I need help deciding how to connect the alternator to the house battery. I have a Lifeline GPL-8DL 255 amp AGM battery and the Promaster 220 amp alternator. I plan to charge with a 300 watt solar panel with mppt solar controller, and use the alternator with a battery isolator. As I understand, the solar controller uses a multistage control strategy that will regulate the flow of charging (voltage and amps) to properly meet the charge profile of the AGM battery. However, the alternator uses a constant voltage regulator with a single regulated step down designed for the starter battery. Should I be concerned that the alternator could overcharge (boil) my house battery during a long day of driving? Do I need a multistage charge regulator between the alternator and House battery?
Alternator to House Battery Charging
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Why bother with the alternator? I have the same basic setup with a disconnect between the alternator and house battery and I keep it off all the time. The only time I would turn it on is when the solar can't keep the house battery's charged and that hasn't happened yet. Just use the alternator for emergency charging and you should be ok. You're correct about the controller charging the agm battery correctly and the alternator possibly overcharging it. I did charge my agm all the time,for close to a year, from the alternator before I put the PV panels in with no observable effect (yet) but it's not recommended.
No isolator or voltage sensing relay? Just hard wired from alt to house battery?
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Me>>> Alt charges the main battery when driving The main battery charges the house when driving. Isolator in between.
Key activates the Isolator. Unconnects when off.Separate wire for (turn on turn off). The charging system will read one
battery.It will not know it has a second battery. Solar for sitting.
Key activates the Isolator. Unconnects when off.Separate wire for (turn on turn off). The charging system will read one
battery.It will not know it has a second battery. Solar for sitting.
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Hi,
I use a Battery Isolator between the van battery and the house battery. It only completes the circuit between the two when the ignition switch is on. I also have a 50 amp breaker in the same line -- I did this in part to protect the wiring in case of a short, but also to let me know if the charging current ever gets up over 50 amps, which would be too much for my golf cart house batteries. This breaker has never tripped.
One good thing about doing it this way is that your house loads can never run down the van battery overnight as the ignition is off and the van battery is not connected to the house.
There really should really be circuit breakers on each end of the wire going between the two batteries (one near each battery) to properly protect the system if a short develops anywhere along the wire.
You can see the circuit and hardware I use on this page:
http://www.builditsolar.com/Projects/Vehicles/PMRV/Electrical/Electrical.htm
The section labeled "Circuits" has the circuit diagram.
The picture just after the heading "Installation" shows the isolator and breaker.
Gary
Interesting that our 140 amp alternator does not deliver over 50 amps.
How hot does your isolator get? Have you tested for parasitic draw while the key is in off?
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hmm, brain waves - I just signed on to ask questions on this topic.
+1 for ITSolar setup
I am following ITSolar concept of the pac-200 isolator as step 1, then add solar as step 2 (but this order could be reversed by others). however eventually both are good since sometimes parked for a week or 2 and sometimes it rains for a week or 2.
1) looking to buy 50 amp breakers between veh and house battery and 150 amp breaker to 1500w inverter - there are numerous breakers at varying prices - any suggestions whether more expensive breakers like blue sea are more reliable ? or which breakers seem to be the best value ?
2) where are people making the connection to only have isolator charging when motor is running ? looks like ITSolar used wiring to a back of van 12v - I don't see any back 12 v outlet on this 2014 promaster - since all elect gear will be right behind drivers seat is there a place to make this kind of connection close to driver seat or floor battery ?
3) is there a safe / easy way to disconnect battery while hooking up ?
thks
+1 for ITSolar setup
I am following ITSolar concept of the pac-200 isolator as step 1, then add solar as step 2 (but this order could be reversed by others). however eventually both are good since sometimes parked for a week or 2 and sometimes it rains for a week or 2.
1) looking to buy 50 amp breakers between veh and house battery and 150 amp breaker to 1500w inverter - there are numerous breakers at varying prices - any suggestions whether more expensive breakers like blue sea are more reliable ? or which breakers seem to be the best value ?
