dual battery install

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So lets clear up the misconceptions about DCB...

Deep cycles will, have been, and are currently used to start engines including big block motors without effort. If that battery has the CCA required by the engine it will spin it just as fast as a starting battery. Not as long perhaps, but as long as the CCA are present there is no difference since the starter cannot tell whether those CCA are coming from a starting, deep cycle or hybrid battery. The FACT is that all batteries at the beginning of their discharge curve start out the same. It is the battery design that alters the shape of the discharge curve. It is true that a starting battery is designed to deliver a high current for a specific length of time after which the voltage drops rapidly. At the other end of the spectrum is a deep cycle which will deliver a much lower current (test spec is usually 23 or 25 amps) for a long period (usually 2 - 3 hours for a group 24 - 27). That does not mean it will not start an engine. It also means that continued cranking on an "untuned" or "balky" engine that a deep cycle would not survive that treatment for any length of time. But it will not be harmed by a 3 - 5 second starter draw

Batteries such as the 2xpower Batteries plus (can't remember who the actual manufacturer is right now) DCB's are totally fine to be used as a starting battery. Mine have been flawless for 1+yr & 25,000mi. Based on the year the 1fz-fe CCA spec is 450-650CCA, most quality group 27 DCB's are rated at around 900CCA +/- 100 (the 2xpower 27 is rated over 950CCA), that is plenty to handle our engine.

So take the 'never used a DCB for starting' statement with a grain of salt.

It is MORE important to have all of your batteries the same type, capacity and in service date.


lets talk abut 2 things

"It is MORE important to have all of your batteries the same type, capacity and in service date " this is correct only if you don't have saprator then a different type (or the same type different date) will discharge on each other because of difference of internal resistance

If they are connected Via diode or separation system this is not relevant

Some of your data are being just publicity and you didn't take into account cost and pay-load weight
 
I have been running accessories and arb fridge 24/7 off the aux battery with solar for 4+ years. I have volt meters installed to check voltage on both batteries. As soon as the sun is up for about an hour, the aux battery will reach full charge, trigger the blue sea 7620, then float to the main battery, and it will keep both batteries in float mode throughout the day. I often see 12.4V in the morning on the aux. I rather have the main battery stay fully charged.
 
Thanks @Funner I intentionally left out the breakers to keep the diagrams easier to read.

When I winch I have the vehicle running (with hi-idle switched on) and I manually link the batteries. I've got 0 Gauge going between batteries with 100amp breakers at each end. 4 gauge wire heading back to the 3rd (Rear) battery, 50 amp breakers on each end and a Blue Sea 7600 dual sense isolator with manual override. The inverter is fused to the Rear battery and the solar input is direct to the Rear battery.

So when the rig is off and the fridges are running (off Rear battery) this is how charge flows when solar is active:

1) Rear Battery is getting more amps than its discharging, reaches float & Triggers Blue Sea 7600 links Rear to Main Batt.
2) Main Batt charges to float voltage & triggers dual battery relay, links Main with AUX "Savior" battery.

Solar--->Rear Batt--->Main Batt--->Savior Batt



When the rig is on this is how it flows:

Alternator--->Main Batt---@13.3V---> Savior Batt
Alternator--->Main Batt---@13.8v---> Rear Batt <~~~Solar Panel


Also note that I've only had my rear battery installed for a week, I've yet to see how the solar will handle floating / triggering relays for multiple batteries. It did do fine triggering the link from main to the savior battery though so I expect it to work.


Just for clarification to the OP and anyone else that stumbles into this thread over the years. I was commenting on his diagram, not yours. I would have replied to your diagram if I was making a comment on yours.:flipoff2:
 
So Not sure if it's been answered, but the whole 'same ground' thing is based on avoidance of ground loops for heavily amplified car stereos. One amp has a good ground, other amp isn't quite as good... hum/hiss happens.

Not sure a common ground has any other actual benefits outside of car stereo noise avoidance...
 
