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Starter Battery Upgrade - Mating to Existing House Battery Setup

M

MR E30

New Member
Joined
Apr 22, 2024
Messages
8
Location
Arizona
I have a set of questions relating to incorporating a new starter battery (the Dakota Lithium 12V+135ah: https://dakotalithium.com/product/d...ar-truck-battery-plus-deep-cycle-performance/) into an existing Renogy LifePO4 300ah battery bank.

Wife and I have been living in our 2021 Tacoma for 14 months now. We power a 12v fridge, and Starlink (via their router) 24/7, and we sit still at camp for 4 days in a row. Looking into adding this dual purpose starter battery to help aid the powering of a new induction cooktop.

Existing setup:
- (3) 100ah Renogy LifePO4 12v (Bluetooth, but not self heating model), wired together in parallel for 12v output (can't find on their site anymore).
- 400w solar (maximum I can fit) Renogy panels wired in parallel also (https://www.renogy.com/renogy-100-watt-12-volt-monocrystalline-solar-panel/)
- Renogy 50A dcdc with mppt charge controller. Solar input from roof, and alternator input from the front of the truck.
-2000w inverter (will be going to 3,000 when induction cooktop is incorporated), 12v DC Bluesea fuseblock, etc.

New Addition:
- The DL 12V+ 135ah battery listed above, with Victron smart shunt, in replacement of my now slowly dying lead acid battery that came with the truck.

Desire:
- To incorporate this dissimilar battery into my existing battery bank (safely!), so that I have (4) batteries in parallel to draw from when set up at camp.

Note:
- I am willing to step away from the Renogy Charge Controller (Victron comes highly recommended by friends) if another product is more intelligent/better equipped to incorporate these two batteries.

Questions:
- If connected appropriately, will all (4) batteries drain down together, like my (3) batteries currently do?
- The DL can be charged at 135a, while the Renogys' are limited to 50a (max), but share a 25a (from alternator) charging rate. With this in mind, I can't simply wire in the DL in parallel or else the three batteries will overcharge, correct?
- If what I typed above is correct, is there an Automatic Transfer Switch type product that will automatically link the (4) batteries together when the truck is off, but separate the DL from the (3) in the camper when the truck is turned on?
- What else am I missing? I got a great deal on the basically new DL from a friend, and an extra 135ah of battery in the same space as my current starter battery is nice to think about.

Pardon my lack of experience/intelligence in this area. It was fairly easy to put together the current system that powers my day to day life, but the addition of this dissimilar battery into the mix creates hesitation.

Thank you for your help.
 
you need to think about if you kill the batteries how do you plan to start the truck? there is a reason why there separated on a motorhome.
 
MakeMePower said:
you need to think about if you kill the batteries how do you plan to start the truck? there is a reason why there separated on a motorhome.
Click to expand...
The DL and Smart Shunt allows me to program in a cut off level, leaving plenty of juice in the battery to start the truck with. I also have a Noco jump box as well.

In the 14 months we have been on the road, most of that with just 200 ah, I have never dropped below 30% charge in my battery bank. I pay close attention, and my energy usage is well understood.
 
MR E30 said:
The DL and Smart Shunt allows me to program in a cut off level, leaving plenty of juice in the battery to start the truck with. I also have a Noco jump box as well.

In the 14 months we have been on the road, most of that with just 200 ah, I have never dropped below 30% charge in my battery bank. I pay close attention, and my energy usage is well understood.
Click to expand...
you can simply use a battery switch to wire around the dc-dc charger to parallel the bank, but most BIRD relays are designed to work opposite of what your asking. you can use a solenoid with a programmable voltage relay to work the other way.
 
MR E30 said:
The DL and Smart Shunt allows me to program in a cut off level, leaving plenty of juice
Click to expand...

Please describe how this works as I'm not aware of any means of doing so. The "discharge floor" value is not a cut-off level. It's the threshold used in the "time to go" reported by the shunt in VictronConnect, i.e., if you have a discharge floor of 20%, the time to go value is how long it will take to discharge to 20%. It will not prevent you from discharging it down to 0%.

MR E30 said:
In the 14 months we have been on the road, most of that with just 200 ah, I have never dropped below 30% charge in my battery bank. I pay close attention, and my energy usage is well understood.
Click to expand...

Yet you plan to more heavily utilize a high drain device? Your past may not be a valid indicator of future results.

Run that cooktop for all of an hour on a high setting, and you'll tap out that new battery.
 
sunshine_eggo said:
Please describe how this works as I'm not aware of any means of doing so. The "discharge floor" value is not a cut-off level. It's the threshold used in the "time to go" reported by the shunt in VictronConnect, i.e., if you have a discharge floor of 20%, the time to go value is how long it will take to discharge to 20%. It will not prevent you from discharging it down to 0%.



