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Balancing of battery bank


SolarNoob
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Hi guys,

I have 8 T105-RE batteries and a BMV 702 with midpoint monitor. I also have 2 HA-02 battery balancers connected to the first four batteries and the last four in the bank.

I see the two halves voltages differ by 0.05 V. Is that acceptable or should I raise the two halves to the same resting voltages? My gut tells me it should be fine?

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Hi

0.05 V difference is good.Since the balancers only operate above 0.01V.  0.05V translates to about a 0.2% difference. Just monitor your batteries as they age and make sure you stay below about 1% (during late absorb - batteries tend to be only out of balance for a short time initially and then the length of time gets longer and longer).

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  • 3 weeks later...
10 minutes ago, Valken said:

Hi SolarNoob,

I just got my T105RE's. What is your experience with them thus far? And another thing, where did you get your HA-02 battery balancers from and how much did you pay for them?

Thank You.

Hi Valken

I am landing a shipment of HA02's tomorrow. I will have the exact cost later today, once it has been cleared by customs. I normally give it to the forum members at cost + all the importing costs. Courier cost to the end user is normally R90.00 and delivery 1 day, anywhere in South Africa. Please let me know if you are interested. The previous batch worked out at R680 + vat each plus R75.00 + vat for courier

 

 

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50 minutes ago, Valken said:

Hi SolarNoob,

I just got my T105RE's. What is your experience with them thus far? And another thing, where did you get your HA-02 battery balancers from and how much did you pay for them?

Thank You.

 

 

@Valken I see Chris has already replied. I got my balancers from him and I have just ordered a third. My two halves of my 48V bank are nicely balanced between the cells but the two banks are roughly 0.06V different, hence the third balancer to span the two halves. I'm very happy with the T105RE's but I am still waiting on my panels so perhaps others can supply more info.

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21 hours ago, Chris Rossouw said:

Hi Valken

I am landing a shipment of HA02's tomorrow. I will have the exact cost later today, once it has been cleared by customs. I normally give it to the forum members at cost + all the importing costs. Courier cost to the end user is normally R90.00 and delivery 1 day, anywhere in South Africa. Please let me know if you are interested. The previous batch worked out at R680 + vat each plus R75.00 + vat for courier

 

 

Hi Chris,

Thank you. Yes, i will be interested. How many do we need for 8 X Trojan T105RE's?

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5 minutes ago, Chris Hobson said:

You end up balancing 1-4 on one balancer and 5-8 on the other but the two halves need to be in balance with each other requiring a 3rd balancer to connect the two halves.

Ok, because T105s are 6V in one string, I was thinking of my 8x 12V bank, where only two would be required as the two parallel strings would be in balance, but not neccesarily the individual cells, correct?

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23 hours ago, Chris Rossouw said:

Hi Valken

I am landing a shipment of HA02's tomorrow. I will have the exact cost later today, once it has been cleared by customs. I normally give it to the forum members at cost + all the importing costs. Courier cost to the end user is normally R90.00 and delivery 1 day, anywhere in South Africa. Please let me know if you are interested. The previous batch worked out at R680 + vat each plus R75.00 + vat for courier

 

 

Hi Chris,

Can i have 2 X HAO2's please.

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50 minutes ago, DeepBass9 said:

Ok, because T105s are 6V in one string, I was thinking of my 8x 12V bank, where only two would be required as the two parallel strings would be in balance, but not neccesarily the individual cells, correct?

Hi DB9 

Just to confirm yours is a 24V system? Then you could attach 1 balancer per string if it is a 48 V system then you need to connect the two halves (3 balancers) or have 1 balancer and pair the batteries to make 12V units.

Addition: Hi I have just re-read your post. A 12V system? In that case you have no real balancing issues (2 balancer would work for 4 pairs) but I would seriously consider changing your system for 24V or 48V to lower the amps.

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Chris, Having 8 x 12v batteries in two strings ( 48v ) What would the correct way be to connect the BMV 702 's? I fully agree with 3 x HA02 's as I can see that my batteries in a string is 100% in balance, but the 2 strings differ. If I am correct the 3rd balancer will be connected between the 2 strings as if each string is one battery?

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17 minutes ago, Chris Rossouw said:

Chris, Having 8 x 12v batteries in two strings ( 48v ) What would the correct way be to connect the BMV 702 's? I fully agree with 3 x HA02 's as I can see that my batteries in a string is 100% in balance, but the 2 strings differ. If I am correct the 3rd balancer will be connected between the 2 strings as if each string is one battery?

If you have two 48V strings composed of 12V batteries then 2 balancers one per string. Each string will be in balance with the other as they are connected in parallel. Each string is 48V and will pop your balancer if connected as the equivalent of a 48V battery.

5835907b5621e_EqualResistanceperString2_wm.jpg.c13ea63451bfefd30e91fa5ae99eb009.jpg

This is from Victron (I think) so midpoint can be connected inbetween the two strings so long as it is fused.

Addition: From the BMV quick installation guide.

Screenshot (16).png

 

 

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21 minutes ago, DeepBass9 said:

Maybe we should start a thread for the definitive answer on certain questions......

Yes, one that only 1 person can post the final definitive answer instead of it getting lost between all the other posts.

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