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jsahara24
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# Posted: 5 Apr 2022 09:29 - Edited by: jsahara24
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I just acquired (free) a powerpack that is pretty old and has been neglected for some time. Xantrex Xpower1500. It has a built in inverter, a DC port and regular battery terminals.
I checked the voltage and it was ~10 volts. I hooked up the charger that comes with it (5 amps) and left it charge for about 18 hours. At that point it was still charging and appeared to be taking a charge. I checked it right after I took the charger off and it was reading approximately 12.5 volts. I let it sit for a few hours and tested it again, 11.5 volts. I turned on the AC outlets and tested them, got ~98 volts.
I'm not sure if I'll be able to bring this thing back to life or not, but I was thinking perhaps I should bail on the 5amp charger and put my 1.5 amp trickle/maintainer charger on it and leave it on for a week or two and see what happens. Good plan? Or should I keep the 5amp charger on it?
If the battery inside ends up being shot, I was wondering if I could possible replace the battery that's in there. Not sure if that is even possible, but I have been watching youtube videos of people building lithium packs and its seems like an interesting project. Couple pics of the unit attached...
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Nobadays
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# Posted: 5 Apr 2022 09:52
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What is the date of manufacture? If it's 8-10 years old the battery is at the end of it's service life but it won't hurt to try to bring it back to life. Honestly bringing it back up to 11.5 (the reading when you disconnected from the charger was surface charge) .... if it holds that is a good sign. Keep on charging! I'd use the charger that came with it unless you have a good smart charger.
Should be no reason you can't pull the old battery out if it's shot and replace it with similar or a lithium pack that fits the box. Good score!
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paulz
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# Posted: 5 Apr 2022 10:01
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Definitely worth playing with. Simplest and cheapest would be another lead battery of course. A lithium battery should work on the output side but might need a specific charger.
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jsahara24
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# Posted: 5 Apr 2022 10:36 - Edited by: jsahara24
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Not sure on the age, I looked and didn't see a date anywhere....It was my father in laws, who has passed a couple years go, so I'm sure it hasn't been touched since then....
The black top is secured on by about 20 screws, if it doesn't take/hold a charge then I'll open that up and see what I find in there....
It would be nice to use at our little cabin on the creek, right now I'm using a walmart 27 series deep cycle with a small inverter....I bring the battery back to the house to charge, which isn't a big deal considering its on our property where we live and I toss it in the UTV....And its a completely wooded setting, the closest place I could install solar panels would be ~350' away so I'm not sure that it makes sense financially...
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gcrank1
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# Posted: 5 Apr 2022 11:19 - Edited by: gcrank1
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Id be all over that! Top would be off already  Break the screws loose by hand then power-screwdriver 'em out.
I thought about having a remote array with a 'doghouse' for the scc and a perm. basic 'marine/leisure' battery that I could drop off/exchange another bat, or unit like yours, for a recharge of a day.
Currently, with my old handy jump-start pack that I use for light-duty stuff, I use a cig-ltr plug in the car. Round trip from the cabin and back pretty much keeps it topped up.
As to re-bat'ing your unit, maybe check the charger output volts. If it maxes out at no more than 14.2 while hooked up to a low'ish battery it should be ok for a LFP (Im using 14.0 on mine even though the company says I can go 14.6; for me that is too high!)
With that unit I wouldnt be surprised if you couldnt drop in at least a 50Ah LFP, which would make it a very nice portable. If it would hold a 75-100Ah, wha-hoo.
Remember, that 60Ah AGM it comes with was only good for a dod 50%, giving about 30Ah, and would have been far better off only using 15-20Ah per cycle.
The built-in inverter is probably only a MSW too.
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jsahara24
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# Posted: 5 Apr 2022 13:07 - Edited by: jsahara24
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haha...yeah I thought about opening it up but I figured id throw it on the charger first and see what happened....
I did check the voltage on the battery when the charger was hooked up, it was around 14.5 volts. Sounds like that may be too high for Lithium?
Correct me if I'm wrong but I believe my deep cycle battery is around 95AH, the power station has 60AH, but we want to limit draw down to 50% to maintain longevity. With lithium we can draw all the way down without affecting longevity?
I also just acquired an electric golf cart from my FIL, an EZGO. It has trojan T105 6V batteries, I opened them up and they are completed dry. Those batteries appear really old, so I was planning on replacing them in kind. But then I ended up down a YouTube rabbit hole seeing a lot of people are switching to lithium in them as well..... My concern is that I won't be able to charge them in the winter, as I don't have any heated space...I have plenty of barns, but no way to really heat them......so id have to wait for a warm day I guess?
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gcrank1
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# Posted: 5 Apr 2022 14:28
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Charging LFP below freezing is not just the ambient air temp, it is the battery temp; they need to be a internal heat above 'about 32*f (for easy figuring).
And the cost of LFP for an elec golf cart would be expensive!
