Is It Safe to Parallel different size or age lithium RV Batteries?
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- čas přidán 19. 01. 2024
- We often wondered what actually happens when different size or age batteries are put in parallel. So we decided to find out!
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I’ve been running a diy 300ah and a chins 100ah in parallel for about a year now with no issues. I’m also running three diy 300hr batteries in series for my 36v trolling motor for over two years now with no issues with imbalances. Great video👍
Love watching different YT channels experimenting with various configurations of batteries. Much knowledge gained from your efforts. Thank you.
Honestly, I thought things might be much worse for the smaller battery…however, to hear that there doesn’t seem to be any real concern doing this..didn’t expect that summary of the experiment! Lots of time I don’t understand what the data means, but you always summarize in the realm of practicality. Very appreciative of that. Thanks
I thought for sure the larger amp hour battery would not fully charge. Great video. Don
Really interesting video. Thanks!
been doing this for a year or so......been working fine. voltage is the constant
IV got 12 cells at 200ah..at 12v set up.
So IV one at 400ah and another at 200ah.
Yes time to time I do kick the power on....rest of time I'm a ,3c discharge.
Time to time I measure the voltage in each cell....
My deli bms's seam to keep them well balanced as I'm 100/200mv out.
I'm using a fluke 112 in calibration to test with.
Great information clip there....thank you.
I’ll guess the voltage during the flat area of the charge/discharge curve will match and the amps will be 32% to the 100Ah and 68% to the 206Ah. The areas 0-20% SoC and 80-100% probably will be different because of internal resistance of each battery and any additional resistance in the path to each shunt 😅
I think you’re pretty close.
Great video! Very informative.
With regards to your recommendation to not series up batteries to get the target voltage, my 24v system is using two 12v 200ah batteries in series (exact same batteries) and have been using it for about a month now. No issues so far. I top balanced them as best as I could before connecting them in series and I got their voltage to within 20mV of each other e.g. one is at 13.43v while the other is at 13.41v. A month later, they're still 20mv from each other. So far so good, I guess.
Will revisit their status and health in around 3 months maybe. I plan to add another battery then - a 24v 100ah battery from a different manufacturer. I'll connect it in parallel to the two series connected 12v batteries to increase my total capacity to 300ah.
Glad it’s working out so far. We’ve installed a few systems with that configuration. We do recommend a battery balancer then, Victron offers one.
Check the battery voltage near top of charge, that is where you’ll see the difference. Use the mid point sensor on the shunt to log the data in the cerbo if you have one. It’s a good indicator of it will be an issue.
If you keep your absorb voltage around 28.4 or so, you should be fine. At 28.8-29.2 it might get tricky with one battery cutting off charge before the other.
Both batteries will charge and discharge at same percentage, ie if 30 ah drain, small battery will give 10 ah and larger battery 20 ah (roughly due to being 206 ah)
My brother awesome video. May I ask a question though? Did you let the batteries sit for about a day and equalize? I wasn't sure if that was apart of the evaluation.
running 2 home built battries, 450ah and 240 ah, the bms's take care of everything, and the amperage gets shared, i ran a 2000 watt ac load approx 200 amp dc as a test until the bms's shut down, works fine.
So what are the discharge stats of each battery when tested seperatly for comparison to when they are paralleled? What is the internal resistance of each battery and is this affecting the discharge/charge rate?
So really the only problems would be over an extravagant amount of time (years) for the smaller battery getting slightly cycled more and balancing from the larger battery.
So really if you’re fine with loosing 1 or 2 of your expected 15 to 20 year batteries life then it’s probably ok to just parallel lifepo4 battery brands.
Well if u have a Lithium 200ah and 2 agm batterys. How do u set it up to use the Lithium battery until it's needs the agm batterys. Is there A specific way you need to set it up.?