So Not sure if it's been answered, but the whole 'same ground' thing is based on avoidance of ground loops for heavily amplified car stereos. One amp has a good ground, other amp isn't quite as good... hum/hiss happens.

Not sure a common ground has any other actual benefits outside of car stereo noise avoidance...

In our rigs your right theres not much else, that is affected by minor ground loops. Unless you have CB / HAM radios.

lets talk abut 2 things
If they are connected Via diode or separation system this is not relevant

Not many people are running a diode between batteries. And are you referring to a charge sensing relay when you say 'separation system'?

Just trying to make sure I understand.

If you have installed a dual battery kit (any brand) you've installed a charge sensing relay capable of either being manually connected / disconnected (lock out). These relays are not current gates like a diode. So when linked the batteries are still able to discharge on each other due to different condition, capacity and age. The effect is likely less drastic when the engine is on and the alternator is charging but its still there. So I maintain that it is important to have the same batteries installed at the same date on a dual battery system.

I'm interested in the diode comment though. What situation would you want to send charge to a battery but disallow it from sending any charge back if needed? Perhaps a rear battery system designed to only run certain accessories like freezers?
 
A diode alone would allow the alternator to charge the main and aux batteries but not allow the aux battery to become drained when a load is applied to the main battery. This would mean, given no other loads and "all things being equal", that you "always" had a fully charged aux battery.
Add to this system a switch to be able to combine the batteries and you could:
1. Jump start yourself
2. Combine batteries during winching
 
Another thing I learned from experiance that I'll share with the group is to be mindful on which battery you run your accessories from.

If you are or are planning on running a solar panel on the roof then run ALL of your accessories (winch doesn't matter) from the main battery.
GHNX78nHXDn5GDXNVAtquLRHsKXPyniyGYZarf3bsSUM5v0ny0qfTTUcTz4JZqTBVMWfgJt28KkZSUPGVey-_uG_xds-7OWZcJv-DyDYZVE-CfGSKqTJvZ2j58sq1Ts8ptKEwX4zFAGV5qxueaURWLBcfij4btuR2AHKKeH5a5UxbUI2dQpjbMkVDj8ber5uP5R4Z_61bQbLkGLfR15cojGJ2gp0pcl3QSP2wT_TwjQGqPT_LOHkvj87YoRd6QPdLR-rMvlkbIaJHRo9zOrrc9c-vEmv1lYIZh0oHlhgqwqPikRx659eRMhV-PYMzkAYOpYvoobxSG-b2NdabTu43ocJYuEC5r00leM1sp4YY9sF-4H1XSXdUaNgOs3-8V8SVl268OvpE1ZWZhIcpaG2zQLicfxl7Bx6uKFVEGJPP2fW3SgW7LiH0ipv6VQWTJ3XoD3c5ahKvSoyfeqylpXme57g-eUpavXh41MOy4uPzctygpm5DsxiNTrF8nsXsvTkb7jOV2HO1hUgAAheXeVYvn6zmADdLlRm8vyO88k7jxKOShjy5ldhFgTXRjt8mr_McbI1l6xg0e6NEK-bpBbwyawhbQwIkqSEmABmEFxeeA=w1198-h925-no


The reason is that as the accessories drain the voltage the solar panel will replace it. Once the main battery is filled up to float voltage and as long as the solar is putting out amps it will AUTOMATICALLY trigger the charge sensing battery relay. Note: The solar will always be tied to the main battery (if you want to utilize the charge sensing relay to automatically link both batteries when the main is up to float voltage)

