Switching to lithium: is new charger necessary?

[steve2777]

I presently have 2 factory fla batteries, and have been thinking of upgrading to lithium. I know my inexpensive converter charger won't properly fully charge them. However I have a good mppt solar charge controller which is selectable for lithium, and 200 watts of panels. Would this work to push the charge voltage to the required higher level and make a new charger less mandatory?

[ducksface]

Do not ask here.
Ask the manufacturer of the batteries you decide to purchase.
Some here are Google Foo (which you can do on your own), some are parrots, some are right, some are wrong.

Ask the battery builder and no one else.
The confusion isn't worth it and ultimately you're going to do what the manufacturer says to do or you've voided your warranty.

[crater]

For battleborn (i just purchased and went through the process) its not required for the charger/converter that comes in my delano (They have lists of different ones and you can see if its okay with the battery). That said the caveat is it won't charge all the way. So if you're trying to spread cost and you have a battery you've verified will be okay with the charger/convert you have then you could do that and use solar which does support lithium to do the topping off till you can afford the additional cost.



As said above, its all dependent on the battery and the specific charger/convert you have now.

[steve2777]

Thank you !

[RadioRanger]

I am looking at doing the same thing. At least using the factory installed charger for a little bit.

One thing to keep in mind is that the battery charge indicator will no longer give you an idea of the level of charge is in the Lithium. That charge indicator looks at battery voltage. Lead acid and AGM drop as they discharge. Lithium keep a pretty high voltage, so it will always looks charged. Look at a battery monitor or just wing it if your loads are not all that high.

[Bill in Redlands]

I also use a battery minder to maintain charge while the RV is idle. The one I use has a setting for lithium. I leave with a full charge and typically keep it with the solar. It helps that we are very conservative with our power usage, especially when boondocking.

[The_Breeze]

The straightforward answer is yes. Lithium has a different charge profile than conventional/other battery systems

[AJMike]

I just converted from 2 wet cells to 2 BB Lithium batteries so perhaps I can tell you what BB told me and what else I have found out.

First, our RV has 3 100 watt solar panels (it came with 2 and I added another one) connected through a Zamp solar controller. The solar controller is set for the LiFePO4 profile for the house batteries but only charges at 13.6 volts, not the 14.4 volts that BB says is proper for their batteries. I called BB last week and asked about that and was told that the resting voltage for their batteries was 13.6 volts and that the Zamp controller would fully charge them just fine.

Next, our RV has a Progressive Dynamics charger that takes shore power or generator power and uses it to charge the house batteries. The issue is the same - the charging voltage is lower than Battle Born says it should be. In that case I bought a $20 remote "pendant" that allows me to manually press a button to change the charging parameters of the charger to 14.4 volts for 4 hours. It then drops back to 13.6 volts and by that time the batteries are generally fully charged anyway. Given what BB told me about the charging voltage from the solar controller I am not sure adding the pendant made a real difference, but I added that before I spoke with them and I assume it will not hurt.

Lastly, our RV has a 210 amp alternator which also charges the house batteries and the chassis battery. Battle Born told me that the Lithium batteries can draw a lot of current and that something needs to be used to protect the alternator, not the batteries themselves, and recommended a DC-DC charger. They told me that the idea here was to limit the current to the house batteries to a reasonable figure so as to not stress the alternator since the Lithium batteries themselves can easily draw 100+ amps each when charging and so stress the alternator. The DC-DC charger only allows a specific current flow to the batteries, thus limiting what the alternator is asked to produce. Battle Born sells one specific brand of DC-DC charger (Sterling) but there are other brands available, and with differing current limits. I bought a Renogy 40 amp charger for our RV. Renogy also offers 20 amp and 60 amp models and Viltron offers a 30 amp model.

One other thing to keep in mind. It might be a good idea to know what your actual battery usage was before deciding on upgrading and one way to do that is to get a Battery Monitoring System installed. That will tell you how many actual AHs you are using and might help in sizing any new system. I had a Victron 712 installed on our system because it allowed me to check on daily usage with the smartphone app, and it told me that our RV uses about 100AH a day, mostly due to our compressor refrigerator. More if it is a hot day, less if it is a cool day. That told me that I needed at least 200AH of battery power and that the idea of only buying one battery for now (which I thought would save me some money in the short term) would not cover our power usage.

I knew none of this when I decided to upgrade the batteries so perhaps there is something here that will help.

