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21K views 36 replies 22 participants last post by  jayden.hewer 
#1 ·
I know there is quite a bit posted about replacing the battery, but I'm wondering if anyone has installed a 2nd battery with an isolator for running electronics? I replaced my battery with an Optima Blue Top 34 series. I did manage to run it down though on a recent Baja Mexico road / camping trip by using the 12-volt cooler for an extended period.

I'm pretty sure there's no room under the hood for another battery, but I see a lot of creativity on this board. Has anyone come up with something ingenious that I didn't think of?

My stock battery is looking neglected, and would just love to get back under the hood. Any ideas?
 
#2 ·
mrsilly said:
I know there is quite a bit posted about replacing the battery, but I'm wondering if anyone has installed a 2nd battery with an isolator for running electronics? I replaced my battery with an Optima Blue Top 34 series. I did manage to run it down though on a recent Baja Mexico road / camping trip by using the 12-volt cooler for an extended period.

I'm pretty sure there's no room under the hood for another battery, but I see a lot of creativity on this board. Has anyone come up with something ingenious that I didn't think of?

My stock battery is looking neglected, and would just love to get back under the hood. Any ideas?
Hey Mrsilly, with an isolator you can run a 2nd battery with no prob. You can easily mount a 2nd battery in the interior of the vehicle since there's so much room but make sure it's the gel type since they give off no harmful fumes.

Thx, Phil
ps Then you can put the stock battery back under the hood and use the optima in the interior for the electronics!
 
#4 ·
It would take some modifying but if you installed an aftermarket intake, cool or cold, you gain a large pocket of free space to the right of the engine and beside the stock battery. The stock filter box is massive and when removed there are several mounting tabs left over where a battery tray could probably be attached. Like I said it would take some work but it should give plenty of room for an extra battery.


 
#8 · (Edited)
Auxiliary Battery and Secondary Electrical Circuit Page 1

I started this project to provide an overnight power source for my CPAP (sleep apnea) machine that could be recharged by the alternator without intervention. The auxiliary battery is sufficient to operate my machine for ~8 continuous hours.



The parts list contains:

U91 Battery (garden tractor fitment, $19.95 at Sam’s)

Auxiliary Fuse Block

Battery Isolator for Type II alternator

Generic Steel Battery Tray

Generic Battery Hold Down

10 and 14 gauge wire

Liquid Tape, regular electrical tape and numerous Z ties

6 ft of spiral wire loom material

30 AMP circuit breaker w/ holder

A selection of general automotive electrical connecters and fuses.

All parts from PEP Boys except battery, but they probably sell it too.



The Element uses a type II alternator requiring a field exciter circuit. I will provide only a general description as the isolator includes instructions and a wiring diagram; also the circuit is described in the Honda service manual. A word of warning, the manual includes dire warnings of ECM damage if this circuit is mishandled and the installation probably voids the battery and charging system warranty. If you do not have a manual and some experience let your local RV dealer install it. The isolator has four connections, alternator output, primary battery, auxiliary battery and exciter circuit. Installation does not require severing any OEM wires. Move the existing alternator output wire to the isolator. Create a new 10 gauge cable from the isolator to the alternator output lug. Create another new 10 gauge cable from the isolator to the positive post of the auxiliary battery including a 30 AMP (my choice) circuit breaker. Create a 14 gauge cable with a 6 AMP fuse to splice into the existing exciter wire at the alternator. I created another 10 gauge cable from the negative post of the auxiliary battery to the engine ground lug near the right engine mount to complete the battery circuit.

Sorry, this will take multiple posts
 

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#9 · (Edited)
Page 2: Auxiliary Battery and Secondary Electrical Circuit

The isolator is bolted to the upper radiator support forward the right side of the intake manifold and is fairly stable. Only time will tell if additional bracketing was needed.

I mounted the battery in the right side of the engine bay forward of the strut tower. I don’t have photos of the battery tray installation, but if you have basic metal working tools there is not much to explain, if not, take it to a local fab shop. I bolted a piece of angle to the front of the strut tower for support. Cut down a generic battery tray to fit the smaller footprint of the U91 battery and welded a leg to it going down to an existing anchor bolt near the right side engine mount. Bolted the battery tray to the angle and a couple of sheet metal screws into the right fender bracing and secured the welded leg for three attach points. A generic hold down secures the battery. In the photo the battery is tilted slightly to prevent interference with the hood and AC tubing.
 

