Adding more Lithium

[Traverson]

I have a 100ah Hublion lithium battery and would like to add another 100ah. My question is do I have to purchase the same brand so the battery monitor systems are compatible. Another brand would be easier to get here in the U.S.

[alanmalk]

Originally Posted by Traverson

I have a 100ah Hublion lithium battery and would like to add another 100ah. My question is do I have to purchase the same brand so the battery monitor systems are compatible. Another brand would be easier to get here in the U.S.

If 2 batteries in parallel (any chemistry) don't have the exact voltages, one will try to charge the other. That is why for a parallel connection it is recommended that the same brand and manufacture date be used. If that is not possible or wanted, try using an "A"-"B"-"Both" switch to keep them separated most of the time.

[SageRpod]

Originally Posted by Traverson

I have a 100ah Hublion lithium battery and would like to add another 100ah. My question is do I have to purchase the same brand so the battery monitor systems are compatible. Another brand would be easier to get here in the U.S.

Our 5.0 came with 2 Hublion batteries and we added another two batteries when we picked the camper up from ETI. We purchased the batteries and another battery box(I'm probably the only on this Forum who actually likes battery boxes ) from ETI so we could have the same manufacturer. In retrospect, 4@100ah of lithium may be a bit of overkill, but we're glad we have the capacity. The batteries were all within the recommended voltage range when I hooked them up. One year and lots of boondocking later, everything is working fine.

[TTMartin]

Originally Posted by alanmalk

If 2 batteries in parallel (any chemistry) don't have the exact voltages, one will try to charge the other. That is why for a parallel connection it is recommended that the same brand and manufacture date be used. If that is not possible or wanted, try using an "A"-"B"-"Both" switch to keep them separated most of the time.

LiFePO4 batteries have an internal BMS. They don't behave like lead acid based batteries. When one is full it internally disconnects (Charge CMOS - Off) from the charging source. While they will balance the voltage between the batteries, they aren't like lead acid based batteries where the weaker one will draw down the stronger battery indefinitely.

I mix two Weize 100 amp hour LiFePO4 batteries in parallel (under my driver's side dinette seat) with a 300 amp hour Chins Smart Battery (LiFePO4 with internal heater) in the front storage box. I do have them on an AB switch, however as long as the temperature is above freezing, where the Chins internal heater might draw power from the Weize batteries, I leave the AB switch set to both and have had no issues.

[Don Flamenco]

Even with batteries from the same brand, if the date of manufacturer (their age difference) is significant, it can cause issues w/ their respective BMS's. A resting voltage difference of a few tenths is fine; even a little above that is ok. 7 tenths and higher is bad. A 1 volt and higher difference is very bad.

The "A"-"B"-"Both" switch makes a functional & low-cost workaround, but it can also introduce issues such as having to manually keep track so that one battery doesn't get more use than the other, ensuring proper charging voltage & time for each battery, managing temperature and heating cycles for each battery, etc. So be aware.

[Vermilye]

I believe I posted this in another thread, but it may be useful here - I contacted Battleborn about adding a 3rd 100 amp hour battery to the two 100 amp hour Battleborn batteries I already had installed. They suggested that best practices would be to add the 3rd battery within 3 years of the first two. I did (after 2 1/2 years) and have had no problems so far.

[John in Santa Cruz]

I would fully charge the new battery and the old batteries using the same charger before paralleling them, then don't worry about it.

[SageRpod]

Originally Posted by John in Santa Cruz

I would fully charge the new battery and the old batteries using the same charger before paralleling them, then don't worry about it.

That's pretty much what I did. I had read stuff about taking them down to 80% then charge them to 100%. I just got them all to 100% using my NOCO Genius and wired them together. All 4 batteries were manufactured with 3 months of each other so all was good there as well.

[Traverson]

Originally Posted by Vermilye

I believe I posted this in another thread, but it may be useful here - I contacted Battleborn about adding a 3rd 100 amp hour battery to the two 100 amp hour Battleborn batteries I already had installed. They suggested that best practices would be to add the 3rd battery within 3 years of the first two. I did (after 2 1/2 years) and have had no problems so far.

I picked my trailer up in July, so the battery is within the three year window, but old enough that I would not be able to get another one with a similar manufacture date. So it looks like the right thing to do would be, get one from another brand and install an "A-B" switch.

[alanmalk]

Originally Posted by Traverson

I picked my trailer up in July, so the battery is within the three year window, but old enough that I would not be able to get another one with a similar manufacture date. So it looks like the right thing to do would be, get one from another brand and install an "A-B" switch.

In practice, if all batteries are from the same manufacturer, you are probably well off keeping the switch on "Both", with the exception of leaving the trailer unused for weeks at a time. That is when "phantom" charging - one battery by the other - might be a problem.


But that said; A little detective work with a multi-meter would confirm if one battery is charging another. 8 years ago I measured the current between my 2 AGM parallel batteries at around 5 milli-amps. That's the tiny drain that might become a problem after many months, so I ignored it. But then again, they were not $1000USD Battleborn batteries.

[C&G in FL]

Originally Posted by alanmalk

But then again, they were not $1000USD Battleborn batteries.

Come on Alan, enough with the hyperbole. Last I knew Battleborn 100 amp hour batteries were only $900 US each!

But yes, they are expensive. There are less expensive alternatives out there.

[alanmalk]

Originally Posted by C&G in FL

...
There are less expensive alternatives out there.

Yes, but I want to know when they drop below $100USD.
I intend to keep my reputation as the Master of Cheap.

[Ron in BC]

Originally Posted by alanmalk

Yes, but I want to know when they drop below $100USD.
I intend to keep my reputation as the Master of Cheap.

You can make those jokes, but you never know.

I remember when 42" big screens made their debut. They were priced well over 2 grand CDN. We were nowhere ready to buy one and were just looking. Finally I told one persistant sales guy "I'm not buying one until the price is less than a thousand". That seemed like a silly statement even to me and he replied that would never happen.

Well now you can buy a TV more then twice that size for less than a thousand. Never say never. The future has a way of surprising us.

Ron