Generator hook-up

[Traviss224]

My batteries are severely discharged and the battery engineer said I need to run a generator on my system until the batteries become fully charge.

I have a 6k growatt split phase mpv unit. I am fully off grid. My only generator source is my 2000 Watt inverter gen. How can I hook up this 120v gen to the growatt. I think it requires 240v.

 

[Vigo]

Does the unit have a current limit for ac charging? If so you can set that low enough to keep the generator happy, as long as you don’t try to power loads off the inverter at the same time. But, to get 240 from a 120 generator, youd have to buy another piece. I have used a large ‘travel converter’ which is really an autotransformer, to turn 120 into 240 and fed that to the ac input on my Growatt spf5000s. It does work, but they’re about $100 for the large 3000-5000w models which you would want to be able to run 1500+w through for long periods (the 3-5kw rating is misleading and optimistic imo, but 1500w would be fine for long periods).

Alternatively, you could buy a 120v battery charger for your battery pack. An actual 48v charger of any decent capacity would probably take the form of a ‘golf cart charger’ and be $200+. If you are ok babysitting the process you can simply use a ‘power supply’ to charge the batteries up to a certain point. I have bought 3x of 48v/10a power supplies for $26 on amazon. Theyre adjustable a bit beyond 48v but depending how much farther you need you might want to buy the 60v versions and turn them down instead.

I have a 2200w inverter generator that makes 120v. I have it hooked up through ~900w of PSUs into my 48v pack for times when i want to recover from a cloudy day when we used the 4500w clothes drier and 1800w induction cooktops too much. It definitely works and is cheap. Not having ‘multistage charging’ is a lot less important when your charging physically cant ‘overcurrent’ the batteryand a single tank of gas on the generator doesn’t hold enough energy to ‘overhcarge’ your pack. When i want to run that generator i just decide whether to fill the tank up all the way or part of the way based on how many hours i want it to run, then just ignore it and let it run out of gas. The Psu’s are hooked to batt full time. Works for me..

 

[Traviss224]

As electric is not my forte, I would feel most comfortable using a battery charger. Would I have to disconnect the inverter for this? This would pose a problem as my freezers are full of meat.

If I bought a 120 to 240 transformer, would I run a plug from the transformer to the bottom of the inverter?

 

[timselectric]

As electric is not my forte, I would feel most comfortable using a battery charger. Would I have to disconnect the inverter for this?

No
Both can be connected to the battery.

 

[Traviss224]

Thanks tim! Can this be done even during the day when solar is producing?

 

[timselectric]

Yes

 

[Traviss224]

Thanks tim! Much appreciated!

 

[timselectric]

Just make sure that the total charging amps don't exceed what the battery can take.

 

[Traviss224]

Ok I will try to find a charger I can adjust. If I can't I'll adjust the inverter down for the time being. Does that sound good?

 

[timselectric]

Yes, that would work.

 

[Traviss224]

Perfect! Thanks ?

 

[Traviss224]

Just make sure that the total charging amps don't exceed what the battery can take.

Tim would a 48v golf cart battery charger work?

 

[740GLE]

What size is your battery? Im guessing 48v, but how many AH. You’d need a lithium specific charger, FLA chargers don’t have the same voltage profile to fully charge.

Are you PV panels under sized for your loads? Maybe there is a setting in the charger controller that can be tweaked so the PV system can help out more.

 

[Traviss224]

48v 390ah lead acid,

Not undersized. I have had the the wrong amp settings. I was way under amperage.

I have 4500 watts of panels. I run around 300 watts usually. If my window ac is on it goes to about 1100-1200 watts. The AC is only during the day.

 

[timselectric]

Tim would a 48v golf cart battery charger work?

Yes

 

[Steve_S]

Why not use the unit to Charge the batteries and Keep It Sweet & Simple ?

Page 12 of Manual

AC Charger The inverter is equipped with an active PFC (power factor correction) multistage battery charger. The PFC feature is used to control the amount of power used to charge the batteries in order to obtain a power factor as close as possible to 1. When AC voltage is in the range of 154~260VAC, the charging current is 100%. Once it exceeds 260VAC, it must be restored to 250VAC before it can be charged. The inverter/charger has a very rapid charge current available, and the max charge current can be adjusted from 10A to 100A in small increments on the inverter‟s LCD. This is helpful if this powerful charger applies charging to a small capacity battery bank.

