Battery novice needs help

[eyemgh]

Following.

 

[Jon R]

Hi Bryan,

This is not rocket science, but it does require a basic understanding of DC circuits and battery behavior. If you are not confident about tackling those areas, I would suggest getting some help beyond internet forum discussions. You should be confident you know what you are doing - not just following advice from strangers.

That said, the reason a DC to DC converter is typically needed to effectively charge a LiFePO battery from a typical modern truck electrical system is the DC voltage that can be supplied by the truck alternator at the end of the long wire run to a camper or trailer battery is that the voltage at the end of the wire run is not sufficient to quickly or fully charge the LiFePO battery.

LiFePO batteries typically need the charging source to be able to deliver 14.2 to 14.6 volts at the battery. A modern smart alternator may supply 14.5 to 15 volts at the truck battery, but when you add the resistive loss of the 40 to 50 feet of wire to and from the camper battery, depending on wire gage, 13.5 volts or lower is supplied at the camper battery if, say, 30 amps are being drawn. This loss will limit the charging current supplied to the camper battery, resulting in a much slower charging process and potentially never fully charging the camper battery.

A DC to DC converter is typically installed to address this issue. Its function is to step up the DC voltage supplied to the camper battery to the desired level, and to control battery charging voltlage and current. To do this effectively it needs to be installed near the camper battery so the wire losses between the charger and charging battery are minimized.

A second important function that the DC to DC converter performs is to limit the charging current supplied to the LiFePO battery when it is significantly discharged. The “internal resistance” of these batteries is low, so they can pull very high charging current when discharged to a low level. A typical camper installation is likely protected for this by the resistance if the wiring from the truck to the camper, but it can be an issue for short wire runs. Regularly pulling the max current your alternator can deliver can prematurely wear out the alternator or overheat inadequately fused wires.

 

[BryanToyFWC]

Hi Bryan,

This is not rocket science, but it does require a basic understanding of DC circuits and battery behavior. If you are not confident about tackling those areas, I would suggest getting some help beyond internet forum discussions. You should be confident you know what you are doing - not just following advice from strangers.

That said, the reason a DC to DC converter is typically needed to effectively charge a LiFePO battery from a typical modern truck electrical system is the DC voltage that can be supplied by the truck alternator at the end of the long wire run to a camper or trailer battery is that the voltage at the end of the wire run is not sufficient to quickly or fully charge the LiFePO battery.

LiFePO batteries typically need the charging source to be able to deliver 14.2 to 14.6 volts at the battery. A modern smart alternator may supply 14.5 to 15 volts at the truck battery, but when you add the resistive loss of the 40 to 50 feet of wire to and from the camper battery, depending on wire gage, 13.5 volts or lower is supplied at the camper battery if, say, 30 amps are being drawn. This loss will limit the charging current supplied to the camper battery, resulting in a much slower charging process and potentially never fully charging the camper battery.

A DC to DC converter is typically installed to address this issue. Its function is to step up the DC voltage supplied to the camper battery to the desired level, and to control battery charging voltlage and current. To do this effectively it needs to be installed near the camper battery so the wire losses between the charger and charging battery are minimized.

A second important function that the DC to DC converter performs is to limit the charging current supplied to the LiFePO battery when it is significantly discharged. The “internal resistance” of these batteries is low, so they can pull very high charging current when discharged to a low level. A typical camper installation is likely protected for this by the resistance if the wiring from the truck to the camper, but it can be an issue for short wire runs. Regularly pulling the max current your alternator can deliver can prematurely wear out the alternator or overheat inadequately fused wires.

Thanks for kindly pointing out that I have no idea what I'm doing, because it's true! Also thank you for the summary on DC-DC, makes sense.

I'd love to pay a nice person to help with this part, but our local FWC people have been a little unresponsive lately. Seems like everyone else in this space is very busy as well. So unfortunately I'm left to figure it out and ask strangers on the internet.

Like I said, I'm handy, but not savvy with electricity (finance is my gig....). I can connect the right wires to the right stuff with the right map. All I really know is my fully charged batteries, straight from shore power, are dead by morning with nothing else running but the fridge. They are 5 years old, right about time to die. So, want to upgrade and the more I think about it, Li is starting to sound like the plan, just need to figure it out.

