2- 4 prong 'Silverfish' style battery - advice needed please

[kangooroo]

Last week my husband bought the Byocycle Boxer 24" folding mountain bike which was fitted with a 10Ah generic/Silverfish-style battery. Really he wanted the 15Ah but this was unavailable with no prospect of fresh stock in the foreseeable future, so instead he ordered a 15Ah battery from eBay before receiving delivery of the bike.

Now we have both bike and the battery: alas the bike has 4 prongs and the original battery has a flush, flat base. The 15Ah eBay battery delivered has a raised ridge around the base (which prevents it seating on the current bike fitting) and just 2 prongs but was also supplied with a 2-prong fitting and attached black/red cables.

The dilemma is what to do. It isn't economic to return the 15Ah battery via specialist lithium-battery courier but equally he doesn't want to sacrifice the original 10Ah supplied with the bike. The hope was that the two batteries would be interchangeable but clearly they are not due to the flat vs. ridged base and 4 vs. 2 prongs.

What would the experts here advise please?

My thought is to replace the 4-prongs on the bike with the 2-prong fitting but is this a straightforward job (husband is moderately ok with electrics but has no experience with eBikes)? What does it involve? Would there be any implications re the warranty by changing this on a new bike? This will mean potentially sacrificing the supplied 10Ah battery but range is important and 10Ah will be inadequate for his needs. He would then happily buy an additional 15Ah as a spare.

Are there any other issues to consider?

All advice and suggestions are much appreciated. Thanks.

 

[WheezyRider]

If you don't care about the warranty, unscrew the end plate from the 10Ah pack and see how many of the sockets are actually wired to anything. If it's just two wires, with a bit of soldering, you should be able to swap the bases over.

 

[vfr400]

Last week my husband bought the Byocycle Boxer 24" folding mountain bike which was fitted with a 10Ah generic/Silverfish-style battery. Really he wanted the 15Ah but this was unavailable with no prospect of fresh stock in the foreseeable future, so instead he ordered a 15Ah battery from eBay before receiving delivery of the bike.

Now we have both bike and the battery: alas the bike has 4 prongs and the original battery has a flush, flat base. The 15Ah eBay battery delivered has a raised ridge around the base (which prevents it seating on the current bike fitting) and just 2 prongs but was also supplied with a 2-prong fitting and attached black/red cables.

The dilemma is what to do. It isn't economic to return the 15Ah battery via specialist lithium-battery courier but equally he doesn't want to sacrifice the original 10Ah supplied with the bike. The hope was that the two batteries would be interchangeable but clearly they are not due to the flat vs. ridged base and 4 vs. 2 prongs.

What would the experts here advise please?

My thought is to replace the 4-prongs on the bike with the 2-prong fitting but is this a straightforward job (husband is moderately ok with electrics but has no experience with eBikes)? What does it involve? Would there be any implications re the warranty by changing this on a new bike? This will mean potentially sacrificing the supplied 10Ah battery but range is important and 10Ah will be inadequate for his needs. He would then happily buy an additional 15Ah as a spare.

Are there any other issues to consider?

All advice and suggestions are much appreciated. Thanks.

Please show photos of what you have: the whole batteries, the different bases and the viwe of the connectors on the bottom of the battery. I might be able to offer a solution if your husband can solder some wires.

 

[kangooroo]

If you don't care about the warranty, unscrew the end plate from the 10Ah pack and see how many of the sockets are actually wired to anything. If it's just two wires, with a bit of soldering, you should be able to swap the bases over.

We've had a look and I think we'll have a go at this if it's just a case of switching the prongs/bases and nothing more. Only two wires are connected via spade connectors and it looks straightforward. Thanks.

 

[WheezyRider]

We've had a look and I think we'll have a go at this if it's just a case of switching the prongs/bases and nothing more. Only two wires are connected via spade connectors and it looks straightforward. Thanks.

Before you do, it would be a good idea to post some pictures here as vfr said just so all the details can be confirmed

 

[kangooroo]

Yes, I will post pics tomorrow.

Thanks.

 

[Deleted member 33385]

I'm looking forward to seeing how this works out! There's no standardisation - it'd be great if there were adaptor plates, so that you could travel along and swap batteries with different prong arrangements as needed.

 

[Nealh]

New silverfish come with a new fitting plate/locking holder/bar. Always confirm any new plate/connectors are connected with correct polarity order other wise you will get an almighty fright and maybe damage.

 

[kangooroo]

Here are the pics of the 10Ah battery supplied with the Byocycle Boxer, the bike's fitted 4-prong plate and the new 15Ah battery bought on eBay. I've also added the original battery from my Oxygen bike (this has 4 connections on the base but the bike has only 2 prongs).

I'm guessing the 10Ah will become surplus but it would be great if the others could be interchangeable if it's simply a matter of replacing the 4 prongs (has 2 wires) with the 2-prongs supplied with the new eBay battery.

All are labelled and any observations appreciated. Thanks.

 

[vfr400]

The number of prongs is not important. They normally only wire the outer two anyway, and if they do use all 4, the wires go two into one, so you still end up with only two wires. What's important is that they're the same way round. Never trust the markings. always test with a meter.

Regarding the flatness of the base, can't you just grind off the two ribs to make it flat?