Yet you plan to more heavily utilize a high drain device? Your past may not be a valid indicator of future results.

Run that cooktop for all of an hour on a high setting, and you'll tap out that new battery.
Click to expand...
I misspoke when I included the Victron Smart Shunt in the statement, my apologies, the DL battery itself has an app that allows you to leave some ah on the table via its BMS.

I hear ya there, except I've already done the math on how much energy my typical day will require (down to the ml of water used to make tea, warm up eggs, and make oatmeal), as well as how much energy my once per week meal prep day will require. I have a friend who has a YT channel and uses a Kill-a-Watt meter to determine how much energy it takes to bring water to a boil (noting start temp, end temp, time, etc), how much energy it takes to heat up food from various states (frozen to enjoyable, fridge temp to enjoyable, etc.). It's fairly straightforward to extrapolate the energy that I will need from the information he presented. Also not sure when I would ever need to run it on high/near high for 1 hour straight, when my most energy intensive meal (making pasta) only takes 5 minutes on high (level 10) to boil the water, and I then drop way down (from level 10 to level 2) to cook it for 8 minutes before it's done.

I have used a NuWave induction cooktop via (2) Ecoflow Delta 2's (way less than 300ah capacity) in an off grid shed for a long time prior to this and never had crazy issues with instantly depleting that battery pack.

Most days my 200ah bank is fully recharged by 11:30 am (Spring, summer, and early fall) and by 2:00 pm (the rest of the year), so I have room to spare in that regard anyways. I pay very close attention to my entire setup, truck, and camper, daily.
 
Please don't take this personally. I see little value in using lithium for a starter battery. Using AGM etc for a starter battery is more resilient to temp etc. I know this battery has heaters and such, but I think it's a poor use of the technology if you have house batteries. An AGM battery is so much cheaper and your vehicle wont have any problems with it.

Not sure which NuWave device you are using. They have small ones that you can easily run with a 2000w sine wave inverter. You could get a 3000w Renogy sine wave inverter. It should run ok on the 3 Renogy batteries of they are healthy. I think those are rated at 100a continuous. Save 600 dollar bucks and just get an AGM starter battery and the Renogy inverter... or if your NuWave is a small one just keep the 2000w inverter.
 
pshoe said:
Please don't take this personally. I see little value in using lithium for a starter battery. Using AGM etc for a starter battery is more resilient to temp etc. I know this battery has heaters and such, but I think it's a poor use of the technology if you have house batteries. An AGM battery is so much cheaper and your vehicle wont have any problems with it.

Not sure which NuWave device you are using. They have small ones that you can easily run with a 2000w sine wave inverter. You could get a 3000w Renogy sine wave inverter. It should run ok on the 3 Renogy batteries of they are healthy. I think those are rated at 100a continuous. Save 600 dollar bucks and just get an AGM starter battery and the Renogy inverter... or if your NuWave is a small one just keep the 2000w inverter.
Click to expand...
No offense taken, I am actually on the fence about this Dakota battery, and I have reservations about its use myself. This post is a part of the discovery process as to whether or not I should go through the trouble of incorporating it into my system.

If I don't use this battery (which it is honestly feeling like I won't be) I'm just going to be keeping a traditional battery up front and be done with it.

I will be using a larger cooktop in the camper, as it will double as a cooking and prep surface (the NuWave in the shed is too small), but it has a 1800w max draw, so people do run it off of a 2k inverter, which I already have. Problem is I run Starlink 24/7 for work, via the inverter (as well as charging (2) laptops), so I want a bit extra capacity in the inverter for that reason.

Thanks for your insight pshoe.
 
You can get a DC power supply for the Starlink to remove it from the inverter. Same for laptops. Most run with inexpensive 12v PD power supplies. That can potentially enable you to turn off the inverter and only turn it on when you are cooking or using some other AC device like an air fryer or microwave. Save some wasted power just keeping the inverter on.

If it were me I would skip the lithium starter battery and keep the original spec.

If you just plain love using AC devices and having that "at home" experience then you could consider upgrades to your system, but don't fix it if it aint broken. There are so many moving parts when it comes to features and dependencies for each persons mobile situation. Like maybe I travel and camp in areas with low direct sun. I need my alternator to charge me up. Maybe I stop at locations that have EV charging and I want to charge with an EV port. Maybe I don't have space constrictions and I want to run air conditioning all night long in Florida off battery.... We are so lucky these days with the amount of innovation we have seen in products and cells. Its really incredible if you think about it. Think about what existed just 5 years ago. Amazing.
 