Thanks!!

 

[Jon R]

Sorry Bryan if my first paragraph came across as insulting. I didn't mean it that way. I also didn't mean to imply that you should have a dealer do this rather than attempting a DIY project. I just think that having a person you can go to for guidance and sanity checks is going to be a big help over trying to teach yourself by research and forum discussions alone. You can save a lot of money doing this project yourself, but as you are acknowledging, it needs to be done properly to be safe.

 

[rando]

For now, you can just buy a 100Ah LiFePO4 battery and drop it into the camper as a straight replacement for the lead acid battery. While this won't be 100% optimal, it won't hurt anything and it will work better than your failing lead acid batteries. If you buy a battery with built in bluetooth, you will also get monitoring of your battery, so you can see how it is doing and assess if you need to change anything else.

As you figure things out and learn you can decide if you need a DC-DC charger, or it you need to change/upgrade your solar controller. There is no real need to do everything at once.

 

[BryanToyFWC]

Sorry Bryan if my first paragraph came across as insulting. I didn't mean it that way. I also didn't mean to imply that you should have a dealer do this rather than attempting a DIY project. I just think that having a person you can go to for guidance and sanity checks is going to be a big help over trying to teach yourself by research and forum discussions alone. You can save a lot of money doing this project yourself, but as you are acknowledging, it needs to be done properly to be safe.

Jon, no need to be sorry! Not insulted at all. I’m new to this stuff and I know it!

Would love to find someone to help me think through. Anyone live in Denver?

 

[NRVhawk]

Hey Bryan, it looks like you've gotten a lot of good advice here. One thing that I noticed is that you mentioned using the LIFEPO IQ4 module with your Iota charger. Since you've got a 2017 FWC, I suspect that your charger is a DLS-30/IQ4 charger that FWC installs in later models (my 2016 Hawk has one). That charger has the IQ4 circuit built into the charger, and the LIFEPO module won't work with it. To use the LIFEPO module, you need a DLS-30 charger. You can tell what you have by looking at the label on the top of the unit, which identifies the model. Also, there's a label next to the RJ-11 telephone-style jack that says "Dual voltage jack disabled" if it's incompatible with the LIFEPO module.

Wish I lived near Denver to lend you a hand. I'm in the middle of switching my camper over to LIFePO4 now, and hope to finish up this weekend. As Jon said, it would be helpful (and safer) to have someone who is familiar with working with DC circuits to help. There are some tools, like strippers, crimpers, torque wrench/screwdriver, wire labels, and multimeter that would help.

- Rusty

 

[goinoregon]

bryan. i find it hard to believe that local fwc wont communicate about a battery and controller, etc. upgrade. they sell things, that is their business. maybe u need to just walk in the door, and talk ?. here in pdx, i bought a lifpo battery, alucab awning, and a few other things from local fwc dealer. all went well. then had them install alucab awning. no problems.
i have an atc shell. while i was waiting for it, i watched for local wtw posts for local folks. hit em up, and asked to visit and see their layouts. learned a lot, met some great folks. picked their brains, etc.
one of the fellows i met, is an retired electrical engineer . he is a wtw member. he lives within a mile of me here in pdx. he made an electrical pick list in 3 emails, with amazon links for products. i bought all the stuff. my new friend came over 3 times, and we put it all together, to power the battery from solar panels.
i got lucky.
but i would recommend actively finding wtw folks in denver area. there are probably way more than here in pdx. and, physically walking into fwc dealer. and i dont know why a local rv dealership would not be a resource

 

[Outnabout]

For now, you can just buy a 100Ah LiFePO4 battery and drop it into the camper as a straight replacement for the lead acid battery. While this won't be 100% optimal, it won't hurt anything and it will work better than your failing lead acid batteries. If you buy a battery with built in bluetooth, you will also get monitoring of your battery, so you can see how it is doing and assess if you need to change anything else.

As you figure things out and learn you can decide if you need a DC-DC charger, or it you need to change/upgrade your solar controller. There is no real need to do everything at once.

