Has anyone tried or know if you can run Li-Ion battery packs in series or in parallel? I know they have the PCB pretector in them and was wondering if it would limit the battery or stop it’s use?
Thanks,
Terry
I do use them both ways and all works quite well with no limiting problems.
Thanks. I’m looking to do an install for an ABA and double up the batteries in parallel for some looong run times.
It will work to give your the result you are looking for, but to make charging simple provide a means to charge the packs independently.
I have the capability to run two packs in parallel in both my trail cars. Each pack has it’s own disconnect plug. I can run with a single or dual pack depending on need.
Curious about the run time. I run two in parallel to increase amperage for large locos. Didn’t know that it would add to run time. I’ve never used up a pack (or pair of packs) in a single day’s running.
Wiring in series you add the voltage together so 2 14.8 would be 19.6. Remember series is connecting one batteries negitive to the others positive effectivly making them one big battery. Wiring in parallel doubles the amps. So, 2 5amp batteries will give you (about) 10 amps increasing run time.
I planned on isolating the batteries to charge them separately, otherwise it would take forever to charge them.
Terry
Oops…29.6 
Terry, just how long are you wanting to run with those 10 amps?
Terry, if it takes a long time to charge, you could find a larger capacity charger most likely, but it’s best to charge the packs separately, otherwise you have no “balance control” for the charging current between them.
Greg
Larry you’re right 29.6… lol sorry.
Steve, the setup isn’t for me. I have a guy that has a layout he likes to switch and operate but when family or friends come over he wants to just let a loco run in circles. The layout never had power put to it (i believe) and would be too much work to redo with track power.
I ran lithium-ion battery packs in parallel in my Evans power car.
(http://ovgrs.editme.com/files/EvansPC/PowerCar.jpg)
I used a four-pole, double throw switch (part # STS-71) from All Electronics.
(http://ovgrs.editme.com/files/EvansPC/4P2T.jpg)
The two charging connectors were attached to the left column of screw terminals, the battery packs to the middle column, and the receiver to the right column. Toggling the switch on way allowed the two battery packs to be independently charged.
(http://ovgrs.editme.com/files/EvansPC/Charging.jpg)
Toggling the other way connected the battery packs in parallel to power the receiver.
(http://ovgrs.editme.com/files/EvansPC/Running.jpg)
The devices attached to the positive screw terminals are diodes to ensure the packs did not interact. The red/pink material is the insulating collar of the loop connector and some insulation stripped from some heavy wire. All the charger, battery, diodes, and negative receiver wires are soldered to number 6 loop connectors. If you want to read the whole story, just click on the link. http://www.ovgrs.org/EvansPC
Wiring two separate lithium battery-packs in parallel will only gain more voltage and not runtime. Lithium cells need to welded in parallel to actually gain more amp hours. You would be better off adding a DPDT switch and keep the packs separate then just switch between the two packs when the PCB kicks in.
We have tested this and what happens is one battery slowly goes out of balance, and if you don’t have a cell balancing charger to bring each cell back to nominal voltage you will loose years of the life of your battery-pack.
Keep the separate!
Rick Isard
Cordless Renovations, LLC
RCS America
Rick Isard said:Really? It gains you more voltage and not run time??
Wiring two separate lithium battery-packs in parallel will only gain more voltage and not runtime. SNIP!!!
Greg!!! How about you explain it please?
Batteries in parallel will give more amps not voltage!!!
If running two packs with PCB charge them seperaty for faster charging…
heck us a 8400mAh 4S2P 30C LiFePo4 Pack for about $75 buckand by a PCB Protection Circuit Module (PCB) for 4S LiFePO4 Battery Pack (5/12A)
Sale Price: $8.28
and be cheaper than the battry company…
So can they build a battery pack for 8400 mah yeah…for under $100 buck … just have to look around. Will it have a balance port to check each cell and monitor them yes, can you balance charge them yes. The other manufactors do not have a balancing port in which you can check each cell…
I use a parallel board all the time for my electric R/C aircraft. I use a custom cable or PC board but unplug my battery packs for individual charging. These are LiPo, but there is no difference in behavior between battery types when hooked up in series or parallel. Series = higher voltage : Parallel = higher amps
By hooking up my batteries in parallel I get much more current available and keep my packs cooler by not over-taxing any one pack.
Mark same thing here… I use packs in parallel in my planes too…
Daniel, have one “burn” on ya yet? Boy, that’s exciting!!!
leah an old one from a crash…6cell 5800 mah at 30c
Whats fun is we have a rc plane club at the high school here!!! Indoor flyins and use the stadium and axu fields.
Daniel,
That’s not accurate, lithium-ion cells have to be welded in parallel to gain more amps or you have to bypass the PCB in each pack, wire 4, 5 or 6 (depending on the voltage) individual wire leads from pack to pack bypassing one of the PCB to gain more amps. You may think your gaining more runtime but in fact you just have two battery-packs in series at twice the voltage.
Rick Isard
Cordless Renovations, LLC
RCS America
Rick - Not arguing with you, but your statement above says both parallel and series. Which is it?
I’d really like a concise answer on this question since both of my trail cars were set up to allow two battery packs in parallel. I rarely run them that way, but the thought was to gain current for larger locos.
Might it be that the issue is muddied by the pulsewidth modulation that we use?
It’s elementary that batteries in parallel will give same voltage 2x current, while in series will give same current 2x voltage (or near enough not to make a practical difference)
In a resistive load like light bulb, the current drawn is directly related to the resistance of the load and the voltage (up to the current capacity of the source). A motot is an inductive load, and has some differences from this, but put that aside for simplification for a moment.
Now, in our locos, we use pulsewidth modulation to decide how much juice gets to the motor. A 1000 v pulse for a thousandth of a second is theoretically equal to a 1 v pulse for a whole second. In practice, the pulses are much shorter, and we’d try never to send 1000v into our trains, but you get the idea.
The net result is that if there is enough voltage at 100% pulse width to make the train go as fast as you want (or faster) and the battery can deliver enough current (an amp or three, generally not a problem) to support the load, then, it seems to me, the speed controller can take care of the rest. Whether your battery bank is 14v or 28 v or something more almost does not matter to desired speed or run-time, as long as you can get your maximum top speed at some percentage less than or equal to 100%.
You may find charging easier if the batteries are in parallel.
Twice the battery capacity, in this view, equals twice the runtime at any given speed, yes? The key difference is maximum theoretical speed. (aka, hit the floor)