DrkAngel
1 GW
bobbill said:
DrkAngel said:
Homemade Battery Packs
- Thread starter DrkAngel
- Start date
bobbill
100 W
Dig! And Thanks, DA.
I buy these cells from 18650battery place on line and they offer applicable graphs?
Will give it a shot.
I buy these cells from 18650battery place on line and they offer applicable graphs?
Will give it a shot.
DrkAngel
1 GW
.
Note voltage drop off point under minimal discharge (eg. 3.35V = good match), but also compare voltage sag under target discharges (wide variance = poor match).
Decision - Poor choice for paralleling!
As long as each "p" (parallel bank of cells) has equal mAh capacity, mAh of individual cell types need not match.
Note voltage drop off point under minimal discharge (eg. 3.35V = good match), but also compare voltage sag under target discharges (wide variance = poor match).
Decision - Poor choice for paralleling!
As long as each "p" (parallel bank of cells) has equal mAh capacity, mAh of individual cell types need not match.
Hope this isn't breaking any rules, but maybe this will be helpful.
[youtube]AnVVCc-fdhU[/youtube]
Cheers
[youtube]AnVVCc-fdhU[/youtube]
Cheers
DrkAngel
1 GW
Just put together a 12.8V 100Ah LiFePO₄ power supply (1.28kWh) for a, near 80 year, old friend. They saw the movie, (cautionary tail imo), Nomadland and mistook it as an admirable life choice.
Anyhow, they need lighting, plan on using an electric blanket, and require a C-pap machine, so, liable to kill vehicle battery pretty quick. I decide on using Lithium-Iron over Lithium-ion due to the more compatible charging voltage, ≦14.4V is perfect for charging LiFePO₄. Just start vehicle and plug into cigarette lighter socket for up to 30A charge.
Well not quite that simple, you need 30A current regulation and a directional diode to prevent backup discharge, most lighter socket have a 30-40A fuse. Lucked into finding a cheap solar panel charge controller: 10A 20A 30A Dual USB Solar Charge Controller PWM 12V/24V Auto Battery Regulator with a LiFePO₄ mode! Has dual usb, voltage meter and on/off output power.
Of course, running a vehicle for several hours for recharge is not often practical so I modified a Meanwell S-320-12 for 14.2V. Had ordered a generic S-600-12 but was sent a S-600-24 instead, and needed something for 4th of July week long trip.
OK, Meanwell S-320-12 oem adjustable voltage is about 9.7-13.8V, which falls way short of effective LiFePO₄ charging which is variously rated from >14V to ≦14.6V. Now the Meanwell S-320-12 is one of the less common\documented models and I had to find the resister in series with the pot to adjust the voltage up. Turned out to be R48, right next to the pot. Metered at 1200ohm. Limited resister selection so tried 500ohm in parallel and faulted the unit, reset and tried 500+350=850ohm and faulted, 1000ohm, my highest worked but allowed adjustment from 12.7V - fault above 16V. recommend 2000+, maybe 5000ohm resister in parallel or 820ohm? replacement for best function.
25A rated Meanwell will over heat into 30A charge controller so temporarily "regulated" with 6' 16awg connection cord.
Replacement 600w 50A PS ordered and will bypass. solar controller for quick charging with dual 12awg leads. If unit overdraws ...
Will dive into S-600-24V cut voltage down to 14.4 and rely 25A x 135% surge regulation for 33.75A charging.
Anyhow, they need lighting, plan on using an electric blanket, and require a C-pap machine, so, liable to kill vehicle battery pretty quick. I decide on using Lithium-Iron over Lithium-ion due to the more compatible charging voltage, ≦14.4V is perfect for charging LiFePO₄. Just start vehicle and plug into cigarette lighter socket for up to 30A charge.
Well not quite that simple, you need 30A current regulation and a directional diode to prevent backup discharge, most lighter socket have a 30-40A fuse. Lucked into finding a cheap solar panel charge controller: 10A 20A 30A Dual USB Solar Charge Controller PWM 12V/24V Auto Battery Regulator with a LiFePO₄ mode! Has dual usb, voltage meter and on/off output power.
