View Full Version : Battery Care FAQ

2009.04.09, 05:37 PM
Can someone point me to a thread that has information on battery care. How often should you cycle them . . . when is it a good idea to discharge your cells . . . what rate should you charge your sells . . . etc etc.

To be honest I don't take care of my batteries at all, mostly because of time but also because of ignorance. I usually just charge them up before a race and that's about it. That was fine when I could barely complete a race but now that i can at least handle my cars I'd like to start taking things like this more seriously.

Any info you could provide or direct me to would be much appreciated.

2009.04.09, 06:15 PM
One great resource is the Candle Power Forums (http://www.candlepowerforums.com/vb/showthread.php?t=217683). I do a lot of research on there about charging, and charger comparisons. I did not run into this specific thread until Soyverde posted it in a different thread. There is alot of good information there.

I let my cells rest (in discharged state) a couple days before the race day, I just bring them to the track, charge normal... and run.

If my cells are only resting for a few days, I will discharge them before letting them rest. This way, I am only charging a few days later, and the batteries should be faster.

If the batteries sit for a long period of time, you want them half charged... then a couple days before the race do a discharge, and charge them up at the track.

I do not discharge/cycle a cell the day or day before a race. The cells dont have as much punch. Which is why I suggest doing it a couple days before the event/use.

My normal charge routine at the track; Once I get to the track, I put my practice batteries in all 4 chargers (2x Duracell 30 min, 2x Lacrosse). Let them charge as I set up my pit space and get the cars ready to run. By the time that I am ready to get on the track, the Duracell chargers are normally done.

The cells arent topped off with the 30 minute charger during the fast charge, 80-85% of the capacity is reached, then it switches to a trickle to top off the cells (after the LED indicators go out).

For practice, this is fine but for races I top the cells off in the BC-900 at 1A right before I get on the track. I put the race cells in the Duracell chargers about 45 minutes before my race if they have not been used already (start from a full discharge state) After the LEDs go out, I pull the cells. I put them in the Lacrosse at 1A when the heat that is 2 races before I am up finishes.

It should take about 10 minutes for them to finish, but if they are not quite done, its fine as they should be high in voltage and are at least 95% charged. There should be lots of speed and power. If you let the cells sit for a while, you lose out on alot of punch.

What chargers/dischargers do you have? Knowing your equipment helps, to be able to give you a good charging routine.

All 15 & 30 minute chargers charge to 80-85% of the capacity, then top off in a trickle... it could take up to 3-4 hours for a large capacity AA to actually charge fully. Most AAA's will be charge 700-750mah in the 15 or 30 min charge period...

2009.04.13, 07:48 PM
Thanks for such a detailed answer.

I have the Maha c9000 Wizard One. Do you have a recommended charging routine for that?

2009.04.16, 09:31 AM
I run R1 matched packs... i do the same routine as EMU just different charging rates... I run mostly mod classes. We race on Thur night so on Tue night i will discharge at 3 amps and when i get to the track Thur night i charge my batteries at 2 amps... I feel the difference in my batteries as far as consitency and performance... my batteries stay faster longer and the power delivery is much more linear... at a 2 amp charge you lose the punch but with mod class that usually isnt a bad thing;)...

I discharge all my batteries at 3 amps to 0.5... when the battteries cool they go back up to 0.9...

If you dont have enough time to charge your batteries when you get to the track charge them the night before and peak them right before you go out to race...

2009.04.18, 08:36 PM

2011.02.11, 10:16 AM
I asked this question and then promptly never applied any of the great advice do to a severe lack of free time. I'm finally finding some time to run again so I want to make sure I'm understanding everything correctly.

For some context I have:
- Powerex Maha C9000
- 4 sets of Peak 900HV's (newly purchased this week)
- 2 sets of Orion 900HV
- 4 sets of Eneloops (for practice)

Here's what I'm gathering from your information and some other posts I've read. Please let me know if am misunderstanding anything.

1. Label each battery uniquely on purchase so you can identify it
2. Record each battery in a notebook with its purchase date and manufacturing date (if known)
3. Put them through a break-in cycle and in the notebook record the capacity for each cell
4. When you have a number of batteries of the same type and approximate manufacturing date, group them into sets of 4 according to similar capacities as recorded in 3

1. Keep batteries charged at half their MAH Rating

1. Discharge your cells completely
2. If time will be limited on race day, charge your batteries the night before race day.

1. Charge up your cells prior to your race at 1A (Up to 2A depending on what you need)
2. Discharge used cells either partially or fully depending on how long they will be sitting.

1. Every six months or so, repeat the break-in cycle on each battery and compare the capacity with the originally recorded capacity
2. When a cell's capacity has decreased to 80% of its original value, consider it recycle material

1. EMU you have a particular process because of the chargers that you own. Is it necessary to charge in the Duracell chargers and then top off in a Lacrosse or Maha if your main charger is a Maha?
2. I see you guys are charging at 1-2A but most instructions for the batteries say to charge at the mah rating so I would imagine .9A is the standard charging method and when you want more punch you peak at the higher rate? Is this correct?
3. When is it appropriate to cycle your batteries and when is it appropriate to refresh them? These are two modes on the Maha.
4. Is it ok to recharge a cell that you used in a qualifying heat later in the day for a Main or should this be avoided?

2011.02.11, 04:40 PM
Lately I have been using just a Duracall 30 min and a Maha. I just put the cells in and charge them up for the race. I probably use the Maha more than the Duracell charger... When they say Done, I leave them in for a couple minutes if I can then hit the track.

Since I normally run 3 or more classes, I have started using my qualify cells in mains as well, but I have been running more mod classes instead of stock, so I dont need as much speed from the batteries as I would in a spec motor/stock class. With 70t, I find the speed is average, but I could be a little faster.