Lithium batteries, you get what you pay for?

[moonzoomer]

[G]

It should have higher cranking amps compared to a lead acid battery.

Not compared to a lithium ion, which will have even higher cranking amps and lower weight.

I would go for a LiPo for a track bike over a LiFePo4.

However, it sounds like yours is faulty.
Whether that's an issue with the battery design (which really should have decent protection etc at that price so it can handle mistreatment) or just you being unlucky I don't know.

[moonzoomer]

[Iain.]

I sell JMT lithium batteries.

A few of our staff use them on daily riders with no issues. They come through a lot smaller then the lead acid battery, and come with stick on sponge pads to space them out. Battery level indicator on the top is pretty trick. The weight thing is just straight up weird though...we ran the first one on an RXV550 and genuinely diddn't think it'd fire it, but absolutely zero greif with it. Have seen a YB4 sized lithium spin over a GSX750F with no greif on a customers streetfighter, he used it daily before writing it off after around six months and I can confirm it still cranked when we assessed it.

The problem is you need a specific lithium charger to charge them with off the mains & the battery voltage cannot at any point drop below a certain point without frying it. Part number for the JMP800 charger is 609.24.80, more expensive variants are availible...but if you plan on pissing £300 on a charger for home use you've got issues

Blurb from supplier about a YTX9-BS;

[cb1rocket]

why the special mains charger?

Doesn't the built in protection circuit protects from frying itself?
____________________
Honda H100S2 Rebuild - https://www.bikechatforums.com/viewtopic.php?t=253852

[G]

[Iain.]

No idea.

Never questioned it, if the manual says use a specific charger or shits gonna catch fire I'm required to reccomend the use of said charger.

[Aff]

I can understand if the inbuilt circuitry cant regulate/rectify 240V and can only handle a small DC range based around 12V. But surely that just means the off the bike charger has to be a simple 12V power brick.

Edit: Just looked up the charger and it appears that it is 50 quid, also charges lead and comes with a permanent pigtail for the bike. so seems a bit more reasonable.
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[moonzoomer]

[G]

[moonzoomer]

[Aff]

I'm curious as to what's inside now. But not worth the outlay just to tear it apart.

If there is actually no proper BMS in them that would be a proper fail.
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[moonzoomer]

[Aff]

[moonzoomer]

[Aff]

[moonzoomer]

[Aff]

So Moonzoomer kindly sent out the dead battery and I took it apart tonight.

It's hard to show on the camera but the bottom is considerably bowed.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0210_zpsifune5x8.jpg

This pic shows the connections, two standard terminals and a JST balance port in the middle. This doesn't look promising on the on board BMS front.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0211_zps99cfmc1f.jpg

Was easy enough to break the top free with a chisel. Inside is what I expected, a board for the JST balance connector and the main power wires (2 pairs of 12AWG). The cells look to be standard pouch cells.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0212_zpsf9pebpoz.jpg

https://i1135.photobucket.com/albums/m637/Biles/IMG_0213_zpsqmtd29zc.jpg

The case was very sturdy and hard to get into, the cells were held in with a very strong, solid epoxy. I managed to cut one of the sides off so that I could lever out the cells.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0214_zpsshyyrqmy.jpg

The epoxy didn't break, it just ripped the heatshrink off the cells.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0215_zps3aosrlck.jpg

They were rather puffy.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0216_zpsiajoakmf.jpg

As I cut the bondage tape holding them together they exploded apart with a loud bang. There was a lot of built up pressure.

https://i1135.photobucket.com/albums/m637/Biles/IMG_0217_zpsu4ootcag.jpg

As you can see NO BMS!!

https://i1135.photobucket.com/albums/m637/Biles/IMG_0218_zpsdbtew5gu.jpg

https://i1135.photobucket.com/albums/m637/Biles/IMG_0219_zpsuu1xtuge.jpg

So the configuration is 4S2P (~2Ah cells). With LiFePo4's that means a hot voltage of 14.6V, so they are obviously trying to get away without a Battery Management System by having the hot voltage "lower" than the output of the bike. This is a terrible idea. These cells would have been getting a massivly varying voltage, likely higher than they needed fairly often, so its no wonder they died.

I will update with some charging results later, but imaging they are all very dead after their ordeal.

I cant believe this company is charging so much for this. It is badly designed and it would be surprising if any of the ones they sold, that went on a bike with a charging system, lasted more than a month.

It would cost hardly anything to put a BMS on this. But I suppose then they couldn't charge 50 quid for their charger.

Also the battery says 210CCA and I'm pretty sure these arent going to be 60C cells, more likely to be cheap Chinese crap so actually starting the bike was probably killing them too.
____________________
Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[G]

Really poor show, then - considering how much a 5ah 4s 30c lipo would cost you, which would handle the voltage better and so have less need for a BMW.

[moonzoomer]

I was expecting at least some kind of thermal protection internally, I doubt if these batteries are suitable for anything other than a hand held torch.

[Iain.]

That's not a JMT battery. Unsure what charger required for that.

JMT batteries don't have the plug to charge from, you charge from the standard connectors. The JMT also has a battery test indicator in the top of it.

If I get a dead one I'll dismantle it, but so far I've had no failiures even over winter.

[moonzoomer]

[Hetzer]

Apparently the JMT ones have the balancer built in:

"For this reason, the lithium batteries for JMT versions of the same start power need only one third of the capacity of a comparable lead-acid battery.
A uniform charge state of all cells is also ensured by a built-in processor ("Balancer").
The dimensions of the lithium-ion batteries using adapters correspond to the dimensions of the original lead-acid batteries.
The connections are identical, so the battery can be replaced without further adjustments in a few minutes."

I find it hard to believe some cunt can legally sell a lithium bike battery without a required balancer circuit, it's basically a time-bomb sitting under your balls.
____________________
"There's the horizon! Ride hard, ride fast and cut down all who stand in your way!"

[B5234FT]

Sorry to dig this up from the dead, but has anyone ever checked the JMT batteries to confirm the presence of a charge control circuit?