Forming Charge On Peak Charger Email Question

Hi Dave;
Firstly- thank you for your quality battery packs. I received my recent purchase- your 1650mah NiMH 8 cell 9.6 tx pack, plugged it in to my tx just to see what it was at, it started at 8.9 but quickly went to 8.5 where I pulled it out. So on to the first break in charge at 0.1A- on a Triton 2 with a thermal probe connected. The pack temp was at 79 degrees, so I set the cutoff temp at 88 (about 10 degrees higher) The charge lasted 16 hours with a delivery of 1670ma- terminated by the temp sensor. I had anticipated a longer charge time but am happy with the results- My question is: should I expect even higher mA delivery?
Matt K.


Your charge time at 100mah would be a bit short for a completely empty 1650 pack. I’d suspect it might not cycle as full but it could. I’ve never checked a Triton to see how accurate that number might be at low charge rates. Normally you have to put in 140% at low charge rates to get a full pack. A NiCad or NiMH has a lot of resistance to accepting a charge.

I would never expect the chosen procedure to work properly and consistently. There is not enough temp rise. The peak in a first charge is more of a “several peaks” along they to the final peak. One of those peaks is often large enough to trick the charger into declaring the pack full. On virgin packs, it will happen about 60% of the time when you use normal rates like Cx.5 to Cx2 (C=capacity). I’ve never run a study on doing it at 1/8th the minimum peak charge rate but I’d expect the results to be very poor. The temp will fluctuate with room temp also. All this is not to say you should have charged the pack faster as an initial peak charge. It is to say never use peak detection on an initial charge, never on a pack coming out of storage. There is no way to have the screen of your charger (or any other) showing NiMH or NiCad mode and not be in peak detection mode.

The best way to form (initial break in charge to complete manufacturing of the cells) on a computerized charger; Put the charger in PB (lead acid) mode, set the rate to .1, the voltage or cell count to a 12v pack (6 PB cells). Make sure all time limits and capacity input limits are turned off. This will get the charger to plod along slavishly well past when the first couple of cells fill. The point is to fill all the cells (which are initially of unequal charge) to overflowing at a very slow rate with gentle overcharge at the end. Peak detection will not get in the way by reacting to any false peaks. Peak detection is not reliable unless the charge rate is about 1/2 pack capacity or more. A new battery might have several peaks before it gets full. Calculating charge time when forming or slow charging (not using peak detection) is; (Capacity (or empty hole in the battery) x 1.4) / Charger output = hours to full. Let it run that long. Rates should never be above 10% of cells capacity. If it’s a AA cell above 1700mah, the rate should never be above 100mah, 50mah is even better.

What I’m going for here is a system that works 100% of the time. Every other kind of form charge is just fraught with problems. Using a peak type charger in PB mode (not in peak detection mode) is the only way to make them work reliably as a forming charger.

Once the pack is broken in, and it’s in regular use, I wouldn’t Peak charge it slower than .8 amps. The slower you go below this the slower it heats up after it’s full, the slower the peak detection happens, the more you hold the pack in an overcharge condition. Heating up is what happens when it can no longer store the energy your putting in it. This causes a slight voltage reduction. The charger knows the pack is full because the voltage is dropping, there for it has detected that it must have “peaked”. Peak charging is a form of detecting heat indirectly by watching for the voltage to drop which can only because the pack is full and heating up. (The exception is virgin packs which may reduce in voltage very slightly during the first charge.)

Never peak a pack that’s been in storage. This kind of charging is only for packs in regular use. After it’s set in storage a few months, the cells could contain unequal states of charge. As the fullest (best cell) is peaking (heating up and dropping in voltage), the others may still be rising (as they do as they are filling). This can mask the peak and apply a damaging overcharge current to the first cell(s) to fill.

I know these steps will prove to get your pack into most reliable service for you.


Hey Dave. I just wanted to let you know that I am very happy with my shipment. It was the charging cable for JR/Spektrum batteries. It was not only packed incredibly well, but it got here in just a few days for only $3 in shipping. Thank you very much and I can honestly say I do plan on doing business with you again as well as recommending you to all of the guys in the RC club! I hope you have many great days ahead of you 🙂

Sincerely, Daron 3-17-13


Ford C-Max Energi Part 2

A full week on the ticker. Remember the very important point presented in part 1. That point was Ford says to wait at least 1000miles before making any mileage calculations. This implies there may be some break in mixture settings that prevent it from reaching it’s potential for a while. That being said, here are my shots of the data thus far.

