Lithium Battery/Charger Question

scottmtaylor

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Encinitas ca
I recently installed an Epoch 460Ah battery. I had previously upgraded my converter/charger (50amp) to be lithium compatible (progressive industries I believe).

I charged the Epoch to 100% when I received it and before install. It has a bluetooth connection to a phone app, so you can read the SOC.

On our first trip out to Arizona, we stayed in locations (9 days) that all had a 50 amp service, so we were only on battery during transit (4 driving days, about 6 hours). During driving, only the WIFI and propane detector and brakes should have been the load on the battery. I also have 200 watts of solar on the roof.

The odd thing, is when I returned and parked the rig, I checked the battery and it was a 38% charge. I cannot understand this - left at 100%, was plugged in the whole time, and return with 38%. It was very cold (we were at the Grand Canyon for part of it) but plugged in to 50amp service.

My uniformed guess is that the battery voltage is/was higher than the converter voltage, so it ended up powering all the dc during the trip (heater mostly, and lights), and that the charger portion of the converter could not keep up the charge on the battery.

Any ideas? I installed the 460ah battery because we plan to do some boondocking this spring, but seems like I won't last long off the grid...
 
I recently installed an Epoch 460Ah battery. I had previously upgraded my converter/charger (50amp) to be lithium compatible (progressive industries I believe).

I charged the Epoch to 100% when I received it and before install. It has a bluetooth connection to a phone app, so you can read the SOC.

On our first trip out to Arizona, we stayed in locations (9 days) that all had a 50 amp service, so we were only on battery during transit (4 driving days, about 6 hours). During driving, only the WIFI and propane detector and brakes should have been the load on the battery. I also have 200 watts of solar on the roof.

The odd thing, is when I returned and parked the rig, I checked the battery and it was a 38% charge. I cannot understand this - left at 100%, was plugged in the whole time, and return with 38%. It was very cold (we were at the Grand Canyon for part of it) but plugged in to 50amp service.

My uniformed guess is that the battery voltage is/was higher than the converter voltage, so it ended up powering all the dc during the trip (heater mostly, and lights), and that the charger portion of the converter could not keep up the charge on the battery.

Any ideas? I installed the 460ah battery because we plan to do some boondocking this spring, but seems like I won't last long off the grid...
Is your SOC coming from a shunt or directly from battery Bluetooth? If is from a shunt it may not have the correct amp hours setting. I went through this with a friend's rv that the dealer installed shunt but did not set it up correctly.
 
What about your battery disconnect? If the disconnect is cutting off power from the converter, the battery heater module could be running down the charge. Use a multimeter to confirm a charge is getting to the battery.
 
Do a voltage check on the battery with a voltmeter and then plug your trailer in and see what the voltage reads at the battery. The voltage will read higher when it is charging. If the battery doesn't change when you plug in follow your system back to a place that is easy to access and check the voltage there.
 
Good start. I will connect my generator at the storage place and see what is flowing in from my multimeter. May be my charger is just weak.

It is ok to increase the size of the charge (50 amp is what came with the coach) to say a 75 amp without any problems?
 
Good start. I will connect my generator at the storage place and see what is flowing in from my multimeter. May be my charger is just weak.

It is ok to increase the size of the charge (50 amp is what came with the coach) to say a 75 amp without any problems?
Perhaps, I am confused. Most people charge with minimal current such as a 2 amp trickle charge or a quick 4,8,12 amp charge. When you are speaking of 30 or 50 amps you are not charging at that rate but that is the size of the (load) breaker that would trip. When you say you want to replace something that is 50 amps with something that is 75 amps, what that translates in my mind is you asking if I can replace the fuse in my house with tin foil to prevent it from blowing. Not a good thing.:oops:
Strictly as an example:
If your battery is 12.4 volts after being charged and drops to 11.8 volts after you drain it, find out if your charger is higher than 12.4 volts. Start there.
 
Good start. I will connect my generator at the storage place and see what is flowing in from my multimeter. May be my charger is just weak.