So what happens if you have all of your accessories off the aux battery and you keep your main battery as the 'clean' / always charged battery?
  1. The main battery is always at 12.8 and when the solar panel is generating charge it reaches float voltage very quickly
  2. Your aux battery has been discharging while you are using your accessories and is at 11.8 volts
  3. AS SOON AS the main hits float voltage the battery relay is triggered and links the two batteries
  4. A large amount of current rushes into the aux battery from the main battery in an attempt to equalize the system that is now in parallel.
  5. Since your solar output is likely 10 amps max (not 80 like your alternator) the main battery's voltage drops to less than float and trigger voltage as it sends current to the aux battery (relay trigger voltage is ~13.3V, Float is between 13.8-14.2V)
  6. The charge sensing relay now senses the main battery is under the trigger voltage and disconnects the two batteries.
  7. As long as the solar is putting out the main will reach trigger / float voltage very quickly once disconnected from the aux battery and the whole cycle repeats.
I saw this first hand in Moab, my buddy has a 100w panel flat mounted on his roof and the same dual battery system as me but wired all his accessories to the aux battery. On a sunny day in Moab the relay was cycling like every 30 seconds it was insane.

Now you could wire your solar to the AUX battery but it won't help the main battery unless manually linked. Or if you wanted to get creative with diodes you could turn the single charge sensing relay into a dual charge sensing relay (or just buy a blue see 7600) and put your solar panel on your aux battery.

I plan on running my starter cable to the AUX battery so that as long as the main battery has enough voltage to trigger the starter solenoid the starter will get the 12.8 volts from the AUX. Its better than draining the main, then linking them to start (pulls the cumulative voltage down).

This is my experience.


Almost none of what you are saying is true or makes any sense. It sounds like your Moab friend set up his system poorly and did not understand the underlying principles.

In most VSR (ACR in BlueSea speak) systems like ours, it makes the most sense to run your Aux loads off the aux battery, and also to run your solar to the aux battery. That allows you to use a real starting battery for starting, and a deep cycle to to run your loads. This also makes certain your starting battery is always fully charged, since no loads are coming off of it and the VSR keeps the batteries separate except under charge.

It makes no sense to run solar directly to your main battery, unless it is your only battery and responsible for aux loads as well. However if you did run aux loads off your aux battery but set up your solar on your main battery, I could see the potential for hysteresis, which is addressed by most VSR/ACR type systems by building in a time delay to prevent rapid cycling. So if your system is set up incorrectly, and you have a short time delay in your circuitry, this is a theoretical possibility, but extremely unlikely in real life.

In a dual battery system based on a voltage sensing relay, your batteries do not need to match. And since most VSR based systems are dual sensing, if either battery has a charge current, once the battery being charged can hold a specified voltage(usually above 13.5), the VSR will close anyway and top the other battery too. Since your starting battery will be basically full, the idea that somehow the VSR closing will drop the voltage of the aux battery significantly does not really make sense.

Plus the voltage differences between the 2 batteries are tiny-less than 1 volt typically, there isn't going to be much battery to battery current. If you think about it, an aux battery being charged will be 13.5 volts, the isolated starting battery will be near 12.8 volts. When the VSR closes the .7 volt difference is not enough voltage to cause a "rush" of current anywhere.

Deep cycle batteries can work fine as starting batteries, but real starting batteries work better. It's all about the specs and what you need. MOST AGM batteries seem to be both starting and deep cycle capable because of the low internal resistance, but you need to decide if you want to run $250 batteries (Lead Acid AGM) or $100 batteries(Normal flooded lead acid).


I have been running accessories and arb fridge 24/7 off the aux battery with solar for 4+ years. I have volt meters installed to check voltage on both batteries. As soon as the sun is up for about an hour, the aux battery will reach full charge, trigger the blue sea 7620, then float to the main battery, and it will keep both batteries in float mode throughout the day. I often see 12.4V in the morning on the aux. I rather have the main battery stay fully charged.


I could not agree more, though I use the 7610s in 3 of my Land Cruisers. It's a nearly perfect system, easy to install, inexpenisve and 100% reliable.
 
In our rigs your right theres not much else, that is affected by minor ground loops. Unless you have CB / HAM radios.



Not many people are running a diode between batteries. And are you referring to a charge sensing relay when you say 'separation system'?

Just trying to make sure I understand.

