Battery Isolator, adding a second battery, opinions and tips

kb0nly · Post by **kb0nly** » Sun Jun 19, 2005 10:51 am

I'm looking to add a second battery to my van, the radio gear is piling up in there, and i want the ability to drain the second battery without leaving me in a parking lot with a dead starting battery!

I have read through a lot of articles and info, and it seems easy enough considering my installation experience. But i just have a couple questions for those that have already done this.

The battery has to be located in the passenger compartment, mainly because with a minivan there is no other place for it! Underhood space is tight, and there will just be enough room for the battery isolator underhood near the stock battery location. I plan on putting the secondary battery in a nice marine type battery box in the far back corner of the van. The ground will go to the frame, and the positive will route forward to the radio console for both powering the equipment, and also for the charging connection back to the battery. I contemplated rerouting the power cables from the radios back to the secondary battery, but it would be a much cleaner install with just one heavy gauge cable going forward.

As for the box, how to keep is stationary? Obviously bolting it down would help, but a plastic battery box bolted to the metal floor could become a deadly projectile in a severe accident when the plastic breaks around the bolts holding it down. What would you recommend for securing it? Some kind of strap around the battery to bolts through the floor perhaps? The amount of work is not an issue to me, the amount of safety and piece of mind is top priority with anything i install.

Second, battery selection! I am thinking a sealed deep cycle marine battery. Perhaps an Optima? I haven't had to select a battery for this use before, so looking for opinions on affordable options. Not interested in the nuclear bomb safe batteries that costs hundreds of dollars, just something durable and reliable. As of right now the secondary battery will be supplying two 100w X9000's, not both transmitting at the same time though obviously, but it is always possible in a future emergency. A couple portable radio chargers, a Maxtrac or two, and a few odds and ends in the future. My main concern is leakage, and venting when being charged. Though with most modern battery designs this shouldn't be a problem.

Then there is the battery isolator. I have read the good and the bad about a simple diode isolator. And i have also read up on the Hellroaring Technologies Battery Isolators/Combiners. They seem like a nice, abeit expensive, option. The nice thing about them is being able to tie the batteries together with the flip of a switch in an emergency, such as having a dead starting battery. And they have a LED which provides diagnostic help. A good option, if i can scrape up the cash for it. Just wondering what other have in use, their experiences with them, model and manufacturer etc.

I want the reliability of a second battery. Also, this gives me the option of having the vehicle turned off for periods of time with the future VRS plan, and not worrying about coming back to a dead starting battery! I can be out in the boonies sometimes around here, where handheld coverage to a local repeater is nill, but a little extra power and its not a problem. Hence the plan to have a VRS tied to my VHF X9000 for emergency use.

thebigphish · Post by **thebigphish** » Sun Jun 19, 2005 12:21 pm

Optima Red Top. Good battery, lots of nut.

gr8amp · Post by **gr8amp** » Sun Jun 19, 2005 1:41 pm

As for the battery box, and securing it to the car, check out the boxes available here. http://store.summitracing.com/default.a ... search.asp I have used the SUM-E890101, and it's a pretty beefy box.

Post by **akardam** » Sun Jun 19, 2005 7:21 pm

For battery selection, I would recommend an Optima Yellow Top. Red Tops are more of a starting battery than a deep cycle battery. Optimas are of course Absorbed Glass Mat batteries, so by their design they cannot offgas, which is something you would have to consider having it in the passenger compartment. I have two Yellow Tops in parallel connected to the starter/alternator via a TJM IBS:

http://www.tjm.com.au/master_frameset.a ... eries.html

This unit is a bit pricey, but it's an excellent system. Comes with a heavy duty solenoid and the cab mounted monitoring/control head, automatic and manual operation, battery charge status LED bar graphs, and charge current monitor. I'm very happy with mine.

As far as securing the battery goes, I'd approach it one of two ways. Either bolt the battery down with a metal strap, and then place a protective plastic box/cover over it, or place the battery in a battery box and bolt it down, thereby sandwitching the battery and the box together. Either way, as long as you've secured the battery and protected the terminals from shorting, you should be fine. Something that might help you is if you are only running one or two heavy gauge leads to each terminal, the Yellow Top units come with side screw terminals. Take a look at the spec sheet for the D34/78:

http://www.optimabatteries.com/publish/ ... heets.html

When I got my first battery, all I had was the high current leads coming from the alternator/frame, and the high current leads going out to power distribution. I mounted the leads to the side terminals, which made it very easy to protect, as I never had to pull the plastic caps off of the top automotive style posts.

