wadingthroughlife Posted March 22, 2023 Share Posted March 22, 2023 (edited) Hey yall, I'm considering replacing our 1987 Sunrader's house battery and wanted to get an opinion on replacing it (Optima yellow top AGM) with a Lithium 100ah battery. I'm not sure how this could play out with our truck battery, also an Optima yellow top AGM, and the isolator as well as plugging into 110 to charge at home or a campground. We do have a recently upgraded converter (PD4045KA) that has a switch for Lithium or Lead Acid on it. I'm trying to determine if we can run 2 different types of batteries - AGM for the truck and Lithium for the House with this setup, or if perhaps a DC-DC charger is needed to replace the isolator, something I think I have to do whenever we do get to adding solar. Reasons I'm considering the change: - We have run down the House battery a few times on extended boondocks, and I was seeking security of not ruining an AGM battery by doing this too often. We don't really stay in one spot for more than a couple nights often, and the alternator charges everything back up in route to another spot. - I haven't taken the dive into a solar setup, but this might be step 1. Ideally it could live in the engine bay in place of one of the (2) Optimas, depending on space. Maybe this is just dumb? I assume most folks doing solar and lithium batteries have sorted out alternator charging and isolation with a separate starting battery. Converter documentation regarding the LA/LI switch: https://www.progressivedyn.com/rv/power-centers/inteli-power-4000-series/ English version discusses it on page 3 - Still not sure about usage when plugged to shore between 2 types of batteries.. Edited March 22, 2023 by wadingthroughlife addl info Quote Link to comment Share on other sites More sharing options...
WME Posted March 23, 2023 Share Posted March 23, 2023 (edited) Got the same problem AGM starter battery and a 12v 200ah lifepo4 house battery. Here is info on my solution. If you don't have solar this is a good choice BECAUSE it has a built in MPPT solar controller and you can add solar later by buying just solar panels Same person on both links, Will Prowse Wire diagram. https://www.mobile-solarpower.com/simplified-400-watt-fewer-wires-and-alternator-charging.html Review . Edited March 23, 2023 by WME Quote Link to comment Share on other sites More sharing options...
wadingthroughlife Posted March 23, 2023 Author Share Posted March 23, 2023 1 hour ago, WME said: Got the same problem AGM starter battery and a 12v 200ah lifepo4 house battery. Here info on my solution. If you don't have solar this is a good choice BECAUSE it has a built in MPPT solar controller. Same person on both links, Will Prowse Wire diagram. https://www.mobile-solarpower.com/simplified-400-watt-fewer-wires-and-alternator-charging.html Review . Well this is a cool unit. His video was helpful. I assume that the unit not kicking on until 13.2 ensures it only charges the house battery when the alternator is running. What about the charge you get from being plugged in to shore running back to this unit? Do you have a PD converter or something else? I would assume I’d leave the switch on the converter to LA unless I intended it to supply the higher Lithium voltage for only lithium batteries, right? Lower charging voltage being better on the Lithium than over voltage on the AGM? I guess I need to read again or get a better understanding on how I’d wire the unit so shore power can charge both batteries still. Quote Link to comment Share on other sites More sharing options...
WME Posted March 23, 2023 Share Posted March 23, 2023 (edited) Lifepo4 rated converter direct to battery. The DC to DC charger does have limits and you need to understand them. But for small Toyota size setups it's easy and fast. I have shore power, a 5.5kw generator and a 2000w inverter. There is an automatic transfer switch (ats) between shore power and the generator. I also installed an Gopower GP-TS 30 ATS between the inverter and converter. When your using the inverter the ATS unplugs the converter so your not trying to charge the 12v battery when your running the inverter off the battery. That would be Perpetual motion, right😁 So my AC power flow is 1. generator power powers everything, 2. shore power powers everything, 3 Inverter powers everything EXCEPT converter and AC. It's all automatic no plug and unplug stuff. It seems backwards between generator and shore power, but that prevents the generator or inverter from back feeding the shore power plug if you were into shore power, the power failed and you started the generator or inverter. Anybody working on the down shore power line much appreciates this. Edited March 23, 2023 by WME Quote Link to comment Share on other sites More sharing options...
wadingthroughlife Posted March 23, 2023 Author Share Posted March 23, 2023 Sheesh - You've got this sorted out well. I think I need to look up and better understand how the power inflow from shore goes back through the converter to the isolator to both my batteries and how that would look if replacing the isolator with the DC-DC MPPT Combo and one of the AGM's with a Lifepo4. I have to imagine this is done fairly often nowadays. I guess I'm hoping my replacement of the stock converter wasn't a waste and/or also wondering if I need to replace BOTH AMGs with Lithium to avoid and voltage confusion from the new converter. Heck, some of the Lifepo4 cost the same as an Optima anyway I guess. Quote Link to comment Share on other sites More sharing options...