As I said, my LFP supplier specs 14.6v for their chargers. The 4 cells in a 12v LFP settle in at rest about 3.45 each, or 13.8v. You charge them higher and they still settle back there. Too high; ie, above that 14.6, and the High Voltage Disconnect will trigger (hopefully!). IF it doesnt you will cook the cells to death.
My choice is to charge at 14.0 which still gets me 99% of 'full charge', never gets to the HVD trigger point or endangering the cells. If I had a 14.5ishv charger Id put it on a cheap timer (so I could actually forget it) and learn its charge curve into the LFP.
And, yes, pretty much ALL the Ah's as 'rated' are usable...repeatedly....FAR more charge/discharge cycles, dont mind being deeply discharged and MUCH faster/higher rate recharge. Now that Ive 'crossed over' they are imo ideal for cabin use as long as you dont try to recharge below freezing. Note that for use below freezing you can draw power from them if you keep it 'light'.
So, if you leave them at 70-80% (NO danger to LFP partially discharged unlike FLA) over-wintered at the cabin (and inside is fine), show up you have lights, get the heat going and everything inside warms up together, inc bats.
For us I bought LFP about the 1st of year. As we ended up going to the cabin more than I had expected I just carried the 100Ah bat (<30#) back and forth; So light weight/No worries! Recharged only once at home after 5? day trips of using it 3-4 hrs each trip (constant cheap ceiling fan to 'circ the warm air and some little led lighting, both 120vac off the 300W psw inverter.
Basically I started out at something a bit less than 100% charged and kept taking it and running whatever I wanted to until the LVD cut it off. This way I found my 'bottom' for usage. Fwiw, it 'fell off' quickly after it hit 12.8v; but between that and 13.8ish (yes, only a 1v spread) I had all those Ah's of use! Now I will just take and use to 12.8 and swap my bats out and keep on truckin'.
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gcrank1
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# Posted: 5 Apr 2022 14:34 - Edited by: gcrank1
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Btw, if you want to find out if your inverter in that unit is msw or psw just try to run a basic cheap house box fan. If msw it will growl and not really want to run right.
On my old jump-pack, it has a 20Ah agm, I had to recharge it several times to get it to take and hold a charge, but it did. Downside is it really only has about 1/2 the calc Ah's it should. It isnt worth putting a LFP into whereas your unit may be.
Take a look online for modding or refurbing that unit, you may find there is already good info out there.
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jsahara24
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# Posted: 5 Apr 2022 16:14
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Got it...Thanks...I will put it back on the charger when I get home from work and report back with my findings....
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Brettny
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# Posted: 6 Apr 2022 07:27
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Typicaly you cant just plop a lithium battery in place of a SLA battery. The voltages aren't quite correct.
If your place is a weekend getaway you should do some simple calculations on how long the 500 cycles of a typical SLA battery will last. In some cases its 5+yrs. In my case its 8-10yrs.
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jsahara24
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# Posted: 6 Apr 2022 09:15 - Edited by: jsahara24
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Good point, my off grid cabin is on my farm so its more a place to stop when we are out riding UTVs, have campfires with friends, etc. Doesn't really get used too much....
Lithium is likely not needed, but I was watching videos of folks building lithium packs with multiple 32650 cells, and it looked like an interesting project that could be done pretty cost effectively....
When I got home last night my voltage had dropped really low, in the 9 volt range....So it didn't hold the charge I put into it, I put it back on the charger and will see what it looks like when I get home tonight....Thanks
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gcrank1
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# Posted: 6 Apr 2022 10:13 - Edited by: gcrank1
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Ime, when the voltage drop is that severe the bat is toast.
When one looks salvageable the voltage will hold above 12.5ish over weeks but the Ah's of use will be down.
Remember, a FLA 12v (nominal) battery is basically dead at 12v.
It is the voltage that 'pushes' the amps, no real voltage means no beans.
You can probably get a replacement SLA bat off Amazon for not too much. For your circumstances I suggest going with the biggest (not just size but more importantly the Ah's) battery that will fit in the box.
Regarding 'building' a LFP.....well, I have the skills but not the time now or motivation, and winter is over. All kinds of info over at Diysolarforum.com but best of all is info from Steve_s both here and there. Fwiw, it isnt just boxing up 4 LFP cells! And for cost effective, it will still be pricey if you use quality components. If it was everybody would be doing it.
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Steve_S
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# Posted: 6 Apr 2022 10:50
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Building "Lithium" batteries can be complicated depending on the Lithium Chemistry (there are a few). Most preferred for "Residential Energy Storage" is Lithium Iron Phosphate (LiFePO4/LFP) because it is the safest of the chemistries and the easiest to work with.
Cells are readily available from China but that can take 6-8+ weeks thanks to the shipping shenanigans. Fortunately there are several Good Vendors stocking cells in the US, sure the cost is higher per cell but that is after S&H, Duties & levies are applied (can't get around that).
