FWC Electrical basics and upgrading to lithium!

First?  Get a shunt based monitor if  you don't have one already.  I recommend the Victron SmartShunt - LINK to canadian amazon.

 

After that, what JonR said.

Thx.. today it is not charging at all.. hmm. Suggestions? Bumpy roads.. loose connection??

Not charging. Does it need to? If the batteries are full, the MPPT will not add more to them.

1. Older IOTA chargers have an option to plug in an external module to adjust it’s parameters to better charge lithium batteries, newer ones do not. In my experience, the IOTA charger is typically not able to charge a battleborn battery more than 80-90%. Do you NEED lithium? 

 

As far as I can tell, IOTA still sells the DLS- series that accept the IQ4 module (non-"X" suffix).  Moreover, they added a Lithium-specific IQ4 module to the lineup a few years back.  I'm wondering if your experience is with the "IQ4-LifePo", or just the original battery module?

 

Switching IQ4 modules from the base IQ4 to the AGM version definitely improved longevity and performance on my current setup, so I had always planned on just swapping to the Lithium version when the time came to replace/upgrade the battery.

Just learning about lithium batteries for campers and have a couple questions about the original post.

 

Is it OK and safe to have a 4 or 6 gauge wire from alternator to camper lifepo4 battery without a dc-dc charger? Original poster seemed to imply a significant boost to the house batteru with a heavy wire alone. I thought it is critical to control the current into a lithium battery.

Also, if the alternator to camper lifepo4 wire is thin, like 12 or 14 gauge, could that thin wire melt when the truck is running, especially if the lifepo4 SOC is low so it wants to be bulk charged?

 

The stock FWC installation uses 10g wire and 30A thermal fuses. The thermal fuse will prevent the wire from melting.

If you use heavier gauge wire, the fuse/breaker needs to be upgraded as well. I use 2g wire in my setup with 100A breakers.

Before I went lithium, I could see 90A going to my camper batteries, but only for a short time (like 10 minutes) before it dropped down to a steady 40A or so for up to 2 hours at a time before the batteries were recharged. I had 225AH of batteries at that time.

Without the DCDC, a single 100A totally discharged lithium battery could conceivably suck up 100A for a whole hour before being fully recharged. That may or may not damage your alternator. I have 200AH of lithium, and preferred not to test that, so use a 30A DCDC now.

Edited by Vic Harder, 01 February 2022 - 12:01 AM.

 

Ironically, lithium is less fussy than AGM. All or nothing is what lithium wants. AND, it it doesn’t like what it is getting, the built in BMS will deal with it.

ALL batteries need a solar controller to convert the output of the PV panels into what the connected batteries need. MPPT is better than the older PWM style of solar controllers, because they are more efficient.

All batteries also have ideal charging parameters, including their max charge rate, and if that ideal is not used, there are compromises in battery life. For Battleborn batteries, that is .5C, or 50A. So if the alternator can put out 200A, the BMS will limited that to 100A and yes, you will shorten the battery’s life expectancy.

Not charging. Does it need to? If the batteries are full, the MPPT will not add more to them.

its at 94.9 %.. does not need to charge for my purposes as we have a rental for a month.. but don't recall it ever doing that before... is there a certain discharge needed before it starts recharging?

its at 94.9 %.. does not need to charge for my purposes as we have a rental for a month.. but don't recall it ever doing that before... is there a certain discharge needed before it starts recharging?

well, no.  It should be charging if the batteries are at 94.9%.  Where are you seeing that number?  Based on a previous comment you made "My charge controller only has a gel mode, but not lithium, how much of a difference will that make to get a better charging monitor"  I wonder if we need to clarify what you have, since there are really 4 major components to the solar charging system:

 

1) MPPT - this is your solar charge controller (could be PWM, but those are getting rare).  It converts 20+VDC to something closer to the 12V the batteries need. Sometimes these have displays that convey what the controller is putting into the batteries.  It can't tell you anything about your battery's state of charge (SOC).  It can guess though.

2) Battery Monitor - such as the Victron SmartShunt I linked above.  It measures the state of the batteries, regardless of what the controller is putting in.

3 & 4) PV panels and batteries... but we are not talking about those right now.

 

If your display is from the charge controller (if you have a factory setup with the Overland MPPT, it came with a round display with several buttons on it) and it says 94.9% charged (a guess) AND the PV Voltage is higher than 20V or so, it should be charging.  At night, for example, the PV Volts will be zero, and thus no charge can happen.  If the sun is shining brightly on your panels, and the display says the PV voltage is 20+V, and you still see zero amps, then the batteries must be fully charged.  (or not connected).  You can also see the battery voltage on that display, which should be 12.6V (for AGM) or more if fully charged and no load is on them.  For lithium, that is more like 13.3V

Edited by Vic Harder, 01 February 2022 - 02:19 AM.