Replacement battery for Christiania

[Graemetherunner]

I have a Christiania cargo bike that has a failed battery. I’ve tested the rest and all seems to work well.
The system is a stock promovec and the cost of the 36v 17ah battery in the uk is £900

I’ve found numerous 36v batteries with claimed 30ah capacity for significantly less example below - https://www.amazon.co.uk/Lithium-Battery-batteria-elettrico-Waterproof/dp/B0DPX7QHVV?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A3JKNFUM6F3TSZ&gQT=1

Is something like this a really bad idea. The original rack mounted battery uses a crude 2 prong connection (looks like it’s the prongs from a g-plug).

any thoughts?

 

[saneagle]

I have a Christiania cargo bike that has a failed battery. I’ve tested the rest and all seems to work well.
The system is a stock promovec and the cost of the 36v 17ah battery in the uk is £900

I’ve found numerous 36v batteries with claimed 30ah capacity for significantly less example below - https://www.amazon.co.uk/Lithium-Battery-batteria-elettrico-Waterproof/dp/B0DPX7QHVV?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A3JKNFUM6F3TSZ&gQT=1

Is something like this a really bad idea. The original rack mounted battery uses a crude 2 prong connection (looks like it’s the prongs from a g-plug).

any thoughts?

If the battery has only two wires, you can use any 36v battery you like, or you can get a 48v controller set and a 48v battery to give more power if you want it. Yose and Greenlance are good suppliers of cheap batteries. We have a 10% discount code for Greenlance. I think it's PEDELECS10.
E-Bike Batteries – YOSE POWER UK
36V Electric Bike Batteries | Greenlance Limited

 

[Graemetherunner]

Thanks for the reply. I did look at those links, neither offer a naked solution so I would end up removing it from its casing to then fit or having to buy other bits to get the battery to fit the bike.

anyone any experience with batteries off amazon / aliexpress etc etc

 

[thelarkbox]

Be ultra sceptical when purchasing battery packs, they are high value easy to fake/fill with sand packages, at risk at numerous points in the supply and manufacture/fabrication chain.

The 'premium' price charged by local importers who assume all the risks is worth every penny imho, of course get the best deal, but dont take a punt..

If yours is like the Christiania bikes google showed me, it looks like a few places to mount a bolt on generic hailong style battery pack, so no need to get all hackaday and deny yourself warranty protection

 

[saneagle]

Thanks for the reply. I did look at those links, neither offer a naked solution so I would end up removing it from its casing to then fit or having to buy other bits to get the battery to fit the bike.

anyone any experience with batteries off amazon / aliexpress etc etc

Why are you making things difficult for yourself? You don't have to squeeze anything into your existing battery case. Chuck the battery and the rack. Fit a normal rack and bolt the Greenlance battery carrier to it. Yose even sell a 17Ah rack battery that should bolt straight on for £265, though sometimes you need to do a bit of jiggery pokery to space it out past the disk caliper.
36V13Ah/15.6Ah/17.4Ah E-Bike Lithium-ion Rear Battery fit for 26"-28" – YOSE POWER UK

You have a massive box to hold any battery. Why not bolt a Hailong type to the back face of the box down low, where it'll give you a more central mass for better handling?

The battery you linked is completely fake. It's 10S2P, so 6Ah at most, not 30Ah. If you run a 2P battery at any sort of useful power, it'll be very stressed, won't last long and will probably catch fire anyway due to overheating.

 

[EthaneFerguson]

I have a Christiania cargo bike that has a failed battery. I’ve tested the rest and all seems to work well.
The system is a stock promovec and the cost of the 36v 17ah battery in the uk is £900

I’ve found numerous 36v batteries with claimed 30ah capacity for significantly less example below - https://www.amazon.co.uk/Lithium-Battery-batteria-elettrico-Waterproof/dp/B0DPX7QHVV?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&psc=1&smid=A3JKNFUM6F3TSZ&gQT=1

Is something like this a really bad idea. The original rack mounted battery uses a crude 2 prong connection (looks like it’s the prongs from a g-plug).

any thoughts?

