Cons of a Solenoid Dual Battery Isolator

[sidewinder]

Hi Paul

I will see if I can find the actual data sheet of the MOSFETs the factory used.

Please seen latest post of factory specs.

[drivesafe]

The facts speak for themselves, this is just prehistoric technology in a fancy package and the truth is that when requiring to charge up a low battery, at the very time when the battery needs both the highest safe voltage and the maximum current available for that type of battery, it’s at this point that this dinosaur causes the most voltage drop and it is nothing but an out and out lie saying there is no voltage drop across this device.

For those who have not come across Derek’s posts on other sites, he will say absolutely anything to get a sale, will beef up the facts on inadequate items as a means to sell anything and thinks nothing of putting people’s lives in danger as long as it gets him a sale.

The net is opened to anybody to try to make a living from it and I for one think it’s a great place for anyone to try out their selling abilities but like anything, there will always be that fringe element that lacks all forms of both moral and legal responsibility and Derek is one of these unscrupulous individuals

I’ve locked horns with with this one on a number of occasions when he has persisted in selling gear that if fitted would actually have more chance of burning a vehicle to the ground than be of any real use to the buyer. Some many people posted how dangerous one of his lines were that he finally had to go and change it, but he still uses the most misleading info he can in attempt to deceive inexperienced people into buying his gear.

He regularly promotes himself as an auto electrical expert but he has no auto electrical experience other than selling auto electrical parts, yet he continually giving unbelievably inaccurate and down right dangerous advice.

I hate snake oil pedlars and this is one of those extreme cases of buyers beware.

[sidewinder]

Well once again you attack me in the most unprofessional and personal ways. Why not buy one and test it before knocking a product. We achieve 30amps at 14.1V to a 120 a/h AGM mounted in a caravan through 9m of 10mm2 cable.

This is my own rig so you are welcome to inspect it any time you come off your mountain.

I like your website by the way you seem to be some what of a copy cat. Your one kit is an exact copy of my one that you abused so well on one of the other forums.

"SC80 Professional Caravan Wiring Kit"

"Unlike some of the amateur kits available on the net which both comprise of substandard materials to do the job properly and are so poorly designed that they are down right dangerous, we have used our more than 30 years of automotive electrical experience and 20 years of working experience in the RV industry, designing, manufacturing and supplying top quality parts and equipment to RV makers, to design a complete kit for the DIY market."

You forgot to mention you copied this from me. I even noticed you selling them on ebay.

Snake oil ? Morals ?

Please ?

Your product should be able to sell itself. You try to be a professional and show a comparison between products and advantages / disadvantages. There is no need to attack a person or product in the way that you do and it won't be long before you will be legally challenged for your abuse.

Please note that WARN winches is now moving to MOSFETs to replace solenoids in their control boxes. Modern MOSFETs are not "prehistoric".

Here is an extract from WARN. "WARN Industries has taken MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) technology and put it to work for serious off-roaders. The 9.5si MOSFET control module eliminates the solenoid pack and its electro-mechanical functions. Operating temperatures from -40°F to +180°F won't faze it. Voltage drop to the winch is minimal for more efficient operation and low heat gain. "

I will order one of your units for testing so I can also conduct a "FAIR" comparison of your product. I would like to see if the 2 outputs are isolated from each other as our BiSolator does, I would like to load test the blue and grey wires to see if they can carry 14V Dc @ 40amps for any considerable amount of time or if one of the wires with the "Optional" 30A breaker is shorted to earth the SC80 blows up or catches fire before the 30A breaker opens.

I will fax an order to your Traxide web number.

If you don't wan't to sell directly to me then place a few more on ebay again and I will buy one.

[drivesafe]

Sorry to disappoint you Derek, but I have never sold or attempted to sell anything on Ebay.

If one of the many companies I deal with, chooses to do so, that’s their business.

By the way, as your kits are STILL a death trap, so I most certainly wouldn’t copy them. I do offer a MUCH SAFER and more cost effective alternative.

