malewithatail
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Post by malewithatail on Jul 28, 2023 8:32:11 GMT 10
Whilst cleaning and oiling the weapons the other day, I noticed that the green dot sight was a bit dim. Further investigation revealed that the battery was less than 2 volts. As it's a non rechargeable battery based on lithium technology, its terminal voltage should have been around 3 volts. Getting a good quality battery is around $15 each, say EverReady or Duracell. And, even though the shelf life of this type of battery is 10 plus years, rechargeable's make more sense, especially if they become unavailable due to society collapse. The paks of 10 for $20 available from Wollies etc are conventional carbon/zinc battery's and not worth it due to their limited shelf life and low ampere hour capacity. Now, a little about battery's. Modern lithium's are around 3.7 volts when charged, so the green dot takes one battery, but the high power led torch next to it takes two, making an over-voltage of 1.4 volts on the led, and 0.7 volts on the green dot. Now, Jaycar sells a special battery and charger that has some electronic smarts that drops the voltage to 3 volts and is therefore compatible with a standard non rechargeable lithium type cell. Ringing the local Jaycar agent revealed that the battery and charger was now a discontinued item, but it may still be available from agents. Into town today and the local reseller did indeed have a charger and battery in stock, so far so good, but that was all. I needed 3 batteries, and they only had the one that came with the charger. Jaycar also has a set of 4 conventional lithium battery's and a matching 4 bay smart charger. All up around $70 odd. These battery's are conventional lithium, unprotected and with a terminal voltage charged of 3.7 volts, may cause damage to the optics. I read the instructions for the optics thoroughly and it didn't mention anything about rechargeable batteries, so I bought these. I charged them up on the way home, and tried them in the gear. The green dot worked perfectly, so I left it running whilst I fitted them to the torch. Switching it on and all that happened was a flash. Obviously the voltage was a bit high, at 7.4 volts vs 6 volts. How to overcome this ? A little electronics theory now. A normal silicon diode has a forward voltage drop of around 0.6 volts, whilst a germanium type is around 1/2 that. So, 2 silicon diodes in series will drop around 1.2 volts, giving 6.2 volts on the torch, much closer to the correct voltage. Digging through my box of diodes for two suitable diodes was easy, and a quick lash up showed it did indeed work. Now to make it permanent. I made two small circuit boards the same size as the battery diameter, and rummaged through the box of diodes to find a single diode that had a reasonable voltage drop. I found a high voltage one that dropped around 1.2 volts and was quite small. This I fitted through a small hole in each circuit board and bent the leads to loops to make contacts. It was fitted between the battery's, the right way around as a diode is a virtual open circuit when reverse biased. Viola it worked perfectly. The lid was a bit tight to fully screw on to make it waterproof, but I finally got it seated and properly waterproofed. I am still concerned that the green dot is being over-driven, but I had it on for the whole time I was stuffing around with the torch and it didn't get hot, so the constant current led driver seems to be able to cope with the extra volts, and I will probably make a single diode version for the green dot. I measured the power consumption of the green dot at 375 ma, and the torch at 320 ma, so the 700 ma hour rechargeable battery should last for around 2 hours continuous, and the charger can recharge the battery's in less than 30 minutes, so a quick battery change every few hours will keep things running. The lesson from this is to be aware of the limitations of your gear, and also having and seeking knowledge to modify stuff is going to be vital after the collapse. Knowledge will be power.
Who controls the energy can control whole continents.
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frostbite
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Post by frostbite on Jul 28, 2023 8:42:05 GMT 10
If you need any parts you can’t get in the wild west send me a link or photo of what you need and I’ll check the local stores in the big smoke.
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malewithatail
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Post by malewithatail on Jul 28, 2023 9:10:55 GMT 10
Thanks mate, will do.
I might do a comparison between green and red dot sights as well soon.
It’s Easier to Fool People Than to Convince Them That They Have Been Fooled.
