Yeah, from reading between the lines on “peak” chargers and seeing what they can charge, it does seem that it can either be -dV/dt or DT/dt…
Thanks Michael!
Todd, I did not research all the Maxium chips, but the common ones are specific to either nicad or nimih, there are actually two different part numbers for the 2 chemistries.
As I said, I did not exhaustively research all the Maxium chips.
Greg
Just a follow up on the final outcome of my battery issue.
I separated the 2 batteries and connected them to a DPDT switch which then selects either pack as required, as suggested by TOC and Tony. I did not go with the centre off because that would have meant that I would effectively have had 2 Off switches in series.
I found when I separated that there was a voltage difference of 0.01V between them (measured 15.02 and 15.01V) but when I connected them into the circuit their voltages dropped to about 8V so I suspect they had discharged to nearly flat. So one is happily being charged as I write this and I will test further.
Regarding chargers I have 2 “Master Instruments” universal NiCd/NiMH chargers and a Turnigy Accucel 6, all auto detect the number of cells and I set the max charge current (usually C/10 or approx. one tenth of capacity) and they switch off when the batteries are charged and maintain a trickle till disconnected. They all apply current in short bursts at least that is what is indicated on the meters/display and judging by the power supply that feeds them (an ATX PSU), loading change ( fan speed changes) that is what is happening
I have no real idea how they work I just know they do what I want and that is all I ask of them.
Thanks for all the information about batteries, it was way more than what I expected but I can now use this as a reference for the future.
I have had another brainwave of using a “Picaxe” microcontroller to monitor the battery pack voltages and auto switch between them via a relay when one is getting low, but that, as they say, is a story for another time.
Todd Brody said:
I don’t know why you guys don’t just make your own using a Maxim chip for a few dollars and some other components. They have chips for charging whatever with all kinds of detection/limiting.
When I put the on-board TE in my FA, I made my own charger using a Maxim chip, and that was for just one train.
I am interested in a wiring diagram for the charger you built if you are willing to share it.
Did you put the charger onboard the loco or have I misread your post?
Hey an onboard charger for each loco what a concept only a power supply with the required voltage needed, make it a variable one and you are on your way.
If they can do it for toy helicopters why not trains.
Hmm may be I should stop thinking about now.
I used the Maxim 712 for NiCads and NiMHs, and the 713 is the same except for a negative charge slope detection. The schematic is shown at the link.
No this is not an on-board charger and requires a wall wart at least 1.5 volt higher than what you want to charge (up to 16 cells or 19.2 volts). I used a 30 volt wall wart as they show in some of their drawings.
http://www.maximintegrated.com/en/products/power/battery-management/MAX712.html
Graeme, if you are thinking of onboard chargers, and then powered sections scattered that will recharge the locos, forget it.
It comes up every several years, and it won’t work for a number of reasons… mainly chargers do not like their power supply interrupted.
You COULD make it work if you parked a train on a spur and left it sitting there… and turned it on when it was at rest.
Greg
Greg Elmassian said:
Graeme, if you are thinking of onboard chargers, and then powered sections scattered that will recharge the locos, forget it.
It comes up every several years, and it won’t work for a number of reasons… mainly chargers do not like their power supply interrupted.
You COULD make it work if you parked a train on a spur and left it sitting there… and turned it on when it was at rest.
Greg
Greg,
I was thinking more along the lines of the charger connected to the battery permanently, onboard the loco, with a power socket for connection to a suitable power source.
No need for the loco to be on rails, just like my locos now, they just sit on the bench while connected to the charger.
On another note the Shay with the battery issue is now running just fine, thanks again for all the advice.
The batteries were flat but all good now, just need to look for when battery A is getting low and Battery B need switching in.
The procedure will be; a) stop loco, b) switch off loco, c) change battery switch position, d)switch back on and proceed, this will prevent spikes that may damage the electronics.
Graeme,
What you describe is doable, and works well IMO. Obviously the initial setup is critical to battery chemistry, voltage and capacity.