Once again you show just how little you really understand about auto electrics. The Warn motor is designed to run at much lower voltages than that required to charge a battery properly, so the voltage drop that occurs is not going to be a problem for a winch motor.

Now just incase you still haven’t got it, the voltage drop across the fets at high current means an unacceptable voltage drop at the battery. This is a major problem when trying to charge a battery.

Last but not least, unlike you, I come to these site to learn and where I can, to help others, the only reason you are on this or any other site is to sell your gear, you make zero contribution to any site.

[sidewinder]

Well you are persistent.

Did you get my order ? I look forward to testing your gear.

[drivesafe]

Derek, you don’t need to buy one of my controller, you already use a simplified version of them.

The BI-80 is a simplified version of my gear and the company that makes them, having business scrupulous, ( something you can’t be accused of ) notified me about 6 years ago that a company I had been dealing with in NSW and I had stop credit to because they wouldn’t pay the bills, had contacted the company that makes the BI-80, sent them one of my controllers and asked them to copy it.

The company refused to make copies but liked the basic principals of my controller so the devised their own simplified version but they also contacted me and both told me of their intentions to make the BI-80 and that the scum bag in NSW was trying to get copies made of my gear.

So if the BI-80s work for you then my gear, as it uses thicker cable and higher current rated relays, will obviously be even safer to use.

As I have posted many times, Derek you have absolutely no idea of the industry you are in.

[chimpboy]

Well you are persistent.

Did you get my order ? I look forward to testing your gear.

It might pay to be cautious with all this stuff. Drivesafe's got cred here and you... haven't.

[sidewinder]

Yes I thought it was no more than a voltage sensing relay.

I would still like to test one please.

[Thylacine]

The facts speak for themselves, this is just prehistoric technology in a fancy package and the truth is that when requiring to charge up a low battery, at the very time when the battery needs both the highest safe voltage and the maximum current available for that type of battery, it’s at this point that this dinosaur causes the most voltage drop and it is nothing but an out and out lie saying there is no voltage drop across this device.

For those who have not come across Derek’s posts on other sites, he will say absolutely anything to get a sale, will beef up the facts on inadequate items as a means to sell anything and thinks nothing of putting people’s lives in danger as long as it gets him a sale.

The net is opened to anybody to try to make a living from it and I for one think it’s a great place for anyone to try out their selling abilities but like anything, there will always be that fringe element that lacks all forms of both moral and legal responsibility and Derek is one of these unscrupulous individuals

I’ve locked horns with with this one on a number of occasions when he has persisted in selling gear that if fitted would actually have more chance of burning a vehicle to the ground than be of any real use to the buyer. Some many people posted how dangerous one of his lines were that he finally had to go and change it, but he still uses the most misleading info he can in attempt to deceive inexperienced people into buying his gear.

He regularly promotes himself as an auto electrical expert but he has no auto electrical experience other than selling auto electrical parts, yet he continually giving unbelievably inaccurate and down right dangerous advice.

I hate snake oil pedlars and this is one of those extreme cases of buyers beware.

Drivesafe's spot-on as usual.
I have extensive design/maintenance experience with low-voltage DC control systems, and have had exactly the same disputes with Derek's claims over the years.
This is basic semiconductor theory, so anyone with an actual knowledge of the field will see these claims as the crap that they are.
I'll believe in perfect devices (no voltage-drop under load) when I see one. Or perhaps read of one in a technical journal or a specifications sheet. I'm definitely not going to believe in them because an advertisement says they exist. Quoting a manufacturer's advertising does little in the way of providing facts.
So Derek, how about posting a link to a spec-sheet for a mosfet that has O ΔV under load. If your claims are correct it should be easy to prove us wrong.
Or stop making unrealistic claims about your products.


ed

[-Scott-]

My, a lot happens in 24 hours!

First: play nice. I'd hate to have to remove this topic, because it's got some good information. By all means criticise products and performance claims, but please avoid personal attacks.