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#10 · (Edited)
Page 3: Auxiliary Battery and Secondary Electrical Circuit

The fuse block I purchased allowed for five separately fused circuits. Fuse the individual circuits according to your needs, the sum of my individual fuses exceed the 30 AMP supply side fuse. I did not have any particular reason for fusing the block at 30 amps other than I didn’t feel the need for more current at any one time. The fuse block is secured to the top of the strut tower with two sheet metal screws just inches from the battery. I put a 30 AMP fuse in a 14 gauge cable from the positive battery post to the fuse block. I also put several coats of Liquid Tape on all connecters at the isolator and the fuse block.

Running the loom into the passenger compartment was much easier than expected. The photo shows four wires in a spiral loom disappearing behind the fender. I loosened a couple of screws behind the front tire holding the fender well to guide the loom around the firewall where the loom enters the passenger compartment behind the right side kick panel in an existing hole just under the hole for rear window washer hose. Honda has a plastic plug in the hole that I cut an opening in the size of the loom making a grommet out of it.


 

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#11 ·
Page 4: Auxiliary Battery and Secondary Electrical Circuit

Once behind the dash the wires exit the loom with one going through a grommet in a hole drilled through the dash cover next to the existing 12V connecter to power a three way outlet. Another follows the rear washer fluid hose down the rocker panel then beneath the plastic floor panel to the center console and a rear facing 12V outlet. A third circuit powers the OEM rear 12V outlet. (See the post for wiring the rear outlet to be always on) I removed the relay for the rear 12V outlet and connected the powered wire to the existing circuit for the rear outlet with a spade connecter, replacing the jumper described in the ‘always on’ post. I just taped off the fourth circuit as I had no immediate use for it. Honda provides a ground lug, also behind the right kick panel; I used it to ground the three-way.



Now I have five 12V outlets (fore, aft and amid-ship) that are always on and powered from a battery that is independent of the cranking system and an unused port on the fuse block that could be used for an under-hood light or some other device outside the car. The OEM 12V switched outlet is still in place and operational.

Note: I have a Garmin 2610 Street Pilot in the car and considered powering it from this circuit; however, the Street Pilot instructions caution against connecting it directly to a 12V power supply as it has no internal regulator. I am not sure what the difference is, just a heads-up. In describing the system it is pretty straightforward but it sure didn’t feel that way while I was doing it!
 

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#14 · (Edited)
Re: Auxiliary Battery and Secondary Electrical Circuit

Point taken Ramblerdan. For what it is worth the cable is short enough that you can see both ends of it at a glance, however I think that the purchase of a short length of black cable will be on my next parts list.

Re: deckeda comment on battery tray. The tray as purchased appeared to be coated with enamel. After all of the cutting and welding done to it there is no protection from corrosion at the moment. You can see surface rust in the photo. In order to insure my wife had transportation to work every day this project was completed a little at a time over several weeks and the tray was modified a second time for stability. I am considering removing it for cleaning and a coat fiberglass resin. If anyone has comment on the wisdom of using fiberglass or an alternate suggestion, feedback is appreciated.
 
#15 ·
Re: Auxiliary Battery and Secondary Electrical Circuit

UPDATE***
I recently left my lights on (dummy) and completely drained the starting battery. I removed the cables from the auxilliary battery and jump started my E using the U91 aux battery. Pretty cool!! You must remove the battery cables from the aux battery first or you run the risk of frying the alternater.:D
 
#29 ·
While this will cost a bit more, there is a unit made that will keep that from happening for others considering this DIY mod: Xantrex makes a battery combineer/isolator called the Pathmaker. It will automatically combine both batteries for simultaneous charging when a voltage source (alternator) is present, and disconnect them when the alternator is off, so your auxiliary battery cannot drain the starter battery. Additionally, it has a cutoff switch that will disconnect the batteries altogether if they begin to overcharge. All of the switch points come with factory settings, but can be user adjusted. There are LED indicators to tell what state of operation the unit is in (connected, disconnected, shut off, overcharging). There is also a moment switch that will combine the batteries for an emergency start, and could be considered an "automatic jump-start" mode. A nice aspect of this unit is that there is no voltage loss across the isolator (as is common with diode-type isolators), so the batteries get the full amount of voltage available to them from the alternator.