If you have installed a dual battery kit (any brand) you've installed a charge sensing relay capable of either being manually connected / disconnected (lock out). These relays are not current gates like a diode. So when linked the batteries are still able to discharge on each other due to different condition, capacity and age. The effect is likely less drastic when the engine is on and the alternator is charging but its still there. So I maintain that it is important to have the same batteries installed at the same date on a dual battery system.

I'm interested in the diode comment though. What situation would you want to send charge to a battery but disallow it from sending any charge back if needed? Perhaps a rear battery system designed to only run certain accessories like freezers?


Look Sir, I am a PHD in physical Chemistry when I was young before I became red neck hooligan and my English is poor but,,,,,

But I used the word OR, diode or separation system

Separation system could be any device that will break the connection when they are not under charging, manual switch stupid timing IC555 based device or automotive timer (it will connect the batteries let say 2 minutes after you open the car switch and disconnect immediately after you close the car switch) which I made a few of for my cheap friends that didn't want to spend the money and after forgetting to use the manual switch and come to dead rig. The work for years with no problem and there are the commercial ones with voltage sensing.


This is totally erroneous I quit and I am polite right now "So when linked the batteries are still able to discharge on each other due to different condition, capacity and age. The effect is likely less drastic when the engine is on and the alternator is charging but its still there. So I maintain that it is important to have the same batteries installed at the same date on a dual battery system "

Looki here Mr :/ if both batteries are above discharging voltage they are not in discharge condition!! What you are saying is against the laws of physics and electrochmistery so if the relay link them when the alternator works even at idle and batteries are empty 12.4-12.8V

Let me amaze you if they are linked no charging at all but a big consumer is pulling a lot of current even then there is no effect of self discharge because of the difference.

Diodes were used because they are cheap and reliable or because EMP reasons or mechanical vibration surrounding
cons
They produce heat it consumes energy
There is a drop of 0.7V
And the charger, i.e. Alternator, does not sense the battery
 
Almost none of what you are saying is true or makes any sense. It sounds like your Moab friend set up his system poorly and did not understand the underlying principles.

In most VSR (ACR in BlueSea speak) systems like ours, it makes the most sense to run your Aux loads off the aux battery, and also to run your solar to the aux battery. That allows you to use a real starting battery for starting, and a deep cycle to to run your loads. This also makes certain your starting battery is always fully charged, since no loads are coming off of it and the VSR keeps the batteries separate except under charge.

It makes no sense to run solar directly to your main battery, unless it is your only battery and responsible for aux loads as well. However if you did run aux loads off your aux battery but set up your solar on your main battery, I could see the potential for hysteresis, which is addressed by most VSR/ACR type systems by building in a time delay to prevent rapid cycling. So if your system is set up incorrectly, and you have a short time delay in your circuitry, this is a theoretical possibility, but extremely unlikely in real life.

In a dual battery system based on a voltage sensing relay, your batteries do not need to match. And since most VSR based systems are dual sensing, if either battery has a charge current, once the battery being charged can hold a specified voltage(usually above 13.5), the VSR will close anyway and top the other battery too. Since your starting battery will be basically full, the idea that somehow the VSR closing will drop the voltage of the aux battery significantly does not really make sense.

Plus the voltage differences between the 2 batteries are tiny-less than 1 volt typically, there isn't going to be much battery to battery current. If you think about it, an aux battery being charged will be 13.5 volts, the isolated starting battery will be near 12.8 volts. When the VSR closes the .7 volt difference is not enough voltage to cause a "rush" of current anywhere.

Deep cycle batteries can work fine as starting batteries, but real starting batteries work better. It's all about the specs and what you need. MOST AGM batteries seem to be both starting and deep cycle capable because of the low internal resistance, but you need to decide if you want to run $250 batteries (Lead Acid AGM) or $100 batteries(Normal flooded lead acid).





I could not agree more, though I use the 7610s in 3 of my Land Cruisers. It's a nearly perfect system, easy to install, inexpenisve and 100% reliable.