Life Time Summary 01/06/13
Life Time Summary 01/06/13

Over 20 miles of driving on engergy generated from braking. 200 miles exactly in pure electric driving. The brakes are interesting. When you lightly press on the peddle, you get a braking action, however it’s really the generator robbing your inertia for energy to charge the battery. As you move down on the peddle you can feel there are about 3 steps in this level of braking (or level of power generation) which each step increasing in rate of power generation and braking force. If you don’t move your foot at all, you’ll come to a complete stop. Obviously, when you are barely moving (moment before you stop) there can be no electronic braking (or little) yet it feels just like the brake pads are stopping you. Some super-brain programming must be managing this and it works perfectly!

Ford C-Max Energi MPG & Miles 01/06/13
Ford C-Max Energi MPG & Miles 01/06/13

Shown here are total miles, state of battery charge and what remains of our first tank of fuel given to us by the dealer. Not bad, close to 500 miles and we have about a 1/4 tank left. Notice, I have changed the mileage calculation. It was at first combined with with electric power. I wasn’t interested in that figure. I wanted to know what we were getting per gallon of gasoline. So, that is now represented. It’s continued to climb all week and as you can see, it’s over 40mpg at this time.

Overall my impression of this car is a “fine ride”. Really enjoying the gizmo factor of playing around with an electric car. It’s as fine a ride as any luxury automobile I’ve ever driven. Comfortable, handles nice, great on the highway. Can’t wait for an excuse to take a long trip in it.

I did run into a couple of irritations this past week. When it comes to any kind of product manual or help file, it seems not to include “my” answer. While switching it from MPGe to MPG I encountered a wrench icon. A retangular yellow light with a wrench in it. Going to the bible like (thin pages and thick!) manual to look over the two pages full of warning icons, I could not find a wrench. Going to the glossary and looking up words like “icon”, “wrench” and “symbol” produced a big fat zero. I’ve come to expect that when I look into any kind of help file or manual. Is a black cloud following me? Probably not. Once I got the setting to what I wanted, the wrench never appeared again. Not sure what it was trying to communicate to me.

The second item is the foot actuated lift gate. It seemed to work iratically, opening partially then stopping at times. I discovered we were using it wrong, wiggling your foot back and forth under the bumper can start it opening and also toggle it to stop. Just sticking your foot under the bumper and pulling it out gets a reliable full open every time.

More to learn: You’ll notice in one photo, a full battery stating it has 12 miles range. We had read this car has about 20-22 miles on battery alone. I’ve still to figure out if this is part of a break in or what the reality is on final full electric range.


Ford C-Max Energi Purchased Part 1

2012 C-Max Energi Plug In Hybrid
2012 C-Max Energi
C-Max Energi[/caption]It was time to purchase a new car. My wife and I are fans of Top Gear, a european auto show. On that show they don’t like many cars, however, they all love the Fiat 500 Abarth. We also liked the Ford C-Max. These cars do not have too much in common, however it was the two we were picking from. We finally decided on the C-Max Energi. (my Abarth dreams are still alive) Her previous car is a 2004 Honda Civic Hybrid. The Civic is 9 years old with a little over 100k on it. I currently drive a 2006 Dodge Mega Cab Cummins Diesel pickup. We have decided to keep the Honda as I have been averaging about $254 a month in fuel expense commuting to work each day. However, I need the truck to travel to trade shows and fly-ins so we’ll be keeping that. I just don’t need to be driving it so much. I am planning that by driving the Civic will save us about $127 a month in deisel fuel.

The C-Max comes in several varieties, we choose the “Energi” version. The Energi is a plug in Hybrid It has an EPA rating of 100 miles per gallon. The car contains a lithium ion battery and can go 10-20 miles on battery alone.

I plan to write in this forum about the C-Max and out experience with it.

When we picked up the car, the avergage fuel economy guage was reading 13.5mpg and it had 59 miles on it. (YIKES!)

