Deep Cycle Battery Charging with your Alternator: The 3 Best Options explained [+ Wiring Diagram]

hello, would it prevent damage to battery if solution 1 is choosen with some full charges from time to time with a specific charger?

Can you use this to add a battery to a single battery bank?

Thanks! Maybe you update for sodium battery...

What if the engine has 2nd alternator solely for house batteries would that works?

Thank you... very helpful. Considering option (3) from Your video noted below, I was wondering if you could recommend an External Regulator, and a DC /DC charge controller combination? Perhaps something off of Amazon
Thanks again.
[Your video:
Deep cycle battery charging with your alternator: The 3 best options]

Excellent video. I’m keen to learn how I can add a jump start function to my system.

I have starter battery > dc with inbuilt regulator and solar input > lithium house battery > inverter and 12v outlets.

I was wondering if I could add a smart isolator solenoid ( like you would use use in option 1) that has an override jump start option that I could wire to a push button switch in the vehicle instrument panel.

Eg starter > smart isolator > dc > house etc.

Or would I have to run a seperate circuit with some kind of link switch that bypasses the dc charger to link and jump start?

Using option 3 puts maximum load on the alternator but in option 2 you said that was bad for the alternator.

How to prevent Lithium battery from smoking alternator?

Ty so much for the info amazing information

Yeah the lead sulfate crystals build up any time you let a battery go all the way dead or beyond about 80% depth of discharge this is why you shouldn't run your batteries all the way dead and stop and recharge them around 10 volts preferably closer to 11 volts. If you have a battery that has been dead for a long time they are hard to get recharged without special techniques and smart battery chargers will not even recognize them and will flash a fault light or just refuse to charge them you need a dumb charger or you can trick the smart charger by hooking it to a good battery and then adding jumper cables in parallel to the dead battery. The higher voltage he is talking about is what battery desulfator chargers do but a lot of guys just hook up a DC welder to their battery on low current setting for five minute sessions allowing the battery to cool in between this is done after the electrolyte has been checked and filled and it is repeated until the smart charger will recognize the battery again you can also add in a little bit of extra battery acid when you refill the battery this will help reabsorb the lead sulfate crystals. If you have a battery with really low voltage you should check for a dead cell before you waste time trying to recharge it also you can do this with a multi meter by probing from the negative terminal and into each of the six water fill holes by touching the lead plates inside you can add on an wire coat hanger extension to one of your multi meter probes so it will reach and you should see the voltage climb up in steps of 2.1 volts on a fully charged battery so between the - terminal and the first cell you will read 2.1V then 4.2V then 6.3V then 8.4V ect until you get to the last cell before the positive terminal and it should read 10.5V with the whole battery sitting at 12.6 Volts if your battery is at a lower voltage you can still do this test for a dead cell as long as you see the voltage increase when you probe each new cell it should be Ok to recharge. Be careful the battery acid can burn your skin so wear gloves and eye protection if you mess with the battery acid I have gotten it on my skin before and it is not that bad if you go wash it off right away but this all depends on how concentrated the battery acid is also and how sensitive the skin area is that it gets on so better just to try not to get the stuff on you and wear protection.

What about a dual alternator with separate regulators..

I am late finding this video I running a 250amp alternator and a 12v 60AMP lithium deep cycle battery and plan on upgrading to a dual battery setup. Reason why I have aftermarket sound system in it that one battery cannot handle that load. What is my best option?

Any recommendations for the #3 external automotive charge controller?

How can I supply power for the engine to work with a separate battery?

Should I fuse option #1? What size?

I have 6 24v panels that have voc of about 38v but my inverter is 12v. Can you wire the system in 24v to charge and somehow tap the battery bank for 12v for the inverter and other 12v loads?

Huh, I always thought the higher absorption voltage was to create more of a voltage difference between the battery and the charger, in order to keep the current high and accelerate charging. I thought if you maintained a lower voltage for the whole charge (say max 14.2) that it would still charge to 100% eventually, it would just take longer because the current tapers off to almost nothing as the battery gets close to 100%.

Great presentation - Thank you Jessie!

I just want to know: can I use my cigarette lighter socket?

ive done a lot of homework with solar but what you did with this and other videos is just that little bit that helpes me understand exactly how to and what. thank you very much

hello jesse. if you would find 5 minutes for me i would be easier minded. You do not need an explanation, i just need your choice. so here is my situation....

I live in a car and such i have to heat myself in the winter. i have a 12V 50w heater and an armaflex isolation of the car. i have to update to 220V 100w IR panel heater for the 50w one just will not cut it in the cold. i have a 120w solar panel on the way that i think i will get a max of 92w out of coz of the pwm controller. the goal is to take a bit of the load off of a car altenator. i have a 72Ah car battery that is just barely enough for 8 hours of heating with 12V 50w heater but i must be waken up by the alarm and start the car so the battery doesent get damaged. so here is what i am thinking.

purchase one 220Ah starter battery that i get for around 200-250€ for the capacity boost connected in parallel with the old battery (3 months old) - need connection cables for batteries 4m=20€ and inverter 50€ + 140€ IR panel / 410- 460€ TOTAL
OR
one deep cycle battery 150Ah 250-300€ connected to duo solar charger - need battery connection cables 3m=15€, inverter 50€ + 140€ IR panel / 455 - 505€ TOTAL
OR
one power station 1000Wh around 500€ + 140€ IR panel and some 15€ for connection cable/ around 655€ TOTAL which will just cut it for 8h of heating 220V 100w heater? problem might occur with charging. dont have access to 220v outlet often. 100w car charging kinda negates this option and solar is whell..... just that. solar. its just lending a help to an altenator and eventually i hope my wallet.

one important notice is that i have a duo solar charger from reimo which has a seperate positive connector for the car battery which will charge the car battery seperately at a rate of 0.8A.
so if i buy a deep cycle battery, i would place all the battery connections of the car to this battery except for the starter plus and minus cable so everything electrical on the car except starting the car, would run on this deep cycle battery.

the question is.... what of the following 3 would you choose?