Pump your brakes there drew, no need to come at me teeth out. I'm not spreading untruths. I'll address you point for point.

Almost none of what you are saying is true or makes any sense. It sounds like your Moab friend set up his system poorly and did not understand the underlying principles.
Yes I stated that

In most VSR (ACR in BlueSea speak) systems like ours, it makes the most sense to run your Aux loads off the aux battery, and also to run your solar to the aux battery. That allows you to use a real starting battery for starting, and a deep cycle to to run your loads. This also makes certain your starting battery is always fully charged, since no loads are coming off of it and the VSR keeps the batteries separate except under charge.
Sure thats fantastic perhaps you can expound on this for my dumb mind. Are you suggesting the individual relocates all of their rigs stock and future accessories to an AUX Deep Cycle Battery? So the Starting battery has nothing but the starter on it? Jesus that sounds like a PITA, fantastic concept and if you do that then gold star for you.

It makes no sense to run solar directly to your main battery, unless it is your only battery and responsible for aux loads as well. However if you did run aux loads off your aux battery but set up your solar on your main battery, I could see the potential for hysteresis, which is addressed by most VSR/ACR type systems by building in a time delay to prevent rapid cycling. So if your system is set up incorrectly, and you have a short time delay in your circuitry, this is a theoretical possibility, but extremely unlikely in real life.
I understand the concept behind having a dedicated starting battery. I'm an engineer.

It does make sense and it does WORK to have the solar float the main (starting) battery in the way that mine is set up, once it floats the battery it will float the others (But my solar isn't on my main if you read my post).. Even with my 'dumb' relay it doesn't rapidly cycle.

In a dual battery system based on a voltage sensing relay, your batteries do not need to match. And since most VSR based systems are dual sensing, if either battery has a charge current, once the battery being charged can hold a specified voltage(usually above 13.5), the VSR will close anyway and top the other battery too. Since your starting battery will be basically full, the idea that somehow the VSR closing will drop the voltage of the aux battery significantly does not really make sense.

Again perhaps you should have more closely read my post. I do not experience the issue my friend did for the reasons previously stated. Not sure why you are hounding this.

As far as matching batteries thats my personal preference. I like having dual DCB's because it gives me the ability to stick weld off of them more safely than starter batteries. Unless you want the possibility of having a battery explode hot acid all over you, whatever floats your boat I guess.

Plus the voltage differences between the 2 batteries are tiny-less than 1 volt typically, there isn't going to be much battery to battery current. If you think about it, an aux battery being charged will be 13.5 volts, the isolated starting battery will be near 12.8 volts. When the VSR closes the .7 volt difference is not enough voltage to cause a "rush" of current anywhere.

Again read my post and focus on the words. You say this but my real world experience indicates otherwise. IDK what battery you have the rest at 12.8v, thats fantastic buy more, almost ALL 12v batteries I have had experience with rest at around 12.6v. 12.7v is 100% charge state (2.12v per cell)

And perhaps what you aren't considering is a charge source like solar on a cloudy day only putting out 30%, lets say 2.1 amps. This 2.1a floats up the aux battery to about 13.6v then the Blue Sea 7600 links to the main battery... One that is aged some and rest around 12.5v, if I've used any interior accessories it may be lower than that by a couple tenths. When the relay closes there is a rush of current to the main battery as the two batteries attempt to equalize and in some cases when the solar output isn't sufficient it can cause the relay to cycle.
Deep cycle batteries can work fine as starting batteries, but real starting batteries work better.

And you are basing this statement off of? just the name of the battery, what the internet has told you or have you actually looked at the discharge curves??

It's all about the specs and what you need. MOST AGM batteries seem to be both starting and deep cycle capable because of the low internal resistance, but you need to decide if you want to run $250 batteries (Lead Acid AGM) or $100 batteries(Normal flooded lead acid).
.