I have several Li-Po flight power batteries used of large RC aircraft that require nothing more than a 12 VDC power source to charge multiple batteries simultaneously. A small flight power systems multi battery charger is integral to the aircraft. Voltage, temperature, individual battery and cell monitoring/balancing/charging, time, charge adsorbed at the least are monitored and bad cell/temperature detection alerts are propagated. (Originally there were simpler chargers that were incorporated within each battery in a plastic hard case shell).
Michael
Graeme Price said:
Greg,
I was thinking more along the lines of the charger connected to the battery permanently, onboard the loco, with a power socket for connection to a suitable power source.
No need for the loco to be on rails, just like my locos now, they just sit on the bench while connected to the charger.
You could certainly do this with a Maxim chip.
But how is this really any different than just having the whole charging system external and being able to charge any similar pack at no added expense (as opposed to a charger in each engine)?
Convenience?
If there’s room in the loco, then less stuff outside to lug around.
I can see it.
Greg
There is the convenience thing, simplicity and your not likely to make a booboo setting up the charger either… Why not the Maxim chips are less than $5.00; throw in another $5.00 for three capacitors, three resistors, a diode, a transistor and you have an onboard charging solution, for another $5.00 you can add a temperature sensor too.
Yet, in the scheme of things proven multi chemistry intelligent balancing chargers are available for $23.00…
Michael
Convenience would be the most obvious benefit.
I am imagining a power board with a whole lot of plug packs (what we call wall warts) at charging stations in a loco shed.
Back the loco in, connect battery, charge, when ready return to service.
Bit like a loco entering a servicing centre for fuel etc.
Just thinking out of the box as I plan and plot my retirement.
As a footnote the Shay I think draws way to much current for the battery packs I have (its running 3 motors) that I am getting poor performance.
One pack failed after half a lap of my track and the other made it nearly twice around before dying.
I am cycling them at the moment but am not confident that will fix the problem.
Next step is back to Li chemistry batteries and charging outside of loco.
I am looking at LiFePO which I have been told is probably the safest of all the Li chemistries.
People in the UK are using what they call the “Blue Battery” which is a Li-ion which comes with charger and has the rated capacity of 8000mAh or greater to great effect.
Like this one;
So that is on the radar.
Graeme,
What sort of batteries do you have in the Shay at the moment?
BTW. I am surprised that no one here has brought up those “blue” battery packs before.
Should prove to be an interesting discussion going by what information was posted on other website forums.
Tony Walsham said:
Graeme,
What sort of batteries do you have in the Shay at the moment?
BTW. I am surprised that no one here has brought up those “blue” battery packs before.
Should prove to be an interesting discussion going by what information was posted on other website forums.
The batteries are 12 x 2700mAh NiMH wired in series to make a 14.4V pack of which there are 2, they same as what I have in all my other 6 locos but they only have 1 motor each.
Some only run 10.8V (9 x 1.2V cells) so all I can think of is that I have a huge current drain with the 3 motors.
The “Blue” battery discussion on the UK sites has been very vigorous indeed, but then again there is a bit of water between US & UK that seems to polarize ideas, unlike downunder where everything is looked at so we can pinch the best ones. (http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-laughing.gif)(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
Are those AA size cells?
Chinese? Japanese?
Regular NiMh or LSD type?
According to Sanyo AA cells do not like giving more than 1/2 amp continuously. Any more than 1 amp and you will shorten their life span dramatically.
Plus they self discharge rapidly and every time they do that, it reduces the life span again.
Hi Graeme, battery life can be frustrating. As Tony has stated, if you use AA cells they are much happier being charged at.5 amp/hr. They do not last if they get hot during charging. Over the past 20 years I have sold chargers that were under 200 ma, 400ma and currently the fastest is 900 ma. Just recently I replaced a AA 14.4v 1450 ma pack in a Shay. The battery pack was purchased on May 5, 2000. The customer used the RCS BACH-3 trickle charger. I agree this is most unusual. I tell folks to expect about 5 years under regular use and a slow charger. I know this might not be very scientific but it is real data.
