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Post by papaof2 on Jun 18, 2022 12:24:46 GMT -6
Use small pieces of 1/4 foam (one inch squares?) at different levels on each cell for the other fill so there can be air flow. This might be a good place to have a friend with a 3D printer who could make some "air ducts" and you could use them as the side bracing and to direct air from a DC fan - lots of DC-DC buck converters to bring your battery voltage down to the 12 or 24 volts of readily available fans.
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Post by biggkidd on Jun 18, 2022 19:37:43 GMT -6
I do have a friend with a 3d printer. lol But I think I'll use strips of foam. If I can work them down in there. Already have a converter mounted to the outside of the box for all my 12V needs including the fan and heat mats.
Been hearing a strange noise the last couple days turns out one of the roof struts broke where a bolt mount hole goes through it. So I pulled the seats apart so I could get at it and tried brazing that only lasted about a minute for a couple hours work. I wasn't a bit surprised I think something else somewhere else may also be broken or cracked making this piece take to much strain. I'll hunt it down later. Got a half baked rear light mounted and wired up part of the way. It's not nearly as bright as I had hoped so I may have to find something else. Also working on moving the meters to a different location where I will be able to see them better. I had only temporarily mounted them before planning on this. They will both be overhead and a little closer for the driver to be able to see easier.
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Post by papaof2 on Jun 18, 2022 22:22:19 GMT -6
The only brazing I've done was repairing some of the bracing on a step-stool, done with a MAPP torch, and that step-stool is still in use 20 years later. I have equipment for flux core (Harbor Freight, 90 amp, about $100 when I got it) and stick welding (banggood.com, some unbelievable number of amps, about $50 last year). The Banggood stick welder realistically is in the 30-90 amp range which is adequate for 3/32" 6013 rod (40-90 amps). 6013 is primarily for clean sheet metal assembly but it has other uses.
The stick welder is something I didn't get to last year (year of the thumb rebuild) and not yet this year (year of the pinched lower back nerve) but I do hope to do that next year ;-) I was a "summer gofer" at a shop that built truck bodies somewhere between high school and college. I welded up a large tool box out of scrap sheet metal that summer. The toolbox turned out almost square and unquestionably useful so I have some ancient learning to fall back on when I again attempt stick welding.
I've used the flux core welder to extend a shepherd's crook hanger for two bird feeders to get the feeders above the "squirrel jump limit" and that was at least 15 years ago so the cheap welder does work and I can make sturdy (not pretty) welds.
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Post by biggkidd on Jun 19, 2022 4:20:52 GMT -6
These struts are Aluminum which is something I've never welded. I have a couple 3 welders here though and I have the aluminum wire and proper gas for welding with it.
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Post by papaof2 on Jun 19, 2022 11:28:57 GMT -6
Welding aluminum is an entirely different animal - at least in the opinions of some of the welders who worked at that shop. Not something I've yet had occasion to try, although I have some "weld aluminum with your torch" material (DuraFix) that looks like a different welding stick (there's also Alumiweld). They make high claims for DuraFix so I added it to my toolbox. I probably qualify for "tool poor" because there's a small fortune in the basement - but I've been collecting tools since my hands were big enough to use those things ;-)
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Post by biggkidd on Jun 19, 2022 16:26:47 GMT -6
I might maybe just possibly resemble that remark! LMAO
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Post by biggkidd on Jun 20, 2022 18:44:09 GMT -6
The super oversize BMS arrived today a whole lot earlier than expected. Now to figure out where in the heck it's going to go it's MUCH larger than what I had designed for. I designed for a 100 amp BMS not this 250 amp BMS. It is HUGE and HEAVY and has 2AWG wires.
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Post by papaof2 on Jun 20, 2022 20:45:24 GMT -6
Well, you didn't really need that front passenger seat, did you? ;-)
Some of the support pieces are BIG :-(
I plan to replace the two 12 volt, 7AH AGM batteries in the pure sine wave UPS that powers the 50" TV, cable box, DVR, DVD and Blu-Ray recorders with an LiFePO4 battery pack. The best deal I found on a 24 volt BMS was a 60 amp one, but the 3.8AH cells that will make up the 8s2p pack can provide 12 amps continuous and 28 amps for 30 seconds. Two strings providing 28 amps is 56 amps so the 60 amp BMS is needed to handle the peaks. The UPS is rated 810 watts, 1325VA and 24 volts * 58 amps is 1392 watts DC (DC VA and watts are the same - it's only AC where they might be different depending on the type of load being powered). If push came to shove, that UPS could be pressed into service for an hour or two of running the fridge or freezer so it needs to have the surge capability. I haven't planned anything on the construction of the battery pack yet because I need to have the BMS in hand to see how big it actually is with the cables attached and whether I'll need to build an oddly shaped battery pack to try to fit it and the BMS in the original battery compartment. I can always add an external "case" for the BMS to the side of the UPS if I must...
