Battery isolator question October 19, 2022, 11:21:07 am I’m going to replace my battery isolator in my 2006 mid bath. The sure power isolator that’s in there is rated at 130 Amp. I’m looking at using a Victron Argo Fet isolator that would be rated either 100 or 200 A depending on which one I buy. In this application, does the amperage rating matter?Any thoughts on this? 1 Likes
Re: Battery isolator question Reply #1 – October 19, 2022, 11:41:27 am Hello Jack,I believe that you need to match the isolator rating to your alternator amperage (130w) - I’m sure that the electrically expert among us will confirm. I can share a couple of options though:The Relay used by Lazy Daze in recent models is this one: https://www.supplyhouse.com/White-Rodgers-586-108111-Solenoid-SPNO-15-VDC-Isolated-Coil-Normally-Open-Continuous-Contact-Rating-200-Amps-Inrush-600-Amps?gclid=Cj0KCQiA0eOPBhCGARIsAFIwTs4gQws6LzxHDOujEFj9i1F0ccfuzbDUgO1hi70607__L02wturKK7kaAju_EALw_wcBAnother, possibly better device: https://www.precisioncircuitsinc.com/wp-content/uploads/2017/06/00-10041-2xx-Battery-Isolation-Manager-Rev7-1.pdfIf you are likely to upgrade to LiPO4 in the future, you may wish to consider changing the isolator at that time. I say this because when I researched the conversion to Lithium batteries, both AM Solar and Battle Born Batteries recommended installing a DC-DC charger rather than an isolator. I hope that others will chime in on this point because I am not sure that I am convinced such an upgrade is necessary. Good luck,WarrenWarren 2 Likes
Re: Battery isolator question Reply #2 – October 19, 2022, 11:46:57 am Good input and I appreciate it. The reason I was thinking about using the 200 amp Argo fet unit was that it’s well above the 130 amp and thus could handle it with no problem. At least that’s what I was initially thinking.I will look at the two you suggested.
Re: Battery isolator question Reply #3 – October 19, 2022, 01:56:28 pm Hi Jack; I removed my diode isolator when I went to LiF batteries. I got a Renogy 60 A DC/DC because I could control how much current was sucked out of the 130 Amp alternator. It also can be set for a Lithium battery charge profile My chassis battery and everything from Ford are all designed for nominal 12VDC. I didn't want to use the (very good) relay to short the LIF and regular chassis lead acid battery together as a routine thing. You can get away with it because the input impedance of LIF is so low, but I wanted it to stay more separated. Time will tell. The Cyrix and Battleborn 'connectors' are smarter and switch on and off depending on voltage and current demands of the batteries. They work too, but are usually in the engine compartment (tight) and about the same price as the Renogy charger. The Renogy has the advantage that its 'LC' terminal can throttle down demand on the alternator. Headlights, air conditioning, (A/C clutch. fan) etc. can push the load on the alternator pretty high. Newer rigs have 200+ amp capability. Is something wrong with your diode isolator? RonB
Re: Battery isolator question Reply #4 – October 19, 2022, 02:25:44 pm Where did you mount your DC/DC converter? I don’t see a convenient metal surface to mount it, needed to sink the heat from the converter. I don’t want to melt the plastic of the battery compartment enclosure, or singe any wood structure!
Re: Battery isolator question Reply #5 – October 19, 2022, 03:33:18 pm My experience using the diode isolator with lithium batteries didn't warrant the use of a DC-DC charger, I'm not seeing more than 30-amps passing through the isolator when the coach battery is low.A relay-type isolator will have different results. I would check the amperage flow through the relay when charging a low lithium battery to see what the maximum amperage flow is before investing in any other devices.Alternators are somewhat self-protecting, the output drops as it heats up.Larry
Re: Battery isolator question Reply #6 – October 19, 2022, 04:58:46 pm Quote from: RonB - October 19, 2022, 01:56:28 pm Is something wrong with your diode isolator? RonBThis all started when I went to do some cleanup/maintenance on the current installed battery isolator. The corrosion is so bad that I believe I risk breaking the post off when I try to disconnect it.It seems like a good time to go ahead and just replace the battery isolator and if I’m going to do so I would like to move away from a diode type. Thus, my leaning is towards the FET type.I read where this would be a good solution,but I’m simply concerned about the amount of amperage that would go through it. The real question is, if I put in a 200 amp isolator unit in, am I good to go?
