Contributor I
Ok I have been looking around and trying to get a clear idea on this. I’ll get pictures when I can. Is this the proper wire set up I have done to my batteries to get equal discharge and charge out of my 3 aux batteries
Batteries and solar
- Thread starter FreeRangeRedneck
- Start date
Member III
FreerangeRedneck,
I would not wire 3 batteries that way, but that does work to have your batteries in parallel, but it is not ideal. All 3 should be the same age and batch of batteries, if possible. Still, I would wire 2 in parallel and the third on a battery switch, keeping it separated that will charge the mains first then the last battery second by it self. With the switch you could use the 3 to start your engine like in the winter, or if the Two main were low anytime, then go back to the main 2 batteries. Same way, you could run all your assessories off of the Third battery, and have the other 2 main for starting. Or one main battery that is the main, starts the motor, and the 2 for assessories, that charge when running and the switch would turn to charge after the main is fully charged. I would wire the solar, to the auxiliary, assessories battery or batteries, only. Using the wired in switch to boost the main if needed. And separate the rest of the time! Vance.
I would not wire 3 batteries that way, but that does work to have your batteries in parallel, but it is not ideal. All 3 should be the same age and batch of batteries, if possible. Still, I would wire 2 in parallel and the third on a battery switch, keeping it separated that will charge the mains first then the last battery second by it self. With the switch you could use the 3 to start your engine like in the winter, or if the Two main were low anytime, then go back to the main 2 batteries. Same way, you could run all your assessories off of the Third battery, and have the other 2 main for starting. Or one main battery that is the main, starts the motor, and the 2 for assessories, that charge when running and the switch would turn to charge after the main is fully charged. I would wire the solar, to the auxiliary, assessories battery or batteries, only. Using the wired in switch to boost the main if needed. And separate the rest of the time! Vance.
Influencer I
Yes this will give you equal charge and discharge through the batteries. It will act as one very big 12v battery. This configuration will keep the source voltage at 12 but will add the ah capacity of all three batteries. So if the batteries are 100ah each you will have a 300ah 12v battery.
Traveler II
Capacity, Age, battery type all factor here... If all three are the same (as mentioned above, size, type, batch or new) this can work. Also as mentioned running 2 in parallel and switching the 3rd using a switch or auto isolator would decrease the dependence on exact battery match. If these are being stored in sleeping area use sealed AGM or similar non-venting batteries, if they are under hood you don't need to worry about off gas during heavy use or charging.
Contributor I
Thanks for the input all of you. These are strictly my aux battery’s they are not wired into the main vehicle system. They only run my camping and living equipment. Yes they are all same made years and size brand. They are only being charged by solar power.
Contributor I
Also they are sealed none vented. These are from a internet hub used to keep the system going till it switched to generator.
Enthusiast I
Look into CTek products. They provide DC to DC charging, solar, controller, and make putting a setup together much easier.
Influencer I
This is a reply I gave in another battery/solar thread.
I have been looking into the dc/dc chargers for a bit. I have a home charger from Ctek that is awesome. I was initially looking at the Ctek 20a dc/dc but now I am leaning towards the Redarc 25a dc/dc charger. The main reason is the Redarc will charge LiFePO4 batteries where the Ctek will not. The Redarc has a built in MPPT solar controller like the Ctek. IMHO the next big thing in batteries is the LiFePO4. They are stupid expensive now but as all tech they will come down in price. You can use 80% of a LiFePO4 battery as opposed to only being able to use 50% of an agm battery. As well as the fact that you can get 3000+ discharge cycles from a LiFePO4 as compared to 300 or so from an AGM battery. For example you could discharge a LiFePO4 battery every single day for 8+ years and get full capacity. With the right charger you can charge a LiFePO4 battery in as little as 2-4 hours from "dead" LiFePO4 also works much better with heavy loads. Think large inverter and the wifes blast furnace hair dryer. My perfect setup would be a Battleborn 100a LifePO4 battery with a Redarc 25a dc/dc charger. That battery is equilivant to 2 100a agm batteries in terms of capacity and is smaller and only weighs 29lbs.
Enthusiast I
Member III
Living off-grid, I would love to replace my Lead acid batteries ( 4 L-16 )with a system with a bunch of LiFePO4 batteries. I have also noted that most of the higher wattage solar panels needed a MPPT Charge controller. I have been using an Outback Flex 60 Charge Controller in my home system for 6 years without one hiccup! Vance.
