Should My Battery Isolator Have Diodes or FETS?

[@franklindmurphy]

Thanks for all the videos Jeff.

[@loupilla2332]

We have a Victron Energy, Argofet Battery Isolator on our Formula BR 310 dual engine boat and we are having a charging problem from the engine to which the isolator is connected. The boat was purchased used. From the manufacturer's literature , it shows two small wires (I will call them signal wires) that are connected to the isolator that are in addition to the connected power cables. The two wires are connected to a terminal marked "Ground" and a terminal marked "Energize". The Energize connection is shown to be connected to the run/stop switch on the boat and of course Ground to battery negative. On our boat the terminal marked "Energize" has no connection to it and the terminal marked "Ground" has a fused (0.5 amp) wire connected to it that is coming from the positive terminal of the cranking battery. In checking with the boat's manual I found that the boat is wired according to the manual. Can you tell me if the isolator wiring on the boat, which is in agreement with Formual's manual, is alternate way to hook up the isolator. BTW when checking the fuse, it was found to be blown.

[@sigaaff]

I have installed about 15-25 argofet battery isolators on different boats in my career. I totally recommend these. Especially when you are dealing with 3 battery banks. With two battery banks you can use VSR (voltage sensitive relay). But using VSR has its own limitations. Only problem with battery isolators i have witnessed is when one of the battery banks should have some kind of failure. In this occasion i have seen faulty battery bank will draw almost all of the charging from alternator. Maybe I´m missing something here and Jeff could explain it for us, why this kind of error would occur and how to avoid it.

[@ericrainey5361]

I have an agm starting battery and a lithium house battery in my RV. What types of battery isolators will work to charge both. Specifically the Victron Energy ArgoDiode Battery Isolators 80-2SC

[@johnnylightning1491]

Good info. I'm not dealing with a boat but with a pickup with camper on the back. Different application same issues. At $120 USD for a Victron argofet 200-2 why would you go with anything less? Thanks.

[@chaserivers4058]

Is it not the case with the diode isolator, you can wire the “sense” lead off the alternator after the isolator which will effectively raise the voltage of the alternator those .4-.7 volts to compensate with the drop across the diodes?

[@larsnielsen6229]

Hi Jeff would recommend a new promariner battery isolator?

[@RollnRye74]

will the isolator drain primary battery when vehicle isn't running and not using the 2nd? i have a small drain that drains my main and can't find it. the 2nd battery is used to operate my wheelchair van ramp and power controls. it's also used to jump my van if main battery is low.

[@scottstolper4473]

Jeff, your analysis is spot-on with respect to the use of silicon or Schottky diodes verses MOSFET based devices. However, if the amount of heat dissipated by MOSFET based devices is minimal, why is the Argo-FET module still constructed on an aluminum heatsink? As you so eloquently pointed out, the devil is ALWAYS in the details. Victron's use of MOSFET's is a step in the right direction, but they've not really cracked the code. Well engineered MOSFET based isolators should have NO NEED for heat sinking, and those products exist, but they're not designed or manufactured by Victron.

[@scottw7267]

Great topic Jeff. I just purchased the victron 200 amp fets unit. I have lead acid batteries now but will be upgrading soon to lithium. is that an issue?? Thanks making your videos basic and easy to understand.

[@speedyhpv]

Question on twin engine. I believe current isolator is diode. It has 2 alternator inputs with 3 battery output. Would I use 2 fet isolators, one for each alternator, then parallel the respective outputs to each battery (starboard and port starter Batts and house batts(4 golf carts series/parallel 12v)). Cheers, Paul

[@sigaaff]

I have done this and it worked without problems.

[@miked1102]

Fet or MOSFET isolators are far more efficient. I just bought a 2009 Beneteau 40 and the previous owner pulled out the Fet isolator and added an ACR. I asked why and he gave the diodes story not knowing the new technology. As well as the MOSFET has a depleting gate, they act as regulators as well therefore the bank with the lower voltage will get the higher load. I have quite a few electrical issues to resolve, even after a purchase survey. Missed switch on charger/inverter etc.

[@braithmiller]

Using VSRelays instead of isolator devices? What is your thoughts? That is my present arrangement.

[@jeffdege4786]

I'm a software guy who's done a bit of playing around with digital circuits. Analog circuits have always confused me, and power circuits scare me silly. But that diodes have a forward bias voltage drop I understand.

[@ernieschatz3783]

So we have something with a twist. We a have generator battery that provides DC power to a communication box on the unit the generator provides AC power to once generator is started. The comm box allows for remote start of the generator among other things. When starting the generator the voltage drops far enough to lose power to the comm box and sometimed pops a fuse on the comm box 12v power suppy, which starts once it gets AC power from the generator. Somebody was talking about using a diode inline between the start battery on the generator and battery near the com box but I'm thinking that using the FET isolator is a better idea because of the lack of voltage drop. Thoughts?

[@leolambert5676]

Jeff I have 2 FETS installed 1 for the starter / house from the alt other for the solar panel system as I have seperated house and starter battery completly

[@fabiogodoy6722]

Hi Jeff, thanks for your sharing knowledge. I always woundered if a DC-DC has a voltage drop similar to a FET isolator. Do you have any onfo on that? Thanks again great channel.

[@darylclark8906]

DC-DC converters, like the Victron or Sterling brands, can actually adjust the voltage (boost or drop) depending on the charge profile.

[@thomasdamato4477]

Should I use lithium batteries for my engines and incorporate them into my inverter system? Or keep them separate ?

[@mikesmultimedia]

All of those issues are pertinent when charging batteries and multiple banks (2× Starter and solar banks). I have learned this over time while developing my system. It's good to hear it in one conversation.

[@thierryg3049]

a FET or MOSFET is a transistor. A transistor is a controlled diode with a gate. In my book it will loose equivalent to a diode based (maybe slightly less). Why does the heatsink a similar size then ????. Forget Isolator, in 2024 go with DC-DC converters with a diigital charging profile like the Victron DC-DC. You batteries will say thank you...

[@rogerkerkmann]

DC toDC converter, problem solved😱🤔, and adjustable

[@martinsonneveld440]

Agree, dc-dc between starterbattery and LFP-banks worrks great: you can adjust the overflow from your starterbattery to the servicebank. My Mastervolt does that for max 50A. That throttles the strain on my 115A alternator (only 35A at low speed!) and prevents overheating the alternator. On longer engine runs I put it to 30Amps, realistically half of flows into the servicebank while the rest is used on the spot. Is more expensive but way more practical.

[@alcibiadesmarcialneto922]

The FET isolator loses 5% of what? If it is in the voltage the result is the same that the 0.7v of diodes ones.

[@brianstone3972]

I thought the same. I hope the FET ones don't lose that much because i just upgraded to them!