It is ok to increase the size of the charge (50 amp is what came with the coach) to say a 75 amp without any problems?
I changed from 55A to 75A. Only needed if you boondock and want to charge faster to not run your generator as long. If you’re battery and converter aren’t next to each other and directly connected you won’t get any benefit because the voltage drop across the connecting wires will be your limiting factor. In fact that sounds like your problem, not your converter/charger.
 
Good start. I will connect my generator at the storage place and see what is flowing in from my multimeter. May be my charger is just weak.

It is ok to increase the size of the charge (50 amp is what came with the coach) to say a 75 amp without any problems?
While LiFePO4 batteries can be charged at a 1C to 3C rate of charge, it appears that charging at that rate will cut down on the life of the battery. It seems a charge rate of .3C to .5C is optimal, so you would be fine with a 75 amp charger considering your battery. With that said, unless you really need the faster time charge it looks like a 50 amp charger should be fine.

In your OP you mention the brakes being a load on the battery. I believe the only time that occurs is when the emergency break away switch is activated. Under normal operation voltage is supplied from tow vehicle.
 
In tow with the battery cutoff switch in my 377mbs, only the residential fridge, schwinteck slide controller and hydraulic level up controller draw current. The slide controller and hydraulic controller only draw about 0.2A. Most of the current draw is the residential fridge.
 
I changed from 55A to 75A. Only needed if you boondock and want to charge faster to not run your generator as long. If you’re battery and converter aren’t next to each other and directly connected you won’t get any benefit because the voltage drop across the connecting wires will be your limiting factor. In fact that sounds like your problem, not your converter/charger.
I am thinking that on the wiring too. I am going to look and see what moving the converter/charger would take.
 
I've seen some bad advice that #6 wire is OK for 55 & 60A chargers. I did #2 on my 70A charger, as the runs are shore enough the price difference was small. Then again if the runs are long you might need #2 for voltage drop.
 
I've seen some bad advice that #6 wire is OK for 55 & 60A chargers. I did #2 on my 70A charger, as the runs are shore enough the price difference was small. Then again if the runs are long you might need #2 for voltage drop.
Mine is #4 but converter/charger and battery are side by side. Except #6 from battery to electric distribution panel which is the factory wiring.
 
Our Solitude has a WFCO 9855 AD 55 amp converter/charger (CC). The CC is located behind the wall of the mid storage compartment and uses 6 awg wire @ 10 feet to connect to the distribution panel.

The batteries are in the up front storage compartment and they used 6 AWG wire @ 20 foot run from the batteries, through the disconnect switch, up to the distribution panel. Thats a long way @ 30 feet, using 6 AWG wire size from the converter, through the distribution panel, then out of the distribution panel going up front, through the battery disconnect switch, to the batteries to pass amps to charge a battery. Typically our CC will only pass 4-4.5 amps to the batteries to charge them.

I didn't want to change out the WFCO CC to something better that would stay in Lithium mode, and all that 6AWG wire to 4 or 2 AWG or try to reduce the wire run lengths by moving things around to get better battery charge amps to the batteries, so I mounted a LifePo4 specific charger right next to the batteries in the up front storage compartment. I can fast charge the batteries with the LifePo4 charger, then the CC will maintain the batteries after that.

This diagram of a distribution panel for a 50 amp RV is typical of how they connect everything. Might come in handy for some of y'all troubleshooting but maybe not exactly how your RV is wired. It's how our Solitude is wired. The diagram shows a 120VAC receptacle on the rear of the distribution panel where a CC could connect to AC.

Or some installations (like ours) there is a romex 120VAC specific run @ 6 feet from a panel AC ckt breaker to a single common AC receptacle box located right next to the Converter/Charger. You can see the battery and converter/charger 12VDC connections (red wires) in the upper right quadrant of the diagram.
 

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I installed the WFCO WF-8955-AD to replace my WF 8955. I shortened the wire to 4 feet to battery and used 6ga. wire vs 10ga. factory wire.
I am getting the full 55amps now which I never did before. I also had to get the jumper from WFCO to get the converter to stay in lithium mode.
I had considerable voltage drop with the factory wire and about 15 foot run.
 