That Amazon battery might technically work, but it’s a bit of a gamble — the claimed 30Ah capacity is probably inflated, and the BMS quality could be questionable. If you go that route, make sure the voltage matches (36V nominal), and be really careful about wiring — especially with that crude 2-prong setup, which isn’t ideal for higher current draw. Honestly, it could work fine for casual use, but don't expect the same reliability or safety as the OEM battery.

 

[EthaneFerguson]

Why are you making things difficult for yourself? You don't have to squeeze anything into your existing battery case. Chuck the battery and the rack. Fit a normal rack and bolt the Greenlance battery carrier to it. Yose even sell a 17Ah rack battery that should bolt straight on for £265, though sometimes you need to do a bit of jiggery pokery to space it out past the disk caliper.
36V13Ah/15.6Ah/17.4Ah E-Bike Lithium-ion Rear Battery fit for 26"-28" – YOSE POWER UK

You have a massive box to hold any battery. Why not bolt a Hailong type to the back face of the box down low, where it'll give you a more central mass for better handling?
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The battery you linked is completely fake. It's 10S2P, so 6Ah at most, not 30Ah. If you run a 2P battery at any sort of useful power, it'll be very stressed, won't last long and will probably catch fire anyway due to overheating.

Totally agree—no point wrestling with a cramped battery case when there are better mounting options. A proper rack setup with a legit battery like the Yose Power one makes way more sense and saves a ton of hassle.

 

[Graemetherunner]

Why are you making things difficult for yourself? You don't have to squeeze anything into your existing battery case. Chuck the battery and the rack. Fit a normal rack and bolt the Greenlance battery carrier to it. Yose even sell a 17Ah rack battery that should bolt straight on for £265, though sometimes you need to do a bit of jiggery pokery to space it out past the disk caliper.
36V13Ah/15.6Ah/17.4Ah E-Bike Lithium-ion Rear Battery fit for 26"-28" – YOSE POWER UK

You have a massive box to hold any battery. Why not bolt a Hailong type to the back face of the box down low, where it'll give you a more central mass for better handling?

The battery you linked is completely fake. It's 10S2P, so 6Ah at most, not 30Ah. If you run a 2P battery at any sort of useful power, it'll be very stressed, won't last long and will probably catch fire anyway due to overheating.

Thanks for reply. Are you 100% confident your simple solution will work / familiar with promovec?

whilst there are only 2 battery contacts, there are several connectors that come in to the battery mount (cadence, lcd screen, speed control twist grip) if I remove the rack then I loose all those.

yes I have space if I mound the battery there I need to run the cable forward to the pivot point (steering) then back to the exiting battery connection approx 2.4m cable run.

This is why I would like to keep it simple and buy a naked battery and connect to the existing connections.

Thanks for the heads up on the fake battery.

 

[saneagle]

Thanks for reply. Are you 100% confident your simple solution will work / familiar with promovec?

whilst there are only 2 battery contacts, there are several connectors that come in to the battery mount (cadence, lcd screen, speed control twist grip) if I remove the rack then I loose all those.

yes I have space if I mound the battery there I need to run the cable forward to the pivot point (steering) then back to the exiting battery connection approx 2.4m cable run.

This is why I would like to keep it simple and buy a naked battery and connect to the existing connections.

Thanks for the heads up on the fake battery.

the wires you mention are for the controller, which sits in a compartment at the front of the battery mount. Functionally, it's independent from the battery. You can mount it in a tool-bag hung from underneath the seat if you want to use another type of battery mounted elsewhere, or you can buy a battery with an included rack that also has the compartment, then you can stick the controller in the new compartment. finally, you can keep the existing rack and controller where they are, sling the battery and get a new one that you can mount wherever you want and however you want, and run the two wires to the compartment where the controller is sitting. In that case disconnect the controller from the connector between the compartment and the battery so that the pins aren't live.

It's generally a good idea to have the controller close to the battery so that the battery wires are not too long. If you mounted your battery on the back of your cargo box, you could get a plastic box and screw it nearby to put the controller in. You could even use one of those plastic boxes with a snap-on lid that you get your Chine takeaway in to save one from landfill.