Head scratcher...RV install

[Newenough]

Picked up on Wills recommendation video a TimeUSB 220ah 12.8v lifepo4 battery The plan is to just replace the house battery with this unit. But, it appears the BMS has a different plan. When I connect it to the existing batteries location, the voltage drops to 0, and you can hear the BMS "click". No output. When disconnected it will show 12.4 again. I tried connecting just a small 300w inverter to it (no load) with just the alligator clips, and it does the same thing, 0v. Unplugged, back to 12.4. plugged the Victron charger in, shows absorbtion mode, at 14.4v, but amps is 0.0? Doesn't sound right...


Thanks for any help...
-Mark

 

[wme]

SWAG... incorrect + - wiring. Check everything 2x more times

P.S. Many RsVs use black wire for +. White -

 

[SamDeleted]

P.S. Many RsVs use black wire for +. White -

Just to make it more fun lol

 

[Newenough]

SWAG... incorrect + - wiring. Check everything 2x more times

P.S. Many RsVs use black wire for +. White -

These are fortunately red/black. Also tried going directly to the convertor +/- with new wire from 3 feet away....same, but I had also tried a 300w invert directly off the battery with no load, and it went to 0v as well, and back to 12.4v when removed.

 

[psolver]

What is battery soc, your battery could be going below bums cutoff voltage under load and restarting as soon s no load charge battery and retry

 

[Newenough]

That's a good idea, but how do I test for that as it goes to zero without a load? When I connect anything, as I stated, a 300w inverter with no load on it, just connecting the leads, makes it go to zero. When I connect the Victron charger, it shows 14.4 volts, Absorb, but at 0.0 amps? Is it possible it's in "sleep" mode? Should I try connecting another battery to it and try waking it up? Wouldn't the Victron do that? This thing is new, purchased in April. Voltage was at 12.8 when I got it, so I set aside until my project was to begin (this week). WTH?

 

[Cal]

I would try a different charging source. Could try vehicle alternator charging. Connect with jumper cables. Ideal if you have a clamp current meter. Connecting a volt meter is also good to verify charge.

 

[42OhmsPA]

Sounds to me like the BMS is in some sort of protection.... Is there an app you can download for that battery/BMS to see what's going on?

 

[Newenough]

Good idea. I just looked at the website. No Bluetooth capability. The Faq was pretty sparce. I already submitted the problem to the support team, but as they're on China time I won't here back until tomorrow, and rather than an answer, it will probably a series of dumb questions from a script that have nothing to do with the issue. "What color is the case?", "are the built in handles in the he up or down position...?". I really want to like this battery,.and hope it's not a bad BMS. Not good for a first order...

 

[wme]

Put the old battery back in. This will check the RV side of things.

 

[Newenough]

Yeah. Already did that, as my father-in-law wanted lights...lol. That's also why I went directly to the converter, skipping all the old wiring from the house battery location to make sure a bad ground or short wasn't an issue, but everything worked as normal on the old lead acid when put back in service. That was tough, considering I told him lifepo4 is "so much better". That sucked.

 

[justinm001]

Sounds like the BMS is tripping overload protection. Plug it all in and also plug in your old house battery to see what happens. Can you try just plugging some 12v led light or phone charger or something small to see if you can get any decent power out of it?

 

[Newenough]

Good idea. Didn't try a small resistive load, like a 12v led light. You also suggest series the batteries and check voltage?

 

[wme]

Try a normal battery charger (automotive type).
According to the standard Lifepo4 SOC chart 12.4v is only 10% or so

 

[Newenough]

That may have done it! I didn't have an automotive charger (gave to my son recently), so I just hooked it to the hummer with jumper cables. After a few minutes I attached the Victron to the second set of battery lugs and where it was showing 0 amps when "charging", it's now showing 3 amps and climbing. Awesome! I'll post an update if this is a complete success, as I've heard of this before, but thought the Victron would have been up to the task. Apparently it has its limits...

 

[justinm001]

Awesome. Inverters have to precharge capacitors and other things like AC units or fridges have start capacitors or require a large amperage to start. These things can draw a huge load for a second and trip the BMS but not affect normal batteries because they can sustain for a few minutes. Hooking it up with a lead acid battery allows it to use the lead acid and less likely to trip bms. Then you just disconnect it. I keep a jump pack in my rig for this reason.... although yesterday switched to 48v so not sure of a good backup for this.

They also make resistors you can get to help if this becomes an issue. Same premise where you use the resistor to help start the load then remove it.