Battery Mounting Locations???

[Ramdough]

I have some questions and would like to get your expert opinions.

I bought a battery isolator a while back and I am about to install it. I believe it is a 160 amp 2 battery bank isolator.

I plan on mounting two deep cycle batteries (wired in Parallel) in the bed of my 2002 Toyota Tacoma Double Cab 4x4 truck. I will eventually have a winch hook up in the front. I am considering 3 options:

Option1:
Have my starter battery in the stock engine bay location. Mount the isolator next to it on the fender. Run two 1-0 cables to the bed, one being the power from the isolator and the other a heavy ground from the starter battery ground. I will have a solenoid eventually for jump starting myself.

Option 2:
Move the starter battery to the bed next to the other batteries. Mount the isolator with the batteries. Run a 1-0 cable from the alternator to the isolator, run a 1-0 cable to the starter from the starter battery. Run a 1-0 cable for ground to the front. The isolator is no longer in the engine heat and most f my hookups are short… in the bed. I will have to run a deep cycle power line to the front also for the winch when that happens.

Option3:
Move the starter battery to the bed next to the other batteries. Mount the isolator to the fender well next to the stock battery location. Run three 1-0 cables to the back. One ground wire for all three batteries, one power wire for the deep cycle batteries, and one power cable for the starter.

The advantage of moving the starter battery to the back is that I am building a circuit that will measure voltage and current on three batteries. I can't monitor the starter if it is in the front. Also, the starter battery weight moves back between the tires. Also, I can have a solenoid mounted with the batteries away from heat for jump starting myself.

All cables will be run through an old fire hose for added protection.

The reason for 2 deep cycle batteries is that my Fiance likes to camp for a few days before moving whenever we find a good camp site. I can always downgrade to a single deep cycle without changing my setup much.

Do you have any suggestions?

 

[Brian894x4]

I’ve run a lot of different electric set ups including at one point duel alternators and three batteries. This is what I’ve settled on for my current system so far and why.

I run my Optima starter battery up front and my Optima auxiliary deep cycle in the bed with a single custom built 150 amp ND alternator primarily charging the starter battery. I run a manually controlled 250amp solenoid between the two that can be turned on/off with a switch or turn on automatically when the ignition is turned on. I prefer this over isolators, because I like the ability to control it manually and isolators usually have a reduced amp load rating unless they're really big, which makes them less desirable to connect multiple batteries for winching.

The primary reason for having the starter battery up front is that the three highest load items are the winch, starter and alternator (especially when winching) and I wanted the shorted lead cables for these items.

When winching, both batteries are connected and this does put a severe load on the lead cable between the batteries as well as the solenoid, but it’s a much better and safer situation than running a winch lead cable all the way to a bank of batteries in the bed. I’m not sure of the gauge wire I used between the two batteries, but it was the largest cable I could find.

My auxiliary battery powers all of my accessories, including off road lights, refrigerator, extra cig plugs, other lights, computer, GPS, communication radios, etc, etc. Since my solenoid is usually switched to turn off automatically when the ignition is turned off, just like an isolator, if any of these accessories were to be left on, I don’t run the risk of killing my starter battery. But if my starter battery should ever die, I can just flip the switch and manually connect the two batteries.

I also run 200 amp slow burn fuses (both fuses and solenoid are from Wrangler NW a local company to me) at each of the battery cable between the two batteries and between my 150 amp alternator and the battery. The last thing I want to do is burn my truck down because one of these long cables got nicked and grounded. Fire hose should probably work to shield battery cable. What I used was heater hose in on my riskiest spots to add some girth to the cable and routed the cable as carefully as I possibly could as well as securing it like my life depended on it.

I don’t see any issues running duel auxiliary batteries in the rear. I wouldn’t mind going back to this as I loved having the extra reserve power. I have found in the past that for some reason, when my auxiliary batteries were always hooked up to each other, they seemed to damage one another for some reason. My two batteries were always the same type, but never the same age so that could have been part of the problem. It’s best to use two auxiliary batteries of the exact same type and age if they’re going to be permanently hooked up to each other.

Good luck.

 

[BajaTaco]

Great input Brian.

Doug, I voted for #2. I like the idea of keeping it all out of the heat and between the axles, since you have the room to do that. This would also leave some space in the engine bay for you to add something else if you wanted to.

 

[asteffes]

I would not put the batteries in the back if you also sleep back there. I know batteries are supposed to be sealed and whatnot, but the idea of breathing hydrogen or other gases that might escape doesn't appeal to me. Could you fabricate a battery box under the truck body, mounted to the frame?

 

[Robthebrit]

One thing to bare in mind with multiple aux batteries is the size of alternator. A basic rule of thumb is the alternator capacity should be at least 25% of the total Ah of the batteries. If you have a common 70-80amp alternator you are looking at around 280-320Ah in total battery capacity. If you are going to use AGM batteries which can take a large charge current the 25% rule is at the upper end.

If you exceed this you are putting a hell of a load on your alternator for a long period of time and in the end it will overheat and fail. If you need that many batteries consider a HD alternator or one of the more expensive isolators which will charge battery A, then Battery B etc. The downside to this type of controller is that it takes longer to fully charge everything.

Rob

 

[BajaTaco]

I would not put the batteries in the back if you also sleep back there. I know batteries are supposed to be sealed and whatnot, but the idea of breathing hydrogen or other gases that might escape doesn't appeal to me. Could you fabricate a battery box under the truck body, mounted to the frame?

He has a d-cab, with a fiberglass shell, and he sleeps in a Technitop tent above the shell. So no worries on the fumes.