Of course, running a vehicle for several hours for recharge is not often practical so I modified a Meanwell S-320-12 for 14.2V. Had ordered a generic S-600-12 but was sent a S-600-24 instead, and needed something for 4th of July week long trip.
OK, Meanwell S-320-12 oem adjustable voltage is about 9.7-13.8V, which falls way short of effective LiFePO₄ charging which is variously rated from >14V to ≦14.6V. Now the Meanwell S-320-12 is one of the less common\documented models and I had to find the resister in series with the pot to adjust the voltage up. Turned out to be R48, right next to the pot. Metered at 1200ohm. Limited resister selection so tried 500ohm in parallel and faulted the unit, reset and tried 500+350=850ohm and faulted, 1000ohm, my highest worked but allowed adjustment from 12.7V - fault above 16V. recommend 2000+, maybe 5000ohm resister in parallel or 820ohm? replacement for best function.
25A rated Meanwell will over heat into 30A charge controller so temporarily "regulated" with 6' 16awg connection cord.
Replacement 600w 50A PS ordered and will bypass. solar controller for quick charging with dual 12awg leads. If unit overdraws ...
Will dive into S-600-24V cut voltage down to 14.4 and rely 25A x 135% surge regulation for 33.75A charging.
DrkAngel
1 GW
Could not pass up a bargain;
Would be great ... if I had any use for 12s!
Watched the accompanying video and loved the 12s2p brick with tabs.
With a bit of de-soldering\soldering I can pull 2s2p and have nice 10s2p 36V bricks.
Wastes 2s2p so why not splice those into another 12s2p and wallah, 14s2p 48V bricks!
Ordered 20, enough for 2 36V 15Ah ($50 each) and 2 48V 15Ah ($50 each). Oops, forgot shipping so ~$60 each.
Bonus, each brick includes a 50+VDC 70A fuse!
Would be great ... if I had any use for 12s!
Watched the accompanying video and loved the 12s2p brick with tabs.
With a bit of de-soldering\soldering I can pull 2s2p and have nice 10s2p 36V bricks.
Wastes 2s2p so why not splice those into another 12s2p and wallah, 14s2p 48V bricks!
Ordered 20, enough for 2 36V 15Ah ($50 each) and 2 48V 15Ah ($50 each). Oops, forgot shipping so ~$60 each.
Bonus, each brick includes a 50+VDC 70A fuse!
Attachments
4S LFP is ideally stop-charged at 13.8V for longevity. No point at all in going higher, the spec sheet 14.4V is only stressful maximum rating.
No need for charge sources labeled "LFP compatible" all you need is user-custom adjustability or a 13.8V setpoint, usually GEL setting works.
Or just use a simple HVC external control.
. . .
Standard ciggie sockets are a dangerous abortion, avoid like the plague for anything important, or that you use regularly. Never more than 5-6A and only for short periods, as in a few minutes. Even then they are risky, an inherently poor design!
Blue Sea has a nice socket design that twist-locks with the matching plug, but will also accept standard ciggie plugs for smaller (<10A) loads.
Also the BMW/ Hella/ Merit/ Powerlet "Euro-style DIN" (ISO 4165) style is very robust.
Anderson plugs for high amps, for me my standard, for almost all power connections.
If you standardize on one of the last two types, there are adapters for guests, temporary use of devices with standard ciggie plugs.
. . .
The Victron SmartSolar MPPT series makes a decent DC-DC conversion charger, but Sterling BB series even better.
Be sure the charge source can **continuously** output the current demanded even in hot conditions, most stock alternators will burn anywhere close to half their fraudulently high label rating.
Leece Neville large-frame firetruck alts can actually deliver 150+ amps 24*7
especially good with external VR like Balmar MC-614 or Wakespeed even better to handle V adjust and current limiting
but most modern vehicles can be impossible to retrofit.
No need for charge sources labeled "LFP compatible" all you need is user-custom adjustability or a 13.8V setpoint, usually GEL setting works.
Or just use a simple HVC external control.
. . .
Standard ciggie sockets are a dangerous abortion, avoid like the plague for anything important, or that you use regularly. Never more than 5-6A and only for short periods, as in a few minutes. Even then they are risky, an inherently poor design!