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Post by biggkidd on Jun 25, 2022 20:10:12 GMT -6
It was nearly an all day ordeal but I finally managed to shoehorn the BMS mostly inside the battery box. It looks like I may have a couple problem cells. One is rather much higher than the others and the other is a little lower than the others. The BMS appears to be trying to balance them as the numbers are SLOWLY getting closer together.
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Post by papaof2 on Jun 25, 2022 22:03:36 GMT -6
One value of a good BMS is the balance function. Given time, it will get the cells to the same voltages but that may take a while with cells in the 100AH range. Regardless of mass production, there's always the possibilty that the cell built at 9:12AM won't exactly match the cell built at 9:13AM and neither may match the cell built at 9:14AM - that's just the vagaries of mass production where every square inch of the cell material isn't exactly identical to every other square inch. The differences are small, but if you're putting 100+ amp drains on cells in series, those on the low side will tend to go lower and those on the high side will tend to go higher unless they have outside help. Remember the Sony laptops that caught fire while sitting on charge? It just takes one cell getting too much current and getting too hot to start that fire and then the entire lithium battery pack goes up in sparks and smoke. UPS lost a cargo jet that was carrying a big cargo of lithium ion cells (something in the tens of thousands). One cell ignited and venting the cargo space to atmosphere at 30,000 feet had no effect on the fire as the cells produce their own oxygen when they get hot enough. The plane went down before the pilots could do a 180 and get it back to the airport.
Execpt for one BMS I came across in looking for a 24 volt, 60 amp unit, most don't do a high current balance. One BMS did offer something like 5 or 6 amps as the balance current, which should work very well with the larger cells. If you watch many videos of DIY battery makers (off-grid garage on YouTube, for example) you'll hear them complaining about how slow the balance function is. I'll probably do some testing of that when the BMS gets here and I build the 8S2P 24 volt, 7.6AH pack. Considering the battery size compared to the BMS size, my pack may have faster than usual balancing because a BMS handling 60 amps was designed to go on a much bigger battery pack than 7.6AH ;-) If there's room in the UPS' battery compartment, I have enough cells to make an 8S3P pack and add 50% to its capacity - and to the UPS run time. Just having a battery pack that delivers power down below the UPS' low voltage shutdown level will extend the runtime some.
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Post by biggkidd on Jun 28, 2022 14:25:13 GMT -6
I've got the Li battery in the house running the AC. Might wait until fall before I put it in the GC. The batteries in there are doing okay. I am also toying with the idea of going ahead and swapping them and trying to use the existing GC batteries to run the AC. I would really like to have this one in the GC for the added performance and weight loss but being able to run AC all night without using gas is worth a lot considering how much fuel has gone up. Still thinking on it.
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Post by papaof2 on Jun 28, 2022 15:53:04 GMT -6
The LiFePO4 battery can handle an 80% discharge much better than the golf cart batteries can, so work out what the Depth of Discharge is - based on current battery capacity, not the original numbers on the older batteries. If an AGM battery is at 12.15 volts under load, it's at or below 50% state of charge and it's time to stop draining it. What are those batteries doing under the load of the A/C?
The 24 volt, 60 amp BMS arrived today and it's smaller than I thought from the numbers on a picture of the unit. I may be rethinking the layout of the 8s2p battery pack - just need to unplug things from that UPS, take the existing batteries out it and measure the actual space available with the BMS in the battery compartment. Be better to have the BMS outside for ventilation, but the way most UPS units charge their batteries, the battery connections could be at line potential - not something I want on the outside of the UPS. I can probably dig up a 12 or 24 volt fan and I have a design for a temperature controlled fan that's been running maybe 10 years in an A/V cabinet so it's a solid design - but the fans keep wearing out ;-) Yet another thing that will require me to lift something heavier than I should or work in the floor - neither of which is kind to my back - I hate being old :-(
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Post by biggkidd on Jun 28, 2022 19:23:48 GMT -6
I don't know what they are doing all they are still in the cart. I should just leave them there for the summer even if I don't want to. My house system is also 48 volts and I try hard not to let those get below 49.6 with a load on. Probably why they've lasted this long...
