Having trouble with new BestGo 12v 400amp LiFePo4

[sunshine_eggo]

I would hit the reset under the conditions I mentioned, cells above 3.40V and charge current < 8A. You know it's within 5%.

 

[Roamingkat]

I was using Katie33kate…but cannot get it to let me change password. Anyway..new profile name but the same ole me.

so, to update this…I finally got a replacement battery from seller. Another BestGo. AND..same problem!!!!!!!
good grief. Now when I get to 14.0 it is the battery #4 that is overcharging (previous battery is was #2). But same exact issue.

seller is claiming it is my configuration causing this. What? Ok..maybe I don’t understand.

I have 2 450w solar panels handled by victron 150/85. I have a second victron 150/70 which handles 4- 100w panels (but this system hasn’t been turned on in quite a while). Also a Renogy 2000w inverter/charger. Is it possible this is the problem? I haven’t found any info on it…but, maybe?

is it possible that Daly BMS cannot handle the large amps my MPPT throws at it?

 

[sunshine_eggo]

85A is not large amps. 100Ah batteries are typically rated for 50 or 100A charge. 4 properly wired in parallel shouldn't be an issue.

I think you've just found the second most imbalanced battery. Back to my original recommendation. Charge to 13.8V and see if it trips again.

Is your battery bank wired in accordance with best practices as shown in Victron Wiring Unlimited in my signature?

 

[Roamingkat]

Thank you… yes, I tried to charge this one to 13.8 just like before. It trips the fault. Today I will drop that to 13.7 and try again

what do I say to this seller? They claim my systems is causing this because “we sell hundreds of these and have never had a problem before”. I cannot see how I could cause one battery to be below capacity and so causing it to overcharge near max volts. But, I could be wrong. Any ideas?

I think it is possible that this problem exists with many of their batteries…but because they sell them without the Daly BMS, the people (mostly EV owners) don’t know it is happening. Possible? My understanding is that overcharging that one battery will slowly drag the entire pack down and shorten the life of the whole battery….is that correct? If so, then people who do not know it is happening would just have to replace it in a few short years and wonder why they didn’t get the cycles they should, Does that sound like solid reasoning?

 

[sunshine_eggo]

Thank you… yes, I tried to charge this one to 13.8 just like before. It trips the fault. Today I will drop that to 13.7 and try again

what do I say to this seller? They claim my systems is causing this because “we sell hundreds of these and have never had a problem before”. I cannot see how I could cause one battery to be below capacity and so causing it to overcharge near max volts. But, I could be wrong. Any ideas?

Your system only charges the battery(ies). There is no way for you to influence the individual cell voltage. You have the direct evidence of a single cell going high and triggering over-voltage protection. This is a battery fault. If you were somehow tapping into the individual calls and charging/discharging them individually, then you could influence cell imbalance directly. You are not doing this, correct?

I think it is possible that this problem exists with many of their batteries…but because they sell them without the Daly BMS, the people (mostly EV owners) don’t know it is happening. Possible?

The first reaction of most suppliers is, "not our fault." If their primary market is batteries that sit there doing nothing almost all the time and only see ~20A load for a fraction of a second before the high voltage DC-DC converter takes over, then they are likely not aware of any cell imbalance issues even if they are present as it may not present a fault.

My understanding is that overcharging that one battery will slowly drag the entire pack down and shorten the life of the whole battery….is that correct?

These aren't lead-acid. They are perfectly happy running at < 100% SoC In the case of cell imbalance, the most typical resolution is achieved by BMS balancing within the cell to bring the cells into balance. I have to believe that balancing is occurring in some way, but I'm struggling to see the evidence of that.

If so, then people who do not know it is happening would just have to replace it in a few short years and wonder why they didn’t get the cycles they should, Does that sound like solid reasoning?

I don't follow.

 

[Roamingkat]

The seller tells me that this Daly BMS does NOT do active balancing. Something you were sure of from the start. I guess they do now have an active balancer…but, there just isn’t anyway I am taking this apart to try to install…(get the wires on each cell).
so what is the long term effect of charging only 13.7. Or…more important..tripping that fault alarm all the time with one cell over charging? I thought it would result in shortened battery life. So, if you never knew this was happening and you continued to charge to 14.2 each day…you would have a shorter battery life and never know the reason…?

