Gtech problem

[worcesterbased]

Hi,

My mum has just tried her first ride of the year on a version 1 of the Gtech bike, I think it's the first mark they sold, about 5 years old. Last year she got a new battery, though the other one was still performing well.

She rode it for a mile or two, then it stopped working, was working fine last year.

I WD40'd the connection between the bike and battery, not sure what to try next.

Anyone else had similar issues they solved or could offer more suggestions?

Thanks,

Bill.

 

[Nealh]

One expects it wasn't looked after since it's last use and is now likely very unbalanced or knackered , sadly with some lithium ebike batteries they often need checking and charging for 10mins or so during quiet spells when not used.

Initial thoughts are that it is badly unbalanced and one cell group voltage is particularly low , but without opening and checking things out one can't be 100%.
A battery is only as good as the worst performing cell group , that group being the achilles heel no matter how good the battery may have been.

Was it even fully charged ?

 

[Nealh]

There are very few places that will check it out and know how to recover such a battery, for the most part battery tech knowlwedge lies with the DIY enthusiast who have the know how and skill .

One can do a simple check with a voltage meter after charging the battery, the voltage reading may give an inkling as to the issue.

 

[saneagle]

I'

Hi,

My mum has just tried her first ride of the year on a version 1 of the Gtech bike, I think it's the first mark they sold, about 5 years old. Last year she got a new battery, though the other one was still performing well.

She rode it for a mile or two, then it stopped working, was working fine last year.

I WD40'd the connection between the bike and battery, not sure what to try next.

Anyone else had similar issues they solved or could offer more suggestions?

Thanks,

Bill.

I've heard that they're pretty good for tying your tomatos to if you want to get something out of it, otherwise it's honeysuckle or other decorative climbing plants.

Seriously though, if you like the bike, chuck the battery and all the other electrics apart from the motor and get some Chinese ones. Total cost would be around £250, which is probably cheaper than a Gtech battery.

 

[worcesterbased]

Thanks,

There are very few places that will check it out and know how to recover such a battery, for the most part battery tech knowlwedge lies with the DIY enthusiast who have the know how and skill .

One can do a simple check with a voltage meter after charging the battery, the voltage reading may give an inkling as to the issue.

Thanks Neal,

Will do a voltage test on them as soon as I can, both are fully charged according to the indicator.

 

[Nealh]

Problem is the battery led may indicate they are charged but it doesn't tell you the SOC, it sounds like a low cell group or one that sags heavily very quickly and can't hold up the voltage for long.
A d8veh/saneagle has said in the end the cheapest option if mum likes the bike is to bin the battery and controller system and replace both with a generic third part system like KT and a reasonable battery.

That's the issue with lot of these bespoke type bikes they cost a fortune to replace the locked in parts and it's not just Gtech, there are others too. A part from the usual chinese mid drive bikes like bosh, yamaha , steps etc, etc, there are the swytch kits, cytronex just to name two.

 

[Bonzo Banana]

The Gtech battery packs are quite low capacity and so each cell is discharged at a very high rate and they tend not to last that long as Gtech battery packs have had a high failure rate. They did a revised battery pack with better cells I believe but still it is asking a lot from these cells although I'm sure those later battery packs were more reliable. This is not uncommon for proprietary ebikes with hub motors and low capacity battery packs. I guess its more acceptable for a cheap £399 ebike, battery pack to fail than a much more expensive model though.

 

[worcesterbased]

I'

I've heard that they're pretty good for tying your tomatos to if you want to get something out of it, otherwise it's honeysuckle or other decorative climbing plants.

Seriously though, if you like the bike, chuck the battery and all the other electrics apart from the motor and get some Chinese ones. Total cost would be around £250, which is probably cheaper than a Gtech battery.

Thanks, the battery was £250, less than a year old, is there anything else on the bike I could troubleshoot?

The Gtech battery packs are quite low capacity and so each cell is discharged at a very high rate and they tend not to last that long as Gtech battery packs have had a high failure rate. They did a revised battery pack with better cells I believe but still it is asking a lot from these cells although I'm sure those later battery packs were more reliable. This is not uncommon for proprietary ebikes with hub motors and low capacity battery packs. I guess its more acceptable for a cheap £399 ebike, battery pack to fail than a much more expensive model though.

Thanks,

Just tested the battery with a multimeter, both fully charged and showing the same number, the new one has only been used once, do you know if there are ways of checking either the controller or motor to see if the fault lies there?

 

[saneagle]

Thanks, the battery was £250, less than a year old, is there anything else on the bike I could troubleshoot?
Just tested the battery with a multimeter, both fully charged and showing the same number, the new one has only been used once, do you know if there are ways of checking either the controller or motor to see if the fault lies there?

The only part of a Gtech I've studdied, apart from test riding one, was the battery, which I opened up to see why it wasn't working. It had dead cells after BMS failure. Everything was glued together with silicone rubber, so it wasn't easy. I would guess that the controller has similar waterproofing, and it would be likewise impossible to fix, but, as I said, I've never looked at one.

The controller is bespoke, but it has the standard 9 pin connector for the motor. In order to do any tests, you'd need to make up a test cable with flying leads attached to a motor connector. You can buy motor extension leads on Ebay and cut it in half to make the test leads; however, I can't believe that there's anything to fix when you find a fault, so a bit of a waste of time and money.

One thing that you must try is that the motor connector is fully in. the connectors can feel like they're fully home when they're not. There is a line around the motor one that indicates how far the contoller side must reach.

If you're sure that the battery is OK, you could probably get away with just a replacement standard controller, that you can stick in a tool-bag under the seat, which works very well. A good controller kit is about £80 and a cheapo one about £50. You'll need Controller, LCD, PAS and throttle (optional but good for testing), and it would be a good idea to get a speed sensor in case your motor doesn't have one or for when the magnets fall off inside it (common problem).

 

[worcesterbased]

One expects it wasn't looked after since it's last use and is now likely very unbalanced or knackered , sadly with some lithium ebike batteries they often need checking and charging for 10mins or so during quiet spells when not used.

Initial thoughts are that it is badly unbalanced and one cell group voltage is particularly low , but without opening and checking things out one can't be 100%.
A battery is only as good as the worst performing cell group , that group being the achilles heel no matter how good the battery may have been.

Was it even fully charged ?

Turns out it was the controller, houses the battery, 90 quid, called them up they identified the problem, sent next day, easy to fit, now back on the road.

 

[worcesterbased]

I'

I've heard that they're pretty good for tying your tomatos to if you want to get something out of it, otherwise it's honeysuckle or other decorative climbing plants.

Seriously though, if you like the bike, chuck the battery and all the other electrics apart from the motor and get some Chinese ones. Total cost would be around £250, which is probably cheaper than a Gtech battery.

Turns out it was the controller, houses the battery, 90 quid, called them up they identified the problem, sent next day, easy to fit, now back on the road.