Adding a lithium Ion battery to FWC

[photohc]

cdbrow1, wonder if it would be better to remove the IQ4 LED/logic from the IOTA to eliminate the Lead Acid Charge protocol. This would make the IOTA less like a lead acid charger (bulk, absorption, float) and more like a constant voltage/current charger? Your thoughts?

 

[PaulT]

Removing the IQ4 drops the voltage to about 13.7 for running as a DC power supply rather than a battery charger. This put the voltage in the float range. You can assemble a replacement cable that bumps the voltage to 14.4 if I recall correctly to accomplish the steady voltage without charging protocol. Discussion and links to the Iota DLS 30 manual.in that thread

I'll see if I can locate the thread
Paul

 

[PaulT]

Found the link to Iota's manual. A few pages down is discussion of the Dual Voltage Plug

Found this link to someone selling a replacement cable although I'd contact Iota first.

Good luck. Good to have early adopters blazing a trail for the rest of us.

Paul

 

[cdbrow1]

From what I understand the voltage is not a problem until it gets above 14.6. The problem is "float mode" and any kind of desulfinating cycle. LiFePo battery's don't like anykind of float charge and the Battery protection system will kick in above 14.6 to protect the battery from damage. Since I don't plan on leaving the camper plugged in more than overnight I am not too worried about harming the battery using the IOTA from time to time.

 

[PaulT]

Problem is that 13.6 or 13.7 may not be high enough voltage to push enough current into your battery to charge it in a timely matter. You would need to consult your battery charging profile to be sure. Or test by unplugging the IQ4 & monitor the Link Lite after drawing down the battery somewhat. That would be an easy enough test.

Paul

 

[cdbrow1]

Problem is that 13.6 or 13.7 may not be high enough voltage to push enough current into your battery to charge it in a timely matter. You would need to consult your battery charging profile to be sure. Or test by unplugging the IQ4 & monitor the Link Lite after drawing down the battery somewhat. That would be an easy enough test.

Paul

My understanding is that LiFePo batteries have much less internal resistance than lead acid.

 

[photohc]

My understanding is that LiFePo batteries have much less internal resistance than lead acid.

that is correct. You don't need to get the voltage that high. In fact, it is perfectly fine to not charge to 100%. The battery much prefers a lower charge of 90%. You should get more from the "plug in" time, with either the solar or shore power.
I just got my LiFePo4 100ah and will be posting soon on this install. I'm still waiting for my BMS (battery management system).
Harv

 

[cdbrow1]

Mine has been on the LiFePo4 charger for about 18 hours (as of lunch time today) and is still running in bulk mode. Voltage is up to 13.4 and charging rate is down to 2.1 amps (from high of 4.7). Unless something is up the battery was not as "fully charged" as I thought it was. Battery is cool to the touch and the charger is not giving me any warning lights so I am assuming everything is alright.

 

[photohc]

Hate to say it, but that Ctek (4.2amps) charger may be too small for a 100ah battery. May want to try the IOTA, which can put out 30 amps.

 

[billharr]

Thank you guys for trying this. Hope you have it worked out by the time I need new batteries.


Bill

 

[cdbrow1]

Hate to say it, but that Ctek (4.2amps) charger may be too small for a 100ah battery. May want to try the IOTA, which can put out 30 amps.

I think you are right. In the future I will probably only use the Ctek after the IOTA has handled the bulk charging. It's a pretty big price jump to a 10 amp or larger charger.

 

[cdbrow1]

The charger finally moved on past the bulk stage after ~24 hours. It's now in the "maximize" stage which is lower amps, but higher voltage. This is the last charging stage. Xantrax is reading 13.7 volts, but the amps reading is not stable enough to read - looks like noise. Hoping to head to the beach and do some camping tomorrow - we will see how it does.

 

[longhorn1]

cdbrow1, Reading your post blows me away. It reminds me of my freshman year in college in Texas. I flew to East Lansing, MI for a weekend to visit my best friend at Michigan State. I went to a Chemistry Lecture, 250+ students. The only words I understood were verbs. I guess I'm lucky having a 2014 Grandby, 2 batteries, 100w solar and a plug for additional solar. So far we have had plenty of power, even with the use of my CPAP machine and the 80amp fridge. I plan on buying the 80w panel this summer. Right now I have the camper covered. I have been checking the Zamp controller every 2 -3 weeks. I've pulled the tarp back once to charge. Once I get the 80w panel I can charge with the tarp on.


Thanks for your post. Someday in the future, I may have to delve back into this.

jd

 

[cdbrow1]

Interesting day.....

I started by pre-cooling the fridge on line power for about 3 hours.

Battery was fully charged - 100% on the Xantrax gauge

I drove about 300 miles to the coast and back (no camping) with the fridge on "full cold" (80liter).

Cooked lunch using microwave for about 7 minutes.

Used the fan on medium setting for about 20 minutes.

When I got home battery gauge read 71%.

This is obviously not what I expected.

From what I can tell from checking the gauge when I stopped the truck is not charging the battery. I was down to 87% after driving ~150 miles and only running the fridge (admittedly on full cool). The alternator should have easily handled this load. Unlike my driveway test at idle when parked I was reading between -1 and -4 amps. I think this is the failure of the FWC battery connection more than anything else. When I left for the drive back the battery was a 75% and I only lost an addition 4% on the return (by this point the fridge was cold and compressor cycling). Obviously using the microwave and fan hit the battery - dropping it around 10% which is very close to what I figured, but the long steady drain from the fridge is the problem (unless I have another power drain in the camper, but I can't think what that would be - camping wiring is all stock).