One of the things that concerned us was the lack of people reporting fuel economy for the C-Max, both Hybrid and the Energi Plug In. The few that did report all reported less than EPA sticker mileage. Typical for the C-Max Hybrid (sticker 47mpg city, 47mpg highway and 47mph combined) was from 32 to 36mpg. That is alarming. However, these reports all seem to come from reviewers who have cars on loan for a day to film and make reports. Also, for photogenic reasons the driving almost always was in the hills and canyons of California or similar. Test speeds always seem to be 70mph plus. We don’t drive like that. Also, what does any reviewer or test driver do? They stand on that throttle to feel the power, they film passing, they film jack-rabbit starts, the test the handling. All things your likely to get tired of doing after owning a car for a 1000miles or so. What am I saying? You can’t trust the media here (like you can’t trust them anywhere). In this case, they don’t have an axe to grind, they have a report to finish. There is no axe to grind, just human nature. So, I’m anxious to see if I am correct or in error. Will the car do much better than previously reported?

Also, not reported by any report is the Ford’s manual which warns not to measure fuel economy during the first 1000 miles. The most accurate time will be between 2000-3000 miles. Having mechanical and racing experience (and a dose of healthy logic), I can assure you with todays computer controlled ignition and fuel delivery systems could easily be programmed to run a little richer for a better break in. The manual does not state it in that way and no research indicates they’ve done that. However, there is no research that indicates they did not either. So, we’ll follow the directions and give it the miles before we get too critical.

I wonder if any of the online reviewers of the C-Max Hybrid bothered to read the manual? Remember, these are humans.

Engergi Lifetime Summary 01/01/13
Engergi Lifetime Summary 01/01/13
We have the Energi version which is perported to get 108mpg in the city and 92 highway. Of course with an electric range limit of about 20 miles, I would presume most of your trips need to be very short with charging before each trip to acheive this mileage. My wife’s commute is 60 miles a day and most of that is Highway. I’ll be quite happy if she averages 60mpg. We are starting with the car in the winter which creates heating loads.

Mileage Data Shot 01-01-13
Here is our first set of guage photos. I’ll try to add these from time to time so you can see how the Energi is doing.


Electric Vocabulary

I love history and electronics. Where do the terms ‘Discharge’ and ‘Charge’ come from? Enjoy this little treasure….


Do A123 LIFE Packs Free Us From Cycling?

One more quick question. I ordered some 1100 2s A123 packs from you today.
Do these need to be cycled? I have a FMA 4S CellPro charger that is A123 compatible. It will charge and balance, but not cycle.
Thanks again.



If you want to check them before flying, Yes.
If you want to find out when they go bad on the workbench rather than at the field, yes.

There is no skipping regular battery testing and maintenance regardless of battery chemistry. All battery types will fail eventually and discharge testing is the only chance to discover packs needing replacement before having an accident.

My answer might seem a bit strange, however, every time there is a new battery chemistry many modelers think the new “miracle chemistry” means the end of regular battery maintenance and testing. I got the question many times at the beginning of the NiMH revolution, the Lipo revolution and at the introduction of A123 Systems LIFE cells. There could be nothing further from the truth. There is never a time when battery maintenance and testing is not prudent.

No jab against the CellPro chargers is intended here. They are very good quality and I recommend them. I don’t know the specifications of all the models they sell but am aware some of them will discharge test packs. It is possible to discharge these in NiCad or NiMH mode on modern digital chargers as long as the mode has NO CHARGE at the end of discharge. In other words, as long as it’s not a “cycler”. A cycle is a full discharge then charge or full charge then discharge. To do this, we want to us a charger that simply does 1/2 the cycle, in other words we want it to discharge and that is all. Just set the (NiMH or NiCad) cell count to 4 for a 2 cell A123. Some let you set the cut off voltage directly and in that case, set it to 2v per cell or 4V for a 2cell A123 pack. The correct discharge rate for any kind of lithium is Capacity/2. They are rated over 2 hours. Since many chargers/dischargers only allow discharge rates at even .1 amp (100mah) increments, set discharge to 500 or 600mah (.5 or .6 amps) to do a reasonably accurate job on an 1100mah rated cell.

I’ve noticed over the years the 2300mah cell (26650 can size) generally cycles to 2100-2200 range. They seem slightly over rated. Don’t be alarmed if your 1100mah (18650 can size) pack tests to 1000 or 1050mah. It’s probably just about right.