I have 2/ 100ah batteries and 1/50ah, for some reason I thought it was not safe to parallel them together. What do you recommend? to have the 50ah in the middle or at the end?
is it possible to parellel LIFEPO4 pack and Lithium iron NMC battery pack together with solar inverte
Can I run the same size lithium batteries from different manufacturers in series, parallel?
I have 2, 12 V 100 amp Li-time batteries and would like to buy two more of the different brand( from a friend) and put them together in a 24 V 200 ah configuration.
Is that safe?
I’d say I’d each series pair is matched, you’d be fine. That said, you need battery balancing to keep the mid points balanced.
Hi there I have a question about my battery relocation from the tongue of my 30 amp Northern Spirit 2649BH. Moving 4 X 100 ah LiTime minis to behind my tv which is about 1/2 way down the rig. I will be installing a Victron MP 3000 watt also, I know I need to connect to the fuse panel to the batteries but how would you do this ? Would you tie into existing cable somewhere as there needs to be power to the tongue area for power jack and break away cable. Thanks for any input
I’d recommend using a bus bar or Lynx Distributor to connect your batteries to the Multiplus. Then run a separate fused 6awg line to the tongue or to the DC distribution panel, whichever is easier/ closer. This will energize the tongue jack and brakes.
@@sotasolar Thanks for your reply, I do have the victron 6 way mega fuse holder and I do have 6 awg OEM wire that is already there from the OEM batteries. Can I tie into this line as there may be other 12v items that feed from this wire. I have one renogy 100ah battery I was going to run off the tongue which will be hooked up to my 100 watt OEM solar.My battery disconnect switch is in front cross beam do I disconnect this? Sorry for all the questions, I do have the explorist life plans that I’m going off of.
@@richmurphy5647 In this case our philosophy is to simulate the old battery location by extending the 12v 6awg leads from the Lynx or Bus bar to the old battery location. This ensures everything still works as intended and we feel keeps the system understandable to others who come to work on it after us, such as RV techs or owners. We'll often use some heat shrink tube to cover a bolt and nut that connects the two systems together. Almost all of our trailer install videos cover this (5th wheel work differently many times).
I'd like to know how the same test would go if the load is greater than the larger batteries max discharge and also if the charge current is more than the max charge
If sustained I’d expect a cascading protection mode shutdown from the BMS. I’m not opposed to this, but what would be the use case?
@@sotasolar Running a high load like convection microwave or AC that could exceed one battery max discharge seems like a valid use case. Similarly if your inverter charger puts out a max current greater than one batteries charge limit but well within the two batteries, you could exceed if one reaches fully charged ahead of the other.
In this case we’d have to add more batteries. We recommend 400a of discharge and 200a of charge capacity.
I might be missing the point of running this test under conditions that would likely cause the BMS to fail. If killed a few myself :-)
@@sotasolar I was just describing a valid test case where dissimilar batteries could "fail" to perform.
How would it look if you added another 100ah battery
I'm assuming adding it to the other 100ah, so you'd have 1x 206ah parallel with 2x 100ah ? I suspect it would not be 100% equal because of different BMS and internals, etc. One of the goals of this test was to show what happens in worst case scenario and to see how critical it is to do this or not.
If you mean adding the additional 100ah battery to the 206 side, I suspect the affects would be compounded further but in the end still be workable for a load like this.
If bms fail , AGM will protect solar Charge Controllers for battery voltage loss , when solar is charging.
Great point
Is there any BMS in those batteries. They control charge and discharge. So no problem
Yes, SOK and Li Time both have BMS. I agree, BMS makes the battery very tolerant of abuse they might not otherwise be.
@@sotasolar the BMS is critical. I build my own batteries with CATL or Eve cells and the BMS is JK. I thew the nice looking Daly out of the window because of bad balancing and no updates
Very interesting video.
I have 2 200ah Enjoybot batteries for my 5th wheel. I also have a 12v Victron Multiplus II 120, solar chargers, & smartshunt. (basic description of setup)
I would like to at least double my battery bank. My existing batteries have been in use for a little over a year. Only have had about 4-6 discharge cycles on them. The rest of the time, they have been on standby/maintenance charge. In the winter months they aren't used.
