Focus Jam2 LTD Charging problem

[Michail]

Good afternoon. I had the opportunity to repair the charger from Focus 03/18. The problem was that I did not want to charge below 10% on batteries and low ambient temperature. The forum said this. Having studied the circuitry of a 4 amp charger, I found many flaws up to the soldered components on the board. Charging itself is simple in circuit design, it is very simple to start and check the jumper, but the microcontroller monitors the 3-pin and many are mistaken that the logic level is there, this data bus is not compatible with the standard (the EnergyBus connector itself), maybe it's 1-wire or serial. Bicycle authorization is simple, the charger needs to get data on the battery capacity, temperature on it, and the service status of the BMS via the bus. Charging problems are caused by the drift of the SMD resistor values in the battery voltage test circuit, when the power output relay is turned on, there is interference (contact bounce), replaced the relay with a better one and shunt the winding and relay contacts with 2 ceramic capacitors. Perhaps the interference from the relay greatly affects the operation of the microcontroller, which controls 3 pins. The fact that the manufacturer changed the battery to the place of charging in this is the logic, perhaps in the new battery there is a different sensor and an algorithm for reading and calibrating data from the sensor, and after that the charger starts to charge normally, receiving normal data on the bus. It was possible to solve the problem with charging, it charges at least 1%, I did not check the temperature. Perhaps the software itself microcontroller watching for 3 pin does not work correctly. I will write after lengthy tests about more specific results.

 

[DrStupid]

I recently bought 3 focus jam2's on a close out from a local dealer. Sold 2 of them straight away and kept one. The one I kept is doing as others here... the charger goes dead after about 10 seconds.

What's worse, it seems to actually drain the battery! While measuring the voltage on the motor leads, I watched mortified as the battery started loosing its charge whilst plugged into the dead charger.

The voltage was at 28 volts roughly, so it was not below the trickle charge threshold.

I brought It all inside overnight, and this morning it still took about 20 successive attempts to get a charge cycle going in earnest.

I'd actually be mad, if I wasn't awe struck amazed at the stupidity of it.

 

[Michail]

I recently bought 3 focus jam2's on a close out from a local dealer. Sold 2 of them straight away and kept one. The one I kept is doing as others here... the charger goes dead after about 10 seconds.

What's worse, it seems to actually drain the battery! While measuring the voltage on the motor leads, I watched mortified as the battery started loosing its charge whilst plugged into the dead charger.

The voltage was at 28 volts roughly, so it was not below the trickle charge threshold.

I brought It all inside overnight, and this morning it still took about 20 successive attempts to get a charge cycle going in earnest.

I'd actually be mad, if I wasn't awe struck amazed at the stupidity of it.

Unfortunately, in our country there are no dealers of this brand. Charger man is already testing. There is an idea to listen to the authorization bus and make your software. Using a regular 42 volt charger. Himself, I made myself a BOSCH charger with a homemade plug and a micro-controller that processes the bus (including various modes and errors). And it works. I charge in hiking BOSCH from the solar panel.

 

[Michail]

I brought It all inside overnight, and this morning it still took about 20 successive attempts to get a charge cycle going in earnest.

Threshold voltage, even lower. This charge conditionally thinks that there is no answer on the power line. When connecting and disconnecting, an unstable state is created, and sometimes it rolls.

 

[DrStupid]

Threshold voltage, even lower. This charge conditionally thinks that there is no answer on the power line. When connecting and disconnecting, an unstable state is created, and sometimes it rolls.

Is there a way to buffer the noisy circuit externally with a capacitor at the connectors?

I'm decent with electronics, and a soldering iron, but have no means (or inclination) to access the communications bus, or program a micro controller.??.
Lol.

I called my dealer, and he said Focus had sent them extra chargers incase of trouble. I'm gonna pick one up today and see what model it is.

 

[Michail]

I called my dealer, and he said Focus had sent them extra chargers incase of trouble. I'm gonna pick one up today and see what model it is.

Very interesting. I think they won the time without acknowledging the problem. It's not nice to buy an expensive thing to get that. And the paradox is such when making various branded Ebike of expensive European brands, chargers, battery, on-board computers, often the ill-conceived design, closed data buses. As we say: business is nothing personal. In our reality, we have to mess around and do it because we completely lack any spare parts and service.

 

[steve_sordy]

I................
I called my dealer, and he said Focus had sent them extra chargers incase of trouble. I'm gonna pick one up today and see what model it is.

Get the 4Amp one instead of the 4.5Amp one.

 

[Michail]

Is there a way to buffer the noisy circuit externally with a capacitor at the connectors?

I'm decent with electronics, and a soldering iron, but have no means (or inclination) to access the communications bus, or program a micro controller.??.
Lol.

My improvements made to the charger will show their effect. I will try to make instructions for revision. (Photo report)

 

[DrStupid]

Get the 4Amp one instead of the 4.5Amp one.

Unfortunately they only had the 4.5 ampere chargers.


If its noise from the Main Charge relay closing as Michail suspects, perhaps some ferrite rings would do the trick?

 

[Michail]

If its noise from the Main Charge relay closing as Michail suspects, perhaps some ferrite rings would do the trick?

