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Old inverters, new batteries

np84

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Mar 22, 2021
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Years ago, someone had installed two Tripp Lite APS2012SW 2000W 12 volt pure sine inverters connected to (one each) VMAX 200ah AGM batteries. These were connected to two circuits in the house and worked great for protecting various tv's, computers, etc around the house (we live in Texas, so you know our grid quality). Well, the batteries were past their prime, so I purchased two of Battery Hookups 100ah batteries made of prepacked 32650 cells. A friend volunteered to change them out and I thought he knew how to do it safely. Hardly. He just pulled the old batteries out and connected the new ones. No turning off breakers or inverters--nothing. The batteries have JBD bms on them, so I can connect through bluetooth and that shows the batteries are ok, but the inverters will not turn on. Did my friend fry them? Is there a way to fix this or do I just need to cough up the cash for two new inverters? Thank you.
 
I have no experience with the APS2012SW or your Battery Hookups battery.

Sniff test: 2000 watts / 12V = 166 amps which is high. Check the battery and BMS output ratings.
 
I have no experience with the APS2012SW or your Battery Hookups battery.

Sniff test: 2000 watts / 12V = 166 amps which is high. Check the battery and BMS output ratings.

I guess the efficiency for that inverter is not great.
2000 ac watts / .8 conversion efficiency / 12 volts low cutoff = 208.333333333 service amps.
 
Any chance the connection was made in reverse polarity even for a second?

Otherwise I have only heard good stuff about TrippLite. Should have run just fine.
 
Any chance the connection was made in reverse polarity even for a second?

Otherwise I have only heard good stuff about TrippLite. Should have run just fine.
I don't think so. I asked him because everything is in a close where only my friend could see. But he said he basically just unscrewed the old batteries, negative, positive, then attached that to the new battery in the same order. He said one of the inverter came on briefly--maybe 10 seconds. It was passing through grid power and charging the battery at the same time. This was normal operation, but it stopped after a few seconds. This has me thinking Delmar is right--the batteries are undersized for the inverters. I have reached out to Tripp Lite to try and find out.
 
Very true. I'm looking into going solar as fast as possible because even when the grid is on, it's sooooo dirty that it's not worth paying electric companies for it. Also, since the big freeze, natural gas and electric companies have monthly increased rates and fees. My bills last month were almost exactly double the price of Aug 2020, but my actual usage was about half for both.
 
Just in case someone else runs into one of these inverters, I did finally find the specs--they do require 250 amps at 12 volts DC.
 
I am sorry but I bring Bad News of a sort. Every single inverter out there has Capacitors and they "require" pre-charge to prevent a Huge & Sudden Surge demand upon connection to power, believe it or not, it really is a big surge but short duration. Older Inverters have less efficient Capacitors (they have changed a LOT in the past 15 years) and in fact, many Inverter Manufacturers use smaller Super-Capacitors now.

When connecting battery packs to an inverter, 1st thing is to have everything turned OFF ! and if connecting from a Common DC Buss (which is what you describe with batteries in parallel) Positive is connected FIRST then the Negative Second.

Pre-Charge:
This is something NOT required by Leaf/AGM and similar as those chemistries are essentially brute force tech and there is no electronics involved (at battery level). Here comes the TRIXY PART, some BMS' but NOT ALL have built-in precharge circuitry, which allows a small amount of voltage through a resistor to feed the capacitors prior to startup for a couple of seconds. Other BMS's require a manual precharge. There are various ways to accomplish that fortunately NONE ARE EXPENSIVE. We have many threads on this here in the forum and of course there is a load of good creative solutions on YT.

The GOTCHA !
This May or May Not have happened to you. The JBD/Overkill BMS' do NOT have a precharge circuit. When connecting such and the Big Spark happens "sometimes" the BMS' (collectively) can deliver that huge surge and survive BUT if it is too much it can trip the BMS into Failsafe cutoff or worse pop the FETS on the BMS making Magic Smoke.

Old Inverters:
While they will continue to work "In General" their charge/discharge profiles & cutoff points may NOT be optimal and generally are not as they were designed for Brute Force Tech. LFP "12 Volt System" needs to cutoff discharging NO LOWER than 10.0V and cutoff charging at 14.6V NO HIGHER. The internal BMS in each pack will cutoff at those points, independent of the Inverter. LFP should also NEVER be charged below 32F and only limited charging (no more than 0.2C) to 45F with Max Charge rate of 0.5C rate.

SPECIAL NOTES:
No Lithium Chemistry takes Equalization !
All Lithium uses only CC (Constant Current) and CV (Constant Voltage) for charging only.
Lithium does NOT Use Temperature Compensation either.
Some older Inverters cannot disable or reprogram Equalization or worse cannot be configured properly which are "toss aways" for Lithium Base Battery systems.

Hope it helps, Good Luck.
 
Just in case someone else runs into one of these inverters, I did finally find the specs--they do require 250 amps at 12 volts DC.
Please confirm the your Battery Hookups battery and JBD BMS you are attempting to run.

For precharge I use an old 100W light bulb that gives a visual indication. When the light goes out the caps are charged.
 
Steve S, thank you so much for taking the time and effort to explain so well in detail. I believe I am safe on all counts, but I do have a couple of new inverters I can use if I need to. The way the old ones were installed by the previous owner makes it really difficult to change out, so I'm hoping once I get new batteries, all is well.

Delmar, a resistor (saw Will's video) was used to pre-charge, so again, I'm hoping all is well.
 
As luck would have it, I just got gifted one of these inverters, and I happen to have an SOK 100AH battery. I found this link:
where BattleBorn discusses using a different model of TrippLite inverter with their LiFePo4s.
I like the 100w Light bulb idea, wonder what the resistance is.
Finding more than a few instances where I want to replace a lead acid battery with a LiFePo4, and not sure how to work around it. I also just installed a DSC home alarm which uses an old school lead acid battery as it's failover power. I'm wondering what the circuit would need to be to use this chemistry with these older fully functional devices.
 
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