Second: MOSFETs, when turned on fully, have a property which is generally referred to in their data sheets as a fixed resistance (RDS, or Drain-Source resistance). For high-power devices this may be low (in the order of .01 ohms) but it is NOT zero.

Third: this resistance is only one contributor to the total voltage drop which may be present between the voltage sensing point (used by the alternator's regulator to control the charging voltage) and the terminals of the second battery. The system will also have resistance due to mechanical connections & resistance in the wires. My Jaycar kit isolator (2 MOSFETs in parallel) can have up to 0.5V drop between fuse holder and the +ve terminal of my 2nd battery (two most convenient points to measure.) The fuse was dropping 0.1V at the time.

Fourth: for the record, Paul's post on the bottom of the first page is about the best summary of dual battery charging I have read.

Cheers,

Scott

[sidewinder]

Hi guys

The manufacturer has replied to my email and I have the data sheet available.

Here is a copy of the emails. I have removed the part numbers ABC**** as there is copyright on these products.

I invite you to test one for yourself.

Dear Derek,

Surely!

But pls promise you will just use it for your own ref and may show to your customer but NOT to give them any copy. Can we count on you?

Since the MOSFETs ABC**** we used are only have a RDS(on) = 0.004 Ohm with a powerful ID to read as 202A.

Even we use the ABC****, it will also come with a RDS(on) = 0.0053Ohm with a powerful ID to read as 131A.

Therefore, all our M-Series can surely be counted as ZERO VOLTAGE DROP.

Rgds.,
Albert YAO


Quoting Derek Bester <djbester@bigpond.net.au>:

Dear Albert

Have you got a data sheet for the mosfets used in the BiSolator. I have a few customers who don't understand the Low Voltage drop, they think I am not serious.

Regards

Derek.

[-Scott-]

For those who don't mind numbers, here's some for comparison purposes:

I had a quick look and found some figures on cable resistance. I'll include figures for 2 ga, 4 ga and 8 ga (approximately 6.5mm, 5mm & 3mm diameter, according to the table I found...)

2 ga = 0.00051 ohms/m
4 ga = 0.00082 ohms/m
8 ga = 0.0021 ohms/m

The "better" of the two mosfets has a resistance equivalent to 2m of 8 gauge wire, 5m of 4 gauge or 8m of 2 gauge. The other mosfet is about a third more; a bit under 3m of 8 gauge, 7m of 4 gauge or nearly 11m of 2 gauge.

When selecting wire size, also consider current rating; PVC insulated 8 gauge wire at an ambient temperature of 50 degrees C is (de)rated to around 30A (continuous.) 2m of 8 gauge + a BIsolator = (very roughly) 0.01 ohms, or a 0.3V drop at 30A - neglecting any resistance associated with making connections. Use better cable and the voltage drop will reduce.

[Thylacine]

My, a lot happens in 24 hours!

First: play nice. I'd hate to have to remove this topic, because it's got some good information. By all means criticise products and performance claims, but please avoid personal attacks.

Not interested in causing disruption, only correcting false information.
Nice to see a 4WD forum with a mod who has 12VDC knowledge though .
So I'll just clarify the specification request that I made of Derek for those that may not understand, and leave it there re product critiques.

Hi guys

The manufacturer has replied to my email and I have the data sheet available.

Here is a copy of the emails. I have removed the part numbers ABC**** as there is copyright on these products.

I invite you to test one for yourself.

Dear Derek,

Surely!

But pls promise you will just use it for your own ref and may show to your customer but NOT to give them any copy. Can we count on you?

Since the MOSFETs ABC**** we used are only have a RDS(on) = 0.004 Ohm with a powerful ID to read as 202A.

Even we use the ABC****, it will also come with a RDS(on) = 0.0053Ohm with a powerful ID to read as 131A.

Therefore, all our M-Series can surely be counted as ZERO VOLTAGE DROP.

