Simple dual batteries for expedition vehicles

[whatcharterboat]

This is obviously a supplement to the last thread and relates specifically to a more conventional Dual Battery System and the methods used to isolate, connect or individually charge them. In the past, a common approach was to use diode isolators. Very simple and virtually no chance of failure but diodes aren’t the most efficient things (nothing with big cooling fins is) as voltage is lost as it passes through. So the auxiliary battery bank may not ever reach the correct voltage.

A locally made dual battery system has been popular here because it isolates the batteries completely and sends the charge from the alternator to where it is needed most. So to one or the other but not both at once. The benefit of this is that the recovery time (or time till fully charged) of each battery bank is quicker. A lot of thought has gone into these but they are complicated and not cheap.

IMO Voltage Sensitive Relays (VSR) are a good way to link/disconnect batteries at the optimum time. VSR’s can be connected to a solenoid to do this and in a 12V system they would typically connect when the start battery reaches 13.7v and disconnect at say 12.6V. So basically as soon as the engine is run the start battery voltage increases with the input from the alternator, makes a connection and disconnects shortly after the engine is stopped and the start battery returns to its “at rest” voltage. I’m sure that I’m not telling most of you anything new.

Doug Hackney (in the last thread) made comment about the benefits of using high-grade marine components wherever possible in an Expedition Vehicle and it’s a rare day that I ever pick up an RV suppliers catalogue either. So the system I thought you might be interested in is from www.bep.com and we buy them here from the importer www.bla.com.au . I know that BEP widely distribute in North America but not sure if their products are used in vehicles there so much. Hope I’m not going to look dumb cause you already know all about it.

BEP are from New Zealand and although they also do a range for RV’s, the marine range is more comprehensive. It’s good to know they’re good electrical designers cause they suck at Rugby. The switchboard/distribution gear they do is all modular, meaning that the boxes can be clipped together (to form a cluster) and linked internally (electrically) with bars instead of wiring. See the switchboard pic in the last thread as an example. It’s the range of VSR’s that are particularly simple and applicable to ExpVehicles.

A common cluster we use has an isolation switch for each battery bank, an emergency parallel switch to jump start and a dual sensing VSR module. They do a wide range of VSR’s, all with different options and it’s easy to add modules that have HD fuses, busbars, circuit breakers, ammeter shunts, distribution studs, etc, etc, etc. The dual sensing VSR is really cool because it will connect and disconnect when either battery reaches the cut in/out voltage. What this means in reality is that it will operate the same way as a normal VSR but with the added bonus of the start battery being maintained when the house battery is fully charged. So any charge source connected to either battery bank will automatically apply to both battery banks. Again simplifying the electrical circuit.

Included the bla website cause it has some good info and pics of BEP’s gear. Just had a look and I see that they have a changed the whole look of the product from what was used in the vehicle in the last thread.

An example: http://www.bla.com.au//index.php?fn...3&eId=10&sId=7ac1ae667b3eeadea524e4663e06bcf3

And the old:

http://www.bepmarine.com/Dual-Battery-Charging-Cluster-180-1464.html

Let me know if I’m over doing the postings. Have taken a few weeks off work to clear some uni assignments and I keep getting side tracked when I’m in front of the computer. I’m going to pay big time come Due Date.

 

[eugene]

So the auxiliary battery bank may not ever reach the correct voltage.

This isn't true. Your vehicle should have a voltage regulator and sinice there is one doide leading to the main battery and one to the aux battery they both get equal voltage and your regulator takes reference from the main and therefore the alternator volatge is raised to compensate for the diode drop, so at the batteries you still get the same voltage as before.

 

[ntsqd]

This isn't true. Your vehicle should have a voltage regulator and sinice there is one doide leading to the main battery and one to the aux battery they both get equal voltage and your regulator takes reference from the main and therefore the alternator volatge is raised to compensate for the diode drop, so at the batteries you still get the same voltage as before.

Yes, and No.
With an old school style diode isolator, no. There is no "sense" stud on these, so the regulator sees the batteries through the diodes. Unless the regulator is offset for the cracking voltage, it stops short of a full charge.

Some of the newer isolators have a "sense" stud that allows the regulator see the true battery voltage of one bank. I'm not aware of one that would allow sensing of both banks, but I suppose that it is possible. The newer Delco/Delphi alternators (LS engine series for sure) need to have this stud, or apparently they do not charge at all.

