An article has been added to the Lone Star Section site on building a 6V battery, to fit into a hard-rubber case, using LiFePO4 cells. Credit goes to oexing on this forum, for the original idea.
Misc: Electrical (General) 6V Lithium Iron Phosphate Battery
- Thread starter LoneStar
- Start date
Yes, had 4 of them LiFePo4 from Ali as the rarely used R 69S showed a dead dry lead battery at the MOT test in August. The lead batteries seem to die early when not used much. So I emptied the case for the total 12 V four LiFePo4 to go in there - a mess to do , some acid on the paper towel layers between plates always remains so you watch your hands and all.
In the end I made an alu lid as the plastic did not survive my operation. This is held by a few screws and in case a battery turns weak it is no problem exchanging it. No need to throw away the complete lead accu as I had in decades often enough. No special electronics required for these Li batteries, had same types in other classics for years, no trouble. For 6 V systems two of them will do, the ones I got are said to be 12 AH, which I do not quite believe. But on the BMW it does not matter - Bosch magneto and 3 ph 280 W alternator. Exactly the 3 ph alternator with its diodes NEEDS the accu, it would not start producing power when no initial field current is provided by a small accu. I had to return from Scotland to Munich many years ago only on the magneto because the battery had collapsed. So no lights and all but the mag saved my return trip , no problem.
Vic
LiFePo4 accu
In the end I made an alu lid as the plastic did not survive my operation. This is held by a few screws and in case a battery turns weak it is no problem exchanging it. No need to throw away the complete lead accu as I had in decades often enough. No special electronics required for these Li batteries, had same types in other classics for years, no trouble. For 6 V systems two of them will do, the ones I got are said to be 12 AH, which I do not quite believe. But on the BMW it does not matter - Bosch magneto and 3 ph 280 W alternator. Exactly the 3 ph alternator with its diodes NEEDS the accu, it would not start producing power when no initial field current is provided by a small accu. I had to return from Scotland to Munich many years ago only on the magneto because the battery had collapsed. So no lights and all but the mag saved my return trip , no problem.
Vic
LiFePo4 accu
Morning Vic, would this type of batteries also be used as starting ones??
of course bit more.
of course bit more.
I have mentioned before I have a lithium 12v battery in a dummy 6v box I have not used a kickstart on my Comet in over a year. A mile or a mile and a half of riding after the start returns the charge ammeter to zero.
It stays up for months It did cost over £100 ... But you know what? its worth it.
It stays up for months It did cost over £100 ... But you know what? its worth it.
If one reads about the charging requirements of Li ion batteries then it would seem that they should not be used unless one has a special charger to use with them. On many sailing boats where they are used many users go to the trouble of having a DC to DC charger to take power from the lead acid batteries to charge the Li ion ones. When people started to fit this type of battery to bikes using a Walkernator, which is just a normal car alternator fitted to a Vin, I was originally worried about the lifetime of these batteries. I recently bought cheap battery charger and that even has a position on it for use with Li ion batteries. However, after several years of use it seems that whatever we should be doing in an ideal world we do get away with it on out bikes. Tim (Vibrac) has had his system for over a year. There are other riders who have been using this combination for five or more years and it would be good to hear from them whether any of them have suffered from premature battery failure.
As to charging these batteries I believe the LiFePo4 type is quite different to the pyrotech plastic bag Li-Ion type you have in laptops and smartphones. These electronic "balancers" for charging may be a good idea for the Li-Ion kind like in e-bikes that light up in times when on the charger. But I had no troubles with the LiFePo4 shown above and run them in 3 or 4 bikes already, some in a 6 V system and with non-electronic regulator, still the old Bosch types - but you check the voltage setting certainly for close to 7 V .
When having a number of small accus connected for running a starter you´d have to look at the bridges between cells. I would be nervous using the thin standard connectors soldered up for power packs. You´d have fatter wires for connecting the lot and maybe have a battery with M 6 screws for starter wires . There are hundreds of amps drawn from accus when a decent starter has to turn a big engine, so maybe you better have a ready-made 12 V big battery instead, not a soldered up combo of small cells. I cannot tell much about these big packs and you´d have to look into peak current discharge properties for starters. They got the balancers inside obviously , makes you feel better I think, as a big defect can lead to quite dramatic fires that nobody can put out.
The alu cover in my gutted out case in photo just squeezes on foam rubber on top of cells, all space is filled with foam rubber too, lot of space left as only 4 cells fit easily in the old case , no trouble. It is a few hours messing around but the 4 cells are only € 18.- total and can be replaced once you notice voltage dropped by a dead cell.
Vic
power pack LiFePo4 12 V
When having a number of small accus connected for running a starter you´d have to look at the bridges between cells. I would be nervous using the thin standard connectors soldered up for power packs. You´d have fatter wires for connecting the lot and maybe have a battery with M 6 screws for starter wires . There are hundreds of amps drawn from accus when a decent starter has to turn a big engine, so maybe you better have a ready-made 12 V big battery instead, not a soldered up combo of small cells. I cannot tell much about these big packs and you´d have to look into peak current discharge properties for starters. They got the balancers inside obviously , makes you feel better I think, as a big defect can lead to quite dramatic fires that nobody can put out.
The alu cover in my gutted out case in photo just squeezes on foam rubber on top of cells, all space is filled with foam rubber too, lot of space left as only 4 cells fit easily in the old case , no trouble. It is a few hours messing around but the 4 cells are only € 18.- total and can be replaced once you notice voltage dropped by a dead cell.
Vic
power pack LiFePo4 12 V
There is a reason normal Li batteries use a special charger.
As the current or resistance or what? can change.
Shorai brings a carger to equal all them cylinders again. Parralell or serial connection does it..
I have used them for over 6 or so years now. More or less as i don't like to throttle up lead...
On one bike its on its 2nd or 3rd now. As deep de-charge kills m.
So looking on.
Cheers
As the current or resistance or what? can change.
Shorai brings a carger to equal all them cylinders again. Parralell or serial connection does it..
I have used them for over 6 or so years now. More or less as i don't like to throttle up lead...
On one bike its on its 2nd or 3rd now. As deep de-charge kills m.
So looking on.
Cheers
What are normal Li batteries ? They are all not the same and when they go onto Vincents I would not think you need much of charging control - not much power coming from Vincent dynamos or Altons for needing control of charge. You want all there is for charging anyway . . .
Vic
Vic