My truck is already wired up with all of the components necessary to run the SL off of DC, which I did for a while (4 months), until my first dish unexpectedly fried one morning in the Arizona desert. After that I decided to just run the flat mounted dish off of the SL router for now, as it is vitally important for my wife's work that she has steady internet day after day, all day long.

It has been a little while, but I was unable to find a 12v power supply for our Surface Laptop 4's. I paid for an extra power cord and cut it up, wiring it into a buck/boost converter, but I was unable to get the laptop to take a charge through that device. I do use buck/boost converters for other things, but I wasn't able to get it to work for our laptops, which unfortunately we use the most often!
 
MR E30 said:
My truck is already wired up with all of the components necessary to run the SL off of DC, which I did for a while (4 months), until my first dish unexpectedly fried one morning in the Arizona desert (I am not certain that the dish being powered via DC and connected to via a 3rd party router was the cause of the destroyed dish, but the hassle it created was enough for me to just go to AC for now). After that I decided to just run the flat mounted dish off of the SL router for now, as it is vitally important for my wife's work that she has steady internet day after day, all day long.

It has been a little while, but I was unable to find a 12v power supply for our Surface Laptop 4's. I paid for an extra power cord and cut it up, wiring it into a buck/boost converter, but I was unable to get the laptop to take a charge through that device. I do use buck/boost converters for other things, but I wasn't able to get it to work for our laptops, which unfortunately we use the most often!
Click to expand...
 
if the laptops have usb -c and have PD capability, you just need a 12v pd charger and usbc cable
 
MR E30 said:
It has been a little while, but I was unable to find a 12v power supply for our Surface Laptop 4's.
Click to expand...

MakeMePower said:
if the laptops have usb -c and have PD capability, you just need a 12v pd charger and usbc cable
Click to expand...

Yea this was my point. Any 12v PD (power delivery) charger with the correct watt rating should work for laptops and devices that are equipped with PD charging. PD chargers have a data exchange between the device and the charger that sets the voltage etc. This is not a basic buck/boost power supply.

There are hundreds of these things on Amazon. You have several form factors to choose from. You can have chargers that are in the 12v socket. These are good for the dash. You have others that are also in the socket that stick out a bunch. You have charger that are surface mount and panel mount that you install into a location. You also have ones that look like a typical power supply.

I am not endorsing any of these and I was careful to remove any affiliate info etc. Examples only.




 
The problems I see from tying your starter into house system is this: charging flows both ways. So when connected, all batteries will deplete at same rate. If you start solar charging your housebatt, then your starter charges back up. That may be ok, but now you dont have a 2nd battery system, you just have one big start battery system.

I could see you having a battery on/off switch, like from BlueSea, mounted in cab on L side above the inverter switch. Then you would manually connect start battery to house system when parked, and disconnect when driving. All the autoconnect features of dcdc battery to battery chargers work opposite this, disconnect when parked. But I wouldn't like relying on not forgetting that switch, and I wouldn't want to run car with a giant 230Ah lithium plus load system connected, just waiting for something to jack up my delicate car electronics and ECU. If I did do a switch, I'd also hook up a diode so power could ONLY flow from start to house, and I'd make a big red light when it was on so I didn't miss it.

Honestly, 135Ah, you're gonna maybe allow yourself to use 100Ah max? For 19 lbs, I'd just buy another 12v 100Ah mini LFP, 1280 Watt-hrs, and use that instead, and leave my whole car/starter batt system separate, alone, reliable, not jerry rigged.

I looked at Surface laptop 4, it's charger is 65W, 15v 3A. The USB-C PD specs have 15v as one of their standard voltages, 3A, 60W, so yes a USB-C PD port will work. I also have bought some of these from Amazon, and have a little pod I made that can do usb c pd laptop, usb c and usb A QC phones, and carport 12v heating blanket, up in bed. You need a pretty large wire for all those loads at once.

I've heard someone else mention burning out their starlink router using a cheap 12-48v converter... maybe it was you, can't recall. That new mini 12v half power looks nice.

I've never seen any threads here on doing what you're asking for the battery. It makes sense, but I don't think an off the shelf piece of equipment exists. I would stick w AGM for cold and simplicity, and just add more battery to house ;)

This pod below will hold those usb c pd ports from Amazon. This one I only have usb A QC, but I did buy some of the PD ones to fit in there too. They make pods that hold 3 sockets too, all these ports are made to fit in a carport format.

youtube.com

✂️ usb pod

27 seconds · Clipped by Dave in AZ · Original video "DC Fuseblock for Truck Campers, Power Station use, Tune M1 wiring" by Dave in AZ
youtube.com youtube.com
 
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pshoe said:
Yea this was my point. Any 12v PD (power delivery) charger with the correct watt rating should work for laptops and devices that are equipped with PD charging. PD chargers have a data exchange between the device and the charger that sets the voltage etc. This is not a basic buck/boost power supply.

