Adding a lithium Ion battery to FWC

[DrJ]

My trimetric monitor also notes a small amp reading as well when everything is turned off and kill switch is on.
There is a small draw somewhere that somehow is part of the FWC system. I've never figured out where. I'm sure the monitor uses some.
I always disconnect my batteries when I put the camper away for a few weeks for this very reason.

 

[PaulT]

The Xantrex LinkLite consumes about 9 ma but the Attwood CO/LP monitor probably consumes much of the 1/2 amp draw you are seeing. Their datasheet shows a 1 amp fuse. It is not unusual for the fuse to be twice what the current draw is so that it does not blow during normal operation. When my camper was installed, I was told to turn off the push/pull power switch if I stored it for a long time as the LP/CO monitor would draw down the battery over time.

Paul

 

[cdbrow1]

The Xantrex LinkLite consumes about 9 ma but the Attwood CO/LP monitor probably consumes much of the 1/2 amp draw you are seeing. Their datasheet shows a 1 amp fuse. It is not unusual for the fuse to be twice what the current draw is so that it does not blow during normal operation. When my camper was installed, I was told to turn off the push/pull power switch if I stored it for a long time as the LP/CO monitor would draw down the battery over time.

Paul

The draw is there with the power switch off and the CO/LP monitor off.

 

[PaulT]

Wow. You have a quite a sleuthing job. Just about down to pulling the ground cable off the battery and inserting a multimeter in current mode to see if it's real.

That 9 ma is with the back light and alarm relay turned off.

Prior to that, you could measure the voltage drop across the Xantrex shunt and calculate the current yourself. See if your calculation matches the Xantrex.From their installation sheet, it looks like it is the green and yellow wires. The instructions say these wires should be twisted together all the way to the shunt. Twisting them reduces error from stray magnetic fields like if they ran close to other wires or a motor along the way.

It wouldn't take much to throw it off by a half amp. The stated resolution is +- 0.1 amp with a measuring accuracy of 0.4%. You may need to use a good current meter and measure directly out of the battery and compare that to the Xantrex reading just to put your mind at rest. You may be chasing ghosts until you use an alternate measurement.

Good luck.
Paul

 

[cdbrow1]

I redid the wiring to the shut last night I did not have time to fully check it out afterwords. I will try to look at it tonight. I did not notice an immediate change, but I did not dig into everything.

I used the Xantrax provided wiring (shielded 5 pairs) with soldered connections and tinned at the meter. I will post tonight if I have time to dig in deeper.

 

[cdbrow1]

I am heading to LA for three days starting Saturday morning. I will be running the fridge and cooking out of the camper with the microwave most of the time. This should be a good check on the battery. The only charging is likely to be from the alternator.

 

[cdbrow1]

Ok time for another update.

I drove to LA and Back this weekend (~1,200 miles with side trips). I did not camp in the FWC, but I did run the fridge the whole time (on full cool). Started with 100% battery and ended at ~65%. Every time I checked the truck with the engine running the Xantrax showed charging, but it APPEARS it was not keeping up with the load.

The IOTA recharged the system completely within 2 hours.

This afternoon I rewired the under hood portion of the FWC wiring, shortening it by about 3 feet and replacing the thermal breaker with a 100 amp breaker with manual override - so I can isolate the truck batteries. I kept the 10 gauge wiring (for now), but eventually I will replace all or part of it. I will see if this makes a difference.

I am going to go through the programming of the Xantrax again with input from the battery vendor to see if I misprogrammed something.

Looking at the system tonight with the truck batteries isolated and the camper power switch off the "drain" was around -0.1 amps which does not concern me. What does confuse me is that the truck is able to send 10amps to the Camper Battery at idle, but I am still going negative with just the fridge on. I don't see how that is possible.

 

[Happyjax]

Hi,
I've been following this interesting thread. I recall you saying the wires going to the camper battery were 10ga? If so you would be losing quite a bit of charging power to the batts. You said you had some 4ga? I would put that in place of the 10ga and try everything again. Hope I'm not all confused by the posts. If so write me off as a loon and keep going

 

[NorCalSteve]

If you are wondering if the battery separator is staying closed when it should be open, you can put your volt meter on each side of the separator to see if there is a voltage difference. If the meter reads zero volts or very close to zero, I would think that indicates the separator has the truck and camper batteries connected.

I am also curious as to what goes on inside the IOTA charger, even when turned off. With the master switch turned off, the IOTA is still connected to my battery. I just wonder if it might draw some current/amps when off. Although, if it does, I would think it would be small. I might try and measure that.

And, I don't see it now but, I thought I saw where a FWC breaker was replaced with a larger one. Just a reminder that the 10 gauge wire should not be carrying much more than 30 amps(?). I put a 70 amp breaker in the line on my truck when I upgraded the wire to 6 gauge. I have seen 60 amps of charging current going to the camper from the truck alternator with a low camper battery and when I just started the truck. It did drop below 50 amps after a couple of minutes.

Doubt any of this will help but I was just thinking. Enjoying seeing people exploring new frontiers!

Steve

 

[cdbrow1]

I checked on things this morning.

After charging last night (using IOTA) and then disconnecting line power I manually separated the (using my new breaker) the camper and truck batteries. The camper power switch was in the "off" position.

This AM the camper battery showed "full" and -0.0amp draw (I am assuming the minus sign means there is a slight draw but it is below the rounding factor for the gauge).

If I have time today I will check the separator to see that it is in fact isolating the battery properly.

I do plan on upgrading the wiring between the truck and camper, but I would rather keep using the Atwood plug.