I long ago gave up on isolators. Lacking finding anything that I felt worth replacing them with I've been using a simple marine combiner switch. So long as I don't brain fade their problems are manageable. I've only kilt one set of AGM batteries.....
I've been looking at the Blue Sea ACR, but recently found a source for the BEP VSR here. I have one coming and I hope to put it into use soon. My current thinking it to put it in parallel with the combiner switch, and leave the combiner switch set to main only. Prior to finding either of these relays I had thought do something similar by bugging my work's EE for a voltage sensing circuit and driving a continuous duty solenoid with it.

 

[eugene]

The sense stud is needed for alternators (such as the GM) with internal regulators. The isolators without the sense stud were regulated fine with an older type external regulator.

The problem with any type of switch/soloniod is when switched on your no longer isolated.

 

[Pskhaat]

FWIW, for about 11 years now I've used a simple solenoid relay to connect my two batteries asserted from the ``alternator good'' line in my Toyota. When the truck stops: disconnect. Very simple.

I've maintained two different battery manufacturers for my deep cycle and starter battery and have not experienced any charge problems on either and semi-regularly discharge the deep cycle when at camp.

How would I benefit from a VSR?

 

[ntsqd]

The sense stud is needed for alternators (such as the GM) with internal regulators. The isolators without the sense stud were regulated fine with an older type external regulator.

Prior to buying my FJ60 I could not tell you when was the last time I saw an external regulator on a light duty vehicle. I think it must have been a friend's 1960 El Camino street rod project in about 1990. Even the FJ's regulator is still mounted to the alternator body, just on the outside rather than the inside.

I'm not quite sure how it would effect other things, but with the pre CS series Delco's there is a separate sense wire that usually just gets terminated on the battery charge stud of the alternator which could be attached to the main bank stud on the isolator. Even without this potential mod the SI series worked, they just didn't sense the proper battery voltage. Same is true of my experiences with Motorcraft alternators.

The problem with any type of switch/soloniod is when switched on your no longer isolated.

As long as they are being actively charged I do not see any problem in this. Sitting connected with the engine off would be, but the function of the various relays is intended to prevent this. I've experienced that problem thanks to GM's original dual battery wiring.

How would I benefit from a VSR?

Other than not intruding on the stock wiring and perhaps a slightly more sophisticated management of the relay, not much. What you have works for you, I wouldn't change it unless experiencing trouble.

 

[eugene]

When I say external I mean external to the alternator, a lot of vehicles have the regulator built into the engine control computer or elsewhere.

I don't like the idea of paralleling a deeply discharged and good battery when the oloniod is switched on. Sure most auto otive electronics should be able to handle the dips and surges caused by this but when I was messing around with on board computers it would sometimes cause issues. As you start to connect electronics that were not designed specifically for automotive use you have to keep power cleaner. I've also noticed I have less radio noise without the need for filters when running off a second battery that is isolated while charging since the diodes help to filter out the noise too.

 

[whatcharterboat]

Vsr

NTSQD said "I've only kilt one set of AGM batteries....."

If I did that to a customer’s vehicle they would kilt more than one set of AGM's and expect me to pay the bilt. Thanks for the expanding on the use of diodes.
And Eugene I understand exactly what you are saying about the noise effect on the electronics but we’ve never yet experienced this. Our equipment is virtually all designed for marine or RV use anyway but I will certainly take your warning on board in the future if we fit something that may be susceptible to the noise.

NTSQD said. “Prior to finding either of these relays I had thought do something similar by bugging my work's EE for a voltage sensing circuit and driving a continuous duty solenoid with it”

Have a look at these. (At the bottom left of the page)
http://electroparts.com.au/page.php?x=15

We used to buy these as a package. Exactly what you are talking about. We then started joining 2 together to make our own dual sensing version and the supplier couldn’t understand why but I see that they now sell them as a package that way. Put one on a friend’s yacht a while back so that when he was moored for a long time he could jump back on and know both battery banks were good from the solar.

NTSQD said "I've been looking at the Blue Sea ACR, but recently found a source for the BEP VSR here. I have one coming and I hope to put it into use soon. My current thinking it to put it in parallel with the combiner switch, and leave the combiner switch set to main only."