Re: Battery isolator question Reply #7 – October 19, 2022, 05:31:20 pm Quote from: Jackhiett - October 19, 2022, 04:58:46 pmI read where this would be a good solution,but I’m simply concerned about the amount of amperage that would go through it. The real question is, if I put in a 200 amp isolator unit in, am I good to go?Since the alternator can only generate a maximum of 130-amps, the 200-amp unit is more than adequate.Besides charging the batteries, the alternator powers the rest of the RV, the ignition, fuel injection, lights, and A/C use a lot of energy that is not available for charging the coach battery.Larry 1 Likes
Re: Battery isolator question Reply #8 – October 19, 2022, 06:11:03 pm Quote from: Larry W - October 19, 2022, 05:31:20 pmSince the alternator can only generate a maximum of 130-amps, the 200-amp unit is more than adequate.Besides charging the batteries, the alternator powers the rest of the RV, the ignition, fuel injection, lights, and A/C use a lot of energy that is not available for charging the coach battery.LarryPerfect and thanks. I will first remove the existing isolator. Maybe I can not damage it, and clean it up. However, the more I’ve read the more I am liking the FET isolator.
Re: Battery isolator question Reply #9 – October 19, 2022, 08:44:20 pm Hi Keith; Well that's one of the things I plan to hook up next week. It has been installed in place, but not needed yet. The control lines just solidified this morning. (thought processes.) It is only good for 60 Amps, and like most switching power supplies using power MOSFETS have very low loss. I'd estimate in the 95% or better efficiency. !5 volts at 75 amps input that's 1125 watts times .05 is a dissipation of 55 watts worst case. Using the ' LC' input to cut down amperage (Low Current) of 50% would only be 30 watts wasted as heat. At full power 60 watts. It does have built in fans (two). It is mounted in free air inside the cabinetry between the drawer under the refrigerator and the two drawers to the right (aft) of that. I do have a 5" fan to suck air out into the room through the air inlet of the space heater right next to it. I have a remote thermometer (digital) 1 meter lead to keep an eye on it's performance when I get it hooked up. I can switch it into low current mode, or totally off if needed at the driver seat. Tito had a YouTube video of how he hooked his up for his RV. It would only produce heat with the engine running, and the dash air can handle 55 watts easily. Tito RV at https://www.youtube.com/watch?v=TDxfRXgQT04&t=180s and of interest at 3:00 minutes in. RonB
Re: Battery isolator question Reply #10 – October 20, 2022, 12:32:58 am Quote from: Jackhiett - October 19, 2022, 06:11:03 pmPerfect and thanks. I will first remove the existing isolator. Maybe I can not damage it, and clean it up. However, the more I’ve read the more I am liking the FET isolator. Why are you replacing the isolator? They are foolproof and have proven themselves over the long run, with no moving parts, they do not wear out. Their only disadvantage is the slight voltage drop.I suggest spraying the terminal bolts with a rust breaker, letting it sit overnight, and seeing if you can loosen the nuts. The worse that happens is something breaks, odds are nothing will.Larry 2 Likes
Re: Battery isolator question Reply #11 – October 20, 2022, 01:00:40 am I agree with Larry. The slight power loss is insignificant with diode isolators, and they always completely isolate the battery banks. This is nice when both are lead-acid chemistry, vital if you switch the house batteries to lithium. The specialized DC-DC converters on the market now for charge isolation are because most motorhomes these days use only a combining relay for charging - bad for mixed chemistries.Steve
Re: Battery isolator question Reply #12 – October 20, 2022, 10:25:56 am Quote from: Larry W - October 20, 2022, 12:32:58 amWhy are you replacing the isolator? They are foolproof and have proven themselves over the long run, with no moving parts, they do not wear out. Their only disadvantage is the slight voltage drop.I suggest spraying the terminal bolts with a rust breaker, letting it sit overnight, and seeing if you can loosen the nuts. The worse that happens is something breaks, odds are nothing will.LarryYou’ve convinced me. I’d Completely forgotten about using some kind of a rust breaker prior to doing this project.I appreciate so much all the help people give on this site. What a great group of people. Thanks to all. Heading down to the auto parts store.