 

[cdbrow1]

Hi,
I've been following this interesting thread. I recall you saying the wires going to the camper battery were 10ga? If so you would be losing quite a bit of charging power to the batts. You said you had some 4ga? I would put that in place of the 10ga and try everything again. Hope I'm not all confused by the posts. If so write me off as a loon and keep going

You are correct. I have the FWC factory installed wiring which is only 10 gauge and I have some high quality 4 gauge available. I plan to make that change, but I have some serious planning to do first. I want to run 4 gauge to both the front grill and the rear bumper for use with jumper cables or a winch. I would rather tie that into the camper set up then to have separate cable runs. Need some serious beer drinking head scratching time in the driveway before I tackle that project.....

 

[cdbrow1]

Checked again this morning.

We truck and camper batteries disconnected using breaker the camper battery is holding at 100% after ~36 hours after charging. In the past they would be "bleeding down." I have an upgraded isolator in the mail on it's way to me.

 

[DrJ]

cdbrow1,

I love this kind of stuff and am really interested about the total cost of your system and how many amp hours you get out of your battery system. I looked at going lithium ion for my battery system but just felt like the cost was too much for me then. But I've spent a fair amount on my system between 3 solar panels, 2 AGM batteries and a MPPT controller. With out running the numbers, I've spent probably between $1000-1250 for my total system (200 amp hours AGM, 30 AMP MPPT controller, 340 watts solar). It works awesome for me, but if my batteries ever died, I'd certainly price out lithium just for comparison.

 

[Happyjax]

I would check the current draw on your winch. I am betting you will need at least 2 gauge or better. The run from the battery to the back might need aught/0 because you create a LOT of heat when you pull 100 amps through 20 feet of wire

 

[cdbrow1]

I would check the current draw on your winch. I am betting you will need at least 2 gauge or better. The run from the battery to the back might need aught/0 because you create a LOT of heat when you pull 100 amps through 20 feet of wire

I have to look at the wire, it might be 2 gauge. I remember needing 4 gauge for the project I was working on, but had a heck of a time finding it. I might have bought 2 gauge instead. Then of course I never got around to doing the project....

 

[cdbrow1]

cdbrow1,

I love this kind of stuff and am really interested about the total cost of your system and how many amp hours you get out of your battery system. I looked at going lithium ion for my battery system but just felt like the cost was too much for me then. But I've spent a fair amount on my system between 3 solar panels, 2 AGM batteries and a MPPT controller. With out running the numbers, I've spent probably between $1000-1250 for my total system (200 amp hours AGM, 30 AMP MPPT controller, 340 watts solar). It works awesome for me, but if my batteries ever died, I'd certainly price out lithium just for comparison.

Right now the total cost is around $1,200 - 900 for the battery, 70 for charger and 240 for the Xantrax monitor. I have another $150 for the new isolator, but that is not really required. Despite all the oddities with the SOC I am happy with the setup. The weight savings alone are very nice - plus no worries about running the battery "too low".

 

[Happyjax]

I definitely want to do LI when we get the kinks worked out. I love the weight savings and true deep cycle of the battery. Glad you gave it a go and shared it with us

 

[craig333]

You've got me thinking about a small one. Annoying when the AGM is just a hair below the voltage the heater likes to see.

 

[cdbrow1]

Another update. System is CONTINUING to hold at 100% with no amp drain. This is much improved from it;s behavior in the past. Having the disconnect breaker between the Camper battery and the truck batteries is clearly paying off. The truck batteries are "resting" at 12.4 volts (parked since Monday) while the camper is resting at 13.8.

Provided my health holds up (bit under the weather today) I going to head to Gold Bluffs Beach Saturday and spend the night. I will be using the refer, microwave, cpap and heater so it will be another good test run.

I will post more when I get back.

 

[cdbrow1]

Had a great trip to Gold Bluff Beach, although Davidson road has been in better shape.

Using the manual disconnect everything seems to work fine. I hammered the battery with the heater all night, cpap, laptop, fridge, lights, cell phone booster and the microwave. The heater was on for about 13 hours and was set at 68 (why not be warm). Outside temp was 42 this morning. I ran the laptop most of the evening (writing for work) and watched about 2 hours of TV on it while in bed. Ran the fridge on battery from 6sat Saturday until 4:30pm sun.

Total driving miles was ~600. I used the manual disconnect whenever I stopped for more than 10 minutes.

Lowest reading was 38 % this morning. Was reading 60 when I got home. I used fans to vent camper for 1 hour at lunch today and used Microwave to cook lunch (~8% used).

Obviously I made no efforts to save power on this trip - I knew it was a one night trip. If I made a reasonable effort to save power I think three nights would be very double. Without using the big draw of the microwave (88amps) a much longer time would be possible.

It was VERY clear to me that the battery isolator is not working correctly. On one occasion it did not function at all (batteries still linked 10 minutes after shutdown and truck battery power being drawn by camper). On four occasions it failed to charge the camper battery from the truck until I restarted the truck (one required 2 restarts). Even with the truck battery reading 14.9 volts and the camper at 13.3 the isolator stayed closed. When it did work I saw charging rates as high as 19amps - although sometimes it was only 3 amps (all at idle). It one point Saturday I drove 80 miles without the truck charging the camper - found out at post lunch pee break- that cost me a lot of amps.

The IOTA charged at 29 amps when I hooked up this afternoon (fridge and all other loads off).

My replacement isolator is here and I will install it this week, it is programable and allows for operator control. I think a properly functioning isolator will help greatly. I also plan to run larger wires, but that might not happen this week.