As I said they do a range of different VSR’s and your idea could be a good way to go. They actually sell a VSR/combiner cluster, also they make a combiner with a VSR built into the back of it and they also do VSR with a small parallel switch on top and to be really tricky they do a VSR with a remote parallel switch so that if your start battery is down you can flick a switch in the cab and it will parallel your banks together for a jump start. http://www.bla.com.au/index.php?fn=...0&eId=10&sId=209b3ff897e0c2f430227b90b810ee3d

We just go for the cluster that I discussed in the original post. It’s the modular system that impresses me. It just makes everything so unbelievably neat, organized and simple.

I also see that BEP do motorized battery switches. Has anyone ever used these? It would be good if Bajaroad could comment, given his knowledge of contactors.

 

[MoGas]

I don't really see a problem with my setup....Open hood, select desired battery(ies) to use or charge via a Blue Sea selector switch, and drive away.

Keep
It
Simple
Stupid

Works for me.

:safari-rig:
Dave

 

[ntsqd]

I have seen the noise in the line. IME it is almost always from the alternator and is likely a leaking diode in the rectifier. A cheep stereo amp is the best way to test for this. I would have expected a battery to be a better noise filter than they appear to be.

My "I've only kilt...." comment was sarcasm directed at myself. I've had the money and occasionally the time to deal with the problem for some time. I've known about the Blue Seas component for nearly two years, yet nothing has happened until recently. As it is, the VSR purchase was spur of the moment purchase as I was placing a large (for me as a non-commercial wirer) terminals/connectors order. Currently that vendor, linked above, is only listing the dual sensing and the single sensing VSR's.
What killed my set of AGM's was leaving the selector switch set to "ALL" while the vehicle sat for a month or more. Not once, but several times. They just don't appear to like that. At least the Exide Optima clones didn't.

I'm more inclined to go the modular route. Seems like any damage will then be compartmentalized instead of possibly wiping out a whole system.

Motorized contactor, as in some sort of motor driven contact switch instead of an electro-magnetic actuation? Interesting. Seems like overkill standing here. I'm interested in what the applications are. They would have a "latching relay" kind of function. hum.........

 

[whatcharterboat]

Kilt

Realized the sarcasm. LOL

I don't know why the motorised switches either that's why I asked
http://www.bepmarine.com/Motorised-Battery-Switch-275Amps-177-1595.html .

 

[MoGas]

I don't know why the motorised switches either that's why I asked
http://www.bepmarine.com/Motorised-Battery-Switch-275Amps-177-1595.html .

I would guess the motorized switches are for larger vessels that the batteries are harder to access than your typical 20-30 ft pleasure boat.

I'd might go with a switch that could be controlled from the cab if there is a higher rated one. The cranking amperage is higher on this one, but the intermittent and continuous are less.

 

[whatcharterboat]

Motorised Switches????

They do a bigger one

http://www.bepmarine.com/Motorised-Battery-switch-500Amps-177-1596.html

But still not sure why cause they also do a completely different product which does the same thing. This is exactly what NTSQD was refering too. A latching relay. Maybe that you can operate them manually OR remotetly is why.

http://www.bepmarine.com/Electric-Battery-Switch-176-1592.html

 

[dhackney]

Here's another quality supplier for dual battery setups:

http://www.balmar.net/

Here's the direct link for one of their dual bank, single charging system components: http://www.balmar.net/page20-Duocharge.html

[full disclosure] we use one of their alternators and voltage regulators as a dedicated charging system for our house bank. Have had no problems with them in one year of use.

I wanted to keep the chassis as close to 100% stock as I could so I decided the extra parasitic drag on the motor, additional weight, additional components, etc. were worth the complexity, etc. [/full disclosure]


One issue that has not been discussed in this thread is the advantages of having a three stage charging system vs. single stage. This can have a big effect on the life of AGM batteries. A dedicated, external voltage regulator can offer three stage charging that you can program to exactly match the characteristics of your battery bank.

Those kilt batteries may have been hastened to the battery great beyond by simple single stage charging.

 

[dhackney]

So the system I thought you might be interested in is from www.bep.com and we buy them here from the importer www.bla.com.au .

The BEP link does not work. The correct link is here: http://www.bepmarine.com/

Great stuff. BEP products look to have a lot of innovative capabilities and features. Wish I would have known about them during the design and build process.

The switchboard/distribution gear they do is all modular, meaning that the boxes can be clipped together (to form a cluster) and linked internally (electrically) with bars instead of wiring.

I especially like your reference to linking via buss bars instead of wiring. I cannot find any photos on their site that illustrates that feature. Do you have a link to anything on their site or any shots from one of your builds that does so?