Rgds.,
Albert YAO

So we can't access these spec sheets?
For those not up with such things, requesting such component specs is the equivalent of asking Toyota what spec wheel-studs they use in a particular model. Obviously they are under no obligation to share such information, but usually do so as it enhances the value of their product.
This info is generally public domain, otherwise repair is impossible by anyone bar the manufacturer.


Danos, you can also achieve intelligent switching without electronics. Digital is all about on's and off's (1's and 0's) and this can be simulated with relays, you just need a lot if you want to get "more" intelligent.
What you can't get is true isolation as Derek's device will provide. These act in a similar fashion to a pair of one-way valves between the alternator and the two batteries, whereas a solenoid simply parallels them
Personally, I drive an old 60 series cruiser due to the fact that I like to keep things simple when in remote locations. Not much on one of them that you can't repair on the track (at least enough to get to help).
So I use a solenoid system, with a cole-hersey type battery switch to provide power to winch. Only concession towards electronics is an "on" LED in the dash.
Solenoid is switched by ignition on AND alternator good AND oil pressure good, and disconnected whenever power is put to winch via battery selector switch. This also allows for "jump-starting" from auxilliary when switch set to "both" batteries.
So car starts on main battery only. When oil-pressure is at normal running pressure and "charge" light on dash goes out batteries are connected in parallel and stay this way until alternator, oil-pressure, or ignition fail.
$40 worth of spares enables me to repair on side of road if things go pear-shaped. Even without this, a simple piece of wire can bridge out any part of the system if it fails, allowing you to at least get to assistance.

Cheap, effective, reliable, repairable, and SIMPLE.


ed

[drivesafe]

When selecting wire size, also consider current rating; PVC insulated 8 gauge wire at an ambient temperature of 50 degrees C is (de)rated to around 30A (continuous.)

Hi Scott, off topic but where did you get the figures for the 8 Gauge cable, this is the first time I’ve seen anybody post the correct current rating for this cable, particularly the “CONTINUOSâ€

[chimpboy]

Solenoid is switched by ignition on AND alternator good AND oil pressure good, and disconnected whenever power is put to winch via battery selector switch. This also allows for "jump-starting" from auxilliary when switch set to "both" batteries.

This is a very good idea, factoring in the oil pressure that way. I like it.

[drivesafe]

Solenoid is switched by ignition on AND alternator good AND oil pressure good, and disconnected whenever power is put to winch via battery selector switch. This also allows for "jump-starting" from auxilliary when switch set to "both" batteries.

This is a very good idea, factoring in the oil pressure that way. I like it.

I missed that one and it’s a better idea than tapping the alternator.

Any idea as to the maximum current the sensor can handle.

It shouldn’t be a problem as a good quality solenoid will draw less that an amp and cheapo crap solenoids draw even less current.

[Thylacine]

I missed that one and it’s a better idea than tapping the alternator.

Any idea as to the maximum current the sensor can handle.

It shouldn’t be a problem as a good quality solenoid will draw less that an amp and cheapo crap solenoids draw even less current.

Been using this system for 20-odd years now on various vehicles, but think I was originally going to call the solenoid on "oil-pressure good" and only threw in the others for fail-safing.

Wouldn't have a clue as to the rating of the pressure-switch, it's used to call a relay anyways, as are the other inputs. All wired to fail-open.


ed

[drivesafe]

I like your idea and I imagine it has been around for a good while as has the more regularly use alternator set up but I have never been a fan of using the alternator, too many potential risks of damage if someone gets it wrong while setting up.

On the other hand, the oil pressure sensor is a simple way to do away with to automate an “Idiot switchâ€

[Cossie]

For those who don't mind numbers, here's some for comparison purposes:

I had a quick look and found some figures on cable resistance. I'll include figures for 2 ga, 4 ga and 8 ga (approximately 6.5mm, 5mm & 3mm diameter, according to the table I found...)