Also I have some data on Bachmann power blocks. I used a new out of the box Bachmann Climax, didn’t have a three truck Shay for this test. Based on the model numbers I believe the Shay motors are similar to the Climax power trucks with different mountings.
Using 2- AA 7.2v 2300 mAh Tennergy cells wired in series. Climax with RailLinx throttle and Phoenix P8 sound sitting on rollers:
idle - .4 amps
moving - .8-1.0 amp
Running - 1.0-1.1 amp
Blow whistle - 1.18 amp
I would tell my customer they will get about 2 hour runtime. Add a third truck and get over 1 hour runtime. Of course this assumes the loco is running smoothly and the length of the train and grades. After the 20 hour loco break-in the runtime should be longer.
I am interested in hearing from others about what they get for runtime on these Bachmann locos.
Don
RCS of New England
Tony Walsham said:
Are those AA size cells?
Chinese? Japanese?
Regular NiMh or LSD type?
According to Sanyo AA cells do not like giving more than 1/2 amp continuously. Any more than 1 amp and you will shorten their life span dramatically.
Plus they self discharge rapidly and every time they do that, it reduces the life span again.
Don’t know the origin of the batteries Tony but I bought them from an electronics components wholesaler (WES Components) they supply the electronics repair industry and I have used for over 15 years.
All my batteries are the same type and I have not had a problem in the past with their quality.
All the batteries in the locos are regular NiMH and in my transmitters I have LSD (Eneloop).
I run most of my locos on slightly over half throttle via PWM ESCs.
Don Sweet said:
Hi Graeme, battery life can be frustrating. As Tony has stated, if you use AA cells they are much happier being charged at.5 amp/hr. They do not last if they get hot during charging. Over the past 20 years I have sold chargers that were under 200 ma, 400ma and currently the fastest is 900 ma. Just recently I replaced a AA 14.4v 1450 ma pack in a Shay. The battery pack was purchased on May 5, 2000. The customer used the RCS BACH-3 trickle charger. I agree this is most unusual. I tell folks to expect about 5 years under regular use and a slow charger. I know this might not be very scientific but it is real data.
Also I have some data on Bachmann power blocks. I used a new out of the box Bachmann Climax, didn’t have a three truck Shay for this test. Based on the model numbers I believe the Shay motors are similar to the Climax power trucks with different mountings.
Using 2- AA 7.2v 2300 mAh Tennergy cells wired in series. Climax with RailLinx throttle and Phoenix P8 sound sitting on rollers:
idle - .4 amps
moving - .8-1.0 amp
Running - 1.0-1.1 amp
Blow whistle - 1.18 amp
I would tell my customer they will get about 2 hour runtime. Add a third truck and get over 1 hour runtime. Of course this assumes the loco is running smoothly and the length of the train and grades. After the 20 hour loco break-in the runtime should be longer.
I am interested in hearing from others about what they get for runtime on these Bachmann locos.
Don
RCS of New England
Don,
Thanks for that info, I am going to run the loco later today to see if the Discharge/Charge cycling has worked.
Well that was a monumental failure!!!
I got 15 minutes out of each battery pack and all the loco was pulling was 3 logging cars with no load and a caboose.
Looks like I am being forced toward Li chemistry batteries just for the power density required to run this thing, will probably need a similar battery for my Connie as well.
Guess this is the end for this thread.
Thanks for all the help.
Graeme.
This does not make sense.
I have converted a number of 3 x truck Shays. I always used 2 x 7.2 volt 2500 mah SRC Sub C NiCd batteries wired in series and mounted in the tender over the third truck.
They always gave at least an hour of non stop running. Usually even more.
Either the battery packs you have been using are duff or there is a short in the loco.
I have also converted a couple of Connies using 3 x 4.8 volt 1600 mah R/C RX NiMh packs wired in series for 14.4 volts.
They give at least 2 hours running on the flat with a 5/6 car train plus MyLocosound.
Graeme, I agree with Tony, something does not make sense. There is a lot of experience with Shays
I think you need to measure the current on the loco. I would test without sound and smoke if you have them (you may have mentioned earlier in the thread, but I’m watching tv too…)
Do not give up!
Greg
