Problems with renogy 170ah batteries

Dktk said:

So on those 170 ah batteries could you connect a balancer to them some how and use the bms that came with them

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Yeah, that's what i've done. It works well. But you also need to top balance each cell with a bench top power supply. I'm making a youtube video with some tips on how to do it, including opening the case without messing it up. I'll post it here if it's helpful.

meerkatmag said:

Yeah, that's what i've done. It works well. But you also need to top balance each cell with a bench top power supply. I'm making a youtube video with some tips on how to do it, including opening the case without messing it up. I'll post it here if it's helpful.

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yes that would be great if you posted that here ,also part numbers?

Hi everybody,

I just registered to add my name to the list of "victims"...

I have been using two of the 170 AH Renogy batteries in my diy camper van for about a year now. First they were "good enough" (charging to about 13.3 V). Now after a winter of sitting in my driveway they won't charge to more than 12.9v.

After reading this thread, I just opened the first battery and found the same situation. The first three cells sit at 3.29V, the last one at 3.41V. I'm now charging the first three cells simultaneously to 10.23V with my dc workshop power supply at about 9 amps.
Will do the same thing to the other battery afterwards. Hopefully the cells will be more balanced after this and give me more capacity.
I will keep you posted...

As I need the car next week, this will have to do for now. I'll see during the next few month, wether they will get unbalanced again.

This thread has been tremendously helpful! Thanks so much!

I would suggest not doing that, if you want to charge individually to 3.5 or so that is fine, but not in a group of 3. 1 group will most certainly go out of balance and overcharge causing damage. Remember you have no protection in place while doing this.

I second take the time and shove only 10a into one cell at a time. Set your voltage to 3.5v then connect the leads.

Or better yet just rip out the junk BMS and install a better one and be done with it.

I kinda want to pick up one of these junk units and rehab it if I could score them for cents on the dollar.

Whinny said:

I would suggest not doing that, if you want to charge individually to 3.5 or so that is fine, but not in a group of 3. 1 group will most certainly go out of balance and overcharge causing damage. Remember you have no protection in place while doing this.

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Thanks a lot for the warning... I'm very careful and check the voltages of each group regularly. They are almost identical (+- 0.01 v).
But I think my PSU is lying about it's current. It's taking far too long for 10 amps.

740GLE said:

I second take the time and shove only 10a into one cell at a time. Set your voltage to 3.5v then connect the leads.

Or better yet just rip out the junk BMS and install a better one and be done with it.

I kinda want to pick up one of these junk units and rehab it if I could score them for cents on the dollar.

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I will definitely get a new BMS to get rid of the problem. For now I just need a quick fix, because the van needs to survive 3 days of winter camping next week and I need the capacity.

fumpel said:

I will definitely get a new BMS to get rid of the problem. For now I just need a quick fix, because the van needs to survive 3 days of winter camping next week and I need the capacity.

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Hi,
definitely be careful charging multiple cells at once while bypassing BMS. It will look fine at lower SOC but if any cells are out of balance they can become overcharged very quickly. Cell at a time is best.

I have fixed mine with a balancer, I found that the BMS in these batteries isn't creating the issue, it's just not fixing it. So you can just fit a balancer and top balance and then they will be ok.

If you fit the JK BMS it will sort it out but it's a tight fit in that case. Also it's a lot more expensive.

Here's my video about fixing these batteries, hope it's useful for someone:

meerkatmag said:

Here's my video about fixing these batteries, hope it's useful for someone:

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Very good, I have helped almost a dozen people fix their batteries using the same method, in my case I did not find a big difference on keeping the balancer on or off so I just kept it running on. I think it may drain the batteries a bit faster but nothing noticeable. This has helped me correct 4 SOK batteries and some other batteries that required opening them up (just like the renogy).

I would recommend you perform a capacity test to see what you have now that the batteries have been fixed.

Alkaline said:

Very good, I have helped almost a dozen people fix their batteries using the same method, in my case I did not find a big difference on keeping the balancer on or off so I just kept it running on. I think it may drain the batteries a bit faster but nothing noticeable. This has helped me correct 4 SOK batteries and some other batteries that required opening them up (just like the renogy).

I would recommend you perform a capacity test to see what you have now that the batteries have been fixed.

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I thanks for the feedback. That's interesting about the balancer being on all the time. So did you bother with a switch? Its certainly a pain having the wire that in.

My old batteries were tested before this and they provided around 80ah in total. After balancing they are pretty much as advertised, around the 170ah. I haven't Discharged them below 12.9v so it's an estimation. It definitely helped a lot.

One of my original batteries has suffered some damage from being so out of balance for so long. It seems to loose charge very quickly and settles to 13.2v after a few days of sitting. It still works well but I think they cells have had a rough time. I'm not going to use this one but the others are all now perfect so I have 4 in my van. More power than I will ever need!