[howzball]

Originally Posted by steve2777

I presently have 2 factory fla batteries, and have been thinking of upgrading to lithium. I know my inexpensive converter charger won't properly fully charge them. However I have a good mppt solar charge controller which is selectable for lithium, and 200 watts of panels. Would this work to push the charge voltage to the required higher level and make a new charger less mandatory?

This is exactly how I’m charging our lithiums. Our built in charger doesn’t have a true Lithium profile, you just manually enter the parameters you need. I intentionally left my top voltage a few points low so the solar panels could do the rest. You’d much rather undercharge your lithium’s than over charge them.

I don’t have BB batteries but the guys there still answered this question when I asked them. The only issue with undercharging lithium is you’ll have slightly less power. If your solar makes up the difference then, even better.

I also installed the Victron BMV-712 battery monitor for insurance in case my chargers built in monitor wasn’t accurate. It had a true lithium profile in the software.

[Bill in Redlands]

Originally Posted by AJMike

Battle Born told me that the Lithium batteries can draw a lot of current and that something needs to be used to protect the alternator, not the batteries themselves, and recommended a DC-DC charger.

You got my attention with that comment and, after doing some further research on the potential damage, I also ordered a Renogy 40 amp DC to DC charger. My plan is to install it on the house battery side of the battery isolator manager. I looked up the one that Thor listed as being installed in our Axis but can't find anything that looks like it (Precision Circuits Inc BIM). I will continue to look for it this week but am curious if anyone can provide guidance. I am assuming that my 24.2 is similar to 24.1 models and others?

Bill

[howzball]

Originally Posted by Bill in Redlands

You got my attention with that comment and, after doing some further research on the potential damage, I also ordered a Renogy 40 amp DC to DC charger. My plan is to install it on the house battery side of the battery isolator manager. I looked up the one that Thor listed as being installed in our Axis but can't find anything that looks like it (Precision Circuits Inc BIM). I will continue to look for it this week but am curious if anyone can provide guidance. I am assuming that my 24.2 is similar to 24.1 models and others?

Bill

My question about this is why could you not use a smaller gauged wired from wherever the Alternator connects to your House batteries, probably the BiRD relay/trombetta switch, and limit the amps the lithium batteries could receive that way?

Say a 6 gauge wire can carry 75 DC amps. If you have a 100 amp alternator then it's never going to be able to push more than the 6 gauge wire can carry so you'd never over-amp it. There Has to be something I'm not considering because that seems too easy.

You also have this option https://amzn.to/3eyN7Z3 that you could use to just replace the BiRD relay/Trombetta switch.

[Bill in Redlands]

Originally Posted by AJMike

Battle Born told me that the Lithium batteries can draw a lot of current and that something needs to be used to protect the alternator, not the batteries themselves, and recommended a DC-DC charger.

Mike, it seems to me that the DC to DC charger eliminates a two way connection between the house and chassis batteries. Is that correct? If so, wouldn't it also eliminate any need for isolating the batteries - in other words, the BIRD and Trombetta?

The downside, in my opinion not a big deal, would be the loss of charging or jumping the chassis battery from house batteries.

Am I understanding this correctly? Is there guidance out there? I looked and found little.

Bill

[PS Cruisign]

Steve, I will go along with "ask an expert" and that philosophy. However, my problem with that is they want to sell you something, and many dont give out free advice. Expert advice that is... so you can get some school of hard knocks experience here.

My take. I have four 100A BB's on my boat. It has a 120 amp Balmar smart regulator. On my coach, I have two 100A BB's which I can charge via, genset, which typically delivers a laughable 30 amps for charging. My 6.7 Diesel has a giant alternator, it really smacks them and I can monitor its volts and amps easy. I have 750 watts of solar. All this and about 4 years experience with them. Still no expert here. Just my MHO.

However, BattleBorns have a pretty sophisticated BMS built in and trust me i have tested it. You cant over volt, over temp, charge when its too cold, etc. They will accept everything your alternator can throw at them, and say no when its too much, and even if it is a "dumb" one meaning no programmable regulator, it should handle the demand to get them up to say 85%. 200W of solar is going to maybe make 12 to 15 amps and only for about 4 hours a day. If you have any demand on your system you wont make any money charging them with a system that small.

Lithium batteries dont float. A Victron or Balmar sg200 are good choices.

BB's are plug and play. You just have take the risk with your wallet. I wouldnt have anything else. Your rig should be fine for them in the stock configuration.

Good luck

[Bill in Redlands]

Originally Posted by Bill in Redlands

Mike, it seems to me that the DC to DC charger eliminates a two way connection between the house and chassis batteries. Is that correct? If so, wouldn't it also eliminate any need for isolating the batteries - in other words, the BIRD and Trombetta?

