Can OEM charger get lithium battery to 100%?

[GD1]

Looking for help with Lithium conversion on a Grande Design 22MLE. Specifically, can I use the existing wiring (8AWG) from the converter to the new battery?


- WFCO 8735AD hardcoded to lithium with a jumper cable, supposedly puts out up to 35A while charging battery

- OEM 165W panel connected to a furrion solar charge connected to the original battery

- Currently a generic lead acid battery, swapping in an epoch essential 300Ah lithium battery soon

I haven’t been able to open up the belly yet, to look, but I’m guessing there’s 20’ - 25’ of wire between converter and battery unless the converter goes to the battery disconnect switch first and then to the battery in which case it will be longer.

Q. Would it be normal to go to disconnect switch first?

Initially, I’d like to just swap the batteries and use the stock configuration until I have time to relocate the battery and upgrade the solar.

Q. Will the converter be able to charge the battery to 100% or will it be less due to voltage loss? Sounds like the lead acid batteries handle that better than the lithium batteries.

Q. Any guess on how high it'll be able to charge?


Thanks

[Country Campers]

I would guess it will get fully charged but it will be slow. Your solar charger will make up some difference.

Brian

[Scott'n'Wendy]

Q1 Yes it would be normal
Q2 Yes it could get it to 100%. It would take a VERY long time for a 35A charger to fully charge a 300ah LiFePO4 battery...but it COULD do it.
Q3 No guess other than a very long time.

IMO....if you are installing in a 300ah battery....it would be well worth your while to invest in a much more capable converter...like 120 amp and upsize your wires.. you can get by with your 35amp but it may take so long to charge you may not often be at 100%

[ncitro]

I agree with Scott and Brian. With lithium they charge linerally pretty much until full. That makes it easy math to work out the charge time. If you are down 100ah (assuming no solar) then 100/35 (assuming you get the full 35A) means 2.9 hours of charging to full. This time really only matters when running a generator and you want to either say fuel or not listen to it run, if you go a day or two dry and then end up at a campground to recharge, overnight it will get the job done regardless (even empty 300ah would charge in less than 10h). That said I would not be surprised if you get less than 35A out of the converter due to the length of the cables. The two best things you can do is shorten that run (either move the converter closer to the batteries or the batteries closer to the converter) and upgrade that wire size.

Another option to consider that most of us have done is a DC to DC converter. You will find the truck charge wire will get you less than 10A from the truck while driving. You can install a DC to DC converter and run larger wires from the truck battery back to the trailer and increase that significantly. howson and I both have the Renogy 40A, and Country Campers was able to use the Renogy 20A with his factory 7 pin wiring. TucsonJim went with the Victron 40A units I believe. With any of these after a long drive day (depending how depleted the battery is) you would arrive at your next stop with a full charge. It has completely changed how we travel, and now on drive days pretty much universally dry camp unless the weather requires use of the AC.

[Cate&Rob]

I would strongly suggest that you incorporate a shunt based monitor into your system. This will allow you to “see” what is going on. My experience is that the distant converter on smaller wires will eventually get the new battery fully charged but as others have described, this will take time. See post 12 of this thread for my experience. https://gdrvowners.com/forum/solar/1...ithium-upgrade

Rob

[GD1]

Thanks for the good feedback. There's a lot of variables to this.

For this phase, I'm good running the oem converter since it sounds like it will be able to charge the battery to full eventually, albeit slowly. Turns out it has a 4 hour limit so if the battery is deeply discharged it'll switch modes at 4 hours and I'll have to cycle power to get it back into bulk mode (I think its bulk).

We'll either be hooked up at home before the trip or at the rv park and as long as it can charge over time / over night it shouldn't be a problem. I just reinstalled my converter after shipping it off for a fw upgrade and jumper wire add. I REALLY don't want to mess with again, plus I need to move on to the solar upgrade phase (800w solar, victron 60amp SCC, BMV-17 shunt).

As ScottnWendy suggested, if it' becomes a problem charging I'll look at upgrading the converter but I'd like to give it a go as is. Cate&Rob, I'll try and get some real world numbers and see how much voltage drop there is. I hope it's better than what you saw or I may have to upgrade the converter after all.

Once the solar it done it should help top things off. I fell better knowing the converter will be able to (probably) get it done if I'm parked under a bunch of trees.

