Living With Lipos--Safely!

Lungcookie said:

Uh oh.
You guys are forcing me to relearn something about chargers.
http://www.rcgroups.com/forums/showthread.php?t=1253796

Take the pack voltage, multiply the charge rate you want (amps output), equals the wattage of the charger you need.

So for a 25v (6cell) battery at 5amp you would need at least 125w charger.
25v x 5a = 125w

And...
25v(6cell) x 3.2a = 80w
16.8v(4cell) x 4.7a=80w

That 80w charger will still work just take longer.
Sorry Magwa, another knee jerk? I am removing that link to that 80w charger.

You started this fiasco you know...
Maybe we will all learn something.

Click to expand...

Hahahahaha! No problem.

I've got two chargers coming.....I'll charge each battery at 3 amps.
What the ****.....I'm retired. I have time.

Lungcookie said:

That PS 180w and up. that seems inexpensive.

That pocket charger would work but it is 50w and has no screen to actually be able to see the cell level voltage, cant discharge or store.

Click to expand...

Yeah that's what I mean by bare minimum. But hey, if its reliable and gets you charged...wouldn't be bad to have just in case or until you can upgrade. Those power supplies are the lowest price I have found. Radio Shack and ham radio etc. are a bit more pricey. I'm still sitting on the fence. Going to wait and see how Magwa does with those 20,000 mega ampers

Right, I hope it is all smooth sailing with Magwa.
He is like the test subject.

Right now charging my 10.0/6cell from storage voltage, at 5amps takes about an hour.
Double that for 20.0 then reduce charge amps by almost half.

That 80w may take close to 4 hours to charge the 20.0/6cell.
That much more time to space off the fact you are charging and leave the house or something.

Lungcookie said:

Right, I hope it is all smooth sailing with Magwa.
He is like the test subject.

Right now charging my 10.0/6cell from storage voltage, at 5amps takes about an hour.
Double that for 20.0 then reduce charge amps by almost half.

That 80w may take close to 4 hours to charge the 20.0/6cell.
That much more time to space off the fact you are charging and leave the house or something.

Click to expand...

Yup. Could happen. But probably happens fewer times to those who built their houses 30 years ago and
would have nowhere else to go if the sucker burned down.

Seems strange, but a four hour wait is appealing to me. That's four cups of good coffee sipped slowly
while I read a book...yummmm.

I got the batteries a couple of days ago

I got some "stuff" in the mail today.

A "Common Sense" carrying/charging bag.
Two charging bags of lesser versatility.
The two Accucell 6's
A CellLog8 (lousy...I didn't read the ad correctly..No USB/logging function)
Two backlit voltage alarms;
Two 12" battery balancing plug extensions;
Assorted connectors;

Still waiting for the power supply...It's sitting in Mather, CA waiting for DHL
A few more connectors (XT90 to XT60 for charger(s) ➨ battery(ies)
100W soldering gun
The Bike...still haven't decided on which one.

Took the motor/controller/throttle assy off of the donor bike and gave the donor a nice new front rim. Noticed that
the batteries have 10ga wire from the (wrapped) terminals. Connector to the controller has 12ga. I'll check that
further at first operation.

Checked the cells in the new batteries for the level of "storage charge". They are 3.88, 3.88, 3.90, 3.91, 3.88, 3.87.
Roughly the same spread in the other battery. Checked the Monitor/Alarms for consistency...and those against the
function that DOES work on the CellLog8...That's the monitor/alarm. Fairly close (like .02), but I'm going with the other ones that were dead on.

Set the alarm function for 3.5v on both alarms.

Will probably drop the voltages and balance to 3.8 storage charge as soon as the power supply comes. I haven't plugged the batteries into the chargers yet.
I want the whole charging station (mobile to move it outside) set up before I start with the chargers.

That's it for now. I'm still walkin'.

Left this reply in this thread for follow up by anyone who is watching the safety issue. And, in case anyone wants, for the sake of all, to bounce more
safety stuff off of this progress/hardware configuration.

When the bike comes, I'll move the actual build to a build thread and get out of the way.

We will have to see how long that 4 hour charge is FUN.

The 20.0 6s looks to have a max charge rate of 2c!
That would be 40amps! what the... is that right?

Don't think I would charge it that fast...myself.

C=capacity/1000
So for 1000 mah LiPo, 1C=1000/1000=1amp.