So, my question is can I add 2 more of the same to the battery bank without harming any of the batteries? What would happen if I did that?
I know....batteries are better off being installed together at the same time.
Just thinking it might save a little money if I could just add 2 more. If not, then going with 3 of their 280ah versions will do the trick if I have to go the route of same age batteries.
You’re fine, add them. If it works fine with a battery double in size, one 1-2% different will be just fine.
@sotasolar Sounds great....thank you!
Hopefully, we are done with sub-zero temps in MN now....🥶
Although we have had a pretty easy winter so far.
Installing new batteries together really only applies to lead acid batteries. You will be just fine adding additional batteries of different age and ah ratings with lifepo4 as long as they are in parallel.you can do it in series as well but they all must be the same or close to the same ah rating.
@lukefarmer5391 They will be the exact same batteries. Of course, the manufacturers usually say only within the first few months or so. Lol
@BradLMN imagine a company selling batteries having a recommendation that favors the sale of more batteries? :-) Some recommendations are well founded, this one, I do not see it.
You need to understand how resistance affects current flow to and from as well as the grade of cells/BMS/Internal wiring.
How many lithiumn batteries can you run in parallel?
I have (2) 200 amp batteries and also just got from a friend (2) 100 amp lithium batteries, Can I add a total of 6 batteries all in parallel if I got 2 more batteries for a total of 800 amps.
Thanks
Andy
With circuit protection between each battery, and overall protection for main wires it’s unlimited in my opinion.
Question, Can you run to battery one 48V and one 51V in parallel?
I’d be curious to see the exact make and model that you referencing but in general I would not. We have successfully paralleled, lithium, and AGM without a problem, and those do run at slightly different voltages, but with the same charge profile, they still charge up equally.
I got one Aolithium 51.2V 100Ah 5120Wh and one it’s TTN 48V 100Ah 4800Wh i’m trying to run them in parallel but doesn’t work. The inverter is using it the 51 V battery first and then start using the 48 V once the first one get to about 15% of usage
@gregfabian4655 that’s similarly to how AGM and lithium work when paralleled. You may need to adjust low voltage cut off down on the inverter.
Thanks for your tip. I will try that I believe that will work.
Yes it is
If both battery are parallel
Both will drain down at the same time
I collected a large number of USED lithium 18650 batteries from different brands.
I want to build a new battery pack 8S10P (8 series by 10 parallel) for my e-bike.
I have set up each battery bank with the voltage as close to each other as possible. 4.199 volts to 4.100 volts throughout 8 series.
eg:
bank01: 4.199volt to 4.190volt (10 batteries in parallel)
bank02: 4.189volt to 4.179volt (10 batteries in parallel)
..
bank08: 4.119volt to 4.100volt (10 batteries in parallel).
The total voltage for the pack will be approximately < 33.6 volts.
Because they are USED batteries. Therefore, they have different voltages and ampere. (Generally, 18650 batteries are 4.2 volts at max. Due to it being USED/OLD, therefore they dropped the voltage under 4.2v each.
*_1) Do you think it is safe to mix the batteries with different voltages in PARALLEL, where the different voltages deviate in 1/1000?_*
*_2) Do you know what the SAFE DEVIATED voltage is when connected in parallel?_*
Please advise.
Thanks
I’m not an expert on 18650 battery pack building. I’d say capacity is more important than voltage. When I did pay attention to DIY packs it seems important to group your cells by capacity. And you want each battery in series to have the same or similar capacity. The lowest capacity cell group will define the usable capacity of the battery as a whole.
I think it is going to fine..... hope I am right because I have several of capacities now. LOL
Draw evenly to 60% then smaller battery draw down faster down to 10-15% then batteries balance out untill dead
Somebody is thinking this through, great comment!