Recently upgraded the inverter/charger and added battery capacity. I initially thought that it might be possible to parallel AC bus A and B so that I could run one of the heat pumps on batteries or at least I thought I'd try it. Nope. Doesn't work and I'm not sure I understand why. Don't have a good wiring diagram of the whole system but it works fine on shore power or with the generator powering bus A. Just flip the parallel switch and B is powered up. Why won't it work with the inverter powering A? Also tried switching the shore power switch on and nothing. Just curious more than anything. Thanks.
P42 paralleling the buses on batteries
- Thread starter HoosierSailor
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,072
To analyze such a situation one needs an electrical diagram.
I would want to know more than “Nope. It don’t work!”
What really happened when you threw the switch? Was the system out of phase? Did something short out? Did you blow a breaker?
I would want to know more than “Nope. It don’t work!”
What really happened when you threw the switch? Was the system out of phase? Did something short out? Did you blow a breaker?
Nothing.....nada.....It just won't power bus B off of bus A with the inverter.What really happened when you threw the switch? Was the system out of phase? Did something short out? Did you blow a breaker?
Whatever you do, don't connect the inverter AC output to shore power. You'll let the magic smoke out.
You need to trace your wiring in order to answer the question. You also need to provide details on your switches and inverter.There is no standard installation that can be referenced once the boat leaves the builder's shed. Even then it's doubtful.
You need to trace your wiring in order to answer the question. You also need to provide details on your switches and inverter.There is no standard installation that can be referenced once the boat leaves the builder's shed. Even then it's doubtful.
The heat pump system is designed to run off of either the generator or shore power, not the inverter. Draw just more than the DC system can reasonably handle. Same reason trying to use the inverter to operate the hot water heater.
So I guess no one has looked at this before. I was hoping someone had tried to parallel the buses with the inverter on batteries. I understand that as originally designed the inverter probably wouldn't have handled the power requirement of an air conditioner. However, I now have a 3000 watt (25 amp) inverter and it should. It's not that the inverter isn't able to handle the load, the bus simply doesn't power up. And BTW, it powers the hot water heater just fine but that is on bus A. I'm just not seeing a reason why the buses will work together on the generator and shore power but not work with the inverter powering bus A. AC power is power. There must be a relay or something that gets switched when you apply power from an "outside" source.
Thanks for the replies. I will continue to investigate.
Thanks for the replies. I will continue to investigate.
There are AC and DC heat pumps. The AC's need a steadied reliable power source. Under and over voltage can take out the rather costly circuit boards within. The DC models are designed to operate on power that fluctuates. Hopefully you are moving in the DC direction.
First, an appropriate battery bank and inverter can run large AC loads no problem. We run everything off our inverter/batteries - A/C, dive tank compressor, water heater, 120V 35gph watermaker, etc. We don't have a genset and are rarely on shorepower.
Assume for now the OP's inverter and battery capacity is not the problem. That might be step 2, but not the issue right now. He states he gets no voltage at all on bus B when he parallels the inverter on bus A, but this works for shore power and genset. He also states no breakers or fuse are tripping.
Without a circuit diagram, it is difficult to say what the issue is. It sounds like it should work, but the devil is in the details. Where are the lockouts for the shore power and genset located? Where is the parallel switch in the panel wiring? How is the inverter wired to bus A, and is the shore/genset wired through the inverter's transfer switch?
These circuits are commonly wired with a lockout selector for shore/genset power. The lockout switch output then usually splits with one leg directly to Bus A to power high load items only from shore/genset, and the other leg to the inverter transfer switch. The inverter is wired to Bus B for low load items, with a lockout switch to lock out the inverter if the two buses are paralleled. So normally, it is not possible to parallel the inverter on Bus B to Bus A, and the inverter is not normally connected to Bus A. It's possible the OP's system has a 3-way selector switch on the AC input - shore/genset/inverter, with all inputs going to Bus A. If so, then this should work as expected.
Mark
Assume for now the OP's inverter and battery capacity is not the problem. That might be step 2, but not the issue right now. He states he gets no voltage at all on bus B when he parallels the inverter on bus A, but this works for shore power and genset. He also states no breakers or fuse are tripping.
Without a circuit diagram, it is difficult to say what the issue is. It sounds like it should work, but the devil is in the details. Where are the lockouts for the shore power and genset located? Where is the parallel switch in the panel wiring? How is the inverter wired to bus A, and is the shore/genset wired through the inverter's transfer switch?