Found the above while looking into using a second battery for my Norcold Fridge that draw's 6 amps hourly (ouch) and may also have to add a second battery if I don't want to drain my starter battery. One suggestion I'm still considering though is upgrading my starter battery with something more substantial that will fit in that tray and carrying a portable jump starter for the few times that I would do the car camping thing. Thanks again for your great post!


UPDATE***
I recently left my lights on (dummy) and completely drained the starting battery. I removed the cables from the auxilliary battery and jump started my E using the U91 aux battery. Pretty cool!! You must remove the battery cables from the aux battery first or you run the risk of frying the alternater.:D
 
#16 ·
Re: E-xtraordinary Car Stereo Install

Well, folks, it's time for the return of an oldie but goodie. I'm reviving this thread.

Spring is coming to the upper Midwest. I know it will soon be spring because driving home last night, for the first time in months, a bug went splat! against my windshield.

[Foghorn Leghorn]It didn't crack, the windshield that is. That's a joke, son, a joke. Son, you're more stick than popsicle.[/Foghorn Leghorn]

You do know what is the last thing that goes through a bug's mind when it hits your windshield, don't you?

Its aśśhole.

Hey, if it's time for an old thread, it's time for old jokes. :grin:

As it will soon be spring, we all know that in spring a young man's fancy turns to...loud car stereos! Or in this case, an old man's fancy. This spring I will be installing two more amps in my Element, a second subwoofer, a trick Alpine processor, doing at least four and probably six more fiberglass buildouts, redoing all the cabling, in general, giving the system a serious upgrade. One thing that will be different this time around is that I will be doing much of the work myself. While I will certainly ask for help from my store's car stereo installers, you can also watch me do a lot of the job. This could be scary.

Hey, this is an old dog that can teach the young pups some new tricks. Yesterday in the bay, we wanted to mount a new tray for my battery (more on that shortly). The new tray completely covered up the mounting bracket and the installer that was helping me yesterday, Coats, was eyeballing where the screws should go. I said, "Wait a minute. You guys don't have any chalk around here?" They didn't but in the back of a deposit book we found some carbon paper. That will do nicely. I taped the carbon paper, carbon side up, on the hidden bracket. I laid in the new battery tray and wiggled it around, rubbing it against the carbon paper. We took out the battery tray and on its back were marks from the carbon paper. We knew exactly where the bracket hit it. If they'd had some chalk, I would have covered the hidden bracket with chalk. The result would have been the same. I marked for Coats where I wanted the three screws to go and when he installed it, he hit solid metal. Yes! I think Coats and Skull, our other installer, were both impressed. God knows I was. ;-)

Before I can install any of the equipment listed above, I have to make sure I have sufficient power. Everything was OK as long as I had only two amps in the car. The car's electrical system could handle it. But with four amps, the strain will be a lot greater. I was going to upgrade the alternator, but in another thread it was determined that (1) there is no upgraded alternator for the Element and (2) our alternator is conservatively rated and probably puts out 130-140 amps anyway. That should be enough.

I will need to upgrade all of my power distribution before I'm done. All of the 4 gauge wires leading from the battery to distribution and the 8 gauge ones going to the amps will be replaced with 1/0 gauge and 4 gauge, respectively. It's will be shame to waste all that old wire but there is no choice. Running 1/0 gauge and 4 gauge under the floor should be interesting.

Some of you will remember that in addition to the standard positive wire distribution system in my car, I set up a ground distribution system. Initially I hooked up my grounds the standard way you hook up grounds in a car, with all of them running to a central point on the chassis. Unfortunately, I had bad noises. I had alternator whine both through the amps and the deck and even ignition noise. Tick...tick...tick... Kicker has been advocating for a while running your grounds straight to the negative battery terminal and I did this, setting up a whole second distribution system. Viola! No noise. The noise floor in my car is now the thermal noise put out by the amps. It is dead fracking quiet. :)

All of that will get replaced and upgraded, too. :sad:

Before I could do any of this, I had to install a second battery in my car, one specifically for the car stereo. That is what this post will be about.

