ADVICE - Batteries -Charging/Alarm Level ??

[bilabonic]

Hi All

Been reading up on Lipo's and it's a minefield !!!!

I will be running six Turnigy 6s, 5A, 22.2v.

When connected to bike i will get 44.4v/15aH (3 in parallel then in series with controller)

I will be charging in parallel and getting confused with figures etc

I have made a harness which puts everything in parallel.

First question is what do i set the cheapo alarm i have to get me going ?

1-8S LiPo Battery Voltage Checker Indicator Tester Alert f RC Battery Quadcopter | eBay

I have read it's 80% of rated voltage drop.

A battery is 3.7 nominal voltage and 4.2v fully charged (what i have read).

Will the sensor above get me going ? What level do i set it to ??

I do not want to invest in a meter yet !!!!!

I also have a Cellpro Powerlab 6 1000w charger and still reading up on this with regards charging etc

Cheers

 

[bilabonic]

Oh and just found out the preset alarm value is 3.3v, is this ok ?

Do i absolutely STOP using the batteries when this voltage is reached to prolong life.

Thanks

 

[Deleted member 4366]

Once your cells are down to 3.6v, they start to go down very quickly. I'd set it to 3.6v, then you have a chance to do maybe a mile, but at 3.3v, it's definitely time to stop. It's much better to use a voltmeter on the handlebars so that you can see what's going on with voltage sag.
0.4 " Waterproof Digital Voltmeter volt 15- 120V Blue Car battery Panel Meter | eBay
Waterproof Digital Voltmeter DC 15V To 120V Red Led Voltage Digital Panel Meter | eBay

Charging is pretty straight forward, but you must remember to disconnect the two packs from each other (your series "Y" connector) before attempting to charge two packs at the same time.

 

[bilabonic]

Thanks dave8, will get one of them.

Yes i am aware that i need to disconnect them and have made another splitter to put all six packs in parallel to charge, still not programmed the charger yet though...

I am still reading up on Lipo's and keep coming across diagrams i think are wrong ?

If you look at 'method 1' on this link at bottom of page he illustrated a 4S4P -16 cells - 16v 20ah

Turnigy Lipo

Are they not wired in series thus voltage increases 'across' the cells. Not in parallel which would give the same voltage but increase in current ????

Cheers

 

[Deleted member 4366]

Thanks dave8, will get one of them.

Yes i am aware that i need to disconnect them and have made another splitter to put all six packs in parallel to charge, still not programmed the charger yet though...

I am still reading up on Lipo's and keep coming across diagrams i think are wrong ?

If you look at 'method 1' on this link at bottom of page he illustrated a 4S4P -16 cells - 16v 20ah

Turnigy Lipo

Are they not wired in series thus voltage increases 'across' the cells. Not in parallel which would give the same voltage but increase in current ????

Cheers

Correct.
When you make a battery out of smaller packs you have the choice whether to join the balance leads to put whole packs in parallel so that your cells effectively increase in size from 5aH to 10ah or 15ah. It does have a stabilising effect on the cells with less chance of balance problems, but you have to be sure of your soldering and wiring.

If I were making six 4s 5ah packs into 12s2p configuration, I'd make or buy 3 sets of "Y"balance leads to join each pair of packs, then join them also by a parallel power lead. Each pair of packs then becomes a 4s 10aH pack. Then I join the 3 sets of power leads in series for 12S 10aH. I have a BC168 charger that charges through the balance leads, which saves a lot of messing about, but I still have to separate the power leads to charge then=m at the same time with the parallel board.

I always charge to 4.2v, and all my lipos still work after 2 years. Charging current depends on your power supply. If you have power supply voltage detection/protection on your charger, set it to 10v or less because it's designed for using lead batteries as a source. Power supplies can sag a bit , which will cause it to stop charging.

 

[bilabonic]

That's basically what i have made with my 6 packs, will charge all in parallel but each set of 3 in parallel will power control unit in series, i will just add another plug to the kit input when it arrives, also used a DB15 plug to disconnect/charge easily and leave things on bike, BIG thanks to Sacko. -



Been playing with that little battery checker as i have a plug for it and may as well use it.

How do you set the voltage ? No instructions with it ??

Cheers

Also ordered waterproof meter, need to find a decent small junction box/strap to mount it neatly.

 

[mountainsport]

Once your cells are down to 3.6v, they start to go down very quickly. I'd set it to 3.6v, then you have a chance to do maybe a mile, but at 3.3v, it's definitely time to stop. It's much better to use a voltmeter on the handlebars so that you can see what's going on with voltage sag.
0.4 " Waterproof Digital Voltmeter volt 15- 120V Blue Car battery Panel Meter | eBay
Waterproof Digital Voltmeter DC 15V To 120V Red Led Voltage Digital Panel Meter | eBay

Charging is pretty straight forward, but you must remember to disconnect the two packs from each other (your series "Y" connector) before attempting to charge two packs at the same time.

Your the right man to ask,HE WHO KNOWS IT-KNOWS IT ALL!!
Good knowledge my friend.

