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Author Topic: dual battery options  (Read 8834 times)
K0BG
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« Reply #15 on: February 24, 2012, 11:32:36 AM »

That's not true. The BCI is an industry standards committee, and is beholding to no manufacturer. To assume—or state—to the contrary, is exactly that!
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ZENKI
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« Reply #16 on: February 24, 2012, 01:19:30 PM »

Maybe you could try the new combination battery technology which use a battery and a supercap. This would be adequate for  2 meter use while keeping size and weight down.

http://www.batcap.net/
http://www.soundstream.com/AudioProducts/cap/capcell.htm



I have an 07' jeep JK that I run a yaesu ft 8900 in.   I am interested in a buying a dual battery set up to run the Yaesu and some lights.   Does anyone have a  dual battery tray/set up they could recommend?

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MDNITERDER
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« Reply #17 on: February 24, 2012, 01:44:50 PM »

 Go with two Deep cycle batteries such as an optima blue top, they are designed to be drained, they are sealed marine batteries, then a simple battery isolator, they are not hard to install, 3 lugs on them, one is in/out and one is in/out and one is just in to the second battery. all 3 get grounded. OR the second battery could be a 12volt 8DHD battery. Used in rigs.

 All it does is charge the two batteries, Allows the car/jeep/truck to run of the main and maintain it and then also charge the second battery. Pretty easy, use 4 gauge or 1/0 wire to the batteries, you may need to upgrade the alternator, Also the isolator will allow you to drain the second battery with out killing your main. You will still be able to start your jeep,

 Remember your alternator is not really made to "charge" a battery but maintain it' So I would check out camping world for solar panels or checkout http://magnet4less.com/ they sell panels and wind generators
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W8JX
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« Reply #18 on: February 24, 2012, 02:14:49 PM »

Go with two Deep cycle batteries such as an optima blue top, they are designed to be drained, they are sealed marine batteries, then a simple battery isolator, they are not hard to install, 3 lugs on them, one is in/out and one is in/out and one is just in to the second battery. all 3 get grounded. OR the second battery could be a 12volt 8DHD battery. Used in rigs.

 All it does is charge the two batteries, Allows the car/jeep/truck to run of the main and maintain it and then also charge the second battery. Pretty easy, use 4 gauge or 1/0 wire to the batteries, you may need to upgrade the alternator, Also the isolator will allow you to drain the second battery with out killing your main. You will still be able to start your jeep,

 Remember your alternator is not really made to "charge" a battery but maintain it' So I would check out camping world for solar panels or checkout http://magnet4less.com/ they sell panels and wind generators

Talk about over engineering. You do not need two deep cycle marine batteries. You also do not need to run 4 gauge or bigger wire to it unless you plan to remote start engine from it  (remote meaning using remote battery and not main battery). And finally I REALLY like the BS about your alternator is only to maintain battery on not charge it and you need a bigger one. If this claim was even remotely try you would never be able to jump a car off with a dead battery and have it recover on its own.  Stock alternator is more than up to it. I have had a few trucks with snow plows and there electric power hydraulic system can draw 150 to 200 amps when operational. You depend on batteries to help with load and alternator recharges them when pump is not running. Never had to hook a battery charger up to it to recharge batteries.  Keep it simple. 
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MDNITERDER
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« Reply #19 on: February 24, 2012, 03:45:32 PM »

 Have you not seen an alternator say DO not attempt to start a vehicle on a low battery, Premature alternator death may occur. as for 4 gauge wire, its cheap from welding shops, so hey when you drain that second battery and you attempt to let that alternator charge that dead battery you go ahead use some 14 gauge wire or 12 gauge wire, anything over several feet i would run 4 gauge period. Overkill maybe but 4 gauge is easy to run, it is cheap and worth the investment.

 But hey, Ive only known a few people that rebuild alternators, and have built race cars..

 the alternator is not designed for charging heavily discharged (dead) batteries. Relying on the alternator to charge a heavily discharged battery can overload the alternator and cause damage. In such cases, use a battery charger instead.

 ON a last note, only reason i recommended a larger alternator is because some after mark lights such as KC 100 watt or 130 watt day lighters can consume as much as 14 amps just for two lights. Some car alternators are as small as 60 amps. If you plan to run a battery dead sitting on the side of a mountain to DX and listening to a radio or having some KC's on yeah, a second battery is not a bad idea.

 I only base this on I have had over 1200 watts of car amps in a car before. I Ran an optima yellow top battery in my daily driver. I ran an alternator over 130amps. Granted car amps suck juice far faster than the average ham radio but in the end a dead battery is a dead battery. how fast it gets there is all how you choose to suck the juice. How you choose to maintain it is your choice to, Side of a mountain and its you and that battery dies then what? dual batteries are never a bad idea, if you move the battery to somewhere else other than under the hood 4 gauge over kill, not really, you could Possibly get away with 8 gauge, but safer than sorry on 4 gauge, Also Something I have learned from the audio world is always fuse equipment twice, ONCE no more than 1ft from the battery and again at the equipment. this will help prevent fires. If you think this is over kill, Ask why they make this mandatory on competition cars.
« Last Edit: February 24, 2012, 04:12:58 PM by MDNITERDER » Logged
W8JX
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« Reply #20 on: February 24, 2012, 05:40:19 PM »

Have you not seen an alternator say DO not attempt to start a vehicle on a low battery, Premature alternator death may occur. as for 4 gauge wire, its cheap from welding shops, so hey when you drain that second battery and you attempt to let that alternator charge that dead battery you go ahead use some 14 gauge wire or 12 gauge wire, anything over several feet i would run 4 gauge period. Overkill maybe but 4 gauge is easy to run, it is cheap and worth the investment.

