrior wandering off into areas not relevant to my post. By the way , the Yose battery has a fused output, and I chose it for this reason.

I am fully aware of the dangers of loose bullet connectors, but this type is used on hundreds of millions of cars in high current applications ( which Swytch gen2 is not), and completely safe if correctly fitted. A choc block is, by it's nature, mechanically secure and the fixing identical to hundreds of millions of 13A domestic plugs - undoubtedly completely safe if correctly fitted and, in my case, in a waterproof casing.

Perhaps you would add a primer on general electrical safety, fire fighting, e-bike maintenance and other distantly related topics. Good luck with that!

 

[saneagle]

May I suggest you post a guide to your best practice on upgrading a battery and, if you have the knowledge, particularly for a gen 2 Swytch. Better this than a keyboard warrior wandering off into areas not relevant to my post. By the way , the Yose battery has a fused output, and I chose it for this reason.

I am fully aware of the dangers of loose bullet connectors, but this type is used on hundreds of millions of cars in high current applications ( which Swytch gen2 is not), and completely safe if correctly fitted. A choc block is, by it's nature, mechanically secure and the fixing identical to hundreds of millions of 13A domestic plugs - undoubtedly completely safe if correctly fitted and, in my case, in a waterproof casing.

Perhaps you would add a primer on general electrical safety, fire fighting, e-bike maintenance and other distantly related topics. Good luck with that!

I already gave you best practice. I'll add a couple of others:

• Avoid using any connector anywhere if you can
• Don't use bullet connectors
• Don't use chocolate box connectors
• Use the correct wire gauge considering the max current it must carry, and use silicone wire for batteries.
• Do not allow any movement in battery wires. They must be properly tied down everywhere. Bear this in mind with bag batteries, which should generally be avoided.

 

[chris_n]

May I suggest you post a guide to your best practice on upgrading a battery and, if you have the knowledge, particularly for a gen 2 Swytch. Better this than a keyboard warrior wandering off into areas not relevant to my post. By the way , the Yose battery has a fused output, and I chose it for this reason.

I am fully aware of the dangers of loose bullet connectors, but this type is used on hundreds of millions of cars in high current applications ( which Swytch gen2 is not), and completely safe if correctly fitted. A choc block is, by it's nature, mechanically secure and the fixing identical to hundreds of millions of 13A domestic plugs - undoubtedly completely safe if correctly fitted and, in my case, in a waterproof casing.

Perhaps you would add a primer on general electrical safety, fire fighting, e-bike maintenance and other distantly related topics. Good luck with that!

Wow!

 

[halfpenny]

You are repeating yourself saneagle, to no good effect. Now, put up a general post on this topic, with your qualifications, experience and referenced authorities.

A few days ago, I sought assistance on this matter in a separate post. A few contributed, and all were useful (and appreciated) except your contribution. I get the impression that you like to comment on posts by others, but are instantly reactive to push back. Absolutism, as in your list, is never appropriate - we should adopt solutions appropriate to the circumstances, which is why my post was specific to gen2 Swytch.

I must say I found this forum very enlightening, but unfortunately populated by the usual know all. If you have nothing useful to say on a Swytch gen2 conversion, please say nothing!

 

[saneagle]

Wow!

It's not his fault. He hasn't seen these every month like we do:

Help! - Melted Motor Wires

Unfortunately I dropped my ebike when accelerating, broke the throttle and appeared to have burnt the motor wire connectors. Not sure if it happened at same time or if the factory motor wire connectors had been slowly melting, which is what it looks like to me. I've ordered some MT60 3 pin...

www.pedelecs.co.uk

Xf001 Bezior phase wires burning out.

Hello all new on the forums but seeking advice. I purchased a xf001 bezior 5months ago and had to get a replacement controller sent after it blew, two days ago my bike came to a juddering stop and after investigating I found the phase wires were completely melted at the connecting points. I've...

www.pedelecs.co.uk

SORTED

Had the bike in a nice warm kitchen today. Worked fine on both batteries until........Sprayed the little conection box with WD40 to clear out any condensation from the very cold bike shed (-3C this morning) I hear a little sizzle and small sparking from the -ve lead from the battery. Back to...

www.pedelecs.co.uk

What happens when you overload phase wires?

Trying to diagnose. Rode up a 17 degree hill. Smelled melted plastic slightly. Rode home another mile up a 7 degree hill. Entering my garage a small zap occurred at the controller area. Lifting rear wheel off the ground and twisting throttle, the tire would judder forward 30 degrees and stop...

www.pedelecs.co.uk

Here's my qualifications if he needs them for some reason:
BSc in Mechanical engineering from Glasgow Uni
MSc in Teaching electronics from Roehampton Uni
2 years as an ebike mechanic in a large ebike shop
Bosch certified ebike mechanic
15 years on this forum with more than 50,000 posts about ebike problems.
15 years on Endless Sphere with nearly 6,000 posts.

 

[halfpenny]

You have not addressed my references to automotive and domestic electrical systems. I cannot comment on poor design or failures of other e-bike installations, but those instances of failure do not justify your prohibition on the use of certain connectors. I hope you have advised the relevant standards authorities. I consider the Swytch kit a good design and well made, if somewhat limited in range and power.
Best practice is another thing, and you should couch your advice (if you must) in those terms. Again I invite you to post something specific in a separate thread, which would be both useful and searchable. Your prolific posting record rather makes my point.
For the record I am a time served C.Eng. with a lifetime in practical engineering. It is often said that those that can, do; those that cannot do, teach.