A: another car start battery
B: deep cycle battery
C: powerstation (correct one of course)

you can share your toughts on anything of couse.

you may even use my situation as a teaching method for others, use as an example and so forward. im here to learn and share.

Great explanation. It has motivated me to fix my RV house battery charging system. The current system is 2 x lead acid batteries of about 140 AH capacity. They are used to power electronics, fridge and a CPAP machine when shore power or the Onan generator is not connected.
Charging is by a 12v charger fed by shore power or the Onan generator. There is also a relay activated connection to the RV alternator but I have disconnected this for obvious reasons. I have also installed a solar panel on the roof. The solar panel includes a charge controller that I have connected directly to the battery. The panel supplies up to 2A when the sun shines.
I want to reconnect the alternator to provide more charge when the RV engine is running but I am concerned that having 3 sources of charging current might cause problems. Is there such a thing as a multi port dc/dc converter that will manage the 3 inputs to give optimal charging for my batteries.

What if I use a smart alternator instead of dcdc controller for the second option

Thanks a million...

would it be possible to have a starter battery bank on its own circuit that is open when a heavy load is needed? like a soft start or pony motor for high voltage appliances? close the circuit to those cells when not needed?

Very informative..thank you!

Thank you sir, been looking for this information for years

Looks like everyone understood it except me , what is the house battery.

4th option: Have your alternator charge your starter battery, then add a battery isolator relay that kicks in @ 13.3 volts (relay turns off when starter battery gets to 12.8v). Normally, people use this to connect to house batteries, Don't. Instead, use this isolator to connect and power up a pure sine wave power inverter. This way, when alternator is charging starter battery it is providing power to inverter. Now run AC extension cord from inverter to a smart battery charger which will charge your house batteries. This is especially good if house batteries are a distance away from starter batteries.

Very informative video , thanks a lot , this information I was looking for

Nice going, well explained.
One more option for campers and boats.
At the second option ( smart switch) with a addon PV panel ( solar ) you may work out that the engine generator dose the bulk 14.4 what will result in 13.8 volt steady charge , the PV may work the float for the deadcycle battery.
Obviously the PV is directly attached to the house deep cycle

The smart solenoid do you mean something like a split charge relay? Sorry, I’m watching tons of videos to do as much research as possible.

What are some commercial product options for implementing wiring option #3?

Can i parallel my lifep04 12v battery with my lead acid battery? Theres no bms just a balancer if that helps

You’re the man 👍 thank you!

Okay… but I think my RV battery is charge via the camper battery charger that also has a trickle charger. Power is coming from the alternator to the truck battery then goes to the camper charger.

Question: I have a victron DC-DC and victron solar charger. will they fight each other during the absorption phase?

Great explanation! Used #2 for my trailer. Pax tecum

I have my start battery/alternator connected to my house battery through an old solar charger, which is enabled with a relay from the car key, this was the most reliable/cheaper solution I found.

great tutorial well done

Heaven sent! I wish I watched this before I wasted the weekend watching do-it-yourselfers and still not getting it. This was professional and fully comprehensive. Thank you

Hey

I would like to ask your option on this .

I have 3 dry cell batteries, 2 at the back 1 in front . A 160 A and 70 A alternator both connected to the front battery and then a lead off the positive to the 2 back batteries.

Batteries-2 xs at the back
1 optima in front

Is my current way of charging correct or can you advise what to do

Hello, I want to replace the batteries of my motorhome for a 300ah lithium. I bought the victron isolated smart dc-dc 12v 30 amps. Can I connect the victron changer with the wires that are currently connected to my auxiliary batteries (by adding 60 amp fuse protection at the input to the output) to my new lithium without modifying the old installation...

great clips man! I like the "quick and dirty" bush method! LOL!!! thanks!

Excellent video. I am finding my way through a lithium battery install. 750 amp lithium house bank, 100 amp alternator, two dc-dc Orion 30 amps each between starter and house. Thank you for posting this!

Great information. I have one question. If I am charging 2 6 volt batteries ran in a series how would I connect the charger to each battery. Thanks for your help.

Hi thanks for your video. I wondered what your opinion was on the Victron Argofet, as this setup isn't covered in your video (i dont think anyhow). Many Thanks

Great information on option 1 and 2. But the 3rd option is actually very bad idea... earlier in video you mention starter battery is meant to run at 14.4 and all electronics in the car are fine tuned to that voltage. Now why would you introduce 14.8V from DC-DC charger to starter battery and risk damaging car sensitive circuits???. Besides all power for headlight, heated seats, window defrosters, etc feed directly from starter battery where alternator wire is also attached... now the 3rd option will put all this load (which is meant for the alternator) on DC-DC charger...
The starter battery is NOT just for starting the car... its more like a reservoir or a buffer of power where the alternator constantly filling it and other car electronics constantly draining it... you dont want this flow to go through a DC-DC charger!!!

umm.