Does the Bluetooth in the battery give the same information as a shunt? What is the difference between the two?
Thanks

 

[rando]

Does the Bluetooth in the battery give the same information as a shunt? What is the difference between the two?
Thanks

Yes it does - most provide state of charge, voltage, current in/out of the battery, internal temperature etc. Additionally, they typically provide the individual cell level voltages so you know everything is OK within the battery. The exact details of what is reported depend on the particular battery, but most seem to be using a similar internal BMS. The SOC is calculated using coulomb counting (Ah in minus Ah out) just like a Victron BMV.

I have both a bluethooth enabled BMS and a Victron BMV - the SOC is typically within a few % of each other. I typically look at the data from the BMS because it gives me more detail. If I were starting again, I would skip the Victron BMV. While the BMV is a great piece of equipment, the battery directly provides what I need to know.

 

[rando]

Jon, no need to be sorry! Not insulted at all. I’m new to this stuff and I know it!

Would love to find someone to help me think through. Anyone live in Denver?

I am just up the road in Boulder, but I am pretty sure you will be able to do this by your self.

First, select the LiFePO4 battery you want to use. Here are just a few options (full disclosure I have a DIY battery and have not used any of these):

1. Battleborn - heavily promoted, have good support and are a safe bet. However they are also expensive ($950 for 100Ah), and don't have any built in monitoring of the battery so you will also want to add a battery monitor (Victron BMV-712).
2. PowerSonic - well established (50 years) battery company with good support, $750 for 100Ah with built in bluetooth.
3. Renogy - these can sometimes be found on sale for $550, and you can add bluetooth monitoring for another $30. Renogy are a large US based importer and should be a fairly safe bet.
4. reBel - smaller US based importer, selling the same batteries available on Amazon/eBay but with US support for $550 for 100Ah. Built in bluetooth, and seemingly decent reviews.
5. Any number of batteries on Amazon (HQST, Aims, Chins etc) - $450 - $550 for 100Ah, some have built in monitoring, support maybe a bit spotty, some have decent reviews. Realize that all the manufacturers are using Chinese made cells, and BMS (including Battleborn) so you shouldn't be inherently turned off by direct from China.
6. Lots of other options, Trojan, LiFeBlue, Relion, etc

You can then just remove the current lead acid battery, and install the new LiFePO4 battery (2 bolts). For the most part, all your current equipment will work fine with an LiFePO4 battery, so you can just use it for a few months and see how it performs. Contrary to popular belief, LiFePO4 batteries are far less picky about charging and the like than lead acid batteries.

Here are a couple of other thoughts:

Your stock Iota converter will fully charge your LiFePO4 battery, but it will also float charge the battery, which LiFePO4 doesn't really want, so don't leave it plugged in for more than a few days at a time. Many of us (with solar) never plug in anyway, so long term this may not matter.

The Blueseas battery isolator will keep the camper and truck connected most of the time due to the higher resting voltage of the LiFePO4 battery - if you park in the sun this is not a big deal, as the solar will charge both the camper and truck batteries. If you park in doors, you may want to pull the fuse on the negative wire to the battery isolator when not using the camper which will turn the battery isolator off. Reinstall the fuse when you use the camper. You won't get a whole lot of charge current to the battery, but that may or may not matter for your usage. In the future you can replace this with a DC-DC charger, an simple ignition controlled solenoid or a lithium specific isolator or just leave it as is.

Your ZAMP solar controller will also charge the LiFePO4 battery. If yours has the Lithium battery mode, switch it to that, if not use the GEL mode, it is close enough. In the future you may want to upgrade just the controller to a Victron MPPT which will be more efficient and has a lithium mode, but this is not urgent.

If you do end up with a battery without built in monitoring, you will want to add some sort of battery monitor when you install the battery. The standard is the Victron BMV-712 , this is a little more complicated to install, but there are plenty of instructional videos.

 

[Jon R]

There are a lot of battery choices out there and if all you want to do is install 100 ah of LiFePO you can probably make almost any of them work, and extra BMS features like bluetooth and charge state monitoring might be primary to your decision. However, if you want to install more battery capacity now or potentially later without having to start over, form factor of the battery becomes a big issue because you have to find room for the battery or batteries in an appropriate location in the camper. Form factor my be more important than extra BMS features In that case.