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Tim Horton
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Post by Tim Horton on Aug 6, 2023 0:22:20 GMT 10
I'm curious to know how your experiment works out over a period of time... I'm suspecting you are quite more knowledgably and experienced with electronics than the average person.. And curious if this replacement can be reduced to a simple enough procedure that someone much less skilled can use it successfully...
That less skilled person being someone like me... I have never had a good experience with rechargeable technology regardless of the battery size or application... KnowwhatImean...
Good luck and please post a follow up...
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malewithatail
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Post by malewithatail on Aug 6, 2023 9:14:19 GMT 10
So far, its all working as it should. Just tested the led torch and green dot and they worked perfectly, so no issues with parasitic leakage currents as its been a week or so since fitting the battery's. The theory behind it is explained, as above, but having the bits may be the issue for the average prepper who doesn't collect 'junk' from the tip 'just in case'. Making a circuit board was easy, just clipped of a couple of pieces from the edge of a defunct remote control, ground it round on the bench grinder, drilled a couple of small holes in them to allow the diode leads to poke through and bent the leads into a circle to make contact with the battery end caps. The circuit board prevents a short circuit. Yes, its a bit fiddly to put the arrangement together, and you need to get the diode the right way around or it wont work (no damage will happen, it just wont conduct as it will be reverse biased). Perhaps a MK 2 version will have 2 diodes back to back, so it wont matter which way the board is inserted. I think the experience we have with rechargeable battery's, depends on the quality of the rechargeable battery you buy. I have some old EverReady AA ones that are at least 10 years old and they still work perfectly, whilst some chain store cheapies have died after a few uses. The Aldi ones are good as well and I have lots of AAA types that are a few years old and used in led torches for the kids. I have several chargers, a couple of the aforementioned EverReady types that came with the battery's, a Jaycar 10 AA or AAA charger/dis-charger and the newest 4 cell multi chemistry, multi size one. It has a digital display that tells the charging current, battery voltage and amp hours gone in. It automatically selects the right chemistry, nicad, nimh or lithium and charges from a USB port on the PC or a separate USB mains unit. I have used it to charge up the popular 18650 lithium cells and it works well, if a bit slow due to only having a 1 amp USB charger spare. It also handles two 18650's in parallel, like in some torches. It cant do the 9 volt types, but I have other charges that can charge them and they are not a very good solution anyway, with short lifespan and expensive. I had a couple of 18650 cells that were dead flat, zero volts, and the charger tried to charge them as nicads. I really fast charged them on the 12 volt charger for a few times, at about 10 amps for a minute, with a break between to allow them to cool down, and after a few shots, quickly placed them into the charger and it correctly set itself up for lithium battery's, and charged them properly. The charger also seemed to do a recovery stage of resting the battery on charge when it got too hot. Cool piece of kit for the price.
This charger, as mentioned, has a display that indicates how much charge, in amp hours, has been put into the battery to charge it. Very useful readout.
Say you have a 18650 cell, from a reputable manufacturer, rated at 2,500 mah. Its no longer able operate the torch, so you charge it up and when its full, the display reads 1,340 mah gone in. Somethings wrong, the cell is rated for 2,500 mah, and only took 1,340 mah. Is it the cell faulty, or the torch ? Fully discharge the cell using a small 6 volt light bulb, and try again. This time you get 2,350 mah, so the cell is good, but it would seem the cut out voltage on the torch is a bit high. Useful information.
By the way, the ads on the net for 18650 battery's with 10,000 mah (10 amp hour) ratings are impossible. You have been told, don't get ripped off. The cell doesn't have enough active plate area to get anywhere near that capacity, even at 100 % efficiency. That's why there is the bigger 26650 and 21700 cells were designed. rated at around 5,000 mah reliably.
They also sold a charger with a 3 volt lithium rechargeable battery, that had internal diodes presumably and didn't need the stuffing around with, but its no longer stocked, otherwise it would have been the solution without needing the extra diodes to drop the voltage. www.jaycar.com.au/lithium-ion-cr123a-battery-charger/p/MB3581OH no, not another learning experience !