I heard back from Renogy today. I was correct in my assumption that their DC to DC chargers effectively isolate the house and chassis batteries since current can only flow from the chassis to the house. The typical setup uses a lead from the ignition side of the chassis electrical to turn on the charger, otherwise the charger isolates current from both directions.

If I proceed with this concept, I loose the ability to charge the chassis battery from the house side and to jump the chassis battery. I gain the ability to limit load on the alternator if the house batteries are fairly low and demanding a lot of current. I also gain the ability to charge the lithium house batteries according to their profile.

[howzball]

Originally Posted by Bill in Redlands

I heard back from Renogy today. I was correct in my assumption that their DC to DC chargers effectively isolate the house and chassis batteries since current can only flow from the chassis to the house. The typical setup uses a lead from the ignition side of the chassis electrical to turn on the charger, otherwise the charger isolates current from both directions.

If I proceed with this concept, I loose the ability to charge the chassis battery from the house side and to jump the chassis battery. I gain the ability to limit load on the alternator if the house batteries are fairly low and demanding a lot of current. I also gain the ability to charge the lithium house batteries according to their profile.

I'm surprised BattleBorn didn't recommend this device then https://amzn.to/3eyN7Z3 They pointed me to it instead of the DC to DC charger so I could retain the ability to jump the truck battery if I ever need to and protect the truck alternator from over amping.
If your coach already has a BiRD relay this just replaces it.

[Bill in Redlands]

Originally Posted by howzball

Say a 6 gauge wire can carry 75 DC amps. If you have a 100 amp alternator then it's never going to be able to push more than the 6 gauge wire can carry so you'd never over-amp it. There Has to be something I'm not considering because that seems too easy.

I am definitely not an expert but I believe that the 6 gauge wire will overheat if it is trying to carry more current than its rated capacity. I don't think that is a good idea. I suspect that it would still push, or try to push, the 100 amps through but overheat, perhaps to a point of being a fire hazard.

[Bill in Redlands]

Originally Posted by howzball

I'm surprised BattleBorn didn't recommend this device then https://amzn.to/3eyN7Z3 They pointed me to it instead of the DC to DC charger so I could retain the ability to jump the truck battery if I ever need to and protect the truck alternator from over amping.
If your coach already has a BiRD relay this just replaces it.

Sounds like the answer to my questions. This is the price I pay for using Amazon for the purchase and not having the benefit Battleborn's advice. I spent lot of time on the web and saw this on Amazon but didn't understand it as being alternative for lithium.

That is why I asked my questions originally.

Obviously I should have paid more attention to your last statement in your prior post.

Thanks for this - much simpler.

Bill

[ducksface]

As you all read this thread, you'll see the answer is in post#2.
Why would you risk getting an answer from someone you don't know or can vette saying wire size self regulates current?
Why wouldn't you call the manufacturer first?

[howzball]

Originally Posted by ducksface

As you all read this thread, you'll see the answer is in post#2.
Why would you risk getting an answer from someone you don't know or can vette saying wire size self regulates current?
Why wouldn't you call the manufacturer first?

Don't you wish it was as easy as contacting the battery people. When I did they directed me to the device I've linked above for Bill. When I had a question about wiring it they told me to contact my coach manufacture. When I contacted them (Thor) I was told they only support original equipment and not 3rd party hardware.

You're pretty much left with whatever source of info you can find, hopefully from someone else who's has some experience with it.
I have no doubt using a smaller gauge wire to try and solve this isn't a great idea But, it is a suggestion I saw posted from another Lithium battery manufacture as a solution to all of this. It didn't sound correct is why I questioned it but it does show you'd better be careful listening to All of the information your battery maker recommends.

For what it's worth, it used to be a common thing to use a fused wire from the alternator to the battery that would trip and reset itself based on charging amps. I assume this was in the days before alternators had built in regulators.

[Bill in Redlands]

Originally Posted by howzball

Don't you wish it was as easy as contacting the battery people. When I did they directed me to the device I've linked above for Bill. When I had a question about wiring it they told me to contact my coach manufacture. When I contacted them (Thor) I was told they only support original equipment and not 3rd party hardware.

I just wrote a longer response that is out there somewhere in neverland. Now the Reader's Digest version.

Ducksface - Point taken.

Howzball - Battleborn's website suggests the BIM is for banks of three or more batteries, I have two. I am waiting for their response to verify the BIM is appropriate for me. I also asked for wiring information but expect to have a similar response.