Lead Acid to Lithium Upgrade

[rtrainer]

I have 2 lead acid batteries that I would like to replace with lithium. My question is, what impact does not changing the DC-DC converter have? I know I won't get a full charge when connected to shore power and am assuming that they would fully charge off of the solar panel when shore power is disconnected.

My goal is to replace the DC-DC charge with a MutiPlus but I don't have the time right now to redo the wiring.

[ncitro]

rtrainer The main benefit of a DC to DC is to get a faster and fuller charge from your truck. For that use, one is not needed, it is just another option for charging. Some also use it to add a layer of protection between the batteries and the truck alternator, due to the additional current that LiFePO4 batteries can take. That said I ran without one for about a year with no issue. Do your own research regarding your specific vehicle and alternator on that front. From the stock charging wire I only ever saw about 7 amps going from the truck to the trailer, whereas the move to a DC to DC can increase that to 20A, or even more if you want to run larger wires in the truck.

The Multiplus would not enter into this consideration, its a completely different function.

[TucsonJim]

I'm reading between the lines here and believe when you say DC-to-DC charger, you really mean the converter? In other words, the device that provides charging power when you plug into shore power?

A DC-to-DC charger is a very specific piece of equipment that receives power from your truck's alternator in order to charge the RV batteries with higher current than you'd normally see with the 7-way trailer connector.

If you are in fact asking about the converter, you can certainly use your existing converter with lithium (LiFePO4) batteries. It won't charge as fast or as completely as a dedicated lithium charger like the Victron. But if you have solar and your solar controller is set properly, it will assist in charging and will get you to a full charge.

Jim

[rtrainer]

TucsonJim You are correct. I used DC-DC converter when I should have used AC-DC converter. That said, I am hearing what I assumed is correct, that I only lose the full charge when on shore power when solar is not supplementing enough. Full sun, I should be ok with since, for now, I just want to make sure that the basics work when we stop at a Harvest Host. Future will be more solar and a MulitPlus.

[TucsonJim]

TucsonJim You are correct. I used DC-DC converter when I should have used AC-DC converter. That said, I am hearing what I assumed is correct, that I only lose the full charge when on shore power when solar is not supplementing enough. Full sun, I should be ok with since, for now, I just want to make sure that the basics work when we stop at a Harvest Host. Future will be more solar and a MulitPlus.

That's a good evolutionary path to get where you want to go.

Jim

[ncitro]

Yes as Jim states you should be fine then. Sorry about the confusion.

[Jlawles2]

I installed a Li battery in place of the lead acid (no solar of any type in the camper currently). The converter / battery with a non Li Compatable converter does a few weird things. I did note that the truck will provide a better charge on the Li battery than the converter, and also the converter when it flips to float mode will allow the Li to discharge quite a bit before it kicks back in and charges it.

I think you get somewhere around 80% of the capacity from the converter only. With the solar that should be capable of bumping the charge up more.

[Organic-IT]

Jim:
As an interim step, you could replace the converter that came with your camper with a converter designed for Lithium batteries. It’s a fairly simple process to replace a converter without rewiring the whole system. There are companies that manufacture such units (Progressive Dynamics, GO Power and others). The cost is reasonable when compared to larger inverter/chargers. The upgraded converter will do a better job of charging the Lithiums. Even when you upgrade to a MultiPlus, you can then use the new converter as a backup or supplement to the Victron Energy (just make sure you’re not exceeding the charge amperage of your lithium battery bank).

[Yoda]

I did note that the truck will provide a better charge on the Li battery than the converter, and also the converter when it flips to float mode will allow the Li to discharge quite a bit before it kicks back in and charges it..

Joseph I believe the reason for that is the TV voltage to the trailer is about 14.4 or 14.6 which is good from most LI batterys. That's what I measured on my charge line when checking out my new truck. I believe it regulates down depending on the battery voltage is senses as the batterys reach full charge.

[Jlawles2]

Joseph I believe the reason for that is the TV voltage to the trailer is about 14.4 or 14.6 which is good from most LI batterys. That's what I measured on my charge line when checking out my new truck. I believe it regulates down depending on the battery voltage is senses as the batterys reach full charge.

I did not measure to voltage at the 7 way or battery while the truck was running. I did note the voltage on the monitor when I got home. Side note, (Lets spend some more of your money) the Banks iDash did show 16.2 Volts the other day when I was driving. That actually worried me for a bit, but it's been normal since.

