I'm planning on installing a dual battery setup in my rig. Lot's to think about and probably lots of questions but the question I would like you to consider is this. Is there a certain compatibility that both batteries must have ? I was talking with a friend today on this subject and he thought there was something to that. Now while I'd like to go with a deep cycle unit for the second or so called "house" battery, I see no reason to use that type of unit for the first battery. Perhaps it may have to do with ampere hours or cranking amps or something like that. Any opinion on this ?
It depends on what you need the "house" battery to do, but there's no reason you couldn't use a separate charge circuit to it that's isolated thru a relay unless the ignition is on. The house battery wouldn't be available for jump starting with that arrangement, though. My Diesel has dual batteries that should be matched as they're just connected in parallel for more starting power. It also has a Trailer battery charge relay that goes to the camper connector in the bed to charge the camper battery, and to the trailer connector. I don't use the battery charge circuit at the trailer connector, but it's there if I ever wanted to pull a trailer with a house battery.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
Thanks for your thoughts on that Kevin. I've been online most of the evening reading about and viewing various setups. Some say matched batteries are ideal, but not all. One scenario that keeps coming up often is that when you start the vehicle and charging begins you do not want to have one battery deeply discharged as the starting battery (or both) will be affected negatively. But an isolator such as a voltage sensitive relay may provide the protection for that.
The reason I plan to wire the system is to make my truck something I can take into the hills to camp, fish, ride my dirt bikes and such. I'll be running lights, audio, two way radio and whatnot. Also like the idea of having a backup battery for starting. Probably put a winch on also. So I'm just trying to sort out the details. Lots to learn.
I have dual batteries on my police Tahoe, and they kept going low on voltage turning over slow.. Turns out the Optima yellow top had gone bad, and it was sucking down the good battery with it. I just disconnected it and now it starts fine off the single normal battery. Actually figured out it was bad after looking at it with my infrared camera while charging. The good battery was still cool, and one dark color. I think I can use the new battery out my 4100 that's in storage for the winter, and I won't really need dual batteries in the summer.
Last edited by 4100 Fire Truck; 11/12/20181:01 AM.
Yes it seems like they are simply wired in parallel. I can just pull the ground cable off of either one and everything works the same.The spec batteries are 660CCA each, and a 160 amp alternator. It does crank over fast with 2 good batteries. Of course it starts with just a bump of the key in less than a second, but my 1950 216 only takes like 2 seconds if I get it set up right with a couple pumps of the throttle, a little choke, and throttle cable adjustment. It starts faster than my Camry when I get it right.
Last edited by 4100 Fire Truck; 11/12/201812:58 AM.
Ah yes. Coming up with the right steps to quickly fire up the old inline. It's a beautiful thing
My 235 fires up pretty quickly also. Doesn't like the throttle pumped. Just let the (electric) fuel pump run for a few seconds. Little choke if cool weather. Bingo ! (usually) Ha ! When warm, right now man ! Mostly.
It keeps the battery that is being heavily used from draining the starting battery and when the engine is started the alternator charge is sent to each battery based on its state of charge. I've had one of these on a van I use to tow a small travel trailer for decades and it's worked perfectly.
I put a Sure Power isolator on my '71 Dodge van (that I bought new and still have) in about 1982 and it's still working perfectly. When my trailer has been sitting at a camp spot for several days the battery can become quite discharged. The isolator keeps the starting battery in the van from discharging even with the trailer umbilical cord plugged in to the van. The best part is that the isolator keeps the voltage regulator on the van from getting "confused" by having to deal with one discharged battery and one that is fully charged.
I don't know how the isolator knows how much current to send to each battery but it does. One of my sons is an electrical engineer and I could ask him if your curiosity on the subject is intense.
On another thread here you will read that wire with thin strands is preferred because electricity flows on the surface of wires.
That assertion is INCORRECT because direct current flows IN the conductor, not ON it. Even alternating current obeys the "skin effect" to varying degrees, depending on its frequency. I like to check the assertions of self proclaimed "experts" because their "facts" are so often incorrect.
Happy Thanksgiving to you too, Ray. Saw your post yesterday but was out of town and couldn't remember my password. I know we are both thankful because the rain finally came. My goodness !
Appreciate your info on the isolator. Do want to be able to bring the second battery into play insofar as starting the engine if needed, I've seen components that allow for that, and heck, I plan on putting both batteries side by side so easy enough to jump.
And not necessary to ask your son about this for my sake. Not that I have an total unwillingness to know, but I'm more of a paint by numbers sort of guy. I can solder and crimp, bolt and unbolt, but just want to get the systems working. You know. Just get it rolling. LOL
