Hello all,
I was wondering. Is it possible on a split phase system to run just 1 generator on both ac-inputs (of course with ATS) Or do the AC-inputs need to be 180 degrees shifted? Then I can just use one generator. Or is it only possible with a split-phase generator? Best regards
Not completely.
See this very on-topic thread, read to the end.
This thread is fairly old, so maybe they’ve added some features that make it easier.
You will want a good separate battery charger.
One of the best 48v chargers, for it’s price is the EG4 Chargevertor version 2. It is designed to accept either 120Vac or 240Vac split phase and you can use a “dirty” generator (ie >3% THD such as a standard open frame generator).
I use one for my 48v battery bank. Using 240Vac input, it can output about 5120 watts to the batteries, this is approximately 100 amps. Using 120Vac input, you can charge at about 2400 watts, which is about 45 amps.
The charge rate is user selectable from 0 amps to 100 amps in 0.1 amp intervals. Unlike most chargers, it ramps up the charge rate on startup so that you aren’t dumping a huge load on your generator.
It supports battery communications, but AFAIK you can only connect batteries to one device, which is usually your inverter. This means that realistically you will need to manually set the voltage to charge at. This means that the battery’s BMS will control the charge rate.
Unfortunately the EG4 Chargevertor does not support any remote control or monitoring. You could, of course install a Victon 300amp smart shunt between the DC output of the charger and your batteries to be able to remotely monitor the actual charge rate, assuming you have a Cerbo GX or similar product. This is what I do.
You can also optionally use a product such as a Hughes Power Watchdog hardwired surge protector on the AC input to the charger. Not only will this protect the device, but it will allow you to monitor the AC power input. There are several versions, one group has Bluetooth and the other Bluetooth and WIFI for remote monitoring. There are versions that are hardwired (permanently installed inside the RV which reduces the chances that the device gets stolen and one less step during setup) or portable like most standard RV “surge protectors”. There are versions for 120Vac 30 amp and 240Vac split phase 50 amp. There are versions with and without EPO (Emergency Power Off).
If you get one, I highly recommend that you get the 240Vac split phase 50 amp WIFI hardwired with EPO.
I have 2 units, one to protect the RV’s 240Vac 50 amp shore power line and the other to protect the generator input.
While the EG4 Chargevertor can accept “dirty” input, I would rather to protect the input than hope that the charger will protect itself. The Hughes surge protector is expensive, in fact less than $100 less than the EG4 Chargevertor, but it’s easier to replace the surge protection module while remote camping than to get a new EG4 Chargevertor. An invertor generator should produce power with less than 5% THD (preferably under 3%) but if it runs out of fuel, it will produce very bad power, especially while under load.
Another advantage of the EG4 Chargevertor is that I can connect shore power to it, either 240Vac or 120Vac. Note that you can not use both the 240Vac 50 amp and 120Vac 30 amp shore power outlets on the same pole. One time I needed to quickly charge my batteries, I have about 32Kwh of 48v batteries because they were down to about 10%. The campground that I arrived at was nearly empty. I was able to plug the 240Vac 50 amp shore power into my power pole (this goes to my inverters with built in chargers) and at the same time run another cable to the power pole next to me. I didn’t have 2 long 50 amp shore power cables, but I do have a long 30 amp and a long 50 amp cable. I used the 30 amp cable to connect the EG4 Chargevertor to the neighboring power pole, setting it to charge at 40 amps, or about 2200 watts. This allowed me to run both AC units and quickly recharge my batteries. As soon as I was back to about 80%, I disconnected the 30 amp cable.
If you have a 12v or 24v battery bank, then it is much easier to find 120Vac chargers for your generator. I recommend that instead of 1 large charger that you get 2 smaller chargers. Remember that the charger will require significantly more power from the generator than it’s charge rate to the batteries. By using 2 smaller chargers you can more easily limit the load on the generator (for fuel, noise and maintenance reasons) and if one fails, you still have 50% of your charging ability. I would aim for about 50-60% of the generator’s load for the total charge wattage. It is not uncommon for a charger to require up to 25% more input power than it’s charge power. You also do not want to run your generator for more than about 2 hours at high load.
If you have a 2000 watt generator, then you would want to chose 2 small chargers that are about 500 watts each. Together they will put about 1100 to 1250 watts of load on the generator (55% to 62.5% load). You could alternatively get two chargers that can charge up to about 750 watts each, using between 860 watts and 900 watts each. This would allow you to normally use a single charger with the generator in ECO mode (much quieter), but when you need to charge faster you could then use both chargers at the same time, requiring about 1720 watts and 1800 watts of load on the generator; I would limit this to about 2 hours at a time.
A couple of notes:
When using a generator to charge your batteries, you should stop charging before 100% SoC. Most BMS’s will start limiting charge rate by 80-85% SoC and significantly reduce the charge rate after 90% SoC. This means that your efficiency of charging using a generator quickly falls off. I generally stop charging between 80% and 85% because after 90% you use more fuel per watt of charge. Only if I know that there are factors that make that extra 15% SoC valuable will I charge longer (maybe a storm is incoming).
If you use shore power at an RV park, ALWAYS ensure that all breakers at the pole are in the off position prior to connecting a cable. People have been seriously injured plugging their shore power cable into an outlet with the breaker in the on position because they didn’t realize a large AC load was on in the RV (air conditioners, electric fireplace heaters, etc). These large loads can cause an arc before the cable is fully inserted.
When you disconnect, always make sure all breakers are in the off position. Too many people do not know that the breaker should be off when connecting, so you taking a couple of seconds to ensure that your pole is safe could save someone’s life or loss of limb. People have lost fingers, hands, toes, and/or feet due to these arcs.
I have had this “prank” pulled on me, luckily it was the grey valve and I closed it before removing my end cap, but that’s still a few gallons of water. I’ve heard stories from other campers about the black tank valve being opened.
Wow that’s a really extensive response. Much appreciated. It’s also my preference, clean power to charge the batteries. exploring all options.