Mine is #4 but converter/charger and battery are side by side. Except #6 from battery to electric distribution panel which is the factory wiring.
By the way, It didn’t come that way, I moved the battery inside by the converter when I switched to lithium so I could get the full charge current and the battery would be in climate controlled area.
 
I like the battery specific charge idea - thanks for that. I have an outlet in the front bay, I can just plug a charger in there when I have shore power and top off the battery. Easier than messing with the CC location or changing the wire gauge.
 
I installed the WFCO WF-8955-AD to replace my WF 8955. I shortened the wire to 4 feet to battery and used 6ga. wire vs 10ga. factory wire.
I am getting the full 55amps now which I never did before. I also had to get the jumper from WFCO to get the converter to stay in lithium mode.
I had considerable voltage drop with the factory wire and about 15 foot run.
I’ve done a similar upgrade. New 460 Ah Vatrer Lithium battery and installed a new WFCO 8955-AD. When I did my first charge I did not get the Blue LED indicating Lithium profile. I drained the battery down to 7% and then charged again. Success! Blue LED came on and it charged to 100%. I have since done this cycle 3 more times with success to 100% charge.
My problem is that it’s taking about 2 days to fully charge from shore power. I’m only getting about 23 amps and 300 watts - per my BMS Bluetooth app.
I contacted WFCO and they have had me checking all the connections and taking voltage reading. At the power distribution center the lugs test at 14.7. At the battery I’m only getting 13.6 volts. So a .9 voltage drop and only about 23 amps as I previously stated. There is a 30amp auto resettable inline fuse just before the battery. I got the part number off of the old one and replaced with a new one. Both sides of the fuse tests at 13.6 volts. I also tested at the factory installed battery cut off (which is before the fuse) and both sides tests at 14.0.
After reading your post, I’m thinking I may need to shorten the wire between the charger, potentially increase the wire size (I think my factory wire is 6 awg - which should be thick enough to support 55amps of charging BUT maybe not), and also may take the battery disconnect out of the wiring.

I have a Momentum 30g and it does not have a lot of easy access to wiring and the underbelly is covered with poly to provide winterization. Dropping it would be a bit of a pain.

I know it’s a big battery but it sure would be nice to be pushing 40 amps+ to charge that big boy.

Thoughts? Ideas? Recommendation?

P.S. I don’t have solar yet. But plan to add to be able to supplement shore or generator charging. Just wanted to get this step optimized before I moved on.
 
The wire being able to support the current is not an issue, it's the voltage drop. You need at least 13.8V at a Lithium battery for it to take much charge current. Also, after 10 hours the converter will drop the charge voltage down to 13.8V so you will get very little charge current after that because the voltage at the battery will be even lower. You can move the battery to be right beside the converter/charger or vice versa. It's usually easier to move the converter/charger to the battery.

Also, that auto reset fuse is only going to let the battery charge up to 30A. Above that it will trip.

Don't count on the WFCO staying in Lithium mode. Mine would not so I sent it to WFCO on a warranty claim and they installed a jumper to keep it in Lithium mode. They paid for all the shipping cost.
 
I appreciate your input!

Is your suggestion to move either the battery or charger closer together because you think the wire length could be causing the voltage drop?

On my 30g the charger is in a cabinet toward the curbside, then the cutoff switch is all the way on the street side (both toward the front) and then the batteries are currently on the front A frame. I wouldn’t think that would amount to more than 10’. But I don’t know for sure.

WFCO recommended to me today to replace the 30 amp fuse with a 60 amp fuse. I have one on order and will be here tomorrow.

WFCO has been a little reluctant to send me the jumper or recommend I send my charger to them to install. They said they’d like to see if they can get it to work like it was designed. Maybe they’ve had some many converters get the jumper installed that it might be giving them a bad reputation for their new auto detection technology.
 

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