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.