Blue Sea has a nice socket design that twist-locks with the matching plug, but will also accept standard ciggie plugs for smaller (<10A) loads.
Also the BMW/ Hella/ Merit/ Powerlet "Euro-style DIN" (ISO 4165) style is very robust.
Anderson plugs for high amps, for me my standard, for almost all power connections.
If you standardize on one of the last two types, there are adapters for guests, temporary use of devices with standard ciggie plugs.
. . .
The Victron SmartSolar MPPT series makes a decent DC-DC conversion charger, but Sterling BB series even better.
Be sure the charge source can **continuously** output the current demanded even in hot conditions, most stock alternators will burn anywhere close to half their fraudulently high label rating.
Leece Neville large-frame firetruck alts can actually deliver 150+ amps 24*7
especially good with external VR like Balmar MC-614 or Wakespeed even better to handle V adjust and current limiting
but most modern vehicles can be impossible to retrofit.
aluminumwelder
10 mW
- Joined
- May 3, 2014
- Messages
- 33
they have 48v panasonic packs that are 2x the capacity 300w for $40, so you "save" $20 by tearing down and putting your own pack. for me I"m just lazy and got those panasonic packs.
DrkAngel
1 GW
I have yet to meter the solar panel controller's LiFePO₄ charge voltage limit, or the lighter socket voltage.
Yes, recommended 3.65V (14.6V) is unnecessarily high for typical use. I manually charge with 14.2V, can go lower. Will likely run higher gauge from alternator to solar charge for faster charge, solar controller is 30A and lighter fuse turned out to be 20A.
Yes, recommended 3.65V (14.6V) is unnecessarily high for typical use. I manually charge with 14.2V, can go lower. Will likely run higher gauge from alternator to solar charge for faster charge, solar controller is 30A and lighter fuse turned out to be 20A.
DrkAngel
1 GW
I recommend both, (48V 6.4Ah $40 = $133kWh) but prefer the 12s (43.2V 3Ah $10 = $100kWh) because I need 10s (36V) for multiple bikes and will likely reuse oem plastic shell for finished rebuilds and, of course, I prefer 14s to 13s for my "48V".aluminumwelder said:
Used, or old, batteries so will:
fully "balanced" charge with any BMS removed;
confirm all cells identical @ 4.200V;
let set for 1 week then meter for self discharge;
remove any bad cells; (self-discharge = bad!)
Monitor cell voltages at 2A discharge on 12s battery for 1 hour, or till any cell <3.00V; (2000mAh from 3000mAh rated pairs seems a reasonably safe expectation)
label all cells with remaining voltage for direct cell capacity comparison of all paired cells;
reposition cells, if advisable, to build 10p battery of equal capacity banks.
2x 2p modules are easily repositioned, de-solder\solder tabs.
DrkAngel
1 GW
DrkAngel said:
john61ct said:
Finally found an old LiFePO₄ charge vs capacity chart:DrkAngel said:
3.40V (4x 3.4V = 13.6V) looks ideal !
Of course will balance banks precisely at 3.400V then charge slightly higher on manual, possibly 13.8V (ala john61ct)
13.8V looks very synergic with the vehicles charging system.
I think I must label a static 12.8V as effectively empty and 12.4V as critically empty? (under, even a small, load LiFePO₄ voltage sags noticeably, similarly, charge voltage appears somewhat high for final charged voltage, I liken this to a "pressure membrane" that slightly restricts electrical passage.)
Actually with top balancing better for your balance point to be a tad higher than where you normally charge to, helps them tend to stay balanced longer.
Yes 13.8 (3.45Vpc) can be a convenient standard, so balance at 3.5V. Or 3.40/3.45 talking really the same ballpark.
At rest a little drop is normal, or after the tiniest load to dissipate surface charge, 3.33-3.34Vpc is still 100% Full.
Note different mfg formulations can change things a little, but not hard to get the curve for your bank experientially.
Critical principle is "avoid the shoulders" both ends.
At rest and isolated, 3.2Vpc (12.8V 4S) should only be around half empty.
If loaded then voltage is meaningless, but of course will go lower then bounce back up over time isolated.