Were do you get this bull pucky to like do not start a car with a low battery as it will damage/shorten life of alternator?  This is getting better all the time! Then you migrate from me suggesting 10ga or so for charging circuit to 14 ga. 10ga is enough here for a CHARGING circuit and its limited resistance will serve to limit charge rate on aux battery when it is low and not load system to point it can effect it voltage wise. As far as 4 gauge is easy to run and hide in a car, this is rich too. 10 or even 8ga would route far easier and if you want to be able to start for aux battery, two 8ga is same as a single 4ga. As far as 4ga being cheap, scrap copper is 5 bucks a pound here.

But hey, Ive only known a few people that rebuild alternators, and have built race cars..

well I have done both long long ago so you know one more......

the alternator is not designed for charging heavily discharged (dead) batteries. Relying on the alternator to charge a heavily discharged battery can overload the alternator and cause damage. In such cases, use a battery charger instead.

They only way you will overload a modern alternator is to short it out. They are very durable and self limiting. They are bigger in capacity and sturdier than ones of 30 years ago because of the increased demands placed on them by newer cars.


ON a last note, only reason i recommended a larger alternator is because some after mark lights such as KC 100 watt or 130 watt day lighters can consume as much as 14 amps just for two lights. Some car alternators are as small as 60 amps. If you plan to run a battery dead sitting on the side of a mountain to DX and listening to a radio or having some KC's on yeah, a second battery is not a bad idea.

When you need a lot of lights the trick today is more efficient lights. I have not seen a car with a 60 amp alternator for many many years. I do remember when a 37 to 42 amp unit was the norm and I used to change stator and rotor to boost them to 65 to 75 amps. Used to used double V belt pulleys to prevent slippage before there was serpentine belts.

I only base this on I have had over 1200 watts of car amps in a car before. I Ran an optima yellow top battery in my daily driver. I ran an alternator over 130amps. Granted car amps suck juice far faster than the average ham radio but in the end a dead battery is a dead battery. how fast it gets there is all how you choose to suck the juice. How you choose to maintain it is your choice to, Side of a mountain and its you and that battery dies then what? dual batteries are never a bad idea, if you move the battery to somewhere else other than under the hood 4 gauge over kill, not really, you could Possibly get away with 8 gauge, but safer than sorry on 4 gauge, Also Something I have learned from the audio world is always fuse equipment twice, ONCE no more than 1ft from the battery and again at the equipment. this will help prevent fires. If you think this is over kill, Ask why they make this mandatory on competition cars.

What you need more than dual batteries with a big car stereo is several farads of active capacitance as they will handle the charge/discharge cycles of high power audio (and a HF amp) better than any battery/alternator combo alone and lowers peak draw on system. Fusing at both ends is always good bit if you at least do it at source of power you are good to go. Also another reason you do not use a bigger wire than you really need because it to can act like a fuse if need be and burn off. A 4 ga wire will likely never burn off in a car.
« Last Edit: February 24, 2012, 06:42:20 PM by W8JX » Logged

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WX7G
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« Reply #21 on: February 25, 2012, 12:54:40 AM »

A wire burning in a car is a fire in the making.
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W8JX
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« Reply #22 on: February 25, 2012, 05:18:54 AM »

A wire burning in a car is a fire in the making.

Well hate to burst you bubble but most cars have a fusible wire link in alternator charging circuit designed to burn off if alternator short circuits. A lighter wire burn off and failure and far less likely to cause a fire than a heavier wire that over heats and stays heated because it cannot burn off and fail quickly.
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WX7G
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« Reply #23 on: February 25, 2012, 07:00:18 AM »

W8JX, I'm aware of fusible link wires in cars and I considered this. But, they are not ordinary wire such as one might use to connect a second battery.

Here is an a blurb from Wikipedia on Automobile Fusible Link Wires:

"An electrical fusible link is a type of electrical fuse that is constructed simply with a short piece of wire typically four American wire gauge sizes smaller than the wire that is being protected. For example, an AWG 16 fusible link might be used to protect AWG 12 wiring. Electrical fusible links are common in high-current automotive applications. The wire in an electrical fusible link is encased in high-temperature fire-resistant insulation to reduce hazards when the wire melts."

The important information is "...high-temperature fire-resistant insulation to reduce hazards when the wire melts."

I believe a fusible link wire is used to protect against catastrophic shorts and not conditions that push the link close, but not quite, to the point of fusing open. Note also that the fusible link wire is short and confined to a small area in the engine compartment possibly in contact with other wires having fire-resistant insulation.