Magwa looks to be fighting gravity more than you CB2 or I, flats and lower weight.

I am guessing coarse gold cali means hills (LC, looks over at metal detector gathering dust), and magwa may not be petite, no offense magwa. The DD motor will pull more amps. Nice they put 10awg on it.

Heater farm.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=65982

Fan will only pull about .10amps, would need a wall of them.

You can also use a resistor.
Attempting to wrap my brain around it.

Just an experiment still.
Its getting HOT, need a different resistor and more fan I think.


Here is the progression of the heater farm.
Resistor in a box, variable DC motor control, volt meter.
Cell-log8 for alarm.

so whats the lowest v you can discharge these too?

http://www.batteryspace.com/PCM-wit...for-37V-Li-Ion-Battery-Pack-at-30A-limit.aspx http://www.batteryspace.com/pcmwithequilibriumfunctionfor37vli-ionbatterypackat90alimit.aspx http://www.ebay.com/itm/36V-37V-42V...-PCB-System-/221769582503?hash=item33a27f47a7 Just wondered because these BMS all have different discharge cutout voltage levels. hers another http://www.ebay.com/itm/Balance-BMS...y-10S21W001-/321790774602?hash=item4aec398d4a

Lungcookie said:

We will have to see how long that 4 hour charge is FUN.

The 20.0 6s looks to have a max charge rate of 2c!
That would be 40amps! what the... is that right?

Don't think I would charge it that fast...myself.

C=capacity/1000
So for 1000 mah LiPo, 1C=1000/1000=1amp.

Magwa looks to be fighting gravity more than you CB2 or I, flats and lower weight.

I am guessing coarse gold cali means hills (LC, looks over at metal detector gathering dust),
and magwa may not be petite, no offense magwa. The DD motor will pull more amps. Nice they
put 10awg on it.

Click to expand...

For my first test, I'll probably charge the batteries to balanced 4.0 and make a few runs. I now
have about four different methods (without the battery charger's LCDs) of checking the charge.

Alarms call set for 3.5v.

On the bike, I'll run two of these at eye level. Of all of them, they seem the best in being "dead on".

The power supply just came today and I'm waiting for some XT60>XT90 connectors. Or a bunch
of connectors to match up with the 100W soldering iron.

Also, for a first test, I ordered a bike. Here it is with the front hub p-shopped on it. The batteries will
go in a separate, padded steel lined box on the front rack. The controller will ride in a similar wooden
box on the rack, but heavily vented so it can get some air flow.

After all the testing, I'm pretty sure the bike will be changed out for something lighter.

Yes: Hills in Coarsegold
Yes: I'm anything but petite

Don't think I'll need a "discharge heater".

And, oh, the "fun" part of waiting for the charger is a lifestyle issue. Learned from running fast and
hard for 41 years out there in the cesspool of the business world.

You can charge to 4.20v/cell.
We are suggesting 4.15v/cell for a longer overall battery life.

All that weight, hub and battery on the front wont help the handling, steering feel any. Guess that's to see the voltmeter.

That 'heater farm' produces negligible heat. Less than a light bulb.
I was just putting out an experiment I did, maybe sparks some ones grey matter.

Lungcookie said:

You can charge to 4.20v/cell.
We are suggesting 4.15v/cell for a longer overall battery life.

All that weight, hub and battery on the front wont help the handling, steering feel any. Guess that's to see the voltmeter.

That 'heater farm' produces negligible heat. Less than a light bulb.
I was just putting out an experiment I did, maybe sparks some ones grey matter.

Click to expand...

Right.

But starting at the 3.8 or 4.0 for a test will give me a tasty baseline on those Ah's. Then, after the tests running, I can go to storage voltage.
The only thing I'll miss would be checking the acceleration at 49.8v or 50.4v. With a new/strange bike, and all the weight up front, a 15mph
run makes more sense to start with.

The low and centered weight thing is a major consideration, of course. I can't do anything about the front hub weight, since I already own it.

But design is a funny thing. If everything "front loaded" ruins the feel, or is dangerous, I'll pull back and away from the "esthetics" of the design function.

Main thing is to be safe and, although up front is nice for the volt meters/alarms, longer wires and primary focus on diligence works as well...or better, maybe.

Since we seem to be posting teaser bike build pics...