Lots of sag under load in the mid ranges means too high a C-rate, or a poor quality manufactured cell.
At rest 3.0Vpc is a good working definition of SoC 0%, which you should not be approaching except in emergencies if you care about longevity.
A 15-20% higher avg DoD can triple lifespan.
But stopping at 40-50% is IMO too extreme, are you trying to preserve the bank for your grandkids?
Yes 13.8 (3.45Vpc) can be a convenient standard, so balance at 3.5V. Or 3.40/3.45 talking really the same ballpark.
At rest a little drop is normal, or after the tiniest load to dissipate surface charge, 3.33-3.34Vpc is still 100% Full.
Note different mfg formulations can change things a little, but not hard to get the curve for your bank experientially.
Critical principle is "avoid the shoulders" both ends.
At rest and isolated, 3.2Vpc (12.8V 4S) should only be around half empty.
If loaded then voltage is meaningless, but of course will go lower then bounce back up over time isolated.
Lots of sag under load in the mid ranges means too high a C-rate, or a poor quality manufactured cell.
At rest 3.0Vpc is a good working definition of SoC 0%, which you should not be approaching except in emergencies if you care about longevity.
A 15-20% higher avg DoD can triple lifespan.
But stopping at 40-50% is IMO too extreme, are you trying to preserve the bank for your grandkids?
bobbill
100 W
John appreciate the info.
Every cell I have acquired, which, admittedly is only 120 cells, or so, has been at 3.6 V which coincides with advice I have received here as optimum storage and at rest voltage. So, I set all to same voltage...as singles. Pack is different. Only cells I use, so far.
Pre-pack voltage begins for them is at 2.6, then I move to (maybe) groups of 3.61 to 3.66, (hundredths) so an in-place BMS is not stressed, also per advice here, and common sense. Why not?
I also know some dodgers here have set cells in packs from 2.9 to 3.7 etc. For me, consistency matters as does operation,These things scare me and I treat with greater respect than gasoline (petrol). Gas has not been as hard on me as cell-science...just a Noob scared-I-cat, I am. And, all y/all save me much grief.
Every cell I have acquired, which, admittedly is only 120 cells, or so, has been at 3.6 V which coincides with advice I have received here as optimum storage and at rest voltage. So, I set all to same voltage...as singles. Pack is different. Only cells I use, so far.
Pre-pack voltage begins for them is at 2.6, then I move to (maybe) groups of 3.61 to 3.66, (hundredths) so an in-place BMS is not stressed, also per advice here, and common sense. Why not?
I also know some dodgers here have set cells in packs from 2.9 to 3.7 etc. For me, consistency matters as does operation,These things scare me and I treat with greater respect than gasoline (petrol). Gas has not been as hard on me as cell-science...just a Noob scared-I-cat, I am. And, all y/all save me much grief.
DrkAngel
1 GW
Bobbill,
Please be aware, recent posts reference LiFe, not LiCo.
LiFe, due to it's narrow discharge optimal voltage range (~3.1-3.4V) is more difficult to trim DOD or Charged voltage. Charge, similar to SLA, uses a higher charge voltage than is maintained in battery, charges faster at higher charge voltage but negligibly increases capacity. Important to use a charger, rather than power supply to charge at higher voltages, charger disconnects as impedance feeds back battery "full". Power supply should be set at nearer the cells 3.40V actual retained voltage.
LiCo has a much broader optimal voltage range ((3.2-3.6V)-4.2V) and can much more easily be tuned for increased lifespan. Cell voltage retains same as charge voltage.
Please be aware, recent posts reference LiFe, not LiCo.
LiFe, due to it's narrow discharge optimal voltage range (~3.1-3.4V) is more difficult to trim DOD or Charged voltage. Charge, similar to SLA, uses a higher charge voltage than is maintained in battery, charges faster at higher charge voltage but negligibly increases capacity. Important to use a charger, rather than power supply to charge at higher voltages, charger disconnects as impedance feeds back battery "full". Power supply should be set at nearer the cells 3.40V actual retained voltage.
