Mixing Lithium Brands

[AJMike]

Is anyone mixing different brands of RV Lithium batteries? If so, what has been your experience?

I posted a question about adding a new LiFeP04 battery to a 5 year old 3 battery system and one of the posters said that he added a different brand to his existing batteries without a problem. My current setup is 3 100AH BB batteries, mostly 5 years old, connected in parallel and I want to add a 4th because one of our favorite dry camping sites has too much foliage for much help from my solar and I am not allowed to run a generator. Even with an hour of unobstructed solar a day we still left after a 3 night stay with only about 25% left in our house batteries, so I am concerned about a stay with little or no sun.

My first thought was to add a new 100AH BB battery, but they are still $750 each and that is a lot just for a place we camp at one time a year. But other brands like LiTime are less than half that price and it is temping to add one of them instead of another overpriced BB battery. I am hoping that people who have done this will post their experience, good or bad. Does mixing BMS cause a problem? Do the batteries charge properly? Do they discharge evenly? Are there any issues?
Thanks.

[Captain8]

Yes you can mix them but typically they won't charge/discharge the same. There really isn't any issues with this

[hclarkx]

See my post (#64) in the first thread you opened on this subject (in Going Green).

Mixing brands or different ages or different sizes isn't ideal but it's close. You don't lose much by doing so. I've had a number of combinations of brand and size and age and all worked well.

[d23haynes57]

Originally Posted by AJMike

Is anyone mixing different brands of RV Lithium batteries? If so, what has been your experience?

I posted a question about adding a new LiFeP04 battery to a 5 year old 3 battery system and one of the posters said that he added a different brand to his existing batteries without a problem. My current setup is 3 100AH BB batteries, mostly 5 years old, connected in parallel and I want to add a 4th because one of our favorite dry camping sites has too much foliage for much help from my solar and I am not allowed to run a generator. Even with an hour of unobstructed solar a day we still left after a 3 night stay with only about 25% left in our house batteries, so I am concerned about a stay with little or no sun.

My first thought was to add a new 100AH BB battery, but they are still $750 each and that is a lot just for a place we camp at one time a year. But other brands like LiTime are less than half that price and it is temping to add one of them instead of another overpriced BB battery. I am hoping that people who have done this will post their experience, good or bad. Does mixing BMS cause a problem? Do the batteries charge properly? Do they discharge evenly? Are there any issues?
Thanks.

Just go for this one. What can you lose?
https://www.amazon.com/HQST-Phosphat...0CR5L3LGS&th=1

[AJMike]

Originally Posted by d23haynes57

Just go for this one. What can you lose?
https://www.amazon.com/HQST-Phosphat...0CR5L3LGS&th=1

While it is hard to know about any particular battery with any certainty until one tries it, this particular brand got smacked in one of the YouTube videos as just being garbage. I looked for the video intending to provide the link, but it is not still in my view list so I will have to look harder.

The battery that I was thinking about using was the LiTime, which is about 1/3 the cost of the BB battery but the LiTime support people told me not to do it. Here is their response to my question about mixing battery brands:

Thank you for reaching out with your question. When it comes to connecting lithium batteries in parallel, especially from different manufacturers, we generally advise against it. Here are the reasons:

1. Different Battery Management Systems (BMS): Each manufacturer may use different BMS configurations, which could lead to incompatibility issues. This can affect the charging and discharging cycles and potentially cause damage to the batteries.

2. Age and Performance Differences: Your existing batteries are about 5 years old. Over time, batteries can lose capacity and efficiency. Connecting a new battery with older ones might lead to uneven performance and could strain the new battery.

3. Cell Chemistry and Specifications: Even if the voltage and capacity are the same, slight differences in cell chemistry and internal resistance can lead to imbalances when charging or discharging. For the best performance and to ensure the longevity of your battery system, I would recommend using batteries from the same manufacturer and of the same age if possible. If you decide to upgrade or replace your battery bank, you might want to consider replacing all the batteries at once with new ones from the same brand.

I am still looking, but also considering whether replacing all of the batteries is worth the cost considering that my battery problem only involves one campground that we visit one time a year. It is one of my favorite trips, but still it is only one visit and I can leave the campground, then run the generator and return. It is a pain, but replacing all of the batteries is going to cost me about $1000 US so the question is which is the bigger pain - leaving the campground to run the generator or replacing all of the batteries at a noticeable price.

[AJMike]

Originally Posted by hclarkx

See my post (#64) in the first thread you opened on this subject (in Going Green).

Mixing brands or different ages or different sizes isn't ideal but it's close. You don't lose much by doing so. I've had a number of combinations of brand and size and age and all worked well.

You can see the response I got from LiTime about mixing batteries in my previous response in this thread. I understand that they may well just be trying to get me to buy more batteries, but I also have to consider that that is their honest opinion and warning, or what adding a new battery might do to my warranty.

One of the things I have been thinking about is having one of these LiTime batteries installed in parallel to my existing BB batteries and if they seem to be causing me issues I could just disconnect that battery. I am just not sure what "causing me issues" might involve so I am unsure that I would recognize serious issues before everything went dead.

[ra_weiss]

As long as the AH and chemistry of each battery is the same it can be done (I've done it!). Just make sure you connect an equalizer to them all to keep them in balance.

