GAP
G Scale Model Trains, 1:1 Sugar Cane Trains
I think he meant a series/parallel set up ie 2 lots in series giving 14.4V each which you have now, then connect the 2 lots in parallel giving twice the capacity ie 6600mAHr.
Battery v Track power - a personal perspective
- Thread starter ge_rik
- Start date
I think he meant a series/parallel set up ie 2 lots in series giving 14.4V each which you have now, then connect the 2 lots in parallel giving twice the capacity ie 6600mAHr.
Gavin Sowry
Garden Railroader and Raconteur
GAP
G Scale Model Trains, 1:1 Sugar Cane Trains
take 2x7.2V batteries and put them in series
do the same with another 2 batteries
you now have 2x14.4V batteries
Take the 2 x14.4V batteries and connect them +ve to +ve and -ve to -ve
You will end up with 1 big 14.4V battery
Pictures speak a thousand words.
And for a real simple and cheap FWD and REV R/C motor control have a look at this
http://www.members.optusnet.com.au/satr/2point4GHz.htm
do the same with another 2 batteries
you now have 2x14.4V batteries
Take the 2 x14.4V batteries and connect them +ve to +ve and -ve to -ve
You will end up with 1 big 14.4V battery
Pictures speak a thousand words.
And for a real simple and cheap FWD and REV R/C motor control have a look at this
http://www.members.optusnet.com.au/satr/2point4GHz.htm
Gavin Sowry
Garden Railroader and Raconteur
Tony Walsham
Manufacturer of RCS Radio Control.
A word or two of warnings about placing two NiCd/NiMh 14.4 packs in parallel.
You need to equalise them with a diode on each pack + v output to prevent one pack back feeding into the other.
The two packs must be the same chemistry and same capacity.
You need to equalise them with a diode on each pack + v output to prevent one pack back feeding into the other.
The two packs must be the same chemistry and same capacity.
PhilP
G Scale, 7/8th's, Electronics
GAP
G Scale Model Trains, 1:1 Sugar Cane Trains
Rik
Haven't used those batteries yet but keep hearing about them on here.
I have 2 Stainz that are destined for damm good bashing.
Do you have any pics of a battery install so I could get an idea of the size of a complete pack?
Zerogee
Clencher's Bogleman
I realise these are not available for export, but I'm posting this link as an example, I'm sure you could find a local supplier of an equivalent.....these have several advantages - they are proper industrial quality ready-made packs, available in flat or "square" configurations, and with a protection board built into the pack. They are only a little bigger than a pack of 4 AA cells.
https://www.rapidonline.com/ansmann-2447-3032-01-battery-pack-li-ion4s1p-14-8v-2-6ah-inline-18-4126
The "flat" pack should sit quite happily on the floor of a Stainz cab - put a black plastic cover plate over it with a couple of chopped-off-at-the-knees crew figures, and it will hardly be noticeable at normal garden running distances....
Jon.
gregh
electronics, computers and scratchbuilding
Gavin Sowry
Garden Railroader and Raconteur
Well, finally, I've got an acceptable battery system up and running. A change to the layout of the BTE aerial in one of the reefers seems to have down the trick. So, all up, conversion has cost me 2 batteries and some Tamyia plugs. Wire, and Basic Train Engineer were 'on hand'.
Am I going to do any more? After hassles with battery failure, broken connections, and wasted time on battery recharging.... short answer, NO. I will percivere with what I have for the sake of being able to participate in group running days on railways without track power.
GAP
G Scale Model Trains, 1:1 Sugar Cane Trains
Have you used them Greg?
Any idea how they compare is size to NiMH AA cells ie will the fit into AA holders?
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ge_rik
British narrow gauge (esp. Southwold and W&LLR)
Hi
I've done a few Stainz conversions. The first couple used three 14500 li-ions (which are the same size as AA cells). These fit neatly on the floor of the cab and are fairly discrete:
https://riksrailway.blogspot.co.uk/2016/05/how-i-converted-lgb-stainz-loco-to.html
Since this post, I've bashed my own Stainz and extended the side tanks - giving me sufficient room to install three 18650 li-ions. https://riksrailway.blogspot.co.uk/2017/04/how-i-anglicised-lgb-stainz-loco.html - It's not a coincidence that the dimensions of the tanks happened to match the length of the 18650s. The 14500s are fine - I found they gave me around three hours running time but, because the 18650s are larger they can be bought with bigger Ah capacities. Not sure how much running time I get out of those but suffice to say I've never run out of juice in a running session with them.
Rik
Gavin Sowry
Garden Railroader and Raconteur
Question for 'expert' reply.
As noted above, I have two Ni-MH 7.2V packs wired in series(same type, same age). Can I recharge these still joined up, or do I have to recharge them separately? Tony's warnings have got me curious.
As noted above, I have two Ni-MH 7.2V packs wired in series(same type, same age). Can I recharge these still joined up, or do I have to recharge them separately? Tony's warnings have got me curious.
Tony Walsham
Manufacturer of RCS Radio Control.
Short answer is no you cannot. Well, not without dropping more voltage by adding more diodes.
This circuit uses just two diodes and allows for two charging ports. One diode for each sets of battery packs.
This circuit uses just two diodes and allows for two charging ports. One diode for each sets of battery packs.
gregh
electronics, computers and scratchbuilding
Of course you can charge them in series. !!!
(I think Tony has got his parallel and series mixed up)
The situation is really no different to charging the 6 cells within the 7.2V pack, as they are in series.
You don't say whether you are
1) charging them to get started after they have been sitting around for a long time, ie as a 'one-off charge', or
2) if you mean every time you charge them after a run.
for 1) Here's what I would do if I could separate (unsolder) the 2 packs.-
I'd measure the voltage of the 2 packs and if they are within say 0.2V of each other it means there probably is no problem with any cell within the pack. So I'd then connect the two packs in PARALLEL for a couple of hours MINIMUM. This will equalize the voltage and charge between the 2 packs so you can be pretty sure they then both have the same charge.
Then I'd solder the packs back in series.
From then on just charge them as a 14V pack after each run. What I'm trying to do is check that each pack has the same charge before I start.
If I could Not separate the 2 packs electrically, I'd measure the 2 voltages as above and if they are within 0.2V of each other, then I'd bite the bullet and assume they were OK, with fingers crossed, and put them on charge as a 14V pack.
Just going a bit further. When I am making up a pack of say 8 cells in series, I connect all 8 of them in parallel and leave overnight to be sure they are equalised. Then I solder them all in series and treat as an 8 cell battery for charging from then on.
The main consideration when using NiMh in series it to NEVER DISCHARGE the battery. One cell in a series pack will always have slightly less charge than the others, just due to tolerances if nothing else. As you discharge the battery, that one cell will be the first to become completely discharged and will REVERSE ITS POLARITY.
You then have a stuffed cell - it will NEVER have the same capacity as before even if it's voltage seems to recover when you charge it. Your whole battery will then have a reduced capacity equal to that one cell.
Gavin Sowry
Garden Railroader and Raconteur
Found that out, the hard way
Switched the Critter off on the loco, but left the battery connected... didn't notice that the light was still on. That drained the battery over the course of a week. Went to recharge, and the charger 'rejected' it. Lesson learned.I've got two shrink wrapped batteries.
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