Re: Battery isolator question Reply #13 – October 20, 2022, 12:41:21 pm Quote from: WhiteElk - October 19, 2022, 11:41:27 amIf you are likely to upgrade to LiPO4 in the future, you may wish to consider changing the isolator at that time. I say this because when I researched the conversion to Lithium batteries, both AM Solar and Battle Born Batteries recommended installing a DC-DC charger rather than an isolator. I hope that others will chime in on this point because I am not sure that I am convinced such an upgrade is necessary. WarrenI have recently read a number of stories where people burned up their truck alternators when they upgraded to lithium batteries. One guy destroyed 2 alternators before realizing there was a problem and figuring it out - first one he thought alternator just went out but second one went out quickly (within a year if I remember right).I don’t know if these were trucks pulling RVs or motorhome or if there was any protective item between the alternator and the batteries.I don’t know if this was just for larger battery of lithium (400/600 AH) banks or also for 200ah. Or if the batteries were being actively charged the entire long trip (eg running energy hog items off it while driving so continually being charged at a high amp rate the entire time).But in the articles they repeatedly pointed to the length of time (eg longer driving time) and the lithium batteries pulling higher amps (where as lead acid only pull higher amps for a while when more depleted then pull a smaller amount after that).Maybe some of the car/truck guys can give more info on how high amp pull for a longer time would harm the alternator.I would throughly check this out before upgrading to lithium. We upgraded to lithium (yesterday) but do not have the alternator charger connected at this time.Jane
Re: Battery isolator question Reply #14 – October 20, 2022, 01:28:08 pm Hi Jane; Watch Tito's youtube I referred to in reply#9 above in this thread. Lithium batteries have a very low input impedance and will take whatever current the alternator can supply. You should be able to draw a lot, but other items such as Larry mentioned are loads on the alternator while driving as well. Air conditioning clutch and fan, fuel pumps, electric radiator cooling fans etcetera. I will be using the Renogy DC to DC converter, available in 20, 40, or 60 Amp ratings. My E350 1999 has the 130 Amp alternator. Newer Fords are 160 A. and your 1989 rig may be just 95 A. Heat build up at near capacity amperage, especially if air flow is reduced at lower speeds going up a long grade, and/or really hot conditions in desert may have been contributing factors. The D+ enable and the LC (Low current) input on my 60A Renogy will allow me to run the engine for a short time to recharge the chassis battery, before turning on charging to the LiF's, at full or half power. I envision on cloudy days (No or low solar) that I might run the vehicle engine just to charge the LiF's at 60 A. With my converter I can also just run the generator for about 55Amps into the batteries. What battery(s) did you get? RonB edit. My two Li batteries can only charge at 50 Amps each. The internal BMS controls that. Still pretty close to my 130A max. Amazon.com: SOK Battery LiFePO4 Deep Cycle Rechargeable Lithium Battery 12V... As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Re: Battery isolator question Reply #15 – October 20, 2022, 02:30:12 pm Quote from: Jane and Scott - October 20, 2022, 12:41:21 pmI have recently read a number of stories where people burned up their truck alternators when they upgraded to lithium batteries. One guy destroyed 2 alternatorsI'm sure there are many stories and urban myths surrounding lithium batteries. I can only comment on what I have seen and have accurately measured. For anyone installing lithium batteries, check the amperage charge rate into a discharged battery, with the engine running, and see for yourself what the rate is before investing in other charge control devices. A battery monitor is useful for checking the charge rate.Our LD's wiring from the isolator isn't huge, the 6 or 8-gauge wire, along with the isolator limit how much amperage can flow. The 200-amp lithium battery could safely absorb the entire alternator output without breaking a sweat, an event that will never happen. When the battery is fully charged, the built-in BMS (battery management system) shuts the charging down.Lithium batteries are controlled by the BMS which protects against overcharging and undercharging, as well as protecting against high and low temperatures. It's very difficult to burn up a quality lithium battery, the BMS should protect it. The BMS is what makes using lithium batteries practical.Larry 2 Likes
