Back to My Lifepo4 48V, 20A Battery

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Arno J. Wulfert
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Last seen: 9 years 3 months ago
Joined: Tuesday, August 12, 2008 - 15:46
Points: 94
Back to My Lifepo4 48V, 20A Battery

Hi Dogman and others,

I still have an expensive battery (Lifepo4 - 48V, 20A) with less than a year's worth of use not working... ARG... Since my last post, I installed a new BMS board. It was really straight forward and not a hard swap... Unfortunately, it did not solve my problem. I also reworked the connections on the charger to make sure the charger wiring was not the problem.

The charger indicator stays green when trying to charge the battery and the battery still will not accept a charge... I am listing a few questions that I hope you may know the answers...

The charger wiring connector I have been using from the beginning (charge hook-up) is very similar to the connector from the battery to the controller (discharge hook-up) . The controller connector is just much more heavy duty. I accidently hooked the charger to the discharge connector (one going to the controller). Do you think that might have damaged the BMS board or the battery?

I tried charging the battery again today after it sat idle for weeks. It still will not accept a charge. Again, (stupid mistake or not) after I tried charging it and got nothing, I pulled the connection and hooked it back up again. This time I hooked the charger to the discharge connector and the charger began charging. Quickly I realized I had the wrong connection and unplugged it…

So, A big question: Can I go ahead and try to charge the battery by hooking it up to the discharge connector without damage to the battery???? It seems like it wants to work that way and worth a try if it won’t destroy the battery….

Second big question: Anybody know where I can get the battery worked on? I don’t have the smarts, courage or equipment to tackle it any further….

Thanks to all for your review and help.

Cheers,
Matt (ajw)

antiscab
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Last seen: 4 days 10 hours ago
Joined: Saturday, July 7, 2007 - 23:55
Points: 1686
Re: Back to My Lifepo4 48V, 20A Battery

Hi Matt,

the design of most PMC - BMS has two sets of power silicon.

the first set is inline with the batteries.
at this point is the discharge wire.
the discharge wire disconnects when a cell falls below whatever the LVC is.

the second set is wired to the discharge wire, and its output is the charge wire.
in addition to cuting out when a cell goes low, the discharge wire disconnects when a cell goes above the set HVC.

if you hook a charger to the discharge side of the BMS, and the pack is out of balance, you will over charge a cell.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

Arno J. Wulfert
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Last seen: 9 years 3 months ago
Joined: Tuesday, August 12, 2008 - 15:46
Points: 94
Re: Back to My Lifepo4 48V, 20A Battery

Thaks for your info... If I did overcharge a cell(s), is there a fix?

Cheers,
Matt

Arno J. Wulfert

JLGRAU
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Last seen: 8 months 2 weeks ago
Joined: Tuesday, July 22, 2008 - 02:39
Points: 98
Re: Back to My Lifepo4 48V, 20A Battery

Arno, steveo, advertises himself as an ebike, batteries , bulider fixer etc. He's on the for sale on endless sphere.
I can't vouch for him, however. Also, check out the for sale section here in V is for Voltage.
It' pretty clear the bad cells can be replaced with good ones. Also, loose soldering or welding may be the problem.

antiscab
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Last seen: 4 days 10 hours ago
Joined: Saturday, July 7, 2007 - 23:55
Points: 1686
Re: Back to My Lifepo4 48V, 20A Battery

unfortunately an overcharged cell is damaged forever.

but before you go throwing anything out, put a multimeter on each cell while the pack is loaded.

that will help you locate which (if any) of the cells is causing you grief.

if all the cells seem fine under load, then perhaps it is the BMS or charger.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

Arno J. Wulfert
Offline
Last seen: 9 years 3 months ago
Joined: Tuesday, August 12, 2008 - 15:46
Points: 94
Re: Back to My Lifepo4 48V, 20A Battery

Thanks for the info... I contacted Steveo and he may be able to help me....

Cheers,
Matt

Arno J. Wulfert

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