 

[Roamingkat]

Brought the MPPT up to 13.7 bulk. No fault alarm, all batts within .001 of each other.
MPPT tripped into absorb. After 2 hours I see the delta v is .014 and climbing. Up to .016 pretty quick.
I turned off charging.
battery monitor says SOC is 97.4%. That is mostly likely plenty for my needs…but I am still feeling I cannot allow charging to happen when I am away from the rig.

I am thinking to drop the absorption time to just that 2 hours.

Aside from the pita, can I accept this situation? Can I find an inverter/charger that is programmable like the MPPT? (My Renogy does 14.2 in bulk…period…). What is the long term effect of hitting this overcharge On a daily basis.?

 

[sunshine_eggo]

The seller tells me that this Daly BMS does NOT do active balancing. Something you were sure of from the start. I guess they do now have an active balancer…but, there just isn’t anyway I am taking this apart to try to install…(get the wires on each cell).

To clarify, "active balancing" is a balance method that moves current from high cells to low cells. "Balancing is active" means balance of some form is occurring. I would expect your DALY to support PASSIVE balancing by burning off excess charge of high cells.

so what is the long term effect of charging only 13.7. Or…more important..tripping that fault alarm all the time with one cell over charging? I thought it would result in shortened battery life. So, if you never knew this was happening and you continued to charge to 14.2 each day…you would have a shorter battery life and never know the reason…?

Charging to lower voltage and not charging to 100% SoC generally equate to MORE cycle life.

I'm sorry, I don't follow the final sentence.

Brought the MPPT up to 13.7 bulk. No fault alarm, all batts within .001 of each other.

All batts in parallel should always be at the same voltage.

MPPT tripped into absorb. After 2 hours I see the delta v is .014 and climbing. Up to .016 pretty quick.
I turned off charging.

.014/.016 is a tiny variation and quite normal as one inches towards full charge. I wouldn't turn off charging for 2-4 hours.

battery monitor says SOC is 97.4%. That is mostly likely plenty for my needs…but I am still feeling I cannot allow charging to happen when I am away from the rig.

Drop to 13.6V and 2 hour absorption. You'll likely charge a few % lower, but you'll likely never see a BMS trip.

I am thinking to drop the absorption time to just that 2 hours.

I would push until a cell hits 3.500 in hopes of SOME kind of balancing is happening.

Aside from the pita, can I accept this situation?

That's up to you. Recommend you document everything and immediately challenge their assertion that somehow charging at the battery terminals can cause cells to go out of balance.

Can I find an inverter/charger that is programmable like the MPPT? (My Renogy does 14.2 in bulk…period…).

Yes. Many.

What is the long term effect of hitting this overcharge On a daily basis.?

Excessive BMS protection triggers should be avoided. It can wear out the BMS.

You never answered my question. Have you connected your batteries in parallel using best practices as shown in Victron Wiring Unlimited (in my sig)??

 

[littleharbor2]

Have you looked into 12 volt dc air conditioners? My son installed one in a Sprinter van conversion and I was impressed with it's performance.

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[Roamingkat]

this battery is contained inside a single case. Single battery terminal. The internal wiring for the 16 batteries (3.1v) is wired however the manufacturer choose to do it. Serial to come to 12v Then parallel to 400amp? Or the other way around? This is not in my control. I have opened the case once to exchange the BMS. (that was the previous battery…when seller thought the issue on that battery was a bad BMS). From the top, no part of the individual batteries were visible. I would guess that the wiring is four in series, then four battery packs in parallel….just because the BMS shows 4 batteries not 16.

I was only asking what happens if you charge to 14.2 with this over charge happening constantly above 13.9. What is the long term effect?

littleharbor2…..I am in the desert…I run a swamp cooler. It is great..uses next to no power. But, with temps above 100 it drinks about 10 gallons of water a day. (PS. Traditional A/C doesn’t work well in the dry air….no moisture to take out). Also…my roof space is totally used up with solar panels and passive solar hot water.