Re: Battery isolator question Reply #16 – October 20, 2022, 03:19:15 pm Clearly I am totally out of my league with any of this, but my solution for dealing with adding "power" is to procure a portable lithium power station rather than upgrading my paltry (70 Ah) battery system, and certainly not try to change out everything for a lithium system in a unit that is not wired for it.The electrical system in place, assuming it is in good shape, would surely run all of the basics (lights, pump, etc.) on the batteries and wiring in place. Then the more intensive, overflow needs could be provided by the stand-alone unit.Of course that brings up the question . . . where does it "stand alone". Space is always a consideration. Even my smallish 500-watt hour unit is big enough to hog a lot of space, and I am struggling to work out a location for the larger, more useful, unit.With cooking, heating, and hot water dealt with by propane; air conditioner powered by the generator when needed; and lights and water pumps (kitchen and bathroom) handled with the built-in electrical and battery systems; I'm thinking that the rest of my particular needs can be satisfied with a stand alone, large battery pack, without needing to install even an inverter into the extant system. These units also provide a flat surface to recharge a telephone on top - no need to even plug it into one of the outlets.Although these portable power stations claim to recharge while driving, as Larry points out, the electrical system has other duties to perform, thus the recharging time might be excessive if one relies on that mode. Fold-up solar panels may be a better option, but require a bit more monitoring in use.With so many USB-powered items coming on the market now, the solar-powered "generator" field is coming of age, and is quite interesting. The smaller 10-, 20-, 30,000 mAh battery packs are great for the smaller units as well, and provide nice portability. I can recharge my USB fan from the largest mAh powerbank about three times.Also, a cow just wandered by on the wrong side of the fence, and drained my animal watering bucket! No electricity needed for wildlife viewing! ;-> Virtual hugs, Judie
Re: Battery isolator question Reply #17 – October 20, 2022, 09:59:52 pm "The 200-amp lithium battery could safely absorb the entire alternator output without breaking a sweat, an event that will never happen."As I understand it, the potential problem here is not burning up the battery, but burning up the alternator by overloading it. This is very unlikely with a lead-acid battery, but apparently it can happen with a LiFePO4 battery bank, because it can demand more power than the alternator can deliver on a continuous basis. 2 Likes
Re: Battery isolator question Reply #18 – October 20, 2022, 10:11:34 pm "My two [200 Ah SOK] Li batteries can only charge at 50 Amps each."That's interesting. That's charging at a maximum of 25% of their rated capacity. My Lithionics 130 Ah batteries can charge at 100 amps apiece, or 77% of each battery's rated Ah capacity. The popular Battle Born 100 Ah batteries can charge at 50% of their rated Ah capacity. Of course, if one's alternator, shore power charger, or solar power system can't deliver high power--and many cannot--perhaps it doesn't matter in practice.
Re: Battery isolator question Reply #19 – October 21, 2022, 01:02:44 am Ron, we got ampere time batteries. They were on sale and were around $650 for $200ah. Will Prowse has great videos on all things solar including tearing apart batteries to see how well they are made, designed, and quality of components. His favorite is SOK but he says when he likes a battery the prices go up. He thought ampere were well made and the only thing missing is a low temperature sensor but having a victron with temperature controller does that job (we have that already). SOKs were much higher, I would guess because Will love them and says so regularly😄.Andy, I am working out now what actually controls the charge amps.I know Lithium.is generally supposed to charge at 2% of capacity (could vary per manufacturer) at least i found this in several sources including from amsolar.Solar Panel DIY Installation Help & RV Solar Power Setup | AM SolarAmpere says to use 2% as optimal maxcharging (improves life of battery). For us (200ah) would be 40 amps. I am guessing you are seeing different suggested charging specs for your battery brand.We have a 60amp charger/converter (progressive dynamics) which does not let us do specific settings other than battery type. We upgraded the charger for lithium (our 2017 one could not do lithium). I noticed that we got a higher amp charging rate on our lead acid batteries was a bit higher when we updated the charger a few days ago (set up for lead acid of course). So maybe progressive dynamics changed their standard changing rates.We are just doing our first charge (from our generator) and are getting 30amps despite our setting of 2%. We are not at 100% SOC yet (will get there tomorrow) and might be doing lower amps because we are closer to 100% SOC (ampere time says they go to a float level but they don’t say what soc they move to that. Still figuring things out.Are you using a charger they lets you set specific specs for charging levels? Jane