[AJMike]

Originally Posted by ra_weiss

As long as the AH and chemistry of each battery is the same it can be done (I've done it!). Just make sure you connect an equalizer to them all to keep them in balance.

This is the first reference to a battery balancer that I have seen in this or my previous threads, so I will have to do a little research.

I don't really know what they are or how they work, but if they compensate for differences in battery voltage or capacity they might be a solution to my concerns. If you (or someone else) could explain what it does it might save me a couple of hours of research.

[Soppy]

Originally Posted by AJMike

This is the first reference to a battery balancer that I have seen in this or my previous threads, so I will have to do a little research.

I don't really know what they are or how they work, but if they compensate for differences in battery voltage or capacity they might be a solution to my concerns. If you (or someone else) could explain what it does it might save me a couple of hours of research.

The only time you need a battery balancer is when the batteries are connected in series. Each battery has a built in BMS which balances the individual cells. When batteries are connected in parallel, the voltage on each battery will be nearly identical. There is no problem connecting different batteries in parallel. When charging, they will all charge to the same voltage, and when discharging, they will also discharge to the same voltage. The BMS will also disconnect the battery if the voltage drops to low or to high. A new battery may have to work a little harder, but that won't matter. I have 4 - 100 ah batteries in parallel with 460ah of AGM batteries. Each lithium has an external meter to keep track of the voltage and amp hrs. I have seen a difference in state of charge of 15% between the lithium batteries. The AGM batteries just sit ther fully charged till the lithums drop below about 20%, then they start taking over the load preventing the lithiums form totally discharging.

[TacomaJoe]

The LiTime response in post #5 is the one good caution with putting them in parallel. I have a 280Ah, two 277Ah and a 100Ah tied together and they track very close, no issues what so ever. The reason being that my BMSs never go to sleep/standby and are always active. The LiTime BMS will go to a standby mode and when two are in parallel, it seems like one of them wakes up and takes the load while the other continues to sleep until the bank runs down enough to wake it.

As for balancers, not needed in parallel but yes for series. Myself, I don't like a series connection, I'd prefer getting a 24V or 48V battery to start with.

[oldenavy]

The quote you have from LiTime is right on the mark. It is not advised to mix batteries of different ages and more importantly different manufacturers for the reasons they outline. Lithium batteries, unlike lead acid, have an extremely low internal impedance. That makes them very sensitive to what they are connected with (both parallel connections as well as the loads/chargers they're connected to).

Can people do it and get away with it (for a while)? Sure! Until they don't and one of their batteries fails. Although LFP failures aren't nearly as spectacular as other Li chemistries, it's still possible for them to heat up surrounding things and start a fire.

If it was my camper where my family sleeps, I would not do it.

[Paul_D]

One issue is BattleBorn batteries are fabricated with cylindrical cells, almost all the cheaper batteries are prismatic cells. So there are could be differences in their behavior.

[ra_weiss]

Originally Posted by Soppy

The only time you need a battery balancer is when the batteries are connected in series. Each battery has a built in BMS which balances the individual cells

To prove this theory out just disconnect all battery interconnects and let them sit for an hour. Even if all of them are the same brand, the same age, the same lot even, you will find that the voltages across them dissimilar. Not only is that just how batteries are - each one having different resistance - but there's also cable lengths and terminators to factor in. Their BMS is to balance each battery's cells but they don't communicate with other batteries.

And especially in this case where OP is introducing a new battery to his older bank. If he does that, which is fine, he should definitely connect an equalizer to them.

Originally Posted by AJMike

I don't really know what they are or how they work, but if they compensate for differences in battery voltage or capacity they might be a solution to my concerns.

If you get a decent one it will do exactly that.

[SafariBen]

Originally Posted by oldenavy

The quote you have from LiTime is right on the mark. It is not advised to mix batteries of different ages and more importantly different manufacturers for the reasons they outline. Lithium batteries, unlike lead acid, have an extremely low internal impedance...

Li, unlike lead, does not care if it's stored at 90%, or 50% (actually better) or 1% (fine as long as it never sits long enough to reach true 0). Lead's higher resistance means one battery will reach full before a weaker parallel battery, and if the charger shuts off the weak one will drain the full one slightly and neither will be fully charged, or if it keeps charging the strong one will be overcharged. Li has a BMS that shuts the battery down at some point to allow parallel batteries to balance, so as long as the daily charging profile does not bring them to 100.00% too frequently, and the occasional (every few MONTHS) charging holds them to full long enough to balance every battery, hence every cell, then they should be fine in parallel with one reaching 90% while the stronger one reaches 95%, that 5% difference doesn't SEEM like it will realistically affect the cycle life of any of these batteries enough for any of us to notice in the real world.



Notice that Litime "generally advises against" connecting ANY batteries in parallel. Some say the same about series. If connected in series, the cell matching IS critical, and one BMS controlling the whole string is best. Lots of the "connecting information" regards connecting lead in series, so is not relevant to Li in parallel.



One member mentioned lots of "dead lead" legends being applied to Li. The manufacturers are the ones saying this, so not much we can do except muddle through until Li is more well established, or we all have flying RV's powered by nitrogen or whatever.