Help! Replace/refurbish Giant Enerypak 400 battery

[JohnMcL7]

My Mum has a Giant Prime+ ebike (or something like that), it's a stepthrough hybrid with derailleur gearing and the battery is an Energypak 400 which slides into the top of the rear rack. The battery hasn't been used in the last couple of years and when the charger is attached is shows a solid red light then changes to a flashing red light so I'm pretty sure the battery is dead and not charging.

I've had a look around and unsurprisingly with it being an older battery I can't find any compatible ones for sale. It appears the only viable option would be to use a battery repair/refurbishment service although I've noticed some explain that they replace all the cells for older batteries as they don't think it's worth replacing individual cells. If this is the only option I'd appreciate any recommendations for a company to use and a rough estimated cost, most of the sites I looked at were not showing prices although one seemed to quote around £400.

 

[saneagle]

My Mum has a Giant Prime+ ebike (or something like that), it's a stepthrough hybrid with derailleur gearing and the battery is an Energypak 400 which slides into the top of the rear rack. The battery hasn't been used in the last couple of years and when the charger is attached is shows a solid red light then changes to a flashing red light so I'm pretty sure the battery is dead and not charging.

I've had a look around and unsurprisingly with it being an older battery I can't find any compatible ones for sale. It appears the only viable option would be to use a battery repair/refurbishment service although I've noticed some explain that they replace all the cells for older batteries as they don't think it's worth replacing individual cells. If this is the only option I'd appreciate any recommendations for a company to use and a rough estimated cost, most of the sites I looked at were not showing prices although one seemed to quote around £400.

This situation is quite complicated. Giant generally use Yamaha stuff, which is hackable, but on many bikes, they have their own versions which have their own software and communications protocols. If you have such a system, the Yamaha hacks that allow you to run any battery don't work. First thing would be to look at your battery and see if it has Giant or Yamaha written on it.

Batteries have an internal management system in them that needs some power to work even when not even on the bike. That means that if you don't charge the battery for a long time, some cells can drain down below the point when the management system allows charging. In that case, the first step would be to open the battery and measure the voltage on the cells to see how bad it is. In many cases, it's pretty easy to get the low cells up to where the charger can be used again. All that can be done by a competent repairer if you can't do it yourself.

 

[JohnMcL7]

I've looked over the battery but I can't see any Yamaha badges, only Giant ones. I'm not an electronics person and would be concerned about frying something so if there's any known good repairers are worth giving a shout, I'd appreciate any recommendations.

 

[soundwave]

if it works and charges it can have the cells replaced if the bms is dead and lost its can bus programming its a bin job.

you could try the guy in my sig and see if he can do anything with it but i doubt it as giant use there own controllers bms and displays and can bus locked.

the original Yamaha motors use uart so more easy to get a standard batt to work with a mod chip but it wont work on giant yamaha motors

 

[JohnMcL7]

I've been having a hunt around and ebike24 seem to have an Energypak 500 for sale with the five pin socket:

Giant EnergyPak luggage rack battery 500 Wh

The Giant EnergyPak luggage carrier battery with 500 Wh is your reliable companion in the city and on tours. The practical positioning of the…

www.ebike24.com

I'm assuming this would be compatible with the bike and they seem to ship to the UK plus the few posts I've seen on ebike24 here seem to be ok. Assuming I get hammered on VAT it will come to a bit over £600 which doesn't seem too bad for a brand new battery given at the moment I'm struggling with options.