Ncitro, a DC to DC charger looks like a nice option to add into the mix. I'll see how things shake out first but can see adding that down the road. The more options the better.

[TucsonJim]

Just for clarification. I have two 30 amp DC to DC chargers which were the maximum capacity Victron was offering at the time I purchased them. In the last six months, they have released the 50 amp version.

Jim

[reubenray]

To the OP why did you choose 300ah Lithium battery? Isn't this very heavy?

To ncitro - will a DC to DC converter drain or damage the truck battery at stops?

[Scott'n'Wendy]

To the OP why did you choose 300ah Lithium battery? Isn't this very heavy?

To ncitro - will a DC to DC converter drain or damage the truck battery at stops?

I believe the DC-DC only charges when the truck is running.

TucsonJim Two 30a dc-dc chargers. Just out of curiosity, did you run one large wire (#6?) from the front of the truck to the chargers or two smaller (#10?)

[ncitro]

To the OP why did you choose 300ah Lithium battery? Isn't this very heavy?

To ncitro - will a DC to DC converter drain or damage the truck battery at stops?

I have mine configured to one of the Ford upfitter switches that are only live when the truck is running. There’s also a remote trigger on the Renogy that I have tied to the running lights so it only runs when they’re on.

[GD1]

Thanks Jim, the victron a 50Amp unit seems like just the ticket. It would work great even on short trips.

Reubenray, it's only 58lbs, pretty light for the capacity plus I'll be moving it further back on the trailer eventually shifting the weight somewhat. I see they just came out with the 460Ah version of that battery which would be tempting if I hadn't already bought the 300Ah version. I voted for the simplicity of 1 battery over the redundancy of multiple batteries.

https://www.epochbatteries.com/produ...och-essentials

[Jkwilson]

To the OP why did you choose 300ah Lithium battery? Isn't this very heavy?

Only 8 lbs more than a typical group 27 lead-acid that is routinely used as the dealer supplied battery.

[TucsonJim]

I believe the DC-DC only charges when the truck is running.

TucsonJim Two 30a dc-dc chargers. Just out of curiosity, did you run one large wire (#6?) from the front of the truck to the chargers or two smaller (#10?)

Good morning. I ran 2 AWG from the truck to the trailer, then terminated the wire on buss bars near the DC to DC converters. Then I ran 6 AWG from the buss bars to the converters.

Jim

[Yoda]

Looking for help with Lithium conversion on a Grande Design 22MLE. Specifically, can I use the existing wiring (8AWG) from the converter to the new battery?


- WFCO 8735AD hardcoded to lithium with a jumper cable, supposedly puts out up to 35A while charging battery

- OEM 165W panel connected to a furrion solar charge connected to the original battery

- Currently a generic lead acid battery, swapping in an epoch essential 300Ah lithium battery soon

I haven’t been able to open up the belly yet, to look, but I’m guessing there’s 20’ - 25’ of wire between converter and battery unless the converter goes to the battery disconnect switch first and then to the battery in which case it will be longer.

Q. Would it be normal to go to disconnect switch first?

Initially, I’d like to just swap the batteries and use the stock configuration until I have time to relocate the battery and upgrade the solar.

Q. Will the converter be able to charge the battery to 100% or will it be less due to voltage loss? Sounds like the lead acid batteries handle that better than the lithium batteries.

Q. Any guess on how high it'll be able to charge?


Thanks

Lots of excellent advice above. I keep this page bookmarked to check wire sizes http://assets.bluesea.com/files/reso...on_chartlg.jpg It look like you stock wiring would be undersized. Yes it will work, but will be slow.

Remember to double the length of the run for using the chart. Why? DC is a circular circuit there and back to the battery.I know it took me a while to understand. I have a DC-DC set up on my ford - Like others I did a write up on the install. One thing - verify your alternator output so you don't overload and if wanting to use the charge line, double check its capacity.. I have the Renogy 60A DC-DC and I have seen it pull close to 80 amps during testing. I have it regulated to 30 amp for my flooded batterys though.

[IDRVr]

Remember to double the length of the run for using the chart..

You don’t need to double it if you are using the RV chassis as the return (negative) side of the loop. You just need to account for the actual length of the wire conductor in the loop, including the length of conductor between the negative connections of the battery and converter/charger to the chassis. It won’t hurt to double it, you’ll just be overbuilt.