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Post by papaof2 on Jun 28, 2022 20:15:35 GMT -6
If you take good care of your batteries, they will take good care of you. I got almost 8 years out of the first set of AGM batteries on the solar syatem - pretty good for batteries with an advertised "5 year service life" ;-)
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Post by biggkidd on Jul 4, 2022 17:47:00 GMT -6
Finally put the LifePO4 battery in today. Holy Smokes alive! Stupid quick is the only thought I can come up with for it. If you can imagine getting axel hop in a golf cart then you know what it feels like. Loosing 260-270 pounds and adding about 7 volts under full load really was a game changer. I'm actually a little afraid to mash it straight out anywhere it might get traction. Can not wait to get some taller SOFTER tires. It rides even rougher with the weight loss. Also looking forward to switching it over to a newer type system some time down the road. It would be nice to be able to run a lot slower without all the heat waste this one has. Went almost exactly 8 miles down logging roads and still had 71% state of charge when I got back. The new systems with regen motor braking would be a lot, maybe even twice as efficient as the current system.
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Post by papaof2 on Jul 5, 2022 10:02:10 GMT -6
Nice when things turn out even better than you expect ;-)
I've been very pleased with the small replacements I've done using LiFePO4 cells (UPS battery replacement). For less than the replacement AGM battery, I have equivalent capacity (AH), a low voltage cutoff that's lower than the UPS' low battery shutdown voltage (UPS stops with battery at 10.7 volts, LiFePO4 BMS is 10.0 or 10.2 volts) and the LiFePO4 pack is good for perhaps 2000 charge/discharge cycles versus the maybe 200 cycles for an AGM - plus the BMS prevents the UPS from overcharging the battery in an attempt to get it back to full charge in minimum time.
I found some 18650 LiFePO4 cells (about 800maH) that look to be useful in many places - they're rated for 10 amp discharge ;-) They were $16 for 16 cells - I ordered 32 but should have ordered more as they were out of stock the next day :-( I have a Chinese "bazaar sales booth" lighting system that uses a 4 volt, 8AH AGM battery (more than 24 hours of illumination using just the light on the unit) but a 1s10p pack of the LiFePO4 18650s would fit in the same space and last almost forever ;-) In that application, I could easily parallel the cells as they each have a BMS and have separate charge and discharge ports which would work with the light's design and provide overcharge and over-discharge protection - over-discharge protection is a good thing if other people might be using your emergency lighting ;-)
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Post by biggkidd on Jul 6, 2022 9:37:05 GMT -6
Went to install a temperature gauge on the cart motor and found I had bent both rear leaf springs since switching the battery! Does anyone else know what can cause leaf springs to bend hard in front of the axel mount? To say the least I was surprised when I saw it. Last time I saw something similar the truck had over 1000hp and steam roller tires. I think maybe my little project could be making some torque. LMAO
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Post by papaof2 on Jul 6, 2022 13:27:23 GMT -6
More motor torque than the spring(s) can handle without the load of the batteries?
Single leaf or multi-leaf springs?
Multi-leaf springs get stiffer as the load increases, so possibly the softest leaf could not handle the torque of the motor because there was not enough weight to bring the other leaves of the spring into play?
I think you may have mentioned "wheelie" in one post...
There's also the matter of 48 volts applied to a 36 volt motor, so the possibility of at least 1/3 more torque than the springs were designed to handle.
That's the best answer I can offer without seeing the thing in person. You ready to drive it to the southeast US? Today there's enough sun to keep it going on solar power alone ;-)
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Post by biggkidd on Jul 6, 2022 13:52:32 GMT -6
Single leaf both sides are bent pretty good too. I wanted HD rear springs so now I'll have to save some more bucks and order a set. Bad news they've gone up from $89 to $119 in two months!
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Post by papaof2 on Jul 6, 2022 15:03:00 GMT -6
Is there a local galf cart junkyard or repair shop? Maybe find something you can adapt (Maybe springs from one of the "limo" versions?) for a lot fewer $$?
Is there a Craig's List active in your area? Check craigslist.org for a local link. You never know what you might find: 140KW diesel generator - free - you move it, and a couple of months later, 8000 gallon fuel tank - free - you move it - if I just had a place to put it and the vehicle needed to move it, I could power multiple houses during the next long power outage ;-) Also lots of clothing, furniture, UPS units and scrap lumber plus chickens, pigs and rabbits if you want to raise your own.