These circuits are commonly wired with a lockout selector for shore/genset power. The lockout switch output then usually splits with one leg directly to Bus A to power high load items only from shore/genset, and the other leg to the inverter transfer switch. The inverter is wired to Bus B for low load items, with a lockout switch to lock out the inverter if the two buses are paralleled. So normally, it is not possible to parallel the inverter on Bus B to Bus A, and the inverter is not normally connected to Bus A. It's possible the OP's system has a 3-way selector switch on the AC input - shore/genset/inverter, with all inputs going to Bus A. If so, then this should work as expected.
Mark
I know why this is happening, and I have diagrams.
Do not attempt to bypass the AC switching, your systems are designed for purpose, and do a good job of it,
If you want heat on board, spend $20 on a small plug in heater, and plug it into an outlet. It will flatten your batteries if you push it too far.
I have been on several boats that have had severe electrical fires. I suggest you avoid that.
I'm not having any issues, and am not the OP.
If you know why it is happening on the OP's boat, I'm sure he would appreciate an explanation.
The surest way to avoid electrical fires when heating a boat is to NOT spend $20 on a small plug in heater. Those are one of the most common sources of boat fires. A heat pump operating off an inverter will not catch your boat on fire even if it runs down the batteries. We run one off our batteries every night, and often much of the day at times.
Mark
Yes. A more detailed explanation would be appreciated. Power is power. It doesnt matter if it comes from shore power, a generator or a 3000 watt (25amp) inverter with 600 AH of batteries. The wiring and systems are designed to handle it or you wouldn't be able to parallel them from the generator. What wasn't designed to handle it, was the 30 year old inverter I replaced and batteries so I understand why it might have been designed that way 30+ years ago. Any assistance would be appreciated. Thanks
Need to clarify this comment. Yes, our 2500W inverter will run the hot water heater, but places a big draw on the house bank, so I do not use it. Run the Genset or with the engine running while underway instead. I've never tried to run the heat pumps from the house bank, but I might see what happens if I try. My thinking is that Hunter wired it this way for a reason; just more than the original 1600W house bank could handle. Running both heat pumps draws almost 30 amps at 120V, which equals about 3600W, plus the inverter efficiency loss. Even running the hot water heater draws 1200W.
Thanks Terry. I recently upgraded the batteries and the inverter/charger so I have the power to handle the load. I also don't plan to run both the fwd and aft AC units. I was just thinking that closing up the aft cabin and just running that AC unit in the evening just before bed for 30-45 mins as the sun goes down would be nice to do without having to crank up my beastly 9kw generator. The aft unit pulls right at 10 amps.
It can be done and I will figure out what in the system is preventing it. Just thought I'd ask around here first.
Thanks,
Jim
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 23,072
Please post your solution when you discover the issues responsible.
Thanks.
I keep wondering if the problem lies with the neutrals and ground. The ground and neutral should be bonded at the source of the power in an AC system. Shore power AC is bonded at the main power panel, generator power is bonded at the generator, and inverter at the inverter. When only one energy source is used, then it works, however when 2 different energy sources are involved, inverter and shore power for example, the circuit isn't really in parallel because the neutrals are separate.
Here's a wiring diagram of 2 Isolation Transformers (Mastervolt Mass GI) jwired in parallel. Note that all the neutrals and grounds are tied together and return through the shore power connection. As a result the load is drawn evenly from both sources. I'm flying at the edge of my knowledge here and am struggling for a good explanation, yet I think the problem lies in the neutral. If we parallel batteries both the + and - posts are connected, there is a continuous path for the electrons. If only the + are connected to a bus bar and the negatives are completely isolated from each other, then the circuits aren't complete and there is no power. There's a good chance that this explanation is incorrect, still I think that's were the problem lies.
Here's a wiring diagram of 2 Isolation Transformers (Mastervolt Mass GI) jwired in parallel. Note that all the neutrals and grounds are tied together and return through the shore power connection. As a result the load is drawn evenly from both sources. I'm flying at the edge of my knowledge here and am struggling for a good explanation, yet I think the problem lies in the neutral. If we parallel batteries both the + and - posts are connected, there is a continuous path for the electrons. If only the + are connected to a bus bar and the negatives are completely isolated from each other, then the circuits aren't complete and there is no power. There's a good chance that this explanation is incorrect, still I think that's were the problem lies.