Agreed, I'm not saying my way is the best way, the right way nor the way everyone should be doing it. Only that its working well for me. Sure there is a cost factor, but with the extra $150 and some 6810 rod I purchased the ability to field weld / repair items that others can't. And yes I've had to do this before.
 
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Look Sir, I am a PHD in physical Chemistry when I was young before I became red neck hooligan and my English is poor but,,,,,

But I used the word OR, diode or separation system

Separation system could be any device that will break the connection when they are not under charging, manual switch stupid timing IC555 based device or automotive timer (it will connect the batteries let say 2 minutes after you open the car switch and disconnect immediately after you close the car switch) which I made a few of for my cheap friends that didn't want to spend the money and after forgetting to use the manual switch and come to dead rig. The work for years with no problem and there are the commercial ones with voltage sensing.


This is totally erroneous I quit and I am polite right now "So when linked the batteries are still able to discharge on each other due to different condition, capacity and age. The effect is likely less drastic when the engine is on and the alternator is charging but its still there. So I maintain that it is important to have the same batteries installed at the same date on a dual battery system "

Looki here Mr :/ if both batteries are above discharging voltage they are not in discharge condition!! What you are saying is against the laws of physics and electrochmistery so if the relay link them when the alternator works even at idle and batteries are empty 12.4-12.8V

Let me amaze you if they are linked no charging at all but a big consumer is pulling a lot of current even then there is no effect of self discharge because of the difference.

Diodes were used because they are cheap and reliable or because EMP reasons or mechanical vibration surrounding
cons
They produce heat it consumes energy
There is a drop of 0.7V
And the charger, i.e. Alternator, does not sense the battery

I'm not trying to disprove you Dino, was just trying to further my understanding on what people are doing. Relax its all good.

You are right the comment you quoted was incorrect, I made a quick assumption based on conceptualizing the systems behavior, I shouldn't have. I was thinking of a situation where you are discharging an amount greater than the charge being provided by the alt. This situation would be infrequent but the batteries would all still be linked. A friend of mine (electrical engineer in the solar field) was telling me that introducing different capacity, types and age batteries in solar systems can cause undesirable and weird charging characteristics. In retrospect he was likely speaking in reference to linked battery banks, as that makes more sense..

And I was just curious as to what you would gain from adding a diode. To increase my knowledge. I am fully aware of what they do and the Vdrop they have across them.

Jesus everyone just chill the f out. There are many different solutions to the question I posed mine, ya'll shot holes in it and thats fine. I'm continually refining my system. I've already had plans to move the starter & systems over to what I call the 'savior' battery which brings the system more in-line with what cruiserdrew is talking about.
 
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Almost none of what you are saying is true or makes any sense. It sounds like your Moab friend set up his system poorly and did not understand the underlying principles.

In most VSR (ACR in BlueSea speak) systems like ours, it makes the most sense to run your Aux loads off the aux battery, and also to run your solar to the aux battery. That allows you to use a real starting battery for starting, and a deep cycle to to run your loads. This also makes certain your starting battery is always fully charged, since no loads are coming off of it and the VSR keeps the batteries separate except under charge.

It makes no sense to run solar directly to your main battery, unless it is your only battery and responsible for aux loads as well. However if you did run aux loads off your aux battery but set up your solar on your main battery, I could see the potential for hysteresis, which is addressed by most VSR/ACR type systems by building in a time delay to prevent rapid cycling. So if your system is set up incorrectly, and you have a short time delay in your circuitry, this is a theoretical possibility, but extremely unlikely in real life.

In a dual battery system based on a voltage sensing relay, your batteries do not need to match. And since most VSR based systems are dual sensing, if either battery has a charge current, once the battery being charged can hold a specified voltage(usually above 13.5), the VSR will close anyway and top the other battery too. Since your starting battery will be basically full, the idea that somehow the VSR closing will drop the voltage of the aux battery significantly does not really make sense.

