Dual Battery Setups! Let's see them! Multiple Batteries Thread!

I have to admit tho, the main reason is I like gadgets and wiring. I'm trying to figure out how I can pack as many fun gadgets into this little truck as I can and still have room. lol

 

thanks for all the input guys

 

It's less about the alternator and more about the charging system. Looking at your profile pic though, it looks like maybe you have a 1st gen, in which case your charging system is already OK. From that perspective, you might try a 24F battery and your alternator, for winching.

A second battery is most useful in camp, where you want to save your main battery for starting up the next morning.

Lots of gadgets that are on when the engine is off is the reason LiFePo is so good.

 

Shouldn't be too hard that's what matters at the end of the day. I'm a wiring guru myself and love doing it. Have fun with it and when you get it done add some pictures in. I'd love to see the outcome.

 

I have a LiFePo in my sportbike. It made sense. Went from a couple pounds to ounces which weight is everything on a sportbike. Plus I rarely have to worry about the trickle charger. It can sit all winter and still be charged in the spring unlike all my other bikes. Thing is, it's no good for accessories. For example, I would never put one on my Harley. That battery is probably 9-12lbs! It'd save a lot of weight, but in order to get a comparable amphour it would be ridiculously expensive. You guys must be paying an arm and a leg for the LiFePos your using.

Yes, I'm dealing with the 1st gen charging system...

 

They aren't cheap that's forsure I'll tell you that I think I paid close to 1k for my secondary LiFePo battery

 

I ran a ML-SCR on my Ranger, with dual AGM batteries. It worked great.

The 2nd Gen Tacoma (not sure which year it started) and most/all new vehicles now have new "smart" alternators. Unfortunately, a smart alternator cannot charge two batteries each to maximum charge. This is why the DC/DC charger has replaced the ML-SCR. Unfortunately, with the charger, you cannot tie both batteries together like the ML-SCR.

 

I’m still using an ML-acr.


I’d go DC-DC if you’re using LiFePo4 though.

 

Ummm... that statement seems a few years old to me...

• A high quality AGM - I'm running 24F Northstars - costs $350 (X2 24F AGM) and has a usable capacity of 76Ah.
• A good LiFePo battery - for instance, the 100Ah WattCycle recommended by Will Prowse - costs $169 and has a useable capacity of 100Ah.

So, that LiFePo costs half as much and provides 30% more usable power. Not to mention the fact that it:

• charges more quickly
• can endure more discharge cycles
• is less susceptible to over-discharging
• weighs significantly less

The only thing it can't do (that a second AGM could) is jump your starter battery, so there's a tradeoff there. But statements about the extreme cost and lower capacity of LiFePo batteries no longer stand up to what's out there on the market these days.

Why do you say this? Ah are Ah, so I don't see why an AGM would be better for accessories...

 

It's probably because it is a few years old. I've had that battery for a couple years and haven't had a reason to revisit it. Not sure, but maybe form factor may have something to do with my impression. When I researched them (for the function of powering a motorcycle) two years ago what I took away was that their strong point was not power storage but rather starting power. If things have changed then I am glad!

 

Gotcha. Yeah, it's amazing what's happened in 2 years. Shoot, in the last 6 months even. Two years ago I considered lithium and felt like if I did it again, I'd still go AGM; now, it's not even a question in my mind - lithium all the way (for non-starter batteries).

Take a look at them again before you get a second battery, you might find the same thing!

 

So how does that work if you have two different batteries with two different technologies? Is that where the DC-DC comes in?

Also noticed theres about 4 different versions of that battery you link to and they're all diff prices. I assume it's just the size of the 'box'?

 

Yep, the DC-DC charger hooks up to your alternator and charges the LiFePo battery (basically, takes the V from your alternator and converts it to the correct charging voltage for a LiFePo battery). For 2nd and 3rd gen Tacos, they have even to use the DC-DC charger to charge a secondary AGM, since their alternators/charging systems wont (without modification) output a high enough voltage to charge an AGM.

Not sure what you mean. I only see two options: 1 battery, or 2 batteries?

 

Scroll down to "From the Brand"...

theres a group 24, 31 and a mini

 

Yeah, I guess those are just form factors/cases. 100Ah is 100Ah, no matter what box you put it in, hahaha.

 

Im running dual battery set up in my 2017 tacoma: dc to dc charger and 2 agm batteries. Super easy to set up solar and I haven't had any problems.

Im about to install a second battery on my 2015 and went dc to dc charger, agm starter battery and a lifepo4 house battery. The lifepo4 battery has to many advantages for me not to go this route...lighter weight, fast charging, bluetooth, self-heating, and smart charging.

Im going to add solar and 200w inverter to the system also.

 

I am running an ML-ACR with dual AGM 24F batteries. It has been a very dependable setup. Into my 9th year with this combo.

I would add that the ML-ACR also adds the ability for self recovery. If the starting battery fails for any reason, with the ML-ACR it is possible to force link the two batteries together to start and run the truck. Unfortunately this cannot be done with a DC to DC charging system. This is less of an issue for a truck with a manual transmission as a simple push start can usually be employed. But for those of us with an auto trans, this feature can save your beans.

 

Like several here, dual AGM (Odyssey pc1200 50ah), ml-acr, cs144 alternator- I’ve constantly out used the system, first single battery, then added a fridge, then added second battery and still ran both batteries down after 48 hrs of sitting stationary- then added 100 watt panel- now more lights, charging headlamps, Bluetooth speakers, etc etc, panel seemed to solve the issue but limited sample size, always in ample sunlight.

Setup is changing from a rooftop tent to a wedge camper, contemplating adding a lithium battery and a dc-dc, possibly 200 watts in solar dedicated to just the camper lights, fridge, with the hope it becomes expandable to keep up with new tech or things I want, gasoline heat system, rv water pump.

The question becomes do I ditch the weight and complexity of the second battery under the hood. Like others have mentioned, always having the ability to jump the starting battery, have a second battery for insurance, heavier loads (pretty much lights, radio, maybe winch duties after the fridge goes to the lithium), plus I’ve become attached to the old system after almost a decade and don’t want to undo it.

I guess I’ll start with the existing system and do as I have the last 15 years, once the system can’t keep up I’ll expand, just not a great way to roll when you’re on day 3 in the middle of nowhere

 

I went from a 92ah AGM for my house battery to a 100ah lipo and it doubled my runtime. Only issue as others have mentioned is the inability to jump start off the house battery but I have a jump pack which is arguably better since it can be used on multiple vehicles without worrying about having long enough jumpers to connect batteries. My charge controller also trickle charges the starting battery off solar when the house battery is charged.

 

Just to throw this out there... while the "normal" charge-the-house-battery wiring of a DC-DC won't save your beans, you should be able to just flip the input/output on it for a short period to recharge your starting battery from the house battery (a LiFePo for instance), to get back up and running. Definitely not as quick as linking the two batteries with the ML-ACR though.

Plus, with the ML-ACR, you get that satisfying click every time the batteries un/link.

Still, tech moves on I think. For both of us, I think LiFePo should be the way forward, even though it would require some reworking of our setups. I'm continually amazed at how you've somehow managed to keep your AGMs in tip-top shape for such an amazingly long time.