 

[BajaTaco]

One thing to bare in mind with multiple aux batteries is the size of alternator. A basic rule of thumb is the alternator capacity should be at least 25% of the total Ah of the batteries. If you have a common 70-80amp alternator you are looking at around 280-320Ah in total battery capacity. If you are going to use AGM batteries which can take a large charge current the 25% rule is at the upper end.

If you exceed this you are putting a hell of a load on your alternator for a long period of time and in the end it will overheat and fail. If you need that many batteries consider a HD alternator or one of the more expensive isolators which will charge battery A, then Battery B etc. The downside to this type of controller is that it takes longer to fully charge everything.

Rob

Rob, again you are bringing up some good considerations. I belive a typical optima 34R battery is only about 55AH, so three regular group 34 batteries of various brands would likely not exceed 200AH, no? I think Doug has the 80 amp OEM alternator.

 

[asteffes]

He has a d-cab, with a fiberglass shell, and he sleeps in a Technitop tent above the shell. So no worries on the fumes.

Wow I need to brush up on my reading comprehension. :smilies27

 

[asteffes]

Another issue to consider is that you probably want the winch cables to be as short as possible. I like the idea of the batteries not being under the hood, in the hot engine compartment, but that will make for some long cable runs to the winch.

 

[Ramdough]

Thanks fo rthe replies guys.

My starter battery is a 55Ah and my deep cycle is 75Ah. If I have 2 deep cycles, then that is 205 Ah.

I plan to not use the starter for anything except starting, so most of the charging load will be caused when the 2 deep cycles are fully discharged.

 

[Robthebrit]

Ramdough, you bring up a good point. Yes you can bend the rules a little by knowing how the batteries will be used. Like you say, you will typically only be charging the aux batteries because the starting battery will be fully charged.

The realistic load on your alternator is significiantly under the limit of the 25% rule.

Rob

 

[Brian894x4]

Great input Brian.

Doug, I voted for #2. I like the idea of keeping it all out of the heat and between the axles, since you have the room to do that. This would also leave some space in the engine bay for you to add something else if you wanted to.

Thanks. The only thing that concerns me about running all three batteries in the bed is that if he does have a D-cab taco, the batteries are going to be further away from really high current items like the winch, starter and alternator.

My rear bed battery is effectively the equivilent of behind his front seat in my truck. But he would need another 3-4 feet or more of cable between his batteries and the winch up front. A winch can draw as much as 400 amps and that's a lot of juice to run through long cables. I would find the biggest cable I could and then maybe run two of them for good measure. The bigger the cable, the less the drop in voltage and less chance of overheating the cable during something like winching. High amp fuses, like the 200amp ones I have are also a REALLY good idea for super long cables like that, because if they get nicked and ground out, you might as well have a torch going off under your truck and with things like fuels tanks, etc, it won't be a pretty picture.

There's also the issue of the alternator being less effecient over that much longer cable. Again, the bigger the cable, the more you can compensate for this.

One way of getting around the long winch cable is maybe mounting the winch on the rear of the truck on a hitch system, which has a few other advantages, like not having to carry the winch all the time and being able to winch backwards, which is usually the direction you want to go anyway when you get stuck.

I'm not sure what it looks like under the D-cab bed, but I have seen set ups with batteries mounted under the bed of the older trucks, because there is a lot of room under there, but it requires some fabrication. Putting it in the bed is the easiest and most convienent way of doing it and gives you ready access to the battery, but mounting under the bed allows you to keep valuable cargo space and keeps the center of gravity low.

Good luck.

 

[Ramdough]

I have the smaller optima red top as my starter battery and a D31M optima blue top as my deep cycle.

If I buy another Blue top, that will be my third battery.

So, unless I sell my blue top, I am stuck with an expensive battery if I try to buy anything else.

I think option 1 is the easiest option and has the fewest long cables (two cables). Option 3 has the next fewest cables (3 cables), and option 2 has four cables.

The reason I was wanting to have all three batteries in the back is that I am building a battery monitor circuit. I will post a thread on that when I get the chance to do a short writeup about it.

The wires are 1/0 AWG.... that is welding cable from here.

I am still undecided.

 

[devinsixtyseven]

was looking this over since im interested in doing almost exactly the same thing.

on the link to the welding cable youre using, they specify 1/0 cable as being appropriate for 350A at 50'. since you're protecting the cables with an additional housing, it sounds like you'd be fine running all three to the bed if you wanted, since i would guess you're running less than 25' of cable between the winch and the batter(y/ies). i suppose another option would be running 2/0 between the starter battery and the big draw items, the 1/0 would be fine for accessories.

im not certain how other trucks are set up, but on my tundra, all the fluids run up the left side of the frame, the wires headed to the rear are actually on top of the frame rail there, and the right side of the truck is completely blank--great for running wires or whatever.

another benefit of moving all that weight rearward, if you go that route, is youve shifted the weight distribution...with winches and trail bumpers weighing as much as they do, i'd be awful happy to put the batteries in the bed, and in general happy to move as much as possible away from the heat of the engine compartment.

dunno if it's possible on your truck, but there may be space in front of the wheel well on the opposite side from your gas tank+fill tube to box one, maybe two batteries. unfortunately there isn't a lot of room under the bed right behind the cab; its farther from the engine but it's right near the exhaust.

-sean

 

[Ramdough]

I was thinking that the cable lengths would be around 10-15 ft. I plan on running a rope through my truck so I can buy exactly the right length (plus a foot or two). That cable gets expensive and I don't want to waste any.

Normal winch electrical cables are 2 AWG. THey are short, and used intermittently.

I think that a 1/0 cable would take alot of amps before it heated up enoug to matter. Even for a long and hard pull, the duration is not all that extreme. Plus there would be alot of coper to absorb the heat.

Just some thoughts.