2) where are people making the connection to only have isolator charging when motor is running ? looks like ITSolar used wiring to a back of van 12v - I don't see any back 12 v outlet on this 2014 promaster - since all elect gear will be right behind drivers seat is there a place to make this kind of connection close to driver seat or floor battery ?
3) is there a safe / easy way to disconnect battery while hooking up ?
thks
This is what I am using. I will be installing the same on my Promaster when I do the inverter installation.
http://www.ase-supply.com/Sure_Power_1314_200_Battery_Separator_p/sp-1314-200.htm
I think It is a better solution that what has been mentioned here, because it keeps the front battery isolated from the back bank until after the engine is cranked. I will close the circuit once it sees 13.2 volts from the main. In other words, it won't close the circuit until the alternator starts charging.
-t
http://www.ase-supply.com/Sure_Power_1314_200_Battery_Separator_p/sp-1314-200.htm
I think It is a better solution that what has been mentioned here, because it keeps the front battery isolated from the back bank until after the engine is cranked. I will close the circuit once it sees 13.2 volts from the main. In other words, it won't close the circuit until the alternator starts charging.
-t
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That's exactly how my Blue Sea one works!
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The internal resistance of the house battery seems to allow less than 50 amps charge rate as I too have never blown the 50 amp breaker. I have the most simple connection to the vehicle battery, just a simple solenoid activated by the cigar lighter socket circuit so it has no parasitic draw.
http://www.americanrvcompany.com/Tow-Ready-118665-Battery-Isolation-Solenoid-Trailer-RV-Camper
It is true it comes on with the key and has no circuit for any charge rate control but you know... it has worked in RVs for 50 years! Simple, cheap, reliable, and proven. We may be over thinking this.
I connected to +12v at the battery under the floor.
I used 150 amp fuses on both ends of the 0ga cable.
Disconnect the neg cable.
According to the Lifeline manual a battery can accept up to 5C charge rate with a recommended charge of no less than 0.2C, C being in your case 150.
There is a sticky discussion on the Sportsmobile Forum here that talks about isolates, etc. -> http://www.sportsmobileforum.com/viewtopic.php?f=14&t=8842
Hi,
I checked the battery isolator current when ignition is on and its 0.44 amps (about 5 watts) -- somewhat more than I expected, but its only a load when ignition is on and engine and alternator are running.
I don't think the isolator ever gets hot -- its only 5 watts, and its a big blocky thing with plenty of heat dissipation capability.
My source of 12VDC for the battery isolator is the wire going to the 12 VDC power plug on the back right door frame. This just happened to be an easy one for me to get to as I had an extra wire going that way.
Agree with RD that the battery isolator is a nice simple and proven way to do the job -- don't know if there is something more precise that uses less solenoid power or not.
Still waiting for my DC wattmeter from ebay to arrive so I can check the daily power usage of the fridge.
Gary
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Thanks Gary for ordering the watt meter. I am hoping you give us lots of watt-hr results for other things too. I wonder about the relative power used by running something through an inverter like a microwave and induction cooktop. It seems inverters may be quite efficient if matched to load but to buy a big honking inverter to run those two together might make it stupidly inefficient to get 120 volts to recharge a computer or tablet or such and I'm sure the standby use might be large too. I just love data.
Gary, there is always the option of a manual switch, or disconnect, that uses no power by virtue of eliminating the solenoid. The risk of course is that of forgetting to actuate the switch manually. Not recommended for obvious reason, but it does have some advantages like serving as a backup starter circuit. I'm not sure if the simple solenoid circuit described above would work if the vehicle battery was so dead that it may not pull the solenoid. It'd be easy to jump anyway.
I've seen some old RVs that had a multiple battery switch. You can set it to battery "A" only, "B" only, "A and B", or all off. I was in a boat 3 weeks ago with dual batteries using this type of switch (although in boat the reason for its use is different).
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