Good luck with your project!

440roadrunner · Post by **440roadrunner** » Mon Jun 20, 2005 6:58 am

I cannot emphasize enough how much I am against the use of diode isolators. There are some other options, one is a "marine" battery selector switch (A/B-both), one I like is a "continuous duty solenoid" which looks like a starter solenoid and IS NOT. DO NOT attempt to use a "Ford" starter solenoid.

I used to sell auto/truck parts and hardware/ logging supplies. We occasionally sold these diode units, as well as solenoids. I've seen several of these diode units---of different brands---, not necessarily the brands we carried failed.

What can happen (!!! in a boat !!!) is that the diode to the main battery can open. Now the regulator sees the main battery going dead, because it is, and increases the field current to try and get the alternator to bring up the voltage. Since the voltage to the regulator sense lead is falling, being hooked to the main battery, what you have, is mucho overvoltage being applied to the auxiliary battery. Lotto acid. Mucho fumes. Explosive. Messy. OOgly. (Ugly, but worse)

In terms of the battery mount, you need to think of worst case wreck. A loose, heavy battery, travelling forward towards the passenger compartment at high speed, is not a comforting sight.

How about venting? If you use a sealed battery, well, fine.

73, Delar, W7DJM

kb0nly · Post by **kb0nly** » Mon Jun 20, 2005 9:08 am

Yep, my thoughts are on the items you mentioned!

I want to avoid the diode type isolators. There is the voltage drop to the batteries, the danger of failure, etc. I have been reading a lot about all this.Which is why i like the Hellroaring product, and many people stand behind their product as well. But, it is a bit on the pricey side. I have been looking at some of the continuous duty relay options. They also seem like a very easy and simple install option. If i understand correctly, its nothing more than a ignition switched relay that ties the batteries together when the key is on, or engine runnning, and opens to seperate the batteries when the key is off? I take it this would also be beneficial because the relay would allow the batteries being tied together in the event that the starter battery is flat. But, my question on this setup, how reliable is it for charging since there isn't anything in place to sense and regulate the charge supplied from the alternator? Are you just depending on the alternator for this setup? If so, i would assume that the other problem comes into place, that the alternator might overcharge the batteries due to the increased draw from two batteries?

As for the battery, as i mentioned previously, its not going to happen unless that sucker is mounted bulletproof! I saw an accident once where this kid hit something head on and his stereo amps were on the hood and the ground in front of him. They popped loose and became deadly projectiles. I can only imagine the increased damage from a heavy battery.

And yes, sealed all the way, i don't want to worry about venting the battery.

Other than the Optima, which i am leaning towards if i can afford it, what else has everyone used in a sealed battery that is suitable for placement in the passenger compartment? I know most that relocate the battery to the trunk for extra underhood room, or to have a second battery for stereo amps, etc, also use sealed batteries. So what other options are availabe?

thebigphish · Post by **thebigphish** » Mon Jun 20, 2005 3:35 pm

akardam wrote:For battery selection, I would recommend an Optima Yellow Top. Red Tops are more of a starting battery than a deep cycle battery.

thx...got my colours all screwed up.

thebigphish · Post by **thebigphish** » Mon Jun 20, 2005 3:40 pm

kb0nly wrote: So what other options are availabe?

Well, if you're really doing a buttload of work on this, and you want it done correctly...i'd say go right down to the flooring and cut / weld a battery tray into the floor in the back. If takes the bulk out of the battery in terms of what will be in the way, gives you more room, and if you mount it so that the tray is more or less flush (or an inch or so above) the body itself will absorb any impact in time of an "undesirable car / tree interface". If you'r ereally hellbent on it, you can make a tiedown similar to what most batteries have in the front (w/ a steel strap w/ bolts) and that should protect it....

...now all you have to do is make sure that it's marked, so that should some thing happen, rescuers will remember to chop the rear cables too!

kb0nly · Post by **kb0nly** » Mon Jun 20, 2005 4:39 pm

I thought about that, putting the battery into the floor that is. Unfortunately the drop down spare takes up all the room available that the gas tank doesn't otherwise use. On the passenger side all the exhaust is tucked up there, and on the drivers side there is the gas filler tube and the washer fluid reservoir for the rear.