There are hundreds of these things on Amazon. You have several form factors to choose from. You can have chargers that are in the 12v socket. These are good for the dash. You have others that are also in the socket that stick out a bunch. You have charger that are surface mount and panel mount that you install into a location. You also have ones that look like a typical power supply.

I am not endorsing any of these and I was careful to remove any affiliate info etc. Examples only.




Click to expand...
We are getting way off topic here,, but just to make sure I am not losing my mind, I am familiar with PD charging and all that, and the camper has (4) 12v sockets, and (4) usb ports within a couple of feet of the (2) laptops (among many others elsewhere).

Thing is, the Surface Laptop 4's (which is not the same as a Surface Pro, which is a tablet) do not have a USB-C port for charging. It has one USB-C port on the opposite side of the primary connector, but it does not accept a charge. They have a small cylindrical, proprietary connector that charges the computer. That's why I listed my exact laptop, with precise language, and wasn't vague about what type it was. My truck and camper are fully stocked with cords of all types to charge all sorts of other devices. I have (2) buck/boost converters wired up to charge other batteries (sawzall, drill, etc.). I have another converter tucked away that can even do solar input, basically replacing my Renogy 50A CC if it ever dies. I am well beyond understanding the concept of plugging a tiny device, regardless of its shape/form factor, into a DC outlet and then plugging another cable into that.

The connector looks like this in this Amazon link. Note: I purchased this and it does not power our laptops. It doesn't specify the Laptop 4 in its list of compatible devices.


The only chargers on Microsoft's site for our particular laptops are all AC based:


Either way, thanks for all of your input. I have moved the conversation offline to discuss the setup with (2) EE's and (1) HVAC/Electrician to see what I can come up with.
 
Hey, sorry if you were offended. I know it can feel like we don't understand you, but in a forum people want to help and honestly can't know what you do and do not know. We make some assumptions based on what little there is in a thread. It's always best to assume we mean well. People also often respond in a thread using a tone and detail that helps not only the OP, but future readers. I can see how this tone could offend someone that thinks they are being addressed personally.

In this case I can only speak for myself. I am in the camp that says you should never use your starter battery for the "house". Second, since you outlined your needs for power I freely offered some personal suggestions unsolicited to simplify to perhaps manage power so your cost was low. Eliminating inverter time eliminates unnecessary loss.

I found another DC charger for the Surface 4 Laptop. Looks like it uses 15v. Maybe this helps you. Maybe you don't care. It might help someone else.


You can also find adapter like this one. They basically need a PD charger that has 15v 3a as one of the available modes. Not all do that, but most do.


Best of luck.
 
pshoe said:
Hey, sorry if you were offended. I know it can feel like we don't understand you, but in a forum people want to help and honestly can't know what you do and do not know. We make some assumptions based on what little there is in a thread. It's always best to assume we mean well. People also often respond in a thread using a tone and detail that helps not only the OP, but future readers. I can see how this tone could offend someone that thinks they are being addressed personally.

In this case I can only speak for myself. I am in the camp that says you should never use your starter battery for the "house". Second, since you outlined your needs for power I freely offered some personal suggestions unsolicited to simplify to perhaps manage power so your cost was low. Eliminating inverter time eliminates unnecessary loss.

I found another DC charger for the Surface 4 Laptop. Looks like it uses 15v. Maybe this helps you. Maybe you don't care. It might help someone else.


You can also find adapter like this one. They basically need a PD charger that has 15v 3a as one of the available modes. Not all do that, but most do.


Best of luck.
Click to expand...
lol don't apologize. let the "ee and hvac" guys help him out.
 
MR E30 said:
relating to incorporating a new starter battery
Click to expand...
This is not a good or practical idea. It's a proven fact that a lithium starter battery has a very short life installed in the engine compartment, degrading significantly within two years due to high temperatures and possible overcharge.
Use the $1189 that the Dakota would have cost and get an AGM starter battery, and an additional lithium house battery. To improve engine charging add an B2B charger, ideally the Victron Orion XS, instead of or in addition to, the Renogy DCC50, ( depends on alternator power).
Renogy batteries seem to have issues, gradually loosing effective capacity due to cell inbalance , perhaps due to poor BMS design.
It would be useful to fully charge the existing batteries and perform a capacity test, the Victron smart shunt would be helpful in carrying out such a test.
 
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