Trouble integrating Orion 24-12 70 with JK BMS 24V EEL, Multiplus, MPPT

DIY
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1

I’m aware that the topic of “pre-charging” is controversial. Many people with the JK BMS have found that inverters with large capacitors will fault when you throw the DC breaker to power up the circuit. This is my experience with having a most basic system of 24V EEL battery box, eight 305ah LiFePO4 cells, JK BMS internally, built in 250 amp breaker, Multiplus 24/2000-50, Lynx Power In modified for fuses, Smart shunt 500. If I pre-charge, my 24V incandescent fades away, I can throw my 250 amp DC breaker to power up the Multiplus and it works great. I can wire in my BlueSolar 150/60 Tr, and while the bulb won’t extinguish, enough pre-charge takes place, and I can turn on the breaker.
That basic system works great, PV keeps battery charged, Inverter runs all my 110 needs. No issues.

BUT… when I wire up my Orions, with them on or off, no load… and I try and power up the system, the JK BMS reads a fault. Either the Multiplus isn’t precharging adequately, or, the Orions are drawing too much current too quickly, and the JK BMS reads it as a short. Some possible solutions?

  1. a battery isolator to the Multiplus was suggested, but I don’t think that will solve the Orion problem.
  2. I could see adding a breaker such as used on the PV to the 24V leads to my Orions, and turn on the the system with their supply off… and let the spark happen inside the breaker… seems inelegant.
  3. I could do more testing, pull the fuse to the Multiplus, see if having just the Orion’s wired up (with or without the MPPT) causes the BMS fault.

I’m at a loss as to how to proceed. If I have the system “on” and touch one of the 24V (+) leads to the input terminal of an Orion, it looks like a welding spark, and it just doesn’t seem right.

I think the “issue” to some extent is that almost all inverters were originally designed to be with lead acid batteries, no sensitive protecting aftermarket standalone BMS units, and those “LA” batteries don’t mind sudden output surges of the current needed to charge up capacitors. But this JK BMS is trying to protect my 8 cells… and it shuts down. I think some commercial complete off the shelf batteries might be designed to put out the current needed to work with a Multiplus, so many people that don’t DIY think its crazy and not needed to recharge. But it is in this case.(I’d rather not buy a new BMS, this is working nicely other than this sensitivity issue)

The vehicle is a sporadically used 36 foot truck converted to haul a race car to motorsport events and has been re-classified as an RV. Eventually it will have more RV features than it has now. The pair of Orion’s are meant to eventually handle the 4-post 12V lift, the liftgate that lifts the car, and the lights, stairs etc in the RV side of things.

Thanks in advance.

2

Hi Alex. Try leaving the Orions wired up and use their Remote ports to switch them in. No sparks… Elegance…

3

Thanks John,
If I wire them up, pull out the green remote on/off plugs, essentially off…. And flip on my main breaker on my battery box to power up my 24V buss, and thus the Orions…. My BMS faults seeing a “short” due to out rush of current.

This happens with no load on the Orions, and when off.

It’s been proposed to me to just put a 50 amp cut-off breaker in line. Precharge, turn it all on, and then throw the 50 amp breaker, let the spark happen in the breaker.

4

The spark is what you’re trying to avoid, wherever it happens. When you precharge have the Orion on too. Why turn it off at all, it only draws “<20mA” on standby? That’s near nothing, and then use the Remote port when you want it to deliver…

5

I was trying to install a pair. Turns out one is defective, presenting essentially a complete short to the system.

The good one presents no problem, doesn’t require pre charging and works just fine.

Lots of effort wasted on a brand new in box defective unit. But I’ll send it in. Got it from a reputable dealer, they offer an additional year warranty even to 6. Worst case, they are not break-your-bank expensive.

6

The risks of using a non-isolated step-down converter. Do you need all that current? Would the isolated flavour have enough power? I have only ever used a non-isolated for stepping up. The worst that could happen is the lower voltage can be seen on the high voltage output if there was a fault.