I'm planning to add a 100W, 12v solar panel and mppt, 20A controller on my hardtop. My questions is can I also run a dedicated battery charger to the solar panel battery (100AH) without damaging either unit? The battery powers an on board inverter. Has anyone performed this type of setup?
There are solar controllers that have a smart setup for external chargers. If yours does not, no woo. Does your inverter have a built in charger? The swamp logic is the solar stuff has diode protection in it and should turn it's charge rate down or off. A better (auto) charger straight on the battery should work as it would turn it's charge rate down when the battery charges. I would think the real charger would maintain the float charge level better also. Out of curiosity, what are you going to run on a 100W panel? On it's best moment of the day, only making 8Amps.
I have a straight inverter to run the refrigerator and a dedicated 100AH battery for the inverter. I have a dedicated 10A marine battery charger to recharge the battery. When I'm on hook I don't want to run my generator for extended periods of time to charge the inverter battery. I'm hoping a solar panel will help keep the battery charged while on the hook. Any suggestions would be appreciated.
If just your fridge is on the inverter, on a boat, A normal modern small/medium fridge will consume 70 - 150 watts of power / hour. I don't care what in on the labels, on a boat, poor air flow, usually warmer than a house, fridges on a boat work harder. More when you keep reaching in for another beer. This is a gross number but depends on how many times you reach in for a beer or just to stare at what is/is-not there. Then more when the ice maker cycles and cools a warm tray of water. Then, the in-efficiencies (Peukert’s formula) of the inverter (and other devices), throw in a cloud or bird or poor angle of the sun,, I see the 100W panel helping but not going to keep the inverter/fridge running all night, especially if you keep reaching in there for another beer. The hardware will help, but your numbers so far, will not last long. IMO, A fully charged 100AH battery will last 12 hours just with your fridge. Crude and ugly numbers but you are welcome to prove me wrong with your real experiences. Your solar panel will help a bit, but that battery will be dead in the morning. Been here, done it, and all good because, the coffee maker needs that gen-set. Really after all that beer the night before.. I would recommend a taller battery charger to get that battery back ASAP to enjoy the rest of the morning quietly with the coffee.
Agree with CR. We like extended periods on the hook-up in our neck of the woods. Short season. We have the following setup. 410 watts of solar with a 30amp controller. 12volt, 3000-watt inverter with the built-in charger attached to a lifepod 300amp/hr battery. Used for house system separate from the start and 12-volt electronics. We run 2 refrigerators 24/7 along with 3 fans also 24/7 most often, music, coffee maker, toaster etc. At 6.30 am the battery may be down to 40%. By 11 am or noon back to 100%. The system works great. The 100 watt solar will just tease you.
Thank you both for your suggestions/recommendations. Looks like I was wishful thinking a 100W panel would suffice. Sounds like a larger AH battery and charger is in order.
The problem with solar, and I believe it is part of the con, is that the pushers are using watts instead of AH. 100 watts sounds great but it a meaningless since batteries are usually labeled in amps… or at least they were. 100 amps will only output about 8AH during peak sun IF the solar panel is facing the sun. So in a day that 100AH panel will only send 30 Amps into a 220 amp 8D. Assuming the battery was at 50% it will take 4 days to charge it. IF you aren’t using any power. the math just doesn’t add up
Thanks Pascal, You along with Capt. Ralph and timvail make perfect sense and I have decided to go with a larger battery and charger.
It was suggested that I should try using two 115AH AGM batteries in parallel, using a dedicated 20amp (10/10) 2 bank charger. I was told that attaching one 10 amp bank lead to each battery would work well. Your thoughts/comments will be appreciated.
When you parallel two batteries you basically turn them into one larger battery of the same voltage. So putting them in parallel and then hooking individual charger leads to each battery doesn't make much sense to me. That would be the same as hooking multiple charger leads to one battery. Also, a 20 amp charger is pretty small and will take quite awhile to charge those batteries. You mentioned in an earlier post that you would prefer not to run your gen for long periods. I recommend you get a much larger charger so you can get some amperage into the batteries quickly.
Hmmm. I need some follow-up on that. I have 2 b banks. One AGM starts for port and 2 AGM together for starboard and genny. I just purchased a Victron 3 bank 12 volt 30 amp charger. Hook up to batteries shows a line from the charger running to all 3 batteries for charging.
I thought you were understanding what we tried to express. This latest idea does not make any sense. It was suggested or a joke.
Your charger should have separate leads to each battery bank (port & stb). I would prefer the gen-set battery not tied to the stb main and on the third (separate) charger lead. If the gen-set battery needs a boost, a battery switch could be used to boost from the stb battery. What battery does the house use? We may need a new thread to discuss this topic more if needed..
Are you certain your Stbd starting battery and your gen starting battery are tied together? This would be very odd. And on your Victron Charger, does the wire diagram indicate any of those 3 batteries are tied together? More likely, it is showing you how to connect with 3 separate batteries. Is that correct?
Increasing the battery capacity will help your inverter run longer. This also increases weight. The batteries you described are in parallel, so in reality, it's still just one single battery, just larger. Then, your still pouring only 20 amps back into it. Last longer, more time required to properly* charge. Watts come out, Watts must still go back in. You want faster re-charge time, bigger charger, either solar or gen-set generated. , Now more weight. Properly charging batteries is a multi step process. The final Float charge must be reached, does not have to stay there long but obtainable. The sun will long be down before your solar panel can properly charge the batteries up. Battery mortality just went down quickly.
no that’s pretty common on small boats or low end production boats. personally I m a big fan of not having all my eggs in the same basket. One bank per engine and gen plus a house bank. If an inverter is added I want it on its own bank so it can never take down the house banks. And bilge pumps. Yes it can be a bit of a challenge on a smaller boat but worth it
I will have to confirm when back on the boat. You have me thinking twice about this now. The house bank is a Lifepod(lithium)300 amp single battery for house use only. I have a Victron 12/3000/160 amp inverter charger, along with 410 watts of solar for keeping the lifepod charged. In addition, I have a 12/30amp DC-DC charger for the Lifepod as well on cloudy days in addition to the genny if needed. The port battery looks after the port engine. I just looked at the manual battery configuration to confirm this. The other two batteries shows wired in parallel and look after the starboard/ generator and 12-volt electronica there is also an emergency start switch to have all 3 batteries tied in together for starting purposes. I m hoping to get back to the boat this week, (still covered minus 11 C here) to see if this is how they are wired. I will say we are happy with the lithium setup so far. @ fridges, fans, coffee maker and toaster etc used regularly. Lifepod at 100% by 1pm at the latest.