Influencer I
Yes they are Lithium Iron Phosphate (LiFeP04). Not to be confused with Lithium Ion Polymer (LiPo). Different animals. The LiFePO4 has some sticker shock but is cheaper by a lot in the long run in more ways than one. Check out this guys youtube channel for a ton of good solar and battery info. DIY Solar Power with Will Prowse
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Enthusiast I
Member III
Yep, LiFePo4 is the future. Prices will eventually fall. It’s much safer than lead acid batteries and perfect for deep cycle auto and marine applications. I’m getting close to dropping a RELiON in and mate it to my Redarc BCDC.
Yeah, even on Amazon this one is $1100.00. But I see what you are saying about longevity. 10X the cost but 10X the life as well, so if I'm spending $1100 in batteries in X amount of years, Id just as soon get this and be done changing them out.
Influencer I
There's even more benefits than just the cost and it's actually cheaper in the long run. It's the size and usable capacity. A 100ah LiFePO battery will weigh around 30lbs compared to a 100ah AGM that will weigh 60-75 pounds or more. It will be smaller as well and does not need vented. LiFePO batteries are labeled as full usable capacity. Meaning with a 100ah LiFePO battery you can use 100% of the capacity where as an AGM can only use 50% of it's capacity without damage or shortening it's life. So a 100ah LiFePO battery is equal to 2 100 ah AGM batteries in terms of usable capacity.
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I went through all this when I was looking for a battery for my teardrop build. I was trying hard to talk myself into LiFePO and could make the numbers work. I went with a Vmax AGM. AGM's can take a bigger discharge (80%) than lead acid can (50%) before damage. The battery I got can take 600 charges down to 75%. 300 down to 100%. So lets say I camp every other weekend and run the battery down to 75%. That would be 26 times a year, I use a CTEK DC to DC charger so really don't get that low but lets go with it. 600 charges of the battery divided by 26 is 23 years. Well the life span of the battery is 8-10 years. Even if you discharged 100% the battery is rated at 300 cycles and that still is over 11 years. I paid $250 for a 120 AH battery. I could replace the battery 4 times and still be under the price on a lithium battery. So lets say I only get 5 years out of a battery, 4 X 5 = 20 years. I'll be lucky to still be camping in 20 years, and a good bet not in a teardrop.
I ran these numbers past a few battery guys and they confirm the numbers give or take a bit. One of the guys was a lithium battery dealer and he was the one that told me to not go lithium that is makes no sense for what I need for overlanding. And probably for what most people here really do, not what they want to do or dream to do. Lithium does make sense if you are full time living off-grid and have heavy power needs like AC. Or you really need to cut weight. He also said that lithium batteries has not gone down in price much in the last 5 years and he thinks prices will not drop much over the next 5-10 years because of the demand for lithium batteries and the supply for raw materials can't keep up with the demand.
This is what I came up with, it is working for me so far. I am adding solar for when I spend more than one night in the same spot. And that is because we run a Snomaster fridge/freezer. If we didn't have the fridge we could stay out 7-10 days with out recharging.
Todd
I ran these numbers past a few battery guys and they confirm the numbers give or take a bit. One of the guys was a lithium battery dealer and he was the one that told me to not go lithium that is makes no sense for what I need for overlanding. And probably for what most people here really do, not what they want to do or dream to do. Lithium does make sense if you are full time living off-grid and have heavy power needs like AC. Or you really need to cut weight. He also said that lithium batteries has not gone down in price much in the last 5 years and he thinks prices will not drop much over the next 5-10 years because of the demand for lithium batteries and the supply for raw materials can't keep up with the demand.
This is what I came up with, it is working for me so far. I am adding solar for when I spend more than one night in the same spot. And that is because we run a Snomaster fridge/freezer. If we didn't have the fridge we could stay out 7-10 days with out recharging.
Todd
Member III
Do you have a link to the Vmax AGM battery? I’ve never seen those specs in an AGM before. One factor to remember in battery life is heat. If the battery is in the engine bay, it’s life gets cut short for sure.
Sorry for the delay. Here is the link for Vmax batteries that I went with. You will find the similar info at Odyssey's website. I called both places and got about the same info.
Heat is a real problem for me. My battery in in the tongue box of my teardrop which is black. We have over 100 days that the temperature is over 100 degree. I bet it gets well over 120 degree in the box. I'm putting up a sun sail to try to keep some of the sun off of it until I can build a shed to keep the camper in.
If a 100ah lithium was under say $500 I probably would have gone that way. Maybe when I need to replace my current one they will be less and I'll get one.
Todd