When I got home I hooked up the IOTA charger and the Xantrax gauge jumped to +27 amps so I know the gauge is working properly.

I am going to think about this a bit. I might try upgrading the wiring to the camper (happen to have 25 feet of gauge 4 wire sitting in the garage looking for something to do). Solar would probably be the cure to this, but I have an issue with the roof on my FWC (big distortions in the metal sheeting - frame is fine) and I want to bring it back to them for a possible warranty claim before I tamper with it at all.

I have some work to do in the morning, but I might try another test tomorrow (with temps in the 60s and 70s its hard not to go outside).

 

[DrJ]

FWC uses a battery separator that will not charge the batteries from truck to camper unless it is at a certain voltage. This is to prevent you from draining your truck batteries from the camper.
But it is a common problem area with our campers. Sometimes the battery draw lowers the voltage and then it won't charge. If your compresser fridge is running it may not charge it.
If my batteries are low, I sometimes need power through my solar or to first turn off the fridge to get it to start charging. Once it's on, it usually stays on and I can restart the fridge.
The separator can go out as well. I replaced mine after owning the camper for about a year.
It sounds like you have a monitor and should be able to pinpoint the problem.
You can hear an audible clunk when the separator turns on.

 

[cdbrow1]

I did hear it come on and saw the results in my driveway test. I did not hear it today, but I was not really listening. I will check this out. It is kind of a major pain if I need to manually turn on and off the fridge at every stop to get that relay to close.

FYI the IOTA charged the battery to 100% in about 2 hours. I have the battery isolated with the kill switch now, but the fride still on so it is pre cooled in the am.

 

[photohc]

The separator will not engage if it senses the charge system is below 12.8 v being drawn down by the truck and camper batteries. This will prevent the camper battery from further drawing down the truck battery. However, with the truck running, the alternator should bring the system voltage above 13v, thus engaging the separator and connecting the alternator to the camper.

It is highly unlikely your camper (lithium) would be that low, even at 70% capacity. Lithiums have a very flat and stable voltage line all the way to 20%.

My guess is, either the separator is defective and not engaging or the wire from the truck is too small. Try running the Lithiums down to 70%, then start the truck up and measure the current going to the Lithium from the truck.

 

[DrJ]

The separator will not engage if it senses the charge system is below 12.8 v being drawn down by the truck and camper batteries. This will prevent the camper battery from further drawing down the truck battery. However, with the truck running, the alternator should bring the system voltage above 13v, thus engaging the separator and connecting the alternator to the camper.

It is highly unlikely your camper (lithium) would be that low, even at 70% capacity. Lithiums have a very flat and stable voltage line all the way to 20%.

My guess is, either the separator is defective and not engaging or the wire from the truck is too small. Try running the Lithiums down to 70%, then start the truck up and measure the current going to the Lithium from the truck.

Good point on the charge curve of lithium vs lead acid.
That is one of the real benefits of those batteries.

The separator/isolater in my camper will not turn on (connect the batteries) unless the voltage of the camper batteries are 12.3 or higher. So if the fridge is running and the batteries are partly discharged it may not connect even with alternator running at above 13 volts.

Many guys have installed higher gauge wire which is always a good idea - this may or may not solve the separator issue. Or you could always just bypass the separator in the first place. I have not done that because my truck is a diesel and takes a fair amount of power to start. Solar solves this problem because it raises the voltage enough to allow the truck to camper connection to occur.

 

[photohc]

Good point on the charge curve of lithium vs lead acid.
That is one of the real benefits of those batteries.

The separator/isolater in my camper will not turn on (connect the batteries) unless the voltage of the camper batteries are 12.3 or higher. So if the fridge is running and the batteries are partly discharged it may not connect even with alternator running at above 13 volts.

Many guys have installed higher gauge wire which is always a good idea - this may or may not solve the separator issue. Or you could always just bypass the separator in the first place. I have not done that because my truck is a diesel and takes a fair amount of power to start. Solar solves this problem because it raises the voltage enough to allow the truck to camper connection to occur.

Good point DrJ. This is such a tough subject because it is not necessarily the voltage of the either batteries but rather what the separator see's as a voltage. The voltage it will see is a combination of:
1. each battery voltage's
2. what the alternator is putting out
3. what is turned on and drawing current (your frig)
4. and the voltage drop due to the wire run from the truck

 

[cdbrow1]

I did some more trouble shooting this morning and hooked up the truck battery (via the isolator in the camper) to the Xantrex.

The readings yesterday may be junk.

I was watching the gauge as I worked in the camper with everything off and I was still getting a negative reading of -1 to -3 amps. This was with everything disconnected and off. Even with the kill switch thrown and the camper on line power I still was getting -3.2 amps.

The isolator is working. Takes about 90 secs for the voltage from the truck to get high enough to open, but it is working as it should. Even with the isolator open, trailer on line power I was STILL getting negative amp readings.

I checked all the wiring and everything checked out STILL negative amps.... (seeing a pattern yet?)

I then started to turn on loads to see what would happen - I hit the inverter power button and ran my drill of of it - no change in amp readings - still negative.

At this point the ONLY thing I could figure was that the Xantrax was glitching out so I did a full reset. Immediately the amps jumped to +9 at idle and started dropping when I put loads on line (but strayed positive).

I have no idea when the Xantrex started glitching - but I can't trust the readings from yesterday. The readings after the reset make a lot of sense and the idea of a 3 amp load with everything off makes no sense at all.

I am going to drive up to tahoe and get out of the heat (it's almost 75 here). I will post the results tonight....