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Beno
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Post by Beno on Aug 16, 2023 22:15:25 GMT 10
These battery's are conventional lithium, unprotected and with a terminal voltage charged of 3.7 volts, may cause damage to the optics. I read the instructions for the optics thoroughly and it didn't mention anything about rechargeable batteries, so I bought these. A little electronics theory now. A normal silicon diode has a forward voltage drop of around 0.6 volts, whilst a germanium type is around 1/2 that. So, 2 silicon diodes in series will drop around 1.2 volts, giving 6.2 volts on the torch, much closer to the correct voltage. Digging through my box of diodes for two suitable diodes was easy, and a quick lash up showed it did indeed work. Now to make it permanent. I made two small circuit boards the same size as the battery diameter, and rummaged through the box of diodes to find a single diode that had a reasonable voltage drop. I found a high voltage one that dropped around 1.2 volts and was quite small. This I fitted through a small hole in each circuit board and bent the leads to loops to make contacts. It was fitted between the battery's, the right way around as a diode is a virtual open circuit when reverse biased. Viola it worked perfectly.
Wow that’s cool that you fiddled with the circuit to drop the voltage. I have a couple of eotechs and they don’t like the rechargeable 3.7 volt cr123s at all. They appear to go into limp mode and don’t fully light up so i reckon there is some over voltage protection going on. With the AA type eotech, using rechargeable lithiums does not seem to worry it and it works perfectly. My thermal scope seems to like the rechargeable cr123’s. go figure?
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malewithatail
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Post by malewithatail on Aug 17, 2023 7:57:10 GMT 10
My thermal scope came with internal 18650 lithium's. Go figure. The lazer works perfectly with the rechargeables, the torch not. Same manufacturer.
De Beers: “A diamond is forever.”
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malewithatail
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Post by malewithatail on Aug 19, 2023 9:27:41 GMT 10
Picked up a smaller camping type lantern from the tip. It has about 30 really bright white leds, and a hand crank on the top. It also had a small 6 volt lead acid rechargeable battery that was split down the side and obviously useless.
What to replace the battery with ? The obvious choice, at least voltage wise, would be 5 off NIMH types, which would be 6 volts (1.2 v/cell), but I wanted something with more capacity for a longer run time. Lithium's were the choice here. So I tried one 2,500 mah lithium cell. It worked, for about 2 minutes, then the light stopped. Probably due to under voltage cutout as the lithium is only 3.6 volts, not 6 as original. So that isn't gunna work.
2 lithium's in series would be OK, 7.2 volts nominal and over 8 volts on charge. How to make the setup 6 volt compatible ?
2 silicon diodes in series would drop around 1.2 volts, and be pretty well independent of the current drain as their voltage drop is almost constant. I tried this and it worked the treat with the lamp staying on for several hours till I got sick of it and wanted to complete the setup.
Charging was next.
The crude charging setup or the lead acid battery was a simple 330 ohm 1 watt resistor, connected to 12 volts dc, giving a charging current of around 40 ma. Whilst constant current charging is OK for lithium battery's, it must be voltage limited to prevent overcharging.
The two series connected diodes wont let any current flow in reverse, that's their function as a type of one way valve for electricity, so just connecting the 12 volts to the existing charging circuit wont work. A resistor across the diodes would allow current to flow, but would also interfere with the forward voltage drop by allowing a current to bypass the diodes, resulting in a higher voltage and possibly an over-voltage cutoff situation. However, another diode connected in reverse across the two already there will work, although at a 0.6 volt drop. As we have a 12 volt supply anyway, 0.6 volts extra drop is of no consequence on charge, and I changed the charging resistor to 100 ohms to get more charging current into the battery's, around 70 ma, making a full charge from flat in around 30 hours. The power rating of the resistor is 0.07 X 0.07 X 100 or nearly 1/2 watt, so a 1 watt resistor will kill it.
Stay tuned.