 

[Outnabout]

Yes it does - most provide state of charge, voltage, current in/out of the battery, internal temperature etc. Additionally, they typically provide the individual cell level voltages so you know everything is OK within the battery. The exact details of what is reported depend on the particular battery, but most seem to be using a similar internal BMS. The SOC is calculated using coulomb counting (Ah in minus Ah out) just like a Victron BMV.

I have both a bluethooth enabled BMS and a Victron BMV - the SOC is typically within a few % of each other. I typically look at the data from the BMS because it gives me more detail. If I were starting again, I would skip the Victron BMV. While the BMV is a great piece of equipment, the battery directly provides what I need to know.

Thanks, so much. Great info. I find the longer I wait to get into this new technology the more information I gather and the technology changes and hopefully becomes cheaper. Cheers

 

[eyemgh]

I am just up the road in Boulder, but I am pretty sure you will be able to do this by your self.

First, select the LiFePO4 battery you want to use. Here are just a few options (full disclosure I have a DIY battery and have not used any of these):

1. Battleborn - heavily promoted, have good support and are a safe bet. However they are also expensive ($950 for 100Ah), and don't have any built in monitoring of the battery so you will also want to add a battery monitor (Victron BMV-712).
2. PowerSonic - well established (50 years) battery company with good support, $750 for 100Ah with built in bluetooth.
3. Renogy - these can sometimes be found on sale for $550, and you can add bluetooth monitoring for another $30. Renogy are a large US based importer and should be a fairly safe bet.
4. reBel - smaller US based importer, selling the same batteries available on Amazon/eBay but with US support for $550 for 100Ah. Built in bluetooth, and seemingly decent reviews.
5. Any number of batteries on Amazon (HQST, Aims, Chins etc) - $450 - $550 for 100Ah, some have built in monitoring, support maybe a bit spotty, some have decent reviews. Realize that all the manufacturers are using Chinese made cells, and BMS (including Battleborn) so you shouldn't be inherently turned off by direct from China.
6. Lots of other options, Trojan, LiFeBlue, Relion, etc

You can then just remove the current lead acid battery, and install the new LiFePO4 battery (2 bolts). For the most part, all your current equipment will work fine with an LiFePO4 battery, so you can just use it for a few months and see how it performs. Contrary to popular belief, LiFePO4 batteries are far less picky about charging and the like than lead acid batteries.

Here are a couple of other thoughts:

Your stock Iota converter will fully charge your LiFePO4 battery, but it will also float charge the battery, which LiFePO4 doesn't really want, so don't leave it plugged in for more than a few days at a time. Many of us (with solar) never plug in anyway, so long term this may not matter.

The Blueseas battery isolator will keep the camper and truck connected most of the time due to the higher resting voltage of the LiFePO4 battery - if you park in the sun this is not a big deal, as the solar will charge both the camper and truck batteries. If you park in doors, you may want to pull the fuse on the negative wire to the battery isolator when not using the camper which will turn the battery isolator off. Reinstall the fuse when you use the camper. You won't get a whole lot of charge current to the battery, but that may or may not matter for your usage. In the future you can replace this with a DC-DC charger, an simple ignition controlled solenoid or a lithium specific isolator or just leave it as is.

Your ZAMP solar controller will also charge the LiFePO4 battery. If yours has the Lithium battery mode, switch it to that, if not use the GEL mode, it is close enough. In the future you may want to upgrade just the controller to a Victron MPPT which will be more efficient and has a lithium mode, but this is not urgent.

If you do end up with a battery without built in monitoring, you will want to add some sort of battery monitor when you install the battery. The standard is the Victron BMV-712 , this is a little more complicated to install, but there are plenty of instructional videos.

My set up is super simple. I have no shore power and no solar. If I wanted to drop a LiFePO4 in and all I had was a Blue Seas isolator and didn't want to babysit it removing the fuse off and on again, what would you replace the isolator with, ideally brand specific? WOuld that change if you were considering solar in the future. Thanks!

 

[Vic Harder]

My set up is super simple. I have no shore power and no solar. If I wanted to drop a LiFePO4 in and all I had was a Blue Seas isolator and didn't want to babysit it removing the fuse off and on again, what would you replace the isolator with, ideally brand specific? WOuld that change if you were considering solar in the future. Thanks!

