Specific battery charger features.

[BeachBuggyPhil]

Does anyone know if there is a battery charger that will charge lipos to a chosen voltage? Say 4.15v per cell instead of 4.20v. My current charger has set voltages and no facility to choose the peak.
I'm guessing there are discharges that could discharge them to that but I'd rather avoid peaking them then discharging them.
Thanks

[RudolfXC]

The LRP Pulsar Touch does.

[bigred5765]

Originally Posted by BeachBuggyPhil

Does anyone know if there is a battery charger that will charge lipos to a chosen voltage? Say 4.15v per cell instead of 4.20v. My current charger has set voltages and no facility to choose the peak.
I'm guessing there are discharges that could discharge them to that but I'd rather avoid peaking them then discharging them.
Thanks

you got me curious phil why would you want to??

[BeachBuggyPhil]

I've been reading up on prolonging the life of Lipos.
I race 5 min races with batteries that have, on average, 5200mah ratings. Resisting the urge to cram 4.20v in each cell and only putting in 4.15v and never running them below 80% of their capacity (5200mah) can greatly increase the life span of the battery. Apparently.
I only use under 2000mah per race with practise.
It'll mean I need to resist the urge to run to cutoff with my two bashing trucks but a stop watch can be used then.

[imull]

http://demonpowerproducts.co.uk/prod...e-graph-p-5812

As this states a programmable cutoff I assume it'll do what you want, but you might need to contact Nick or google

Thing is that you'd be better charging on a limited capacity charge as lipos are designed to be charged CC/CV, contast current (to 4.2V per cell) then constant voltage. The charger lowers the charge current when it reaches 4.2V per cell and keeps lowering it whilst maintaining the voltage. So everytime the cell goes to 4.21 the charge current drops by say 0.1A, but if you're not at 4.2V the voltage isn't going to be stable (espcially as low as 4.15) as the cell will always try to reach its terminal voltage. (I know this won't apply for older cells that no longer achieve that but the chargers get them as high as they will go as the cell will remain at its max voltage)

[bigred5765]

Originally Posted by BeachBuggyPhil

I've been reading up on prolonging the life of Lipo's.
I race 5 min races with batteries that have, on average, 5200mah ratings. Resisting the urge to cram 4.20v in each cell and only putting in 4.15v and never running them below 80% of their capacity (5200mah) can greatly increase the life span of the battery. Apparently.
I only use under 2000mah per race with practise.
It'll mean I need to resist the urge to run to cutoff with my two bashing trucks but a stop watch can be used then.

to be fair phill i think its slight false economy
first your run time will be greatly reduced
and as your bashing you don't need max performance all the time so if the cells go of slightly you'll never notice
and being as i know people using same Lipo's for over 2 years week in week out i doubt its worth your time how long were you expecting to use them any way

[BeachBuggyPhil]

Now I'm confused.
I had heard Lipos discharge at a fairy flat rate until the end and then dip as they near 3v per cell. If I'm only using a small percentage of the capacity per race then not peaking them to 8.4 didn't seem so necessary.
One of my "bashing" trucks is an SC10 4x4 FT that I only do laps of our buggy track with so I'm happy to do 10 mins and stop if it means I can prolong the life of my batteries rather than run it flat out to cutoff straining the battery and making other stuff a bit warm as well.

Since we've finished racing out doors I've been using my saddles as single cells in my Mardave and I've noticed they don't fully peak when charged as a single cell and take more charge when balanced together but then don't end the charging procedure balanced with one at about 8.17 and the other at about 8.20 with some being as low as 8.12. I'm thinking the long run times and deep discharges to LVC have damaged them.

[bigred5765]

shouldn't damage them as long as you don't dip below 3v per cell,
full charge or just top up doesn't matter which on Lipo's they have none or very little memory so to speak,damage is usually done buy over charge or running below 3 volts
they only noticeable thing we saw on old old cells were loss of punch but they were well over 2 seasons old,tested against new same cells,and the difference was minimal run time didn't seem to be affected
weve ran old cells for over 20 mins in a 2wd car none stop

[mattr]

Couple of things. Can you not just set your cutoff on the ESC to 3.2 or 3.4V? That'd have the same net effect. Just have to be careful with big throttle inputs, might make battery voltage dip. But by that point, its probably 10+mins running anyway!
And doesn't running saddles as individual cells change the characteristics over time i.e. if one is run more than the other, or run differently. So making it tricky to run them as a saddle pack again?

[BeachBuggyPhil]

That would appear to be happening with mine.

[CrashBangWallop]

The Turnigy Accucel 6 is programmable to enable different voltages. And its cheap!

[trax de max]

The power lab8 can also, i'd guess the PL6 does too.