 

[saneagle]

You have not addressed my references to automotive and domestic electrical systems.

This is an ebike forum.

 

[saneagle]

It is often said that those that can, do; those that cannot do, teach.

I teach here, but some are incapable of learning. That doesn't stop us from giving everyone an equal chance, though, and we generally persevere with those that struggle because some are just a bit slow to get it. The worst are those that think they know better or those that ask questions and they think they already know the answer. When you've been on forums like this for 15 years, you see all types. We're used to it - just treat them like anybody else unless they become rude.

 

[saneagle]

or the record I am a time served C.Eng. with a lifetime in practical engineering.

I also have many qualifications in the field of quality assurance, industrial engineering, production engineering, sailing and model plane flying, just to mention a few of them, but like yours, completely irrelevant to this matter.

Normally, I don't mention these things, but you specifically asked for them.

 

[halfpenny]

Well, you make a forum contribution which was intended to be helpful to others - and it becomes a cesspit of obfuscation and diversion, rather than a useful addition to the subject title.
Saneagle says my use of certain connectors is absolutely wrong, disregarding my reasoned response. Not his opinion, but his fact. I'm content for those enjoying this thread to make their own judgement, though I now see he may know about flying kites.
I have not said that I know better - it is saneagle who says that he knows best, yet fails to provide an answer to my reasoned reply, repeated here:
1. What is wrong with a correctly installed crimp connector (Japanese style bullet)?
2. What is wrong with a correctly installed choc block ( in a waterproof housing)?
The answer, as he knows, is nothing - though either may fail in some circumstance, both types are sufficiently reliable to be used by the hundreds of million, and are all around us.
He will also know that a crimp connector is considered much more reliable than soldering, and I'm surprised to see that method suggested.

Saneagle's personal preference is just that, and no reason for his unreasoned rant.

He must have education materials at hand, so why not post in a separate thread his recommendations for fitting an uprated battery? This would be a genuinely useful contribution, which I should have been pleased to find when I first searched the forum

 

[Cadence]

I came to this forum looking for advice about ebike conversions. I had a lifetime in practical engineering. As I got involved in electrics I joined the Institute of Electrical Engineers and passed a PAT testing course, so I know my volts from my watts and my amps. How is this relevant to electric bikes? Not very! I have occasionally sought help and saneagle, among others, has always been prompt with his replies- some of which I was dubious about but I have since realised he was right. Rim brakes are marginally inadequate and hydraulic discs are much better. Don't buy a bike with proprietary electric components. 48v. gives more torque and speed than 36v. KT controllers give by far the best control options and riding experience - and much, much more.
If I had listened and acted on his recommendations I could have saved myself a lot of time and money. The advice on this forum is free and you don't have to take it. Nobody is right every time. But experience is worth it's weight in gold. Saneagle has bucket loads of it!

 

[chris_n]

Domestic electrical systems don't move or vibrate so strain relief is not required in the same way that it is with a vehicle. Choc blocks are a bodge at the best of times, these days you would very rearly find a sparky using them in anything other than a light fitting. You would never find a decent system designer specifying then for anything other than a potential final consumer connection such as the aforementioned lights. Some of the shortcomings are mitigated to a degree with a correctly sized and crimped ferrule. There is still a small area that is under a significant crushing force that with time and vibration will lead to fatigue. Wago or similar spring loaded connectors are much superior but don't have stress relief so are unsitable for applications with vibrations. You can of course put both types of connector in a box or pot them to provide stress relief.
As for Automotive no manufacturers use standard aftermarket type bullet connectors for anything let alone high current connectors. Aftermarket bullet connectors have many of the same shortcomings as choc blocks i.e. no significant stress relief and usually a small crimped area with a significant amount of stress. Crimped connectors certainly can be better than soldering under certain conditions that are highly unlikely to be available to the average DIYer.
Anything that uses something resembling a typical bullet is fitted into a moulded plug/socket which will provide stress relief and waterproofing in one go. When the connectors are made they are crimped with calibrated machinery before being moulded. If they are for a safety critical part, the parameters from every crimping operation are stored in a database either as a batch or in many instances as an individual component.
Yes I have worked in electrical system design and spent many years in the engineering department of a first tier automotive supplier.

 

[saneagle]

He must have education materials at hand, so why not post in a separate thread his recommendations for fitting an uprated battery? This would be a genuinely useful contribution, which I should have been pleased to find when I first searched the forum

All the education materials on the things you mentioned can be found on this forum with a simple Google search. Everything I post comes from my head, apart from a load of photos I have of the things I've done, which are on a hard disc somewhere, if I can find it. Normally, I do a Google search to find similar photos, which is quicker than finding my had disc and booting up a PC to read it.

 

[saneagle]

Yes I have worked in electrical system design and spent many years in the engineering department of a first tier automotive supplier.

I used to come and check on guys like you to make sure you were doing your job properly. I was a first tier Quality Manager for 20 years. Maybe we met!