If, when initially charging a heavily discharged battery through a #10 wire the battery current draw was 200 amps, the wire could heat such that it could ignite material it is in contact with yet the wire will not melt open.

So, for connecting a second battery something safer than only a common thin wire wire is needed to both limit current and provide fuse action. Three options that come to mind are:

1) A common thin wire with a fuse
2) An electronic battery isolator with a fuse
3) A sealed beam headlamp.

The common thin wire is subject to blowing the fuse when the second battery is heavily discharged. This will then require an external current-limited charger to be employed.

The electronic battery isolator is certainly the best from a performance standpoint but involves more installation effort.

The reason I recommend - and have used - a sealed headlamp, rather than a bulb, is because the sealed headlamp surface temperature remains low enough to not be an ignition hazard. It is cheap, safe, easy to install, and effective while providing a visual indication of the state of charge.

« Last Edit: February 25, 2012, 07:17:18 AM by WX7G » Logged
K1CJS
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« Reply #24 on: February 25, 2012, 08:52:44 AM »

If you're that worried about it, connect your second battery directly to the first with a twenty or thirty amp fuse and a heavy duty switch in the lead to the secondary battery.  If the secondary battery is so low that it's going to take more than that in charging current, that fuse will blow, disconnecting the secondary battery and preventing damage to the charging system.  That's how I've got my secondary battery set up, no fancy diode packs or relay centers, and it has worked for me for that past few years, no problems.
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W8JX
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« Reply #25 on: February 25, 2012, 10:08:37 AM »

On one of my dual battery setups I have it is in a old suburban I bought new and while second battery is in a tray under hood I have separate charge and feeds to and from it.  I have a 10 ga wire via a 35 amp push type breaker that feeds it from a line directly from alternator to charge it. (When pulled second battery is isolated from main system) It has NEVER blown even when charging a dead battery. I have a 8ga wire from it that feed into car to power HF rig, VHF/UHF mobile and a few accessory outlets. It is on a 50 amp fuse. Each rig has its own push type breaker. By pulling them I can isolate the circuit in question. I also include a feed from master 50 amp through a 35 amp to feed back to main car buss  if extended time is needed for car lights with engine off. (normally it is pulled) While it is true the some will feed back through alternator charge circuit, the extra strap circuit reduces the resistance in this transfer though not rated for staring vehicle. I also have a large transfer relay that will strap both batteries together with 4 ga for starting on demand. BTW, the alternator is a 105 amp unit.
« Last Edit: February 25, 2012, 11:43:36 AM by W8JX » Logged

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KB1LKR
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« Reply #26 on: February 25, 2012, 02:50:02 PM »

Noting that the question was about MOUNTING HARDWARE for automotive form factor lead acid batteries in a 2007 Jeep JK, not about the limitations of lead acid batteries when used for non engine starting power supply applications in automotive type vehicles, I might suggest a Google search for "Jeep dual battery tray" or similar, as this generates a list of Jeep vehicle specific battery mounting hardware as well as some installation examples w/ photos and commentary. Sorry I cannot offer any first hand experience.

Alas, this thread seems to have wandered off the subject of mechanical considerations and specific hardware experiences in mounting multiple lead acid batteries in Jeep (or other) brand on/off road vehicles; not to say that the discussion of the electrical limitations of automotive batteries, their care and upkeep, and the capacities, the limitations of automotive charging and wiring systems and charging/discharging management of multi-battery vehicle systems isn't also interesting in its own right.

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W8JX
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« Reply #27 on: February 25, 2012, 05:27:02 PM »

Check out this link

http://www.quadratec.com/products/17004_4004_07.htm
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K3GM
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« Reply #28 on: February 25, 2012, 09:12:02 PM »

I have a two tray setup in my 2007 Tahoe.  I run an Optima Yellow Top which is isolated, and charged thru a Hellroaring BIC-95150B battery isolator.  Forward voltage drop thru the isolator is insignificant, so the the isolated battery see the proper charging voltage.  Additional details of the isolator can be found here:

http://www.eham.net/reviews/detail/8294
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WX7G
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« Reply #29 on: February 26, 2012, 08:59:47 AM »

Noting that the question was about MOUNTING HARDWARE for automotive form factor lead acid batteries in a 2007 Jeep JK, not about the limitations of lead acid batteries when used for non engine starting power supply applications in automotive type vehicles, I might suggest a Google search for "Jeep dual battery tray" or similar, as this generates a list of Jeep vehicle specific battery mounting hardware as well as some installation examples w/ photos and commentary. Sorry I cannot offer any first hand experience.

Alas, this thread seems to have wandered off the subject of mechanical considerations and specific hardware experiences in mounting multiple lead acid batteries in Jeep (or other) brand on/off road vehicles; not to say that the discussion of the electrical limitations of automotive batteries, their care and upkeep, and the capacities, the limitations of automotive charging and wiring systems and charging/discharging management of multi-battery vehicle systems isn't also interesting in its own right.

No, the discussion did not wander off topic. Read the second post by the originator of this thread.
« Last Edit: February 26, 2012, 09:01:29 AM by WX7G » Logged
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