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2 Renergy 12v 100 ah, want to put into series.

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marauderm

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Jan 3, 2020
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I am assembling a solar system. I purchased 2x12v 100 ah batteries that I intend to use on a 24 volt system. I purchased everything to do so but just read the warning on the Renergy battery that states that it is NOT designed to be in Series. My understanding is that this is the only way to get a 24v system to function. I contacted Renergy and they again stated that these were not designed to be in series...... Below is the system I am designing....I chose 24v as I like the idea of smaller wires running through the RV I am building.

2 Renergy 300 watt - 24 volt panels
2 Renergy 12 v 100 ah batteries
MPPT 24 volt all in one controller/charger/ power distributor.

Should I just return the 2 batteries (I am at less than 30 days) and purchase the 1 24v 50 ah battery that Renergy sells? I know I should have purchased it this way in the beginning but did not see a 24 volt option when I purchased the 2x batteries.
 
Yup, return them and get either that one 24V battery or choose a different manufacturer that allows series connections.

And welcome to the forum.
 
Last edited:
I just checked in with Renergy.....There is a 20% restocking fee and I have to pay shipping. This might be close to $500.00......Is there a reason they don't go in series or is Renergy just erring on the side of safety?

I pressed the tech support guy and he said that they could be placed in series but it would bump up the voltage....as long as I took the necessary "Precautions" it would work.....

To that end.....what "Precautions". Here is what I assume is precautions-
-no more than 2 batteries
- Identical (same generation/age/charge) I purchased these at the same time.
- Quality controller - MPP Solar 24v hybrid

Are there any more precautions I am missing. Don't want to burn the rv down.......
 
@marauderm am I correct in assuming that these are Renogy's 100Ah LFP drop-ins? If so, the issue is the BMS; a BMS that's locked into 12v nominal mode will see a series connection as high voltage and shut down the battery.
A lot of LFP drop-ins have a BMS that's been programmed to accept series connection (Battle Born, LiFeBlue, etc) but there are also quite a few that won't, like the Victron SuperPack and, evidently, these Renogys.
If the BMS isn't programmed to accept a series connection, there's no "precaution" to be taken unless you want to tear apart the batteries and reprogram the BMS. That "tech support" guy is frankly full of it... which, given that it's Renogy, doesn't surprise me.

Your coach is native 12v anyway, right? Why not just change tactic and plan your system to be 12v nominal? You'll spend a little more in proper cabling, but you'll spend less in the long run given that you won't need to plan for 24 to 12 DC to DC converters on your system, and that 20% restocking fee will go a long way toward your additional cabling costs...
 
What does a drop in look like? Is there anyone out there on this forum that nows if the Renergy is locked in. The tech did not indicate that but I see your point about renergy.

You are probably right about going 12 v. But I am building the electrical system from the ground up and have already invested in multiple 24 volt components. Looks like I will have the nicest car batteries in my neighborhood......it is killing me to pay that much to fix a simple mis understanding.
 
Your best bet is probably trying to sell them to someone here.
 
Listing here may save you some $$ instead of using Renogy’s surprising return policy fees and shipping. Taking a smaller hit on cost and learning about Renogy can be chalked up a learning experience. I learned a while ago about that companies poor tech support. This forum is invaluable for any experience and questions on many things that inexperienced Co. tech support pretends to offer.
Although renogy makes some great products, depending on them for support sucks.
 
I’d sell the renogy’s and get ohmmu LiFePO4’s. They have 100’s and 150’s and can connect in series for a 24v system.
 
For the price of one of those 100Ah Renogy’s the used BYD 200Ah 24v banks from batteryclearinghouse or battery hookup are a bargain... WITH A GOOD BMS of course...
 
I have nothing constructive to add...

I just wanna add my name to the No Love for Renogy list. If I were a boss at Renogy, I would do whatever I could to reeducate this customer, make this exchange, and lock in a customer for life. But, alas, I am not.

B.
 
Update.....so I was I contacted Renergy tech Support on my way to returning the battery to get clarification on “Are there’s batteries capable of being in series or does Renergyjust preferthey not be due to the other factors involved in putting the in thus configuration”.

He stated they could not be placed in series. So I asked if it was due to the BMS voltage sensing and he said yes. If the BMS senses over 16 volts that it would go into shut down mode.

The in ability to be placed in Series was confirmed by Will P. of the DIYSolar YouTube channel when he did a comparison of Renergy, Battle Borne and home made cells that he makes. He clearly stated this short coming.

Thanks for all the suggestions. I have returned them and am now looking through this Forum’s resources to get a 24v LiFePO4 replacement. Once they issue the refund, I will do the purchase. Lesson learned.....have a clear plan and read the fine print.
 
marauderm said:
Update.....so I was I contacted Renergy tech Support on my way to returning the battery to get clarification on “Are there’s batteries capable of being in series or does Renergyjust preferthey not be due to the other factors involved in putting the in thus configuration”.

He stated they could not be placed in series. So I asked if it was due to the BMS voltage sensing and he said yes. If the BMS senses over 16 volts that it would go into shut down mode.

The in ability to be placed in Series was confirmed by Will P. of the DIYSolar YouTube channel when he did a comparison of Renergy, Battle Borne and home made cells that he makes. He clearly stated this short coming.

Thanks for all the suggestions. I have returned them and am now looking through this Forum’s resources to get a 24v LiFePO4 replacement. Once they issue the refund, I will do the purchase. Lesson learned.....have a clear plan and read the fine print.
Click to expand...
Just CRAZY they would prefer to charge a restocking fee and lose a customer vs trading for a 24v battery... NUTS!
 
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