Lots of time versus money alternatives.
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Post by biggkidd on Jul 6, 2022 15:26:43 GMT -6
I could swap the springs off the other cart BUT I think I'd end up right back in the same place. I'll hold off and order the HD springs when I can. Need new shocks all the way around too.
I search CL for deals just about everyday. Problem is everything worthwhile is so dang far away.
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Post by biggkidd on Jul 6, 2022 16:22:36 GMT -6
So I just went out to check the current voltage and charge status. The only charge it's had today was from the solar roof and the battery is pretty much full. It's actually a little fuller than I'd like it for the longest possible battery life at 55.3 volts resting. I have the BMS programed to shut charging off at 56.8 which it had done. I may have to drop that a little lower. I'm not so worried about all the power I can get but I am trying to make this battery last as LONG as possible! That does seem to answer the question of if just one 300 watt panel in place of the roof can provide enough charge for my daily use. I didn't do a lot of extra running today but I did make the chore rounds and a few other things.
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Post by papaof2 on Jul 6, 2022 16:37:02 GMT -6
You have to figure the round trip cost per mile into anything "free" ;-) Same when you're paying directly - if it's $2 cheaper at the Walmart that's 20 miles up the road, how much gas/diesel do you burn driving there instead of buying at the "more expensive" local store? In my teen-aged truck (14 years old), I get 20MPG in town and maybe 25 on the highway. At $4.42/gal, 40 miles at 25MPG is $7.07 - don't think that $2 savings is worth the trip - unless I'm buying at least 4 things that are $2 cheaper ;-) 20 miles round trip for five 12 volt drill/drivers is low cost when I have a stack of "bad" Ryobi 40 volt battery packs (2AH+ cells) that I can salvage to have power for all those drill drivers. Not worth it if I'm paying $5-$7/cell to re-battery those packs but OK at $1 or less per cell. Basic 3 cell pack is $3; a 4 cell pack (18 volts) is $4, a 5 cell pack (20 volts) is $5 (plus a little time). A 4AH pack is twice the price (twice the cells) but most of the cheaper drill/drivers only come with a 2AH battery pack and Joe "Can I borrow a dril?" Jones doesn't know the difference. I can "loan" a neighbor a bottom-of-the-line Black & Decker cordless drill/driver and be a "great guy" - and it's no great loss if I don't get that drill back. I won't be loaning the 18 volt Ryobi drill/driver that just won't die or the 18 volt Ryobi hammer drill ;-) If those old 18 volt tools would die, I'd have reason to replace them with the latest and greatest - but they just keep running and my frugal gene won't let me replace any tool that gets the job done :-( You should plan your solar charging around not having sun half the time when you need it. The solar panel(s) should be able to recharge two days' typical usage in one day's sun. That's the rule of thumb for my "never in the dark" solar designs - for you that might be a "never on foot" design ;-) No matter how good it looks right now, do you have even half your current sun hours in the winter? For me, the numbers from www.solarelectricityhandbook.com/solar-irradiance.aspx work out to ~5 hours/day in summer and ~3 hours/day in winter (before adjusting that for more days of clouds in winter). If you need to do the same number of miles in winter as in summer, you'll need solar power - or a plug-in charger - adequate to keep up with the winter usage. Winter use typically means more hours of using headlights, so the total battery power used will increase for the same number of miles driven.
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Post by biggkidd on Jul 6, 2022 16:57:33 GMT -6
Today was only "sunny" half the day and even then it was through a haze / overcast. But yes you are correct I will not truly know until freezing weather when the battery heat has to come on and days are all cloudy. On the plus side I'm a lot more active in warm weather and on sunny days. Cold and cloudy doesn't do much for me.
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Post by biggkidd on Jul 6, 2022 17:06:40 GMT -6
I just changed the charge controller parameters from lead acid to LFP 15s we'll see how that does. I haven't gotten everything figured out for custom programing the charge controller for a 16s system yet. I may not have too since this looks like it may be just what the doctor ordered for long battery life. If I am guesstimating correctly this will let the charging current get up to about 55.5-56 which for my purposes should be just about perfect! That should limit the battery voltage to about 54-54.5 which is right in the neighborhood I'm looking for.
From my tests so far it looks like I can do chores and stay on the property for about 4 full days without ANY charging. So I am of this moment fairly convinced it will suit my purposes nicely.
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