LiCo has a much broader optimal voltage range ((3.2-3.6V)-4.2V) and can much more easily be tuned for increased lifespan. Cell voltage retains same as charge voltage.
bobbill
100 W
Dark Angel, Dig, but most is way over this dodger'ss noggin.
Am a simple dodger who powers me two bikes (now) to ride, using 18650 packs, which am sure will be replaced with trickier, more juiced cells, in short time...
Opps, am now doing mower...was using wet 36 but replacing with 10s7p pack. Kinda fun too.
Am a simple dodger who powers me two bikes (now) to ride, using 18650 packs, which am sure will be replaced with trickier, more juiced cells, in short time...
Opps, am now doing mower...was using wet 36 but replacing with 10s7p pack. Kinda fun too.
LFP is **much** safer than the higher voltage li-ion chemistries like NMC.
Also lasts at least 10x longer, care factors being equal, can be decades.
Only downside is lower energy density, so not used much for flying propulsion.
...
Using a PSU or DCDC converter for normal usage cycle charging can be done,
output voltage set to 1% higher
primary stop-charge done via an HVC circuit, usually at pack - level V, isolating source input,
with a failsafe HVC usually at cell - level via the BMS, set to say 5% higher than the pack - level setpoint
Also lasts at least 10x longer, care factors being equal, can be decades.
Only downside is lower energy density, so not used much for flying propulsion.
...
Using a PSU or DCDC converter for normal usage cycle charging can be done,
output voltage set to 1% higher
primary stop-charge done via an HVC circuit, usually at pack - level V, isolating source input,
with a failsafe HVC usually at cell - level via the BMS, set to say 5% higher than the pack - level setpoint
bobbill
100 W
LFP cell are interesting, but in for a penny on 18650s
DrkAngel
1 GW
Was gonna go 8s LiFe on my old 24V SLA mower but bought a pile of the 7s LiCo modules, $50/kWh, too cheap to pass up! At ~30 mows per year, should last me ...bobbill said:
bobbill
100 W
John, no problem. Am learning, and, for me, current money is in 18650a. Thanks...learning new stuff is fun. I figure DC is DC and might make changes later, but taking time.
DrkAngel
1 GW
Dismal disappointment!DrkAngel said:Could not pass up a bargain;
Would be great ... if I had any use for 12s!
Watched the accompanying video and loved the 12s2p brick with tabs.
With a bit of de-soldering\soldering I can pull 2s2p and have nice 10s2p 36V bricks.
Wastes 2s2p so why not splice those into another 12s2p and wallah, 14s2p 48V bricks!
Ordered 20, enough for 2 36V 15Ah ($50 each) and 2 48V 15Ah ($50 each). Oops, forgot shipping so ~$60 each.
Bonus, each brick includes a 50+VDC 70A fuse!
Bought 20 and received 19 totally dead (<1V) and 1 @ <5V.2 pair (4 cells). 99% dead with < 70% capacity on the "good" 4.
Requesting return-refund or replacement with working.
bobbill
100 W
If you end up having to keep...let me know...may have link to how to revive cells...
Sorry to hear....
Sorry to hear....
DrkAngel
1 GW
Complained of problem and was promptly offered full refund!DrkAngel said:Dismal disappointment!DrkAngel said:Could not pass up a bargain;
Would be great ... if I had any use for 12s!
Watched the accompanying video and loved the 12s2p brick with tabs.
With a bit of de-soldering\soldering I can pull 2s2p and have nice 10s2p 36V bricks.
Wastes 2s2p so why not splice those into another 12s2p and wallah, 14s2p 48V bricks!
Ordered 20, enough for 2 36V 15Ah ($50 each) and 2 48V 15Ah ($50 each). Oops, forgot shipping so ~$60 each.
Bonus, each brick includes a 50+VDC 70A fuse!
Bought 20 and received 19 totally dead (<1V) and 1 @ <5V.2 pair (4 cells). 99% dead with < 70% capacity on the "good" 4.
Requesting return-refund or replacement with working.
Will harvest 20x 50.4VDC++ 70A fuses. No volt rating on fuses, likely 83VDC or higher?
Overclocker
10 kW
copper. with cooling holes strategically placed to allow reading of voltages from each p-group
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