Every car I've owned since 1989 has used two batteries. I'm a firm believer in two batteries. One of them is dedicated to the car with the other one for the car stereo. Two batteries solve a couple of problems. One, even if you are cranking on the stereo all day, the car will still start. Two, the second battery acts like a giant filter cap, providing the stereo with juice when it needs it for transients. There is another thread going right now about the need for add on capacitors in a car. Some people like them, others don't. I do up to a point. Still, no cap is as beefy as a battery. That is what you really need. You could just upgrade the undersized battery that comes with the Element. There certainly is room for a bigger battery. It would help both the car and the stereo. But nothing beats a second battery, dedicated to the car stereo. It is the best solution.

You need something that will separate the two batteries from each other when the car is off. Otherwise the inevitable potential that will exist between them will cause current to flow and they will drain each other. You can use a battery isolator but I like a relay more. It is simple. The alternator thread refered to before is mostly dedicated to discussing relays. I won't duplicate the discussion here except to mention the conclusion. For my E, I bought a superb relay that was designed for the International Space Station. The one that's in my car is the same one used in space except it hasn't had to pass NASA certification. Cool, dude. :cool: I visited outer space more than once back in the '70's. It was out of sight, man. With my new relay, I'm ready again for the countdown. Too bad my rocket motor is out of propellant. :grin:

Enough talk. It's time for pictures:



How did Linda Park make it back into this thread? :? It must be all the space talk.

end of part 1
 
#17 ·
Re: E-xtraordinary Car Stereo Install

beginning part 2

Let's get down to serious business. If you want to follow along, my picture site has been updated with new pictures. There are additional new photos on that site over the ones shown here.

Let me show you what an Element looks like without a battery or even the bracket the battery sits on:





There's a ton of room in there. After removing the battery bracket and pounding down the metal wings that secured the stock battery in place, I put a couple of coats of spray paint on the bracket to protect the now new bare metal.

I needed to make a new battery tray. It really should be out of sheet metal but I don't have access to a good metal shop. I'll have a machine shop make me a new battery tray, but for now, a wood one will do just fine. I made it out of ½" plywood and some molding, screwed and glued in place. I used a plunge router to add some slots for straps to hold the batteries down. Eliminated for now was the plastic tub the battery was in. It will get re-installed, along with a second one for the car stereo battery, when we put in the metal battery tray in two or three months. I did coat the wood tray with a couple of coats of polyurethane to protect it.

The tray has interior dimensions of 10" by 9¼". The 9¼" is for the long side of the batteries. The two batteries together take up 10", side by side. With the moulding, add an inch onto each dimension for the tray's overall size. The metal version, which will use battery tubs again, will be a bit larger, although there isn't a lot of extra room. I'll have to be careful with my design. I think the inch I dedicated to the moulding will save me.

Here's the new battery tray on the router table:





Coats, the installer who helped me with this project, installed the relay on the left wheel well:





After letting the paint and polyurethane dry, it was time to start installing everything. I put the straps on the battery tray before we put it in. Here is the car with a single battery in it, the one for the car. I used the best DieHard I could get at Sears and still keep it a 51R, our recommended battery. Optima doesn't make a Red Top, which is the type you'd want strictly for car use, in a 51R.





In no time we had the second battery in. You will notice the tie down straps are in place, too. Sticklers will also notice that the positive battery terminals are uncovered, not insulated as they should be. What can I say? This is only a temporary install. Real sticklers will be proud of Coats for having the fuse for the stereo directly attached to the Optima battery.





I like the way it looks. There was also just enough room for both batteries using one tray. When I complimented Coats on his good work helping me install everything - he did all the wiring while I did the system design, woodworking, painting and another project that will go unmentioned here except that it will probably cost me $200 and a trip to the body shop to get my car back into the shape it was before I started my ill-fated adventure :grin: - I said it looks especially good considering everything will be torn out and replaced in a couple of months. Skull says he's quitting.