Mountainsport

 

[Deleted member 4366]

In the land of the blind, the one-eyed man is king.

 

[mountainsport]

In the land of the blind, the one-eyed man is king.

And in the land of cyclops?

Mountainsport.

 

[Deleted member 4366]

How do you set the voltage ? No instructions with it ??

Cheers

Also ordered waterproof meter, need to find a decent small junction box/strap to mount it neatly.

I never had to set mine, but it's got the tienest of buttons on the edge that looks like a jumper. Push it and see what happens.

Those leads look expensive!

For the meter, I'd make a small aluminium or SS bracket like a little bucket, and fix the meter to it with a cable-tie around it.

 

[bilabonic]

So not sure what voltage i need not to go below since i will be monitoring the whole voltage (not the paralleled cells through the JST- i have set the little monitor to 3.6v and ity's quite loud)

As above i have x2 groups of 3 batteries in parallel giving 22.4v /15ah, i will then series these at the controller to give 44.4v/15ah.

Do i just get one monitor and not go below 21.6v or should i get two and monitor each parallel pack and monitor each at 10.8v ?

What would you recommend ?

Cheers

 

[Deleted member 4366]

i've got loads of those monitors, but I've never used them. I found one voltmeter on the whole pack was enough. Just make sure you check the cell voltages when you charge them the first few times. You soon get to recognise whether you got any weak ones, which is unusual anyway. Once you see that they all go down evenly, start heading for home when you get to 44v. Depending how much current you take, you'll only have a couple of miles left.

One time I forgot to charge half of one of my packs, so when I first switched on I could see that the voltage was only 47v instead of 50v+, and it sagged a lot as soon as I opened the throttle, so I figured something was wrong. If you have the alarms, put them on as many cells as possible. Cells in parallel count as one. I think that you'll end up using just the voltmeter like me.

One other thing.: I've bricked two sets of lipos by leaving them switched on, and there were no LEDs on the bike to see it, so it's a good idea to have some means of showing that your bike's switched on.

 

[wurly]

You might want to read this thread i started. I made a few mistakes when i started using RC LiPo.
Endless-sphere.com • View topic - Did i kill my new lipo pack?

I now run 8s2p on my little folder. I fitted a voltmeter on the handlebar and this definately helps you judge what state of charge the is. I know when the voltmeter hits 29.6V that the cells are around 3.7V and i should think about charging them soon. BUT, i only started trusting it after i had used my packs for many journeys. I was balance charging them and noting if any of the packs had any duff cells in there.
Now i parallel charge with the occasional balance charge of eack pack.
If i was to make a long journey with this battery, i would connect all my alarms (set at 3.6V), but i don't usually do this anymore...just rely on the voltmeter.
It's down to your confidence of your battery, which will come in time.
Personaly i think you should balance charge eack pack until you are confident all the packs are ok then you can start parallel charging.

(my post crossed with Dave)

 

[bilabonic]

Cheers guys ,

Is it worth bothering writing down resistance/voltage on each battery ?

I bought a balance board that connects to all types of size cells to charge but the plug (think its JST) does not fit into my cellpro 6 charger.

It is slightly different.the controller comes with a remote on/off input for switch ??

I have no switch or indication that the bike is on so will have a search on here, sure

Can't wait for my gear to come now,

????

 

[Deleted member 4366]

Most chargers show individual cell voltages as soon as you connect them. You don't need to write anything down, but just make a mental note of the difference. They should stay within about 10% of each other. The lower you go, the more the difference. If you can, check each pack on the board before plugging them all in for charging. Obviously, if one cell has dropped lower than the rest, it's that pack that you should put your alarms on. After checking a few times, and everything's OK, you can have confidence to use the voltmeter to monitor pack voltage. It might sound a bit complicated, but once you've charged a couple of times, it'll make more sense.

Your charger will look after the maximum charge voltage, but the first time you charge, you should keep an eye on it to make sure it cuts off at 4,2v per cell. They usually stat reducing the current when they get close, so you can see everything's OK. Most of the danger is from over-discharge, so charge after every time you use them if you can, and don't try and squeeze too much out of them.

When you've made your pack, use gaffer-tape to hold all the wires in place so that there's no rubbing on them. If you wear through the insulation, there'll be an instant fire. Also, make sure that there's no tension on the balance wires.

 

[bilabonic]

Thanks again for an excellent reply, my kit has just arrived this morn !!!!

Can not believe the weight of the wheel and NO INSTRUCTIONS at all !!

Going to start a new thread on the build, genned up enough on the batteries/charging etc

Cheers

 

[Sacko]

You dont need to use the balance board you have bought, I made the parallel lead so it fits directly to the charger

To charge one individually. Plug the long lead into the charger, plug the battery into the end of it.

 

[bilabonic]

Yea i understand that mate.

Just charged on battery and all cells at 4.19v / 25.18v.

Charging second one at 5a, noticed when flicking through display it shows resistance of each cell as well whilst charging, there is a 200kohm difference ?