Not enough room!

However, you gave me another idea on what to do for the battery box. I'm going to have a local metal shop that does all my work make a battery box, then i'm going to bolt that sucker down in all four corners to the floor and the battery will be held down in the box with a battery hold down kit, the kind with the j-bolts and the h shaped insulated piece that goes over the battery. Then to top it off there will be a battery box cover also, and the entire battery box is going to be covered in automotive carpet the same color as the vehicle interior.

I'm also thinking about lining the battery box with some of that dynamat or something to pad down any noise and keep the battery from being in direct contact with the metal sides. The local stereo shop has some stuff that is non conductive on the surface, its not the usual stuff with the foil top. More of a self adhesive rubber. Like the ice shield we using for roofing up in these northern climates.

That just leaves the isolation setup.

What is everyones opinion on the setup using a continuous duty relay? I have seen a few installs like this. I see that the way its done is that they have the batteries connected via the relay for charging when the ignition is on, and disconnected when off. There is still the chance of leaving the key on and draining both batteries with this setup. But other than that, is this a safe way to do it???

Also, what is the difference between an optima yellow top and a blue top? I was looking in a catalog that listed both of them as deep cycle batteries.

kb0nly · Post by **kb0nly** » Mon Jun 20, 2005 4:40 pm

Oh, one more thing. The rear battery will have an emergency disconnect switch. For a couple reasons. The first is in case of emergency, and the second is that it makes it nice to flip one switch and disconnect power from the radio console for repair or servicing.

Post by **akardam** » Mon Jun 20, 2005 6:29 pm

Having a nice solid "ker-chunk" disconnect switch in the positive lead between batteries and in the lead running to your console is a good idea. I have one of those nice big marine switches. You could also just use a circuit breaker, for dual purpose cutoff and circuit protection.

For the soundproofing/padding, why not just use some carpet padding? The stuff's cheap, and it works as soundproofing wonderfully.

kb0nly · Post by **kb0nly** » Mon Jun 20, 2005 7:27 pm

That's a good idea, i got some carpet padding! Never thought about that. The stuff i have must be at least 3/4 inch thick.

Still pondering the hookup methods though. Diode isolator is out! Read some horror stories about them failing and pulling the alternator ouput to ground, etc.

Still interested in the Hellroaring isolator, but it's spendy.

How about the use of a continuous duty relay? Anyone on here using that type of setup?

tvsjr · Post by **tvsjr** » Mon Jun 20, 2005 7:56 pm

Go with the Hellroaring system. They're spendy for a reason. The vast majority of those running serious multi-battery systems are using the Hellroaring devices. They Just Work.

You're right about the diode-based isolator failing. Had one fail in our rehab truck (I didn't install it), which took out the alternator. Of course, it failed when enroute to a working structure fire. Now, I just have the batteries paralleled (trying to save money).

EVModules · Post by **EVModules** » Mon Jun 20, 2005 9:40 pm

This is the setup I use frequently with no problems. The 200a solenoid is a Cole-Hersee 200a continuous duty solenoid (P/N -24143). The setup allows you to have an emergency override connect to help boost the primary battery via the momentary switch. In normal operation, if the Secondary battery is low or dead, the system allows full juice from the Primary battery instead of shunting some power to the secondary when starting.

Besides Optima, there is a battery called Odessey that is sealed & rated for any mounting position and like the Optima, can be mounted in a passenger compartment without a venting system. I fabricate my own battery mount that is bolted to the floor and the battery installed in the battery mount for locations in the passenger compartment for serviceability.

Two 150a breakers are a MUST when the battery is mounted remotely. The reason for two is if the middle portion is grounded like in a side collision, both breakers will protect their respective end batteries. Accessory connections can be made on either breaker end, cold side (terminal away from the battery).

The system shown is a simple setup. Most of the time, I use an additional 200a solenoid to feed power to the accessories. The solenoid is controlled by a Power Tamer that provides a power-off delay to the accessories after ignition is removed.

<img src="http://i4.photobucket.com/albums/y120/E ... ysetup.jpg" alt="Image hosted by Photobucket.com">

kb0nly · Post by **kb0nly** » Mon Jun 20, 2005 10:24 pm

Thanks!

That's very helpful! I was thinking about going with the relay for the second battery for now to get everything installed and working, and then later once i can afford to i can always put the Hellroaring isolator/combiner in place of the relay.