There is lots of good info on this forum already in other threads.... (just sayin'). Recently I saw a FB post by KP that presented a pretty good summary of all you need to know (20+) Four Wheel Campers Owners : FWC Lithium Manifesto | Facebook

Other opinions are also valid.

To answer your question directly, I'd suggest a Victron Orion - Victron Energy (pkys.com) and an upgrade of your wiring from truck to camper to at least 6AWG. That unit needs a lot of ventilation, so mount it somewhere it can "breathe" or install a fan to cool it.

This recommendation would NOT change if you are considering solar in the future.

Also, consider reading the threads in my sig....

 

[rando]

My set up is super simple. I have no shore power and no solar. If I wanted to drop a LiFePO4 in and all I had was a Blue Seas isolator and didn't want to babysit it removing the fuse off and on again, what would you replace the isolator with, ideally brand specific? WOuld that change if you were considering solar in the future. Thanks!

Vic's suggestion of the Victron DC-DC is spot on, particularly if you are relying on getting a decent amount of charge from the alternator to your LiFePO4. I assume as you have no solar or shore power, that this is very important.

If you just want something that is equivalent to the current blue seas isolator, but is set up for lithium voltages, then the Victron Cyrix-Li is a drop in replacement for the blue seas.

 

[eyemgh]

There is lots of good info on this forum already in other threads.... (just sayin'). Recently I saw a FB post by KP that presented a pretty good summary of all you need to know (20+) Four Wheel Campers Owners : FWC Lithium Manifesto | Facebook

Other opinions are also valid.

To answer your question directly, I'd suggest a Victron Orion - Victron Energy (pkys.com) and an upgrade of your wiring from truck to camper to at least 6AWG. That unit needs a lot of ventilation, so mount it somewhere it can "breathe" or install a fan to cool it.

This recommendation would NOT change if you are considering solar in the future.

Also, consider reading the threads in my sig....

Vic's suggestion of the Victron DC-DC is spot on, particularly if you are relying on getting a decent amount of charge from the alternator to your LiFePO4. I assume as you have no solar or shore power, that this is very important.

If you just want something that is equivalent to the current blue seas isolator, but is set up for lithium voltages, then the Victron Cyrix-Li is a drop in replacement for the blue seas.

Thanks both of you! I started digging through old links, but many were broken, hence the hijack. Lots to consider, but dropping in two 12V AGMs might be the quick and dirty for now.

 

[BBZ]

Woah.. just read through all this as I am in the same boat as the original poster..


My takeaway, please correct me if I am wrong..

I can just drop a LIFePO4 in place of my 2 AGMs.. switch to GEL mode as I have a 2013, with 160 watts of solar I should be fine (Colorado)?? But get a battery monitor.. and eventually switch the controller? (Also need to look at isolator and probably just disconnect as it doesn't do much)..

I dont worry about weight, but would like more storage space..

 

[rando]

Woah.. just read through all this as I am in the same boat as the original poster..


My takeaway, please correct me if I am wrong..

I can just drop a LIFePO4 in place of my 2 AGMs.. switch to GEL mode as I have a 2013, with 160 watts of solar I should be fine (Colorado)?? But get a battery monitor.. and eventually switch the controller? (Also need to look at isolator and probably just disconnect as it doesn't do much)..

I dont worry about weight, but would like more storage space..

Yup, that is a good summary. If you get a LiFePO4 with built in bluetooth, then you don't need the battery monitor. One 100Ah LiFePO4 is roughly equivalent to 2x 75Ah AGMs.

Longer term you may want to consider upgrading the solar charge controller to a programmable MPPT, or adding a DC-DC if you want charging from the truck, but neither is a pressing requirement.

 

[Vic Harder]

Woah.. just read through all this as I am in the same boat as the original poster..


My takeaway, please correct me if I am wrong..

I can just drop a LIFePO4 in place of my 2 AGMs.. switch to GEL mode as I have a 2013, with 160 watts of solar I should be fine (Colorado)?? But get a battery monitor.. and eventually switch the controller? (Also need to look at isolator and probably just disconnect as it doesn't do much)..

I dont worry about weight, but would like more storage space..

Yup, you could get away with this plan. For hardware upgrades, I do favor the Victron gear (no affiliation!). Their BMV is great, but they also have a bluetooth shunt that would do the trick for less.