Moving to Lithium

[Danjr1]

Re: Moving to Lithium

the wiring isn't damaged, was just a little flattened. and anyway, I'm pretty sure its a single cell causing all the issues (its discharging fine and linear but the recharging is erratic to say the least!) but when i look at the price of the single cell and the new soldering iron i would need, just makes sense to go to lipo.

[Danjr1]

Re: Moving to Lithium

Just wanna check a few things. Lipo's on it's way. I'm guessing u discharge first then balance cycle a few times? And at an event, can you top up the battery after a fight or do they need to be full discharged then recharged?

[typhoon_driver]

Re: Moving to Lithium

Don't bother discharging them. Lipos don't like being discharged like nicads and nimh. Just charge them up and the balancer should do it's job on the first charge.

[PJ-27]

Re: Moving to Lithium

You shouldn't ever need to cycle Li-Po's it won't do them much good either.

[Danjr1]

Re: Moving to Lithium

It's all finally arrived and as my luck with batteries and chargers isn't amazing I wanna run through a few things first.

1. Will the charge time be the same as previously with a NIMH battery, if everything is constant?
2. The charger has a storage function that seems to want to bring the battery to 3.7v per cell. I'm guessing this is my discharge function? As the discharge function wants to bring the battery to 18v overall?! And that's bad for lipos isn't it? I want to charge the battery up just to check it's all working but I don't want to leave it fully charged (or is that ok for lipos?)
3. Lipos should be stored at 3.7v per cell, correct?

Thanks
Dan

[Danjr1]

Re: Moving to Lithium

It's all finally arrived and as my luck with batteries and chargers isn't amazing I wanna run through a few things first.

1. Will the charge time be the same as previously with a NIMH battery, if everything is constant?
2. The charger has a storage function that seems to want to bring the battery to 3.7v per cell. I'm guessing this is my discharge function? As the discharge function wants to bring the battery to 18v overall?! And that's bad for lipos isn't it? I want to charge the battery up just to check it's all working but I don't want to leave it fully charged (or is that ok for lipos?)
3. Lipos should be stored at 3.7v per cell, correct?

Thanks
Dan

I've looked into the storage mode and it does charge/discharge the battery to 22.2v. I just need to know the very rough balance charge time (for the timer cut-off)
thanks

[PJ-27]

Re: Moving to Lithium

I think storage mode is deigned for when you plan on actually storing you Li-Po, ie. not using it for a long time. What you want is balance mode, just keeps the amps low.

[Danjr1]

Re: Moving to Lithium

I'm currently charging in balance mode at 1.5A then ill leave it a while and storage discharge it to 22.2v, just wanna check everything is working but the new battery is a beautiful fit my bot!

Also, the difference between the lowest and the highest cell is 0.1v, that good or bad?

[PJ-27]

Re: Moving to Lithium

Why are you discharging? You should avoid doing that on Li-Po's, just charge until you have 4.2V per cell. They should all be 4.2v.

Try balance charging at 1a, or less.

[Danjr1]

Re: Moving to Lithium

not discharging yet. I've read that storing them at a full charged state isn't great so i was going to use the storage function which will discharge to 22.2v? i don't want to stop the charge now (but i wish id known! lol) but next time, ill balance charge at 1A

[PJ-27]

Re: Moving to Lithium

Just don't STORE at full charge then, charge them (fully), stick them in your bot, bash other bots around!

And then balance at a very low amperage as often as possible to keep them in good condition.

[Danjr1]

Re: Moving to Lithium

seriously, how long to these things take to charge/discharge?! I let it balance charge last night for 5 hours and it only got to 2800 out of 4800mah?! it went into this funny routine where one of the cells reached 4.2v and the overall charge amps started to jump from 0A up to 0.5A, rather than being at 1.5A (which i know isn't great). Its currently discharging to storage level at 0.2A (thats the max i can get out of it), at this rate, its going to take 14 hours to discharge the 2800mah!

[Laser]

Re: Moving to Lithium

at this rate, its going to take 14 hours to discharge the 2800mah!

proberbly not, it depends on how many amps the load is how long it will take to discharge.
ie:
a 4000mAh batt wiv a 8000mAh load will take half an hour to fully disharge if fully charged

How many amps are you charging this batt at?

[Danjr1]

Re: Moving to Lithium

it was charging (on balance charge) at 1.5A (which i know isn't great but i didn't know) until one of the cells got to 4.2v. At this point, the Amperage started to basically bounce from 0A to 0.5A so the charging slowed right down! I can't make the discharge rate go any higher than 0.2A

[Laser]

Re: Moving to Lithium

What charger are you using?