Cornerman, Depending on the year of your 4runner you could install a Odyessey 34R in the stock location and another 34 in a shrockworks battery tray on the opposite side and just carry it there for a back up battery till you can complete the dual battery mod at a later date. but for now you will at least have a back up in case you need it. just carry some jumper cables. Charge it at home with a good charger when your truck is not in use.
I was going to do this then I went down that rabbit hole and ended up with a whole dual battery mod. This forum can be very informative and very expensive at the same time. Have Fun.

Rack,

I've got a Beatit 2,000 Amp portable jump starter that I've used several times myself and to start a flat dead Ford 6.7 Diesel truck. Never go anywhere without it.

You mentioned the Odyssey 34R. The Northstar / X2Power 24F has mostly better specs than the Odyssey, and the 24F is only $250 with rebate, etc.
But I'm actually leaning toward the X2Power (Northstar) 27F ($294) with even better specs. Although the 27F weighs 68 lbs which I'm cautious about.

I worked for a large city and was given a 4th Gen 4Runner as my work vehicle. They had many divisions of city mechanics that worked on all the city vehicles. I had them install a dual battery system (one for power ports, one for starting) in the 4Runner, but had trouble until they installed EXACTLY identical batteries of the same chemistry. Otherwise there were charging, or over charging issues, etc. I know little about batteries, and I'm sure the dual installation technology has improved. That dual system was great.

It sounds like the AGM batteries today are almost a deep cycle and starter battery all-in-one.

Right now I lean toward a single battery. The 27F has a 20 hr Rate Capacity of 92Ah, a Reserve Capacity of 195 mins, and 930 Cold Crank Amps. I think I can run a lot of stuff off that battery with the 195 min RC, still lots of cranking amps, and I've got that portable jump starter in case I'm wrong.

I've had dual batt set up's and loved them, but it's still a lot more weight and the whole system is REALLY expensive... especially if I'm the one paying for it!!

My only real worry is that the 68 lb 27F battery isn't too heavy and crack any of the sheet metal under it. If so, I think I'd probably go with the X2Power 24F at 57 lbs.

I’ve spent a lot of time around batteries, done numerous dual battery systems, including designing custom lithium systems.

Thing about batteries is they all have their intended applications. A true starter battery is terrible at deep cycle duty, and a true deep cycle isn’t ideal for starting duties. Then you have the grades of compromise between the two. It’s the way the physical plates inside the battery are designed.

That said, not all AGMs are designed equal. You can buy a starter AGM or a deep cycle AGM. AGM just means absorbed glass mat, meaning it won’t spill acid like a traditional flooded battery. Bottom line, if you are using a true deep cycle as a starter, you are giving up CCA to be able to cycle deep.

For those who want a dual usage, there will come a time your starting performance will slowly degrade as you cycle deeper, and you will find that you will need to maintain higher voltages to reliably crank as it ages, essentially reducing your deep cycle amp hour capacity or promoting early replacement.

If you were having under/over charging issues in your dual battery system that was fixed by putting in the exact same battery/chemistry then there is a chance the system wasn’t designed correctly in the first place. An Automatic Charging Relay (ACR) was most likely used instead of a DC-DC charger which gives zero hoots about chemistry differences or voltage for that matter. ACRs have their place as well depending on the use case.

Truthfully a dual battery system can be simplified so much that it can be very affordable. People tend to complicate it a lot more than needed. Plus you just get a much better ROI on your batteries as you can select and optimize batteries for their respected uses, instead of trying to make a compromise and finding you might need to replace ahead of schedule.

I would be more than happy to try and help anyone that has questions and wants to do it in an affordable manner. There are a lot of options to consider that are never discussed around here.

Appreciate the details. For those of us that will always run a stock setup/DD, what would you install for an OEM replacement in a 5th Gen? Thanks
.

Bumbo,

Thanks. All good info to consider.

I don't have plans to run a refrigerator, or other appliances that I can think of at this point. I do play the radio, leave interior lights on too long sometimes, recharge some electronic gadgets, and power some small accessory equipment every now and then. I have run the stock Panasonic batt below starting voltage twice in the past (not good I know) but I pay better attention now.

The stock battery is on it's last legs at 3.5 years. A Panasonic, 24F, 530 Cold Crank Amps, 20 hr Rate Capacity of 65Ah.

Thinking of replacing with a single battery- Northstar / X2Power 27F, 20 hr Rate Capacity 92Ah, CCA 930 Amps, Reserve Capacity 195 mins, 68 lbs. $294. (X2Power Premium AGM BCI Group 27F Car and Truck Battery - SLI27FAGMDP at Batteries Plus Bulbs)
Is this 27F a poor choice for Gen-5 4Runner? Recommendations?

Maybe go the dual batt route down the road if my activity and needs change? I've had a dual set up before and used it to good advantage at the time, but my needs and usage are not as great as they were back then.

Thanks for any advice you might have.

If you are killing the stock panasonic in three and half years then its probably a good idea to run a deep cycle agm. You will also need a voltage booster as well as a larger battery tray to fit the 27f. Alternatively, you can save a few bucks and get the stock sized 24f but you will still need the voltage booster.

I think most of the cracking isses have been people using the factory battery tray, get a solid battery tray and make sure everything is bolted down tight and can't move and the force stays on the top of the fender and doesn't roll over the edge and cause problems

i've got a group 31 in the factory location on a solid metal tray and offroad a good amount and so far about 3 years in no cracks or issues

The first thing that should be asked is what is the application “what do you need the battery for”.