Plus the voltage differences between the 2 batteries are tiny-less than 1 volt typically, there isn't going to be much battery to battery current. If you think about it, an aux battery being charged will be 13.5 volts, the isolated starting battery will be near 12.8 volts. When the VSR closes the .7 volt difference is not enough voltage to cause a "rush" of current anywhere.

Deep cycle batteries can work fine as starting batteries, but real starting batteries work better. It's all about the specs and what you need. MOST AGM batteries seem to be both starting and deep cycle capable because of the low internal resistance, but you need to decide if you want to run $250 batteries (Lead Acid AGM) or $100 batteries(Normal flooded lead acid).





I could not agree more, though I use the 7610s in 3 of my Land Cruisers. It's a nearly perfect system, easy to install, inexpenisve and 100% reliable.

Thanks for the education, agree with everything EXCEPT nothing is 100% reliable. ;)


Also, can a mod please move this to the "power" area/section? It applies to all types of vehicles.
 
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Almost none of what you are saying is true or makes any sense. It sounds like your Moab friend set up his system poorly and did not understand the underlying principles.

In most VSR (ACR in BlueSea speak) systems like ours, it makes the most sense to run your Aux loads off the aux battery, and also to run your solar to the aux battery. That allows you to use a real starting battery for starting, and a deep cycle to to run your loads. This also makes certain your starting battery is always fully charged, since no loads are coming off of it and the VSR keeps the batteries separate except under charge.

It makes no sense to run solar directly to your main battery, unless it is your only battery and responsible for aux loads as well. However if you did run aux loads off your aux battery but set up your solar on your main battery, I could see the potential for hysteresis, which is addressed by most VSR/ACR type systems by building in a time delay to prevent rapid cycling. So if your system is set up incorrectly, and you have a short time delay in your circuitry, this is a theoretical possibility, but extremely unlikely in real life.

In a dual battery system based on a voltage sensing relay, your batteries do not need to match. And since most VSR based systems are dual sensing, if either battery has a charge current, once the battery being charged can hold a specified voltage(usually above 13.5), the VSR will close anyway and top the other battery too. Since your starting battery will be basically full, the idea that somehow the VSR closing will drop the voltage of the aux battery significantly does not really make sense.

Plus the voltage differences between the 2 batteries are tiny-less than 1 volt typically, there isn't going to be much battery to battery current. If you think about it, an aux battery being charged will be 13.5 volts, the isolated starting battery will be near 12.8 volts. When the VSR closes the .7 volt difference is not enough voltage to cause a "rush" of current anywhere.

Deep cycle batteries can work fine as starting batteries, but real starting batteries work better. It's all about the specs and what you need. MOST AGM batteries seem to be both starting and deep cycle capable because of the low internal resistance, but you need to decide if you want to run $250 batteries (Lead Acid AGM) or $100 batteries(Normal flooded lead acid).





I could not agree more, though I use the 7610s in 3 of my Land Cruisers. It's a nearly perfect system, easy to install, inexpenisve and 100% reliable.


What he said :flipoff2: thank you @Cruiserdrew
 
I pulled my old dual battery system from my previous rig and I am going to install it on Piggy minus the electrical switchboard which will be new
Worked hard for 8 years supplied electricity to the big cooler that pules 7 amp main battery always fully charged the yellow Optima works for cooler converter 220V and chargers camping lights etc.
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There's nothing more rewarding than pulling a frozen bear in the hot desert


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Okay, finished install, got a battery tray and washer reservoir relocation kit from Slee and some cables/ends off amazon. Ended up going with the Blue Sea 7610 as is was cheaper and I didn't need the battery combine feature due to the marine switch. For the switch I ended up going with the Blue Sea 6007 as it was smaller than the 9001e and still had the current rating I needed. Made a quick couple of brackets to mount the switch near the winch and the ACR near the cranking battery. The switch allows me to winch off either or both batteries and acts as a combine switch to boot. Used 2ga welding wire and cable armor to protect the wires where they ran through the radiator support.

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