WME Posted March 24, 2023 Share Posted March 24, 2023 (edited) Unless you have a smart isolator, your converter 12v output should go direct to the house battery and not to the isolator. Factory set up doesn't charge the truck battery. The isolator is used to charge the truck battery and the house battery only when the alternator is running. A normal deep cycle LifePo4 battery makes a poor starter battery due to the BMS discharge limits. LifePo4 automotive starter are just becoming available and are priced accordingly. Standard LifePo4 12v 100ah battery is in the $300 range and a starter battery is $450+ AND then a LifePo4 rated alternator😁😁😁. Also due to the charging cycle of Lifepo4 BMS they can be very hard on stock alternators due to being able to take a 100 amp charge. and a Toy alter is only 60 amps so you would be running it full tilt and it will quickly overheat. Also the battery can go from full tilt to 0 in the blink of an eye. Alternators don't like this. The DC to DC charger will prevent all this and acts as an isolator. All things considered K.I.S.S Edited March 24, 2023 by WME Quote Link to comment Share on other sites More sharing options...
wadingthroughlife Posted April 5, 2023 Author Share Posted April 5, 2023 On 3/23/2023 at 11:59 PM, WME said: Unless you have a smart isolator, your converter 12v output should go direct to the house battery and not to the isolator. Factory set up doesn't charge the truck battery. The isolator is used to charge the truck battery and the house battery only when the alternator is running. Dragging this point back up after double checking the isolator wiring. The connection to the converter is from the isolator then to the house battery. In a prior post about replacing the isolator, that’s where we’d landed on connecting it up. This would make for charging both the house and truck battery when plugged into shore, right? I guess I’m still sorting out if and where the isolator fits in with the Renogy unit we are talking about. Is it just done away with? That’d surely leave shore charging to the truck battery out of the picture right? I wish I lived closer to another rig, haha. Quote Link to comment Share on other sites More sharing options...
extech Posted April 5, 2023 Share Posted April 5, 2023 truck battery only charges when the engine is running. if it needs a charge you could connect a battery charger plugged into one of your house ac outlets when connected to shore power Quote Link to comment Share on other sites More sharing options...
wadingthroughlife Posted April 5, 2023 Author Share Posted April 5, 2023 Noted! I thought that by being connected through the isolator it topped both battery’s off. Doh. Quote Link to comment Share on other sites More sharing options...
WME Posted April 5, 2023 Share Posted April 5, 2023 Basic isolator stuff. Think of the isolator as a one way switch. You posted in the beginning that you had depleted your house battery a few times. With out an isolator you would also deplete your truck battery. Then how you gonna get home? So the isolator "isolates" the truck battery from the house battery load and you can start the truck when it's time to go home. There is a similar function used with factory installed generators. The generator fuel line only goes 3/4 of the way into the fuel tank. That way when the generator runs out of fuel you can still start and drive the MH. On home installed units you have to be careful about the install. Other wise you may find yourself pushing your Toyhouse to the gas station after boondocking . The DC to DC charger acts as an isolator so you can remove your old one. Your converter still won't charge the truck battery, BUT if you add a solar panel to the DC to DC charger it will charge both batteries. At this point in time a 100w solar panel can be had for the princely sum of $70 and a 200w for $170. Easier to install 1 panel. P.S. Friends don't let friends buy flexible solar panels. Quote Link to comment Share on other sites More sharing options...
wadingthroughlife Posted April 5, 2023 Author Share Posted April 5, 2023 Oh that’s fantastic. Thanks so much! For the flexible panels, is it because of lack of airflow under the panel causing extra heat or the fact they wear out quicker? Quote Link to comment Share on other sites More sharing options...
WME Posted April 5, 2023 Share Posted April 5, 2023 Yes flexible panels overheat when flush mounted. Even if they have an air gap the covering clear material fades from UV. Seem kinda dumb for a solar panel to have UV problems. I tried some typical flex panels 3 years ago and they lasted 1.5 years before they failed. There is a very good type of flexible panels, they are called CIGS panels, the gotcha is size and $$$, a 200w CIGS panel is $600.00 vs $170 for a rigid panel. They are less effective, so they are larger for the same output. A CIGS panel would be 86x26" and a rigid panel is 65x26" Quote Link to comment Share on other sites More sharing options...
Andrewups Posted July 10, 2023 Share Posted July 10, 2023 Hi wadingthroughlife, did you finely find an solution for your setup? I'm going thru the same situation right now so I wander if I can ask you some questions about your setup. Thanks. Quote Link to comment Share on other sites More sharing options...
wadingthroughlife Posted July 19, 2023 Author Share Posted July 19, 2023 On 7/10/2023 at 5:45 PM, Andrewups said: Hi wadingthroughlife, did you finely find an solution for your setup? I'm going thru the same situation right now so I wander if I can ask you some questions about your setup. Thanks. Ah, I havent messed with it much lately, honestly. I'm still leaning this way when the spare change falls into my pocket though. Quote Link to comment Share on other sites More sharing options...
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