gtd2000

Would something like this actually work? https://www.ebay.co.uk/itm/Li-ion-lithium-Battery-Charger-for-electric-bicycle-e-bike-36V-42v-VOLT-XLR-plug-/264387055133?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=710-127635-2958-0

Thank you both for the replies. It sounds like I'll need to do a bit of research but looking on eBay etc., it appears that the Giant chargers are around £120+...!!!! I'll have a look at my existing charger for the 36v lead acid battery pack and see what kind of voltage that outputs.

I was dropping off a trailer load at the local recycling centre last week and a woman was about to toss an Energy Pak Battery (Giant) into one of the containers. I said I could possibly repurpose the battery and I'd take it if she didn't mind. Was thinking of using it on my old school lead acid powered bike. She explained that it wouldn't charge but I thought that the worst case scenario would be harvesting any usable cells in the pack. After a cursory look at the Energy Pak it looks like a few of the connections were somewhat furred up with corrosion, presumably from being stored in damp conditions or water ingress. Is there any cheap and cheerful way to attempt charging this battery without the official unit? One of my pals thought the BMS might be in the charger, rather than the battery pack? Any ideas?

NMDP

When you have something like this old bike, with no known spec or details etc...it's obviously setup to use 36v but what would occur if say 48v was used instead? Would it simply blow the controller or burn out the hub motor?

I watched a few videos on YouTube where they tested a variety of 18650 batteries and most were only a fraction of their rated capacity. I'd suspect something like this type of battery may very well be made from the same low grade cells? Also read about the dubious practice of putting new wrappers on old mobile phone batteries and selling them as new...

Does this seem too good to be true? US $71.71 39%OFF | 36V 20AH 10S4P electric bicycle battery pack 18650 lithium ion battery 500W high power 42V motorcycle scooter https://s.click.aliexpress.com/e/BRpaBpPiL

This bike was really just a project to see if I could get it back up and running. I knew the square root of nothing but at least now I know that somebody telling the battery is perfect isn't something to be taken at face value I'm perhaps thinking of selling this one and using the money to get a kit to put on my older Raleigh MTB. Then again, this one would be fine for occasional use. Decisions, decisions...

The price of the first one is attractive, as it would be a bit more than double the price of replacing the lead acid batteries.

Sorry didn't notice your earlier reply. I don't know the full history of the bike but I'm led to believe it was kept on the back of either a camper or a caravan. It doesn't look like it was actually used very much, tyres look original and are very much unworn. The grips still had plastic wrapping on them but I removed that. I'm pretty sure that blob on the red wire was shorting on the controller (as you suggested), there was also only about 4 strands of wire making a connection with the terminal. Didn't take much to remove it and it's now connected on the inside of the post, similar to the black wire. I can't see any evidence of leaks from the batteries but I've no idea if they are the original fitment? I'm not sure which purple wire connector you are referring to?

On another note, here's the batteries that I was using. Now that the problem has been resolved, it's time to think about upgrading the current power source. Should I just buy three new NP12-12's and save a lot of hassle and effort or should I switch to another solution. I've got some 18650 batteries on the way that could be used for a variety of things but is it worth trying to make a homebrew battery for this sort of ebike? I still don't actually know what the make and model of the bike is, or the specs.

Well, glad to report back with success! I firstly re-soldered the discharge positive connector cable...and put some insulating tape around the terminals, more on that later... Put in a fresh fuse and used 2 x 12-12's and 1 x Yuasa battery. Now all taped up and re-installed back into the frame, I think we can see what the problem was... From my point of view, I think the controller was touching the exposed wiring of the discharge connector positive terminal. Put it all back together and no pop of the fuse and the motor turns freely again. Here's the battery box connector details - any idea what the name of this discharge connector type is?

Start of the strip down, discharge connector soldering looks pretty suspect... Live terminal is only hanging on with a few strands of cable. I'm absolutely crap at soldering but I'll give it a shot!

I've done a start to tearing down the bike end of the connection. Here's the wiring that comes from the hub motor. Which two wires do you think will be the ones?

It was working fine on Monday. Just tried to give the old batteries a final "revive" before deciding on buying new replacements. Then the problem with the fuse blowing.