If it is just a replacement for a the OEM battery for what I would assume most people would consider regular use (engine cranking, minimal accessory loads, daily driving) then I would not consider anything more than a regular starter battery. I generally lean towards Costco Interstate or Walmart Everstart Maxx. Usually run you about $100 for a 5 year warranty battery. With normal use you should get at least 5 year service life. I see little benefit of spending premium money on a battery for something like this. Expect to change it every 5 year or so +/- depending on how you treat it.

If you need some capacity to support electrical loads like device charging beyond basic phone charging, fridge, work lights (small but persistent drain), then a starter/deep cycle blend might be the best solution. You will spend 2-4x more on the battery, but it will most likely hold up much better as well over time. The only thing I would add to protect the battery from damage is a LVD (Low Voltage Disconnect). Blue Sea makes a nice affordable user programable unit.

m-LVD Low Voltage Disconnect - Blue Sea Systems

You would install something like this between the battery and the accessory fuse block which would be powering these persistent loads. This way you can set the disconnect voltage to prevent the accessory from draining the battery flat. This way you can leave it unattended and allow for some reserve capacity to crank/start the truck. I feel something like this is essential for a single battery setup. It protects your investment and gives you some piece of mind as well. (Note: To those who are only running a fridge as an accessory load, many fridges have a built in LVD, so you may be able to utilize that and save a little coin too)

Very general high overview comment here, but I think it’s also worth mentioning that in the world of lead batteries, you really don’t want to discharge them more than 50% regularly. If you have a 100ah of deep cycle capacity, you should consider that 50ah usable to cycle with if you want to maintain some long term battery health. Service life of lead batteries are very fickle depending on how you treat them.

Considering many owners report a 5 to 9 year service live with the OEM Panasonic, and you are seeing signs of fatigue at 3.5 years, is a perfect example of how battery service life can be reduced when being hard on your battery. Running it flat certainly helped contribute to its degradation as well.

That said, I think you are on the right track with your replacement.

I did mention the LVD, but for things like radio and interior lighting become hard to protect because they are OEM loads, and would require some re-wiring to protect so it becomes a lot more difficult to implement. In your case throwing more battery at the problem is pretty valid / easy option.

Bumbo,

Thanks for all that free information.
I've realized that the "50% Rule" is something good to follow from now on when powering stuff off the battery!

That Blue Sea LVD sounds like something worth considering for the reasons you mentioned. I've heard others refer to it also.
When you refer to the Radio and Interior Lighting being OEM and may need to do some rewiring (in relation to a LVD), does that mean that the radio and interior lights drawing down the battery, would NOT cause the LVD to disconnect, OR did you mean the radio and interior lights maybe being rewired in order to bypass the LVD?

Last thing (if you know & have an opinion):
If I install the 27F with the slightly larger footprint, I was planning on getting a stock Toyota battery tray which is larger to fit the 27F battery, but has the same pins in the bottom of the tray that match the mounting/alignment holes in the Gen-5 4Runner.
Someone here mentioned using a more rigid, after-market tray, as that would reduce the chance of the weight cracking the sheet metal over the wheel well. Does that seem viable if the battery is bolted down tight? The battery itself seems pretty rigid.

Thanks again.

I would have some concerns installing the LVD between the battery and the OEM power distribution block. I haven't measured it but it would probably be subject to more than its continuous current rating of 65 amps. In addition to that it adds additional complexity to the topography of the entire vehicles electrical which I would highly advise against.

These devices are more commonly installed on the main power feed to an AUX fuse panel which would be separate independent load center for accessories. I made these comments because I would envision re-wiring those accessories to the AUX panel as many do for accessory loads. For example, my stereos power feed has been moved so it is fed off the 2nd battery and ignition bypassed so I don’t need my key in to turn it on. It is switch controlled. It’s not something most would do, but it is something someone should do if they know they will be running various persistent loads, like a inverter, fridge, lighting, or other unattended loads.

In your use case, I would opt for keeping it as simple as possible, and just add a volt meter in a convenient location so you can monitor your batteries state of charge and act accordingly. You could in turn add a voltage controlled buzzer, which alarms once system voltage hits a threshold, alerting you to crank the engine. If you are working in or around the truck, its generally more than sufficient to prevent yourself from going flat.

Just so you know, you can still use the Blue Sea LVD to make all this happen... it has an alarm output which can be used for alert/notification/buzzer.

LVD Instructions
http://assets.bluesea.com/files/reso.../980016770.pdf

Bumbo,
For the Buzzer Low Voltage Alert Device:
Is there a particular brand or model you would recommend?
Is something like this adjustable to set the voltage alert level?
If so, what voltage would you recommend it to be set at?

I'll be using a single X2Power AGM 27F Battery- 92Ah Capacity (20 hr rate), 930 CCA, 195 min Reserve Cap.

Thanks for all this info. I hope others are seeing this and making use of the info too!!

I don’t actually use one, and I’m sure you can find various options if you search for “12 volt buzzer”, but there is a link to the one on the BlueSea website. Cost about $15-20 depending on where you look.

Floyd Bell Turbo Series Alarm - Blue Sea Systems

I typically have my LVD set at 12.1 volts, but I will lower it occasionally depending on the situation.

Typically you need some sort of control circuit, LVD, voltage activated relay, or similar to control the buzzer. I would just recommend buying the LVD because its quality equipment.

Here is a SoC (state of charge) chart. Should get you pointed in the right direction.

I know this is hella old...but, do you know if you can fit another 31 near the airbox/passenger side rear of the engine bay?