JMT Lithium battery stress tested

I've not used the bike for quite some time (just too damn busy with kids and work to sort the starter motor). The JMT battery got neglected but hey it's safe for long periods of disuse. You think?

This weekend, I dragged the bike out to replace the starter and get the battery charged. OMG the test button showed nothing. Booger! I should have disconnected the battery earth. Looks like I've bricked it. What a plonker for not getting my finger out.

My standard car charger has not seen the light of day in a (very) long time and of course it self toasted when plugged in. I rigged up a pair of wires from the car battery to connect the JMT for charging. Started the car and connected the JMT. After a while, I disconnected the car battery negative terminal clip and ran the engine for an hour. The system voltage sat around 13.8 volts. At one point, I connected the multimeter in current mode and found it was pulling 1.3 Amps.

After an hour, the battery test button was showing three lights. It's only 4 amp hours, so an hour at 1.3A wont be 100% full but test button said yes. Great news the new starter is great - A LOT BETTER than the Motorworks service exchange ever was - and 24 hours later the battery test is still showing the full three lights.

The JMT Lithium battery protection circuit works. The cells were not allowed to get harmfully flat and the used starter motor from Poland was well worth the punt. Now to find a reasonable plain vanilla car battery charger to get it properly topped up.

Bendy toy said:

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The JMT Lithium battery protection circuit works. The cells were not allowed to get harmfully flat and the used starter motor from Poland was well worth the punt. Now to find a reasonable plain vanilla car battery charger.

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Used starter motor from Poland?

Mmmmmmm, I wonder where that originated from.......................

Andres

Outtomunch said:

Used starter motor from Poland?

Mmmmmmm, I wonder where that originated from.......................

Andres

Click to expand...

I can't possibly comment. But everything else at the time looked ropey.

And tommorrow starts the thread


"Great use the car battery to jump charge my bike, and now ive borked the car electrics"

You should never disconnect a car battery while the car is running,

The alternator & other electronics can be fried , when you charge with no return path to the battery

Santa-2512 said:

And tommorrow starts the thread


"Great use the car battery to jump charge my bike, and now ive borked the car electrics"

You should never disconnect a car battery while the car is running,

The alternator & other electronics can be fried , when you charge with no return path to the battery

Click to expand...

Dead right - very risky. On a side point - the car engine should not be running when the battery is used to jump start another vehicle. Most people do and get a way with it. But voltage spikes are not good for the electronics.

I didn't use jump leads and didn't disconnect both batteries at the same time with engine running. However you can't charge two batteries in parallel. Once one has filled up, the charging rate will drop so the other never gets to full charge. That's why I disconnected the car battery leaving the JMT connected.

The JMT was wired parallel to the car battery terminal blocks but left disconnected. Car was started on normal battery. JMT was then connected and allowed to charge for a while. It can happily handle a high charge rate, so I unclipped the car battery earth. JMT stayed in circuit taking the full charge available. Car battery earth was reconnected before engine was shut down. At no time was the engine run with no battery.

To protect the car's systems, the same thing was done when the ammeter was connected.

The little JMT would happily start the car but it's not big enough to cope with heater, lights, electric power steering, etc that are all on at the same time.

Santa-2512 said:

And tommorrow starts the thread


"Great use the car battery to jump charge my bike, and now ive borked the car electrics"

You should never disconnect a car battery while the car is running,

The alternator & other electronics can be fried , when you charge with no return path to the battery

Click to expand...

I’ve done it a few times. Flat battery no jump leads. Swap battery start car swap back. Never had a problem. JJH

It's a theoretical issue and the alternator should be more than capable, but the costs of damage can be nasty so I avoid doing it.

I boogered the alternator on another bike - arc welding some frame brackets. I had disconnected the battery but the alternator regulator got fried. I now disconnect everything I can get to that's likely to be sensitive.

Bendy toy said:

It's a theoretical issue and the alternator should be more than capable, but the costs of damage can be nasty so I avoid doing it.

I boogered the alternator on another bike - arc welding some frame brackets. I had disconnected the battery but the alternator regulator got fried. I now disconnect everything I can get to that's likely to be sensitive.

Click to expand...

Ironically reg/ regs on most alternators are available as a spares item However some repair places wont tell you that, and will go down the new / refurb unit route!

Santa-2512 said:

"Great use the car battery to jump charge my bike, and now ive borked the car electrics"

Click to expand...

That’s a PROPER word!

Santa-2512 said:

Ironically reg/ regs on most alternators are available as a spares item However some repair places wont tell you that, and will go down the new / refurb unit route!

Click to expand...

It was the Yamaha Diversion 900. A used alternator solved the problem but a hassle I really didn't need.

Lithium battery is still doing fine.