Please help diagnose an electrical problem. Is this a short?

[Red_Liner740]

I thought u were an aircraft mechanic, not an electrical engineer

...I stayed at a Holiday Inn once. LOL. I built high performance ebikes as a hobby. Lipo and lifepo4 batteries are used extensively. My ebikes uses 75v and the controller can pull 100 amps. 75 kmh and wheelies like mad.

Brian. The no warrantees is a CYA tactic. Obviously don't drain em all the time.

 

[toysareforboys]

...I stayed at a Holiday Inn once. LOL. I built high performance ebikes as a hobby. Lipo and lifepo4 batteries are used extensively. My ebikes uses 75v and the controller can pull 100 amps. 75 kmh and wheelies like mad.

Vids?

-Jamie M.

 

[Red_Liner740]

Just to add, Brian, once again you're right...depending on the chemistry of the LifePO4 they can or cannot be discharged to zero. They can be brought up but the cells become REALLY unbalanced and unsafe to use.

Now here's a kewl tidbit....want the new fandangled batteries because they are smaller, lighter, crank harder and longer but dont have the scratch to buy a 150 dollar battery? Nooo problemo!

Google or ebay Lifepo4 18650 cells. If you're close to power tools and the industry they also come in Dewalt 36V battery packs. For lighter applications such as smaller 4 cyl bikes use 4 in series. For larger applications or twins and thumpers use 4 in series paralled up so that would be 4S2P configuration. Some soldering and shrink tubing later you'll have as good a battery as the pros!!

 

[Red_Liner740]

Vids?

-Jamie M.

[video=youtube;ewv-GmB_3jQ]http://www.youtube.com/watch?v=ewv-GmB_3jQ&feature=related[/video]

Not mine, i dont have any vids of mine but they are comparable....mines not built on a DH bike frame, just a normal mountain bike hard tail...battery enclosure in the triangle...

 

[RockerGuy]

Just to add, Brian, once again you're right...depending on the chemistry of the LifePO4 they can or cannot be discharged to zero. They can be brought up but the cells become REALLY unbalanced and unsafe to use.

Now here's a kewl tidbit....want the new fandangled batteries because they are smaller, lighter, crank harder and longer but dont have the scratch to buy a 150 dollar battery? Nooo problemo!

Google or ebay Lifepo4 18650 cells. If you're close to power tools and the industry they also come in Dewalt 36V battery packs. For lighter applications such as smaller 4 cyl bikes use 4 in series. For larger applications or twins and thumpers use 4 in series paralled up so that would be 4S2P configuration. Some soldering and shrink tubing later you'll have as good a battery as the pros!!

Wouldnt it cost the same or more eventually? I think a spare battery for those tools cost around $100

Sent from my phone using my paws

 

[Red_Liner740]

Wouldnt it cost the same or more eventually? I think a spare battery for those tools cost around $100

Sent from my phone using my paws

Ofcourse if you bought new and in store you'd pay exorbitant amount of money. Damaged packs sell for pennies on the dollar, "worn out" battery packs or "dead" battery packs usually have only one cell in the series that fail or the BMS (battery monitoring system) crapped out. Open it up and usually 80% of the cells are in good working condition.

I did that with laptop batteries. I recycled over 200 battery packs and usually one or two cells would be dead while the rest would be fine. I have over 800 18650 Lithium Ion cells that i made battery packs before i switched to the more potent gel pack LiPo battery type.

I also want to add that 18650 is NOT the right size for LifePO4 cells used in motorcycle batteries, its 26650. My bad...

Usually, an 8 cell battery would cost you about $40 to $50. Thats a third of the price of comparable retailers although prices have been going down. 2 years ago it was 200+ for the 8 cell batteries.

 

[natlat]

You sure your battery is not being overcharged? Has this happen to me, could barely get 3 cranks off the battery. Was going to replace thinking it was just a crappy bat (not even 3 months old) and as it turns out i cooked it by overcharging. The rectifier regulator went on me causing it to overcharge the battery and in turn fry it.

One tell take sign of a bad rr is a black/cooked connector (although mine seemed fine).

GL

 

[sircastic]

OOkay, lets clarify some things

Running the volt meter in series with the battery terminal, ie, disconnect one lead, attach one side of voltmeter to battery the other side to the now disconnected lead while the voltmeter is on the AMP setting will tell you your parasitic amperage draw.

Point of clarification ... so will an analog voltmeter which I had assumed was the test described in the original post.

 

[johnp]

An update. I had misread the instructions from online and repeated the test on AMP setting. There was no draw. I then tested for overcharging and undercharging according to same link as in post 1 - all fine. Battery had by then held a charge for a week and was still in normal range. I reinstalled the battery.

So two possibilities, other than I had just let it sit too long:

[1] I had accidentally turned on the alarm from e.g. stuffing the fob into a bag in the house. I've done this before, and it does have the range. Also it did give a mysterious squawk when I first was unable to start. So there had been a draw from the Scorpio. According to Scorpio "The SR-i300 system will draw approximately 5 to 7 milliamps per hour armed with all functions." which they say should be OK for months, but there might be a problem leak with an armed alarm which I did not test for.

[2] For some reason when I (by mistake) first tested for leakage with VOLTS setting, I did get a 10volt reading. So there still might be something weird going on.

Hopefully will start next time I try. Thanks for all the useful thoughts.