[Yoda]

I did not measure to voltage at the 7 way or battery while the truck was running. I did note the voltage on the monitor when I got home. Side note, (Lets spend some more of your money) the Banks iDash did show 16.2 Volts the other day when I was driving. That actually worried me for a bit, but it's been normal since.

That high voltage is due to the fact you have a Chevy

Actually I had a discussion on my DC-DC project with my Ford service manager. He indicated from time to time I might see voltages near there - especially in cold weather while running my instant cab heat on a cold start.

Now as for the Banks iDash I would need to check on if it would affect warrenty. I was going to get Forscan, but found out the Ford was having warranty issues if used - as it reprograms stuff. I was told the computer is so smart now that it tracks any time anything is plugged into the port, or collecting data from any other sensor. IE even a scan tool.

Besides with the Victron phone app and can see the voltage and amperage going to the trailer. That's how I check if the DC-DC is working when driving.

Besides If I have issues with my truck the dealer can pull up the data scan directly as the truck reports everything back Ford. Not sure I like it, but it has been good to me when things have happened or scheduling service as the can look at the data before deciding if something needs to be serviced.

Keith

[Cate&Rob]

Jim:
As an interim step, you could replace the converter that came with your camper with a converter designed for Lithium batteries. It’s a fairly simple process to replace a converter without rewiring the whole system. There are companies that manufacture such units (Progressive Dynamics, GO Power and others). The cost is reasonable when compared to larger inverter/chargers. The upgraded converter will do a better job of charging the Lithiums. Even when you upgrade to a MultiPlus, you can then use the new converter as a backup or supplement to the Victron Energy (just make sure you’re not exceeding the charge amperage of your lithium battery bank).

A caution on installing a Lifepo4 capable converter in the original location. I did this and despite the converter manufacturer data that 6 ga wire was acceptable between converter and batteries, my Victron shunt was telling me that charge rate was restricted to about 20A with the 10 ft run of OE 6 ga. I moved the new converter to within a foot of the batteries and wired with 4 ga. Charge rate is now at 55A which is the capacity of the converter.

Another plus of putting the converter in the front compartment of the 5th wheel rather than behind the aft wall of the pass through is that the cycling cooling fan is no longer audible inside the trailer.

Rob

[Jlawles2]

That high voltage is due to the fact you have a Chevy

Actually I had a discussion on my DC-DC project with my Ford service manager. He indicated from time to time I might see voltages near there - especially in cold weather while running my instant cab heat on a cold start.

Now as for the Banks iDash I would need to check on if it would affect warrenty. I was going to get Forscan, but found out the Ford was having warranty issues if used - as it reprograms stuff. I was told the computer is so smart now that it tracks any time anything is plugged into the port, or collecting data from any other sensor. IE even a scan tool.

Besides with the Victron phone app and can see the voltage and amperage going to the trailer. That's how I check if the DC-DC is working when driving.

Besides If I have issues with my truck the dealer can pull up the data scan directly as the truck reports everything back Ford. Not sure I like it, but it has been good to me when things have happened or scheduling service as the can look at the data before deciding if something needs to be serviced.

Keith

The iDash is strictly a monitor and can read / clear codes. I had mine plugged into the OBDII port the day I brought the truck in for the High Idle update and they told me nothing.

I'd be curious to see how much voltage / amperage a stock alternator that is PWM controlled could push. PWM is 128Hz signal, but its the duration of the "on" that control output. Shoot it direct 5VDC and see what that puppy will do since they are not internally regulated any longer (I KNOW THE BOOK SAYS THEY ARE, BUT TAKE ONE APART AND FIND A REGULATOR).

[rtrainer]

The iDash is strictly a monitor and can read / clear codes. I had mine plugged into the OBDII port the day I brought the truck in for the High Idle update and they told me nothing.

I'd be curious to see how much voltage / amperage a stock alternator that is PWM controlled could push. PWM is 128Hz signal, but its the duration of the "on" that control output. Shoot it direct 5VDC and see what that puppy will do since they are not internally regulated any longer (I KNOW THE BOOK SAYS THEY ARE, BUT TAKE ONE APART AND FIND A REGULATOR).

I also have an iDash and the dealership has never had a problem with it. The truck does know that it is there because the GMC app complains about is all of the time,

[Jlawles2]

I also have an iDash and the dealership has never had a problem with it. The truck does know that it is there because the GMC app complains about is all of the time,

What year truck are you running? The 2024 does not complain but I do have the data package (must run the LM2 protocol instead of L5P for the 24 Ultimate). FYI - My 18 complained as soon as the data package ran out.