Here's a circuit diagram for what I installed in my car. This drawing is adapted from one made by motie for the alternator thread mentioned before and I'd like to thank him for it. I won't say too much about the circuit as the other thread goes into detail on it except that the Tyco relay I used is both a really BFR and has the diode isolation built into it. There is also a lot of talk in the other thread about which line to use to switch the relay. I was going to use accessory but at the very last moment I changed my mind and used true ignition. Everything I've ever read says use true ignition for this application. I am sorry, fellow EOC'ers, but in the end I trusted the experts as opposed to this brain trust. I know, I'm a big chicken, but what can I say except cluck, cluck.





I did have one part left over - the front of the factory air intake. It no longer fit. I may install an aftermarket air intake. We'll see. I'm not wild about the way they sound. I've spent tons of money making my car quiet through multiple layers of Dynamat. I don't want it to whine and aftermarket intakes often do.





So how does it work and sound? Fine so far. The car started right away. That's a good sign. I also still have absolutely zero engine noise. That's even a better sign. I'll give the two batteries a good charge tonight when I drive to Minneapolis to see one of my favorite folk singers in concert, Loudon Wainwright III. You younger folks may know of his son, Rufus. But before I leave for the Cities, it will be back into the install bay this afternoon to take care of one piece of old business that I'll detail here this weekend.

Look, up in the sky. It's a bird. It's a plane. It's...SUPERTWEETERS!
 
#18 ·
Has anyone added a second battery?

Just curious if anyone has added a second battery to and E. Seems like a natural for folks that camp, run inverters, big amps, or whatever?

On an aside, I've noticed a thread or two suggesting that some folks have replaced their regular battery with a deep cycle battery. There are a couple of problems with this. One is that what ever you are running will be draining the starter battery so you risk needing a jump. Another is that deep cycle batteries do not put out nearly as many 'cranking amps' as traditional car batteries. So your risk of not getting started goes up under harsh conditions. Maybe it's not a problem if you keep your E in tune and live in a warm climate. Just remamber that that's the trade off for deep cycle: fewer amps for a longer period and designed for repeated recharge, in exchange for lots of amps on tap.

I'd also mention that the E's alternator is not designed to constantly be recharging deep cycle batteries. It puts a lot more load on the alternator. Anyone have any factual info on this issue??
 
#19 · (Edited)
No I have not, but I ran a high amp altenator, second battery & caps on my car a few years back (phat sound system). I had to put it in the trunk and use a isolator. 0 gauge wire is a bit pricey too. I would love to see if anyone has done this two (pun intended). I have future plans for electronics and increased power demands! :D
 
#20 ·
Ah, more "deep cycle" mythbusting needing to be done.

Putting it out there: while I wouldn't consider myself a professional in the battery biz, I have a lot of experience with batteries, going back over 30 years to when I was an engineering assistant in the battery shop at one of the NASA facilities. I own an electric car, have a side business in battery R&D for electric cars, and have about 10 years of recent experience in industrial uninterruptible power supply systems.

I believe I was the one behind putting larger, deep-cycle batteries in the E.

The primary difference between starter (normal car battery) and deep-cycle batteries is plate thickness. Thicker plates mean more sustained ability to yield ionized lead into solution - discharging - and more ability to return lead to its metallic state during recharging. But thicker plates mean less surface area exposed to solution, so less power capacity available for storage in a given volume.

As a related aside, "marine" batteries are frequently thumped as "deep-cycle", but anyone in the business knows they are not - they are halfway between starter and deep-cycle. Put a marine battery in a true deep-cycle application such as a UPS or electric vehicle, and it will become so much scrap lead in just a few weeks.

So let's get to the mythbusting:

The larger deep-cycle battery I use (Size Group 31) has more starting capacity - 900CCA - than the stock Element battery (Group 27) at, if I remember right, 550CCA. "Regular" aftermarket replacements for the E's battery are in the 450CCA ballpark, or half of the deep-cycle. So I'll take my deep-cycle over the stock battery on any cold day, thankyouverymuch.

Increased alternator load? Where do people get that? You use X amount of charge, you put back X amount of charge, at the rate the alternator puts out, regardless of battery type. A different battery type does not "suck harder" on the alternator. If you develop a habit of sitting with the engine off with the stereo blasting - regular or deep-cycle - the used-up charge will have to be replaced. So you will draw on the alternator for a longer period of time. But do that more than a couple of times with the regular battery, and you're going to be stranded.