AC Charging Current: AC Charging Current: 6KW model @48V/60A

You can use 120V for Charging INPUT per manual, connected to L1. This will require the use of an L5-30 (120V/30A)+ plug on an Inverter Generator which goes to a 120VAC/40A Breaker and then to the Growatt Inverter. See Page 8 of Manual

Alternatively, you can use a 240V out from a Generator to a Breaker then to AC Input on the Growatt.

Hope it helps, Good Luck.

 

[Vigo]

well there you go. I didn’t know the exact model but I looked up the spec sheet for a 6KWMPV of some kind and it said it took 240 input so I assumed it wasn’t possible to hook the 120 generator directly to it. turns out read the manual. ?

 

[Steve_S]

I think this would make for a Great Video for @Will Prowse to do, covering Growatt, MPP etc... He seems o have the various models. As Grid Power becomes less reliable, charging by Genset in case of "emergency" is becoming ever more important. Not to mention the rapidly growing Off-Gridder community.

 

[Traviss224]

Will I need to change the parameters in the growatt?

 

[740GLE]

Why not use the unit to Charge the batteries and Keep It Sweet & Simple ?

Page 12 of Manual



You can use 120V for Charging INPUT per manual, connected to L1. This will require the use of an L5-30 (120V/30A)+ plug on an Inverter Generator which goes to a 120VAC/40A Breaker and then to the Growatt Inverter. See Page 8 of Manual

Alternatively, you can use a 240V out from a Generator to a Breaker then to AC Input on the Growatt.

Hope it helps, Good Luck.

A 2kw most likely doesn’t have a 30amp plug, prob standard 15amp receptacle.

 

[740GLE]

48v 390ah lead acid,

Not undersized. I have had the the wrong amp settings. I was way under amperage.

I have 4500 watts of panels. I run around 300 watts usually. If my window ac is on it goes to about 1100-1200 watts. The AC is only during the day.

That is a nice sized PV array. Now I’m thinking something might be up with the bank such that its damaged and has reduced capacity. Have you been keeping up on maintenance of the cells If they are low on water it might impact the capacity of the cells.

What’s the max voltage the batteries see each day via PV charging?

 

[Traviss224]

Basically about 2 weeks ago, I had a code 4 error. (I was set to 20 or 30amps then)(at this point I havent been using solar for very long, we weren't in the house prior to this so fridge was running at night and that was it)

Spoke to growatt, they told me to update my software. I began that process which wiped the programming out. Dead in the dark, I had to replace the control board ($200).

Since replacing that, my battery light hasn't quit flashing. It hasn't went to solid green since. I've tested the batteries hydrometer readings three times. Once when I got the first 04. Reading have went from 1260 down to 1170 (these are averages) yesterday I increased the amps to 80 amps max, and my readings began to come up a little.

This morning, my voltage never went below 50. Friday night I believe it was high 47s or low 48s and I got a 04 code.

Charging voltage is around 58v

Batteries are only a few months old.

 

[Traviss224]

120v generator can not be hooked up to this unit. It is specifically 240v.

 

[Vigo]

Can you be specific about which amp setting you are referring to?

And what was your thought process for setting it?

Even 100a is not patently bad for a 390ah pack. But there is a minimum below which you are only ‘superficially’ charging the batteries. It sounds like your setting was somewhere in the middle, doing some charging but, at least considering charging inefficiencies, not exceeding your consumption, leading to ‘deficit charging’.

I would leave the setting maxed out until it gives you a reason not to. Look for a guideline on what to watch for during equalization charging (SG, temps, etc) and if the battery never gives you those signs during ‘normal’ charging and you are not charging beyond the recommended voltages, id just leave it at max current until the batteries either A: stabilize at a healthy level of voltage and balance, at which point you could consider backing off the max charge rate to possibly maximize the remaining longevity of the batteries, or B: are clearly not going to fully recover from normal Charging and you will have to implement manual balancing and equalization, after which you could do A. ?