Unlike cylindrical cells, LFP is a Prismatic and have either screw-in studs or welded on studs to interconnect the cells which makes it simpler for DIY.
LFP can safely discharge to -30C/-22F but cannot be charged below 0C/32F. They can be stored in cold with a Charge but NEVER EVER when Flat !
LFP Assembly guide I wrote here:
https://diysolarforum.com/resources/luyuan-tech-basic-lifepo4-guide.151/
LFP Full Voltage Range for 12V (2.500-3.650)
10.0V = 0% SOC completely flat @ 2.500V per cell.
14.6V = 100% SOC+ @ 3.650V per cell.
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Working Voltage Range is 3.000-3.400 Volts per cell.
This is where the AH delivered comes from. ie: 12V/100AH
Working Range for 12V (12.0V-13.6)
YES, this is Lithium and that is the Flat Voltage Curve!
With Lead, AGM,Gel using Voltage for DOD is "loose" because of the chemistries & their curve. This is NOT the case with Lithium Based Batteries. SOC is measured by 3 Decimal Point place Voltage ! 100mv represents a significant amount in the real world. These batteries unlike Lead etc are Millivolt & Milliamp sensitive.
Consider that you can have a Battery at 100AH and that 100AH is delivered from 3.000V to 3.400V per cell... That is 100AH spread over a 400mv spread.
I had to mention that again because for some reason everyone misses the fact of the Tight & Narrow window. But also because this is where much older equipment (pre lithium era) kind of fall short as they are not designed for this "fine" of a useage.
Hope it helps, Good Luck.
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paulz
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# Posted: 6 Apr 2022 11:36
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Co-incidentally I was just about to trash my original jump starter pack (I have a couple of lithium ones now) but figured I'd take it apart first for parts (only 8 screws..). I checked the big SLA, it was around 12.5, so I put a charger on it. That was a week ago, and it's holding a 12.6 charge. So I guess I'll keep it around, and probably find some use for it.
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gcrank1
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# Posted: 6 Apr 2022 18:32 - Edited by: gcrank1
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Paul, I ran mine on its own charger several times, didnt get past a certain point. For all I know that charger may have never really fully charged that SLA bat.
I think mine may have got the best results after I hooked up my smart charger that has a recondition mode, and let it go for days. My charger has a 2, 10 and 20 amp selection so for that little 20Ah bat I used the 2A setting. I dont use its oem charger any more.
It is just a little handy power pack for me, I took off the jumper cables and wired on a SAE cable & connector for easy plug in of those kind of accessories.
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Brettny
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# Posted: 6 Apr 2022 21:11
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Generaly smart chargers for bringing batteries back to like arnt very good. they charge a specific amount and then turn off. You want a transformer charger. They really push the juice and dont turn off. This can knock off the sulphate off the lead plates. I have hooked a 4a charger for days on end and it does help but you need to keep an eye on the water level.
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gcrank1
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# Posted: 6 Apr 2022 23:25
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Mine has been a dandy, it hits its target, does a pause while monitoring and restarts to cycle again as needed. It has given 'new life' to several of my seasonal equipment bats, the old solar system agm's, the jump-pacs, etc.
Ive got an old plain transformer 6A that has killed a few bats, too easy to forget about. All on me but when a guy gets used to 'automatic' chargers........timers are helpful for me.
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jsahara24
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# Posted: 8 Apr 2022 14:43
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So I've tried charging it 3 times now, each time after a rest period its back down to 10volts or so....So I took the lid off, three small 20AH - 12V batteries, wired in parallel.....
Going to see what I can find that will fit in its spot....Thanks for all the advice....Couple pics attached..
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Brettny
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# Posted: 8 Apr 2022 15:44
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Looks like a typical 21ah SLA battery. They should be about $50 each on amazon.
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paulz
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# Posted: 8 Apr 2022 17:39
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Yep. I used to get those for free from a pal who changed them out on a calendar cycle (not usage or condition) for big companies, used it alarm systems, backup power etc.. Always had plenty of life left in them.
Also about the size of a Harley battery.
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gcrank1
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# Posted: 8 Apr 2022 17:50 - Edited by: gcrank1
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Remember, the 'lead acid' of any type bats have that max 50% dod/soc or you kill 'em, much better at 25-30% dod (70-75% soc).
So, those 3 20Ah bats were 60Ah when new, then pretty quickly degraded to 50Ah.
That is 25Ah at the 50% MAX, 12.5Ah at 25%.
If you bought one 40Ah LFP you would get at 40, even a 20Ah would give you 20, well more than the 12.5.
Deduct the price of replacement LA bats from the price of an LFP to see if you can stand the extra spent, then figure the LFP will last easily 2x as long.
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Brettny
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# Posted: 9 Apr 2022 11:58
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It's also likely that the battery cant even support an output of 1500w for more than a few seconds.
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