2 ga = 0.00051 ohms/m
4 ga = 0.00082 ohms/m
8 ga = 0.0021 ohms/m

The "better" of the two mosfets has a resistance equivalent to 2m of 8 gauge wire, 5m of 4 gauge or 8m of 2 gauge. The other mosfet is about a third more; a bit under 3m of 8 gauge, 7m of 4 gauge or nearly 11m of 2 gauge.

When selecting wire size, also consider current rating; PVC insulated 8 gauge wire at an ambient temperature of 50 degrees C is (de)rated to around 30A (continuous.) 2m of 8 gauge + a BIsolator = (very roughly) 0.01 ohms, or a 0.3V drop at 30A - neglecting any resistance associated with making connections. Use better cable and the voltage drop will reduce.

Is that right? 3mm diameter cable handling 30A continuous?
Narva appear to state only 10A for their 3mm cable.

Also worth noting that the given size in mm is merely an industry refence and not the actual size of the cable. The actual size of the copper core can vary greatly between manufacturers.

[-Scott-]

Also worth noting that the given size in mm is merely an industry refence and not the actual size of the cable. The actual size of the copper core can vary greatly between manufacturers.

No argument there.

I started talking 8 gauge cable, and gave the core (copper) diameter as an approximate equivalent to help people not familiar with AWG sizes.

Is that right? 3mm diameter cable handling 30A continuous?
Narva appear to state only 10A for their 3mm cable.

I have no doubt. I have no idea where mobs like Narva get their sizing from, but it doesn't appear related to core size.

A 3mm diameter core has a (nominal) cross section of about 7 sqmm. 1.5 sqmm PVC double-insulated mains cable is commonly rated to 15A.

[drivesafe]

Is that right? 3mm diameter cable handling 30A continuous?
Narva appear to state only 10A for their 3mm cable.

Also worth noting that the given size in mm is merely an industry refence and not the actual size of the cable. The actual size of the copper core can vary greatly between manufacturers.

Hi Cossie, 8 Gauge is 7.9mm2 cable and and Gauge, AWG and B&S are all the same size and are comparatively accurate system of sizing cable as size is based on the actual cross sectional area of the copper.

Your referring to that crap cable sizing system used here called Automotive size and yes your right, the actual size is based on the copper and the insulation so is opened to vary large variations in copper size.

Cheers.

[Cossie]

Glad we cleared that up anyway. Theres no way I'd be using 3mm cable for anything, never mind trying to put 30A through it!

Theres far too much confusion and misleading information relating to cable sizing being provided by the manufacturers! I also find most cable manufacturers dont actually use 'gauge' as a measurement. Most state overall diameter which is next to useless and cross sectional area (mmsq) of the cable which is more beneficial.

[drivesafe]

Theres far too much confusion and misleading information relating to cable sizing being provided by the manufacturers!

Not wrong there and unfortunately this is a problem with just about everything related to 12 volt issues.

I buy cable in bulk and the company I buy it from supplies all the info I need relating to correct cable size and far more importantly correct cable maximum current carrying capacities.

Scott’s post above is the first time I’ve seen anybody else give anywhere near the correct load rating for cable.

[Cossie]

I buy cable in bulk and the company I buy it from supplies all the info I need relating to correct cable size and far more importantly correct cable maximum current carrying capacities.

Scott’s post above is the first time I’ve seen anybody else give anywhere near the correct load rating for cable.

Any chance of sharing some of info for the more popular ratings/cable sizes?

[-Scott-]

Cable current capacity is one consideration, but (to me) the more important consideration is the voltage drop. For most 12V power installations, if somebody chooses cable based SOLELY on current capacity, they'll have an unacceptable voltage drop - and the question of voltage drop is how we stumbled onto cable size in the first place.

Remember that the current rating of a cable is a measure of the MAXIMUM power you can waste in that cable before it gets too hot (for its insulation.) If you run a cable at its maximum rating, then you're wasting too much power (IMHO.)

Auto-electrics is more than just pullng a few wires and joining them up.

[-Scott-]

Any chance of sharing some of info for the more popular ratings/cable sizes?