This is not suspicion, but a fact! This affects the operation of the checking microcontroller. Also in this SMD chain, the resistors change their value (low quality, overheating due to incorrect power), and this underestimates the logical level of the input voltage, and charging does not include the coveted 42 volts.

 

[DrStupid]

This is not suspicion, but a fact! This affects the operation of the checking microcontroller. Also in this SMD chain, the resistors change their value (low quality, overheating due to incorrect power), and this underestimates the logical level of the input voltage, and charging does not include the coveted 42 volts.

Perhaps you can set up a small shop and start fixing our detective chargers for a fee? I'd send you one of mine!

 

[Michail]

Perhaps you can set up a small shop and start fixing our detective chargers for a fee? I'd send you one of mine!

Principle is possible. But shipping services cost much more. And how does the manufacturer react to this?

 

[DrStupid]

Principle is possible. But shipping services cost much more. And how does the manufacturer react to this?

I'm sure your right about shipping cost.
Eventually they will be out of warranty either way and will need repair by somebody?
I be watching to see if your follow up on the fix is something I can handle.

Thanks in advance

 

[DrStupid]

Here is my ultimate solution to the tec pack and the charging trouble.

This is an off the shelf shimano external 504 WH battery. With a custom bracket (3d printed... not in picture), it will bolt up and either bolster the derby city pack, or replace it completely.

What do you all think...genius or stupid?

 

[Michail]

Here is my ultimate solution to the tec pack and the charging trouble.
View attachment 25968
This is an off the shelf shimano external 504 WH battery. With a custom bracket (3d printed... not in picture), it will bolt up and either bolster the derby city pack, or replace it completely.

What do you all think...genius or stupid?

The idea is very cool. But there was a deplorable experience using a battery from Shimano. A standard charger killed him. It is not clear why the system from Shimano did not immediately put their battery?

 

[DrStupid]

The idea is very cool. But there was a deplorable experience using a battery from Shimano. A standard charger killed him. It is not clear why the system from Shimano did not immediately put their battery?

I using a shimano pack becuase
1) the packs, and mounting hardware are available on ebay and Amazon.
2) I already have a pack and charger to do all the testing before committing to a purchase.
3) the packs have a power button already on them making installation on the Focus super simple (in theory).

I'm going to set up a parasitic line from this battery to the shimano motor plug right at the motor, and see if pressing the button on the shimano pack powers up the rig... if so, I'm done. Print the bracket, bolt it in and roll.

Using the shimano pack will require powering on the shimano pack.

Using the derby city pack requires powering on the derby city pack.

Dont cross beams however.

My current investment is $95 for the mount kit, to try it, without having to disassemble my battery loaner bike, which is a completely functional bad ass Voltiac.

 

[DrStupid]

So far I can confirm that the bike will power up normally with a regular shimano battery. No focus pokus or hokus pokus by focus.

 

[Michail]

So far I can confirm that the bike will power up normally with a regular shimano battery. No focus pokus or hokus pokus by focus.

This is not surprising. Since the brain motor from shimano. It is interesting to connect computer diagnostics from shimano, what she will say. And you are good.

 

[DrStupid]

I'm gonna try and find the shimano connectors and make a y-splitter to be sure both batteries are ok in parallel, one powered at a time. That is if I don't sell the bike first.

 

[steve_sordy]

I think I'll leave it to you two guys to talk tech until you end up with a saleable proposition.

 

[Michail]

I'm gonna try and find the shimano connectors and make a y-splitter to be sure both batteries are ok in parallel, one powered at a time. That is if I don't sell the bike first.

Good. I told you about this device.
I use it. A lot can be customized and in addition you can freely buy. Unlike Bosch.

Shimano Setting Kit for STePS and Di2 - incl. SM-PCE1

 

[Michail]

I'm gonna try and find the shimano connectors and make a y-splitter to be sure both batteries are ok in parallel, one powered at a time. That is if I don't sell the bike first.

I can draw you a plug in SolidWorks.
Print on a 3D printer.

 

[DrStupid]

I think I'll leave it to you two guys to talk tech until you end up with a saleable proposition.

I believe its could be possible to create a sellable kit at 504 wh for around the same price as the tec pack. It would weight about a Kg more though. It would be off the shelf shimano except one small wire harness and an aluminium or 3d Bracket.

 

[DrStupid]

I can draw you a plug in SolidWorks.
Print on a 3D printer.

Let me try and find one first, thanks! I'll get back

 

[Tisme]

My improvements made to the charger will show their effect. I will try to make instructions for revision. (Photo report)

Well done on finding out the fault with the 4.5 charges. Did you post the instructions on how to get the chargers working. Ive got 2 batterys and 2 charges and its a pain having to charge one up over 15% to be able to get both on charge

 

[Chuckinboulder]

HI - I am looking for a used Focus charger - specifically the cord which plugs into the bike. It doesn't have to function. Anyone have an old charger they want to make some $$ on?

 

[Jonny360]

Were these charging issues ever resolved/acknowledged by focus? I have a 2018 focus jam2 I bought used. It hast the 4.5a charger. I'm in southern california and the temps are warm but it will not charge a low voltage battery frame or tec. But if I unplug the charger from the wall after the first click and plug back in again then it charges. I assume this is at the full 4.5amps. Is that harmful to the battery? Focus is no longer being sold in the US and i'm not sure where/how to get a replacement charger?