Hi all. I’ve got a boat that came with an Victron Multiplus 12/1600/70 inverter/charger. I need to do some really small tack welds in my boat, using a cheap flux-core MIG welder. It’s probably obvious, but the Victron inverter doesn’t provide enough watts, and shuts down after ~10 seconds of me attempting to weld. It needs a small boost. (battery is a DIY lifepo4 battery with name-brand 280Ah cells and a 200A JBD smart BMS, battery isn’t an issue here)
I’ve also got a DIY e-bicycle, with a 36v (42v when fully charged) 60A li-ion battery pack with 60A BMS. For this battery pack, I’ve also got a 950watts Chineesium with “sine wave” inverter. It can power my angle grinder (900 watts) just fine.
I’d like to connect the e-bicycle inverter to the AC-in of the Victron Multiplus to add 1000 watts of output power. From my very limited knowledge, I’d need to buy a “Victron Energy VE.Bus to USB MK3-USB Interface”, to lower the maximum amps draw from the AC-in. QUESTION: am I correct in all of this so far?
Second question I have is: I’ve got doubts about this Chineesium inverter, outputting a clean sine wave. Probably blocky, no tools to check. Would this cause issues with the Victron Multiplus?
Third question: Assuming the wattage output would be enough for my small welder, would welding damage the inverter in any way, and should I take other precautions? (inverter is grounded to the hull of this steel boat, boat is in the water, and I need to weld on the inside of the hull/bottom)
Sidenote: my budget is upset with the costs of a “Victron Energy VE.Bus to USB MK3-USB Interface”, but I can see it being useful in the future, because local-to-me harbours have different shore power limits. And no, current harbour power limits are set up really low/less then my Chineesium inverter.
I think yes because (IIRC) the MP has no ve-direct nor bluetooth connectivity to adjust that input power limit other than through the MK3-USB. But I’d also suggest a 1500W chineesium or larger even might be cheaper than that dongle.
36v inverters are kinda really uncommon. Finding (cheap) 36v inverters with higher capacity, is finding half a unicorn.
I’ve also got a “2000 watts” 12v Chineesium inverter. But it tends to clunk out when I try to use my grinder. And it would need to share the battery the Victron is connected to. (and at that point, I’m likely going to hit the BMS limits)
Will try this setup first, and go from there. And thanks for confirming that this setup should work! (except maybe just not enough watts to weld)
A quick and dirty solution would be to pull a 12V battery out of a car, preferably your own or with permission of the owner at least, put the 2kW on it and plug the MP into that.
The 2kw quickly trips a breaker when I use my 900 watts grinder. But the 950 watts (36v DC in) does play nice with the grinder. Expecting that the internals of this “2 kw” chineesium inverter are kinda fake. Maybe low-tier barely able to hit 1kw. And it doesn’t auto-reset the breaker either. (the 950 watt inverter does reset itself in seconds, after having tripped the breaker)
As for a secondary battery: I probably could use the 12v lead-acid boat engine battery. But it’s somewhat old, and I don’t have an easy way to charge it again once it gets low on power. (and because the boat engine is a diesel, it kinda does need some power to get it started. Glowplugs and all that stuffs)
is that MP not already set up to match the harbours shore power limits? If so your chineesium should do just fine. Or just ask around in the harbour to borrow somebody elses MK3
I’m not sure how I’d check the current current limits.
The harbour is a small harbour filled with elderly people and their old boats. (most of them at least) I highly doubt many have this modern Victron stuffs installed. And as for the boats which I expect to have Victron electronics: those boats are really spencive, and likely just have a display with a knob to set AC-in limits. (or have it installed by a professional)
Did end up buying the MK3-USB-c magic box, should get here tomorrow. (because cheaper then the regular USB version?!?) If I don’t see the added benefit of keeping it, I might return it after I’ve lowered the AC-in limits.