There's a number of charts and tables out there, hopefully drivesafe has them more readily to hand than I do. Bear in mind that each table will give slightly different figures, because there are so many different manufacturers, core constructions, cable configurations, insulation types, intended applications, cable testing and rating methods. If in doubt, go larger.

For what it's worth: In a previous job, where we were developing a product range running on 24VDC, we chose to use 14ga for circuits up to 10A, and 12ga for 15A. Duty cycle and cost of cable came into that decision.

[drivesafe]

Hi Scott, you obviously have opened pandora’s box before.

The reason I asked my question of you earlier is in a hope you may have come across some comprehensive info, but I see you are in the same boat as most of us and just try to sort through the mountain usually only partially related info.

Again my question is based on the fact I, through total frustration of dealing with suppliers and manufacturers who usually know nothing about their products, am about to put some cable and cable protection device info up on my web site and I’m trying to source as much cable related data as I can find.

You have made the unusual choice of using the Gauge standard to select your thinner cable, where the vast majority of cable uses here in Australia only use the Gauge standard for cable sizes from 8B&S and above and everybody else uses “Automotiveâ€

[me3@neuralfibre.com]

Just to slip another in. I notice Toyota gets away with very thin wire for much of the factory loom (headlights especially). They seem to use hard copper for theirs, not sure if that helps. I assume they look at it all for weight / cost, and I know that an upgrade doesn't hurt, but the point being, the factory loom works with factory loads. If you told me you were going to run headlight off the wire the factory loom consists of I would be very nervous. Finally, the factory loom is bundled, increasing it's heating and theoretically de-rating it significanftly. Again, they seem to get away with it....

Paul

[-Scott-]

Paul

Owners of late model Pajeros have made similar complaints - the factory wiring is ridiculously thin. I think it comes down to copper is now in high demand, and (I've been told) bulk cable prices fluctuate with the price of copper. The less copper a manufacturer uses, the fewer cents it costs them - and I'm sure the final decision is made by the bean counters and not the engineers.

drivesafe

Sorry, no comprehensive info - just a small collection of pages from here and there. The rating I mentioned earlier came from a Helukabel data sheet. I guesstimated where the 8ga would fit in their metric table, then used their de-rating factor (for PVC insulated cable) of 0.61 for 50-55 Deg C.

I used to work in terms of sqmm, but (quality) automotive power stuff seems to be rated in AWG - and some stuff I ordered according to metric sizes (don't remember what sizes I ordered) came labeled with AWG.

Just to drift further off track, I wonder how many people are aware that Australian Standards for 240V wiring mandate that all PVC insulated cables be limited to 75 Deg C maximum temperature - regardless of the manufacturer's rating. I still come across stuff labeled as 90 Deg C - but for AS design purposes, it's not allowed above 75.

Cheers,

Scott

[drivesafe]

Hi Scott, correct me here if I’m wrong but I think it doesn’t matter if the cable is V90 but all calculations must be based on the cable having a worst case rating of V75.

I know most automative cable MADE in Australia, note I mean MADE here and not imported from Asia, is V75 but my supplier uses V90, it’s just a little extra safety but one of the reasons I use there cable.

Although AWG is pretty well standard in it’s sizes I still wish we used the European Metric cable sizing, much more straightforward.

The main reason I intend to post info on my web site is because of all the confusion relating to the correct cable to use.

Your 8Ga current rating is just about on the money but it’s surprising how many outlets are marketing 8B&S cable as 100 amp rated cable, even when it’s twin sheathed 8B&S.

There’s one clown on Ebay flogging a wiring kit with 8B&S cable and 100 amp fuses to protect it.

It’s a shame the vehicle will burn to the ground before the fuse can protect the overloaded cable.

A 30 amp circuit breaker is the highest current rating safety device that can be used with 8B&S cable.

This all may be way off subject but a safety warning is always good for everyone.

BTW Scott, that’s exactly what I have, bundles of different data sheets and charts

Cheers.