The "advantage" of two batteries is that you can blast your audio or run that inverter until depleting one battery, and still have something to start the car with. Another, deeply-technical advantage of two batteries is that you can locate the second one closer to the point of use, such as a high-wattage amplifier. That reduces the amount of wiring between source and load, which reduces impedance losses (I told you it was deeply technical!). The disadvantage of two batteries is extra high-amperage wiring and a diode block to split the load, the diode block having a minor cost in increasing time to replenish the battery.

If you are serious about enhancing your battery capacity, I recommend the Enersys "Odyssey" line of batteries. They are essentially consumer-packaged aircraft batteries, and they are virtually bulletproof. Expensive, yes, but you definitely get what you pay for in this case. I have seen one application where a pack of six have been depleted to near-zero every day for a year, and are still running at 75-80% of their new capacity. Any other battery treated like that - even the popular deep-cycle brands - would have packed it in, in a matter of weeks.
 
#21 ·
Mike I agree with most of what you said, but...

You didn't bust any myths.
1) surface area of the plates is directly proportional to 'CCA'. You compensated by putting a much larger battery in your E. So no worries there. If your deep cycle battery was the same size as your car battery you would have fewer CCAs simply because your battery would have less plate surface area.
2) You state that you do not add additional load to your alternator. That's great and no doubt true. But if you don't have appliances that demand the additional capacity of the deep cycle battery, then why did you install one? It's bigger, heavier and it costs more?? Conversly, if you turn your car off and run your amp and/or other toys off the battery, you will increase demand on the alternator to recharge the deep cyccle battery. In short, if you are not increasing the load on your alternator then you are wasting money on buying a deep cycle battery because it is unnecessary.
 
#22 ·
I'm still interested in the original question

:rolleyes:

Has anyone installed a second battery? And if so any advice on all the small issues -- loaction? Wiring? Isolation circuit?

Cheers
 
#23 ·
I guess I'm starting to not understand your point. I personally feel that a second battery is a waste of time and wiring. Put the money into a deep-cycle battery that's double the capacity of stock - there's room for it - and get a better result (more reliable, longer life) with a lot less hassle.

The over-the-top audio guys like the second battery for the impedance reduction. And that's about all.
 
#24 ·
i got one

When all my controls and the computer were installed in my E there was a "backup" battery installed. Just incase the standard factory installed battery were to fail for some reason... Say i left something on, and didnt know it.

Anyway, the backup battery is a group 27 gel cell. mounted behind the left rear seat close to the rear gate. in a sealed box of course.
To use the backup battery a momentary push button switch was installed on the left side dash trim, and a solenoid switch under the hood. I'll try to get pics soon.. my camera died... :mad:
 
#25 ·
Mike

What I'd like to know is if anyone has installed a second, isolated battery to run stuff while camping (or whatever) without discharging the stock battery? If so, what sort of isolator, wiring and location did they use?

Thanks
 
#26 ·
I did this. I have two batteries, one for the stereo and another for the car. I use a relay to isolate the two from each other. I can run down the stereo battery (a yellow top Optima) and still start the car. The relay is talked about in this thread and the dual battery installation is in this second thread.

Beyond the ability to always make my car start, I like having two batteries because of the isolation it gives me from the rest of the car's electronics. A battery is a damn good filter cap. I am totally isolated from the car's computer and anything else that could give me noise. My car stereo is absolutely noise free.
 
#27 ·
I was at Batteries Plus last week for some other items and asked them about this (putting in a carputer). The first guy went to the deep cycle batteries but I expressed concern about venting and size. He asked the boss, we looked at some Werker batteries, I have used these in UPS (that is what I was there for) and bike lights, they are gel type so they don't need venting. Lots of different sizes and amps, you could probably get something in that line after doing the math that would meet your needs.

If you're going with a battery under the hood the venting issue doesn't exist, I don't want that. I'm still working through the whole charging thing and how to isolate when starting or when the car is running (I'm open to suggestions or links to web sites that explain how to do properly).
 
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