Happy Flying


Battery Storage In Reverse

For many of us there is a winter storage season. How do we bring our fuel powered models out of storage confident our RX battery packs are up to snuff? Were they nearing the end of life at the end of last seasons flying? Did they survive being in the trailer or garage ceiling for a number of months? Here are important steps to greatly reduce your risk of shouting “I Ain’t Got It!” when you hit the field this spring. These recommendations are intended for NiMH and NiCad packs although the similar principals apply to any mission critical TX or RX pack regardless of chemistry.

1. You should have cycled your packs and noted the value on them when you put the model in storage. Did you do this? A simple round of cycling in the fall will help weed the weakest packs from the herd.

2. Check the purchase date on your pack prior to model reactivation. Did you date your packs? Noting the purchase date in permanent marker should be a routine with new packs. Has this pack made it 3 seasons already? If it has made it 3 seasons, it’s time to replace it with a fresh one even if it’s still cycling well. It never seems like a good deal to “squeeze one more season” out of a pack if a model is lost doing so. There are no battery experts in the industry, nor any magazine writers that are willing to dare recommending using packs beyond 3 years. Most recommend only 2 years. The incident of surprise failures increases with each season. It’s much cheaper “not” to find out how long it will take to have a failure. Think about it.

3. Similar to a new pack, a pack having been in storage for some time is in need of a slow “forming charge.” A forming charge is a simple full-to-overflowing charge on a non-peak detecting charger like your factory wall wart. While in storage the cells slowly discharge. Not every cell will discharge at the same speed. After a few months, you could have one cell at 80%, one at 60% and two at 50%. When form charging, It’s important the charge rate does not exceed 10% of the packs mili-amp-hour (mah) value when doing this procedure. This type of charge allows all the cells to fill fully and the first cells to fill won’t be overheated by the ongoing charge. The danger of peak charging a pack that has been in storage is the best cell (the 80% full one) can be ruined as it’s overcharged while the other 3 are still filling up. Also, your pack may false peak meaning that although the charger reports it is full, it really might not be. Re-equalize the cells with a good long slow wall charger charge prior to any peak charging to avoid most problems.

4. Test for Capacity. Discharge the pack on your favorite charger (with discharge function). For the purposes of this kind of test, the correct rate to test against factory rating is 20% or 1/5 of the rated capacity. It’s ok if you can’t get that setting exactly, just get it close. Example: A 1000mah pack would be tested at 200mah discharge. Most chargers will display this as .2A. Your pack should test at least 80% of it’s rated capacity. If it does not, then a few more charge / discharge cycles are in order. If you can’t get the pack to test above 80%, it’s time to replace it. Although it might seem like a money saver to succumb to temptation and overlook marginal packs, one crashed model will pay for a great many replacement battery packs. And that’s to say nothing of the risk to others when a model goes out of control. Good pack or no go!

5. When you recharge the pack after your final discharge test, check the charger input mah. Did it put in about the right amount? A pack that’s been in storage, particularly if you’ve skipped the step of re-forming it is very prone to a false peak. A great pack that tests perfect but only takes 50% of the expected recharge amount could cause some unwelcome excitement.

6. Test your Switch. First, use a loaded tester to check your fully charged pack directly. Note the value then test it through the switch harness. If it tests good directly but marginal through the switch, it might be a sign the switch is getting dirty internally, worn or perhaps some connectors are going south. Like battery packs, finding out how long a switch will last is costly knowledge to acquire. It’s a good idea to replace the switch with every other new battery just to avoid trouble. Load testing your pack with and without the switch harness looking for any substantial difference is a good way to detect a problem before starting the season. Did you notice what I omitted? After checking the battery through your switches charge lead or charge jack, unplug it from the RX, turn the switch to the “ON” position and check it again. Is it load testing similar to the charge jack/charge pigtail? The most important place for your pack to deliver it’s energy is to the RX. Make sure it’s solid to this point, not just the charge harness.

Integrate these practices into your seasonal routines and many common pitfalls are avoided. Don’t forget to scrutinize your TX battery in similar fashion. Ongoing TX function is every bit as important as RX functionality.

Dave Thacker, Owner:
Blogsite: Radical RC Workbench