Re: Battery isolator question Reply #20 – October 21, 2022, 03:03:23 am Hi Andy; Yes I got the two 206 AH SOK batteries for the ability to go days without much charging. I wasn't so concerned with quick charging from generator or engine alternator. 50 A. per battery is plenty. Together at 100 A. it may still be more than the 130A. alternator can supply. I think the rapid charge generally degrades the battery faster over time, and my goal was to preserve the lifetime, to reduce the overall long term cost. For just a few $$ more the 60 A. Renogy was acquired. While the alternator may not have an issue, the LC input allows me to reduce the load on the alternator. Batteries capable of absorbing more power is immaterial. I can only source 30 A. per battery. The solar can only provide 15 A. per battery. (likely much less) My only high drain loads are a microwave using about 100 A for a few minutes per day, and a hair dryer (for my wife, I don't have enough hair for it to matter) at just a few minutes per day. But in a shaded cold spot, I can go days running the heater, lights, etc. without having to consider battery saving measures. RonB
Re: Battery isolator question Reply #21 – October 21, 2022, 03:05:23 am Quote from: Andy Baird - October 20, 2022, 09:59:52 pm"The 200-amp lithium battery could safely absorb the entire alternator output without breaking a sweat, an event that will never happen."As I understand it, the potential problem here is not burning up the battery, but burning up the alternator by overloading it. This is very unlikely with a lead-acid battery, but apparently it can happen with a LiFePO4 battery bank because it can demand more power than the alternator can deliver on a continuous basis.Will the alternator overheat? It depends on the alternator and how it is regulated and if it is self-protected. The alternators used on the 6.8L V10s are internally regulated. The regulator is a solid-state device mounted on the rear of the alternator that monitors the alternator's temperature reducing its output as it heats up by reducing the field current.Go to the page below and click on any 130-amp alternator's photo to see rear views showing the regulator.2003 FORD E-450 6.8L V10 Alternator / Generator | RockAutoCan a V10 alternator be overheated and burned up by charging a lithium battery, well maybe, I have not heard of it happening.As I suggested in Reply 15, for new lithium installations, checking the amperage flow into a drained battery will show if the amperage draw is excessive. If it is, install a DC to DC charger or one of the charge regulators. If the amperage charge isn't excessive, save your money and enjoy one less point of potential failure.An AC/DC clamp meter is a handy tool for this type of work. An example.KAIWEETS HT206D Digital Clamp Meter T-RMS 6000 Counts, Multimeter Voltage...Larry 1 Likes As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Re: Battery isolator question Reply #22 – October 21, 2022, 03:19:32 am Hi Larry, good taste in meters. I like the two color backlight to get your attention with higher voltages. I use the similar Uni-t Pro. UNI-T UT210E Pro Mini Digital Clamp Meter, Auto Ranging TRMS Backlit VFC NCV... Already have this. I'd like to point out to others that both of these meters have test leads that lets them act like regular test meters, with the additional capability for direct current measurements. A drawback is that just one current carrying lead can be inside the pickup loop. So some wiring situations don't allow that. And there has to be enough room also for the meter. RonB As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Re: Battery isolator question Reply #23 – October 21, 2022, 12:06:29 pm Quote from: Jane and Scott - October 21, 2022, 01:02:44 amI know Lithium.is generally supposed to charge at 2% of capacity (could vary per manufacturer) at least i found this in several sources including from amsolar.Solar Panel DIY Installation Help & RV Solar Power Setup | AM SolarAmpere says to use 2% as optimal maxcharging (improves life of battery). For us (200ah) would be 40 amps. I am guessing you are seeing different suggested charging specs for your battery brand.I think you are misreading something here. First, 2% of 200AH is 4A not 40A. 4A charging would be an extremely low charge and doesn’t make sense for lithium batteries. I looked at the AM Solar link you provided and the 2% that I found was for “Tail Current”. I’m not familiar with that term but I suppose it’s the maximum float current after the battery has reached its full charge. Lithium batteries can take an enormous amount of charge current and a 60A max would not be excessive for a 200AH battery.- John 1 Likes
Re: Battery isolator question Reply #24 – October 21, 2022, 12:43:00 pm John, Sorry I grabbed the wrong info.The batteries we got have a max charge and max discharge of 100amps (for 200 ah batteries).We could have paid just a little bit more and gotten ones that have a max charge and discharge of 200 amps (for 200 ah batteries).However recommended charge is 40 amps.As Ron said low and slow helps prolong the life of the batteries. And we really only use the generator when we have multiple cloudy days in a row (took 5 very cloudy days with flooded lead acid batteries). We don’t go above 5 amps use at a time ever and while we are planing on adding 2 items that draw more amps we don’t expect to ever go above 20 amps ever even at peak bursts.Attached is ampere time documentation for the battery we got (200 ah with 100 ah max charge and discharge).
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