I also picked up another Companion brand camping lantern that uses a 12 volt lead acid battery. Its bright red and in perfect condition and came with the original carry bag. It is old school in that it uses a miniature fluorescent lamp, but I have several spares anyway. The battery was obviously totaled, so its a candidate for a lithium upgrade. 4 off 2,500 mah battery's from an old laptop battery pack will give around 14.4 volts and should work well. Once again, stay tuned.
Knowledge will be power in the newly fallen world. Knowing how to adapt things to work will be vital for survival. Learn now.
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malewithatail
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Post by malewithatail on Aug 19, 2023 14:19:17 GMT 10
Follow up on the led camping lantern battery mods.
Measured the current drain of the lamp at around 700 ma, 0.7 amp. So a 2,500 mah lithium battery will last about 5 hours, that's adequate, and with the charging circuit modified to charge at 400 ma, will fully charge in around 6.6 hours. So far, so good.
Left the lamp running whilst set up the electric fence for the sheep and came back 1/2 hr or so later. Still lighting up, but the battery's were quite warm, hot even. Not to melting the tape off the insulation type heat, but still uncomfortably hot to touch.
Obviously, old laptop cells are not designed to be discharged at the 4 hour rate. Luckily, the charge reaction of lithium battery's is slightly endothermic, so as they charge the battery's will cool a little. Left them on charge and after they did indeed cool, when they approached full charge at the constant current, they began getting quite warm again. Practically I don't think its going to be much of an issue as during use, its gunna be an emergency situation and not necessarily an every day occurrence. And even if it is, the battery's are rated for 2,000 cycles to 100% discharge, so should last for a few years.
The only issue could be if we had to bug out and rely on the lantern for light, the battery's would eventually fail. But that what backups are for.
Did some more measurements of currents etc, and decided to change the charging resistor to 8.2 ohms from the original 3.9 ohms. This will 1/2 the charge current, effectively doubling the charge time to 8 hours in full sun, but that's still acceptable. The power the resistor needs to dissipate will also drop to around 300 mw, and a 1 watt resistor will be OK. The only fly in the ointment would be if the lantern is on whilst charging, then the resistor will dissipate about 2 watts, which it can do for a short time, but will eventually damage it. I also added a protection diode to the circuit to prevent the battery from discharging back into the solar panel in the dark.
See, a practical demonstration of knowledge, not boasting, but you all need to know at least basic electronics theory so you can repair your own gear after TSHTF. Or you will be risking extinction. Basic formulas for voltage drop, power dissipation and current flows. Learn now folks before there is no more time left to learn.
Perhaps if we ever have a meet up I could run a workshop on basic electronics, solar and electrical. That will take me back to my TAFE (then called Technical College) teaching days !
Now, on to the red Companion lantern, like I said, backup.
Don't let anybody ruin your day, ruin it yourself !
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malewithatail
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Post by malewithatail on Aug 19, 2023 16:20:39 GMT 10
Now to the red Companion lantern.
It used a 12 v, 4.5 amp hour battery, which would have given around 5 to 6 hours use. It was being discharged at 0.86 amps on full and 0.54 amps on 1/2 brightness. I'm ignoring the nite light function as its a minuscule power drain anyway.
So, 3 off lithium ion cells at 3.7 volts, would be 11.1 volts open circuit. In practice, the lithium battery terminal voltage is a bit higher than this. 4 would be 14.8 volts, a bit higher than our 12 volt lead acid battery.
Some tests were in order.
Using 3 battery's in series, the open circuit voltage was indeed around 12.4 volts dc, dropping to 11.1 after 30 minutes or so. The lamp continued to function at 11 volts for several hours until I turned it off to finish off the install. Charging happened at around 1.8 amps initially, dropping slowly to 0.8 amps after a few hours, but once again, the charging method is rather crude with just a resistor and diode in series with the 12 volts power adapter. The battery pak again runs quite hot during discharge and charge, but it does work. Considering a new lead acid battery is over $30, and old laptop battery paks are free at the local tip, its a no brainier.