 

[kangooroo]

This is going to be our job for the weekend. We're completely new to eBike electrics and if grinding ribs help a battery fit, then that's what we'll do. It would be great to have batteries interchangeable between 3 eBikes.

 

[Deleted member 33385]

To maintain resale value - I'd be tempted to cut the cables between the batteries and motors and solder on common XT60 connectors, after establishing polarity. But you'd have to fashion a mounting plate, to attach the different batteries with battery prong connectors attached, onto the mounting bracket you've made, onto the frame.

 

[kangooroo]

A good idea to help maintain flexibility. Comment forwarded to grateful husband. Thanks.

 

[kangooroo]

Just to update this thread... The plan was to swap over the prongs at the weekend and replace the fitted 4 prongs with the 2-prong supplied with the new replacement 15Ah battery. Alas, the slot on the bike is too small for the 2-prong fitting. We'll look for a slimmer version if there is one but feel it would be an unwise move to start cutting the bike, particularly as it is new and under warranty.

 

[WheezyRider]

Just to update this thread... The plan was to swap over the prongs at the weekend and replace the fitted 4 prongs with the 2-prong supplied with the new replacement 15Ah battery. Alas, the slot on the bike is too small for the 2-prong fitting. We'll look for a slimmer version if there is one but feel it would be an unwise move to start cutting the bike, particularly as it is new and under warranty.

Can you unscrew the bases from the batteries and swap the battery bases over? That is likely to just need the soldering of two wires.

 

[kangooroo]

We removed the screw-on battery bases but beneath them, the small rectangular slot through which the prong connection fits, is far too narrow. The 4-prong unit is about half the thickness of the 2-prong fitting so doesn't fit through the framing on the actual bike. The job was going well until this point, new connection soldered, reversed polarity corrected...
(There might be a smaller 2-prong unit available - so will look.)

 

[WheezyRider]

We removed the screw-on battery bases but beneath them, the small rectangular slot through which the prong connection fits, is far too narrow. The 4-prong unit is about half the thickness of the 2-prong fitting so doesn't fit through the framing on the actual bike. The job was going well until this point, new connection soldered, reversed polarity corrected...
(There might be a smaller 2-prong unit available - so will look.)

But could you not swap over the battery bottom ends complete with prong fitting?

So if I understand it right, the 10 Ah battery fits the base on the bike, but the 15Ah doesn't. So I would remove the bottom completely from the 10Ah battery pack (undo the 4 screws), along with its connectors, cut the two wires to the battery inside. Then remove the bottom entirely from the 15Ah pack and cut the two wires to the battery inside. Then solder the 15Ah battery wires to the correct wires of the bottom from the 10Ah pack. Insulate the joints and screw it back together. Then the modded battery should slot into the base you have on your bike.

As someone else said, you may even want to at some stage get rid of the spade connections all together and use XT60 or even XT90 connectors.

 

[WheezyRider]

This thread may be of interest to you too:

Yose Power Failure!

The other day I was on my bike and there was a terrible smell of burning, then the bike cut out completely. After peddling the last 5 miles home without assist (phew, hard work for me these days!) I found the Yose Power battery pack had died. The main 20 A fuse was ok, so I opened up the pack...

www.pedelecs.co.uk

I've gone off silverfish style batteries, as the metal shell is 450g and all the unnecessary gubbins that comes with it is another 550g. So in total an extra kg to lug around. Also, the key switches are not really up to the job of handling large currents and the wiring inside is far longer than it needs to be and the gauge of wire is quite small.

If you have a local maker space you can go to, you could 3D print a new base, case & fittings of your own design...once lockdown ends...

 

[Deleted member 33385]

Maybe you could mount the 15A battery on the pannier, after installing a pannier? I'm not quite sure how you'd be able to secure it sufficiently... perhaps some sort of box to slide the battery into? You might need a lower rear mudguard than the one in the photo, to make room for a pannier. No warranty voided.

 

[kangooroo]

@WheezyRider That's an idea! We hadn't thought of swapping battery bases around.

This could be a possibility for the future. At the moment, we don't want to 'mess' further esp as bike electrics are new territory. Also, both the bike and battery are new, delivered just 2 weeks ago, and both have warranties we don't want to invalidate.

We've learned a valuable lesson that the seemingly-generic batteries aren't quite as generic or interchangeable as first thought and it seems to be pure luck that those I've bought cheaply on eBay have fitted all of the bikes I've used.

Before making any further modifications, we've concluded it is probably better to wait a year(ish) before making any obvious adaptations just incase there is a warranty issue. This is based on earlier experience where I had 2 bikes which needed to be returned due to electrical issues - without any battery changing I hasten to add!

A future option could be a modification of a slightly oversized pannier rack already fitted, intended for 26-29" wheels whereas the bike's wheels are 24". Both this and a chunky mudguard have already been modified to fit.


In the meantime, I will be using the eBay Silverfish battery on my Oxygen bike because it is more economic than returning it at huuuge expense. I didn't really want a 4th battery but it could be useful for hilly socially-isolated rides if Covid continues through the summer. I note your (@WheezyRider ) observation re the Silverfish case weight but as I'm only 52kg myself, weight really isn't an issue and there's plenty unused payload on my bikes!

Thanks to all for your suggestions.