The right thing to do is 4 lithium's in series, giving 14.4 volts under load, rising to over 16 volts on charge. Once again, diodes to the rescue. I will probably do this as it will give more capacity, and hence a longer run time. There is plenty of room inside the lantern for 4 small 2,500 amp hour lithium cells. The current drain of the lamp at 0.86 amps, will give about 3 hours run time, which is adequate for emergency use, and about 6 hours at 1/2 brilliance.
Stay tuned........
All the scarcity in the world is engineered as a means of control.
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malewithatail
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Post by malewithatail on Aug 20, 2023 9:13:51 GMT 10
Modified the 3 cell pak by adding a 4th cell. Open circuit volts now nearly 15 volts, so much too high for normal operation of a device designed for a 12 v lead acid battery with a nominal working voltage of 13.8.
Time for some more diodes.
This time I used some fast recovery type diodes I had recovered from discarded equipment, type RGP20J. The data sheet showed that at 2 amps, the forward voltage drop was 1.2 volts, almost twice that of a standard silicon diode, and perfect to drop the volts down. A test setup was made and the voltage under load at the lamp terminals was 13.5, perfect.
Once again, a second diode was connected reverse across the first, allowing the battery's to charge. The 240 v power adapter worked OK, but the 12 v charging cord was not particularly well designed, as it only charged at whatever voltage the 12 v battery was at. In the car, with the engine running it would have charged the lantern battery reasonably well, but without the engine running, the charge voltage would be too low. For bugging out/camping purposes, this isn't an issue as I have several 12 v (nominal) solar panels removed from defunct electric fences that have open circuit voltages over 18, so will satisfactorily charge the lantern over a period of 6 to 8 hours in full sun.
On test, the lantern ran at full brightness for nearly 4 hours, and was charged in 1 day. On low it went for over 6 hours, so the modification works quite well. Add to the fact that lithium battery's are far better than lead acid types when cycled and the overall life span of the setup is improved.
The next job is to make up some decent cables to charge from the solar panels, as the supplied one is very flimsy and wont take too well to continued use. That's an easy job for a rainy day, if it rains again before the second coming !
Another mod may be to add a second pak in parallel with the first to allow for a longer run time, but this would not charge fully in one day, so could be self defeating.
These lanterns, even though several years old, are well worth the effort in modifying for lithium battery's as they are robust and do give a bright, white light, much better that leds. Probably not EMP proof as they have electronic jiggery pokery stuff that runs the tube.
Governments produce scarcity by shutting off pipelines, shutting down farming operations, taxing productivity and deliberately causing food shortages and inflation. Money printing steals savings from everyone, creating scarcity of the purchasing value of dollars previously earned.
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malewithatail
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Post by malewithatail on Aug 20, 2023 12:09:11 GMT 10
At this stage I haven't added any cell monitoring or battery monitoring system, BMS, as its a device under test. Ultimately, a BMS will be needed as the cells age to compensate for the ageing.
Anyway, the less electronics the better in an EMP event, and a simple series circuit of 4 cells without monitoring will survive better than one with a BMS. Besides, the BVMS also gives a better life from the cells, but as they are basically 'free' from old laptops, who cares ? There could be some safety issues with self immolation of cells under charge, but once again, my risk assessment is 'so what ?'. The amount of damage one set of cells can do is minimal, I know as Ive destroyed some just to see how they perform, and anyway, during a SHTF event they will be charged outside from the solar panel. Keeping them charged before needed just means charging them in the open air, and I have a charging shelf beside the radio room for just such items. It is about a meter long and 250 mm wide, so can take everything that needs charging, is outside, but under an awning, so if something suffers a meltdown, the smoke etc will dissipate easily. The 240 v to the charging rack is also on a light sensitive switch so it turns off at night.
Fear, panic, grief, a sense of pervasive loss, and the shattering of meaning and purpose would make an adaptive response difficult, perhaps impossible …
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