I recently installed 8 x US-145-XC2 6Volt batteries.

I am almost clueless when it comes to flooded batteries, so would appreciate some help on the following settings:

Bulk Charge = 7.35 x 8 = 58.8v...so 58.4v bulk as this is the highest my Axpert can go?

Float Charge = 6.51 x 8 = 52.08

And lastly is it normal that when the batteries reach the 58.4v charge they make bubbling sounds?

US 145 XC2 Specs.pdf

Edited September 3, 20186 yr by GVC

1 hour ago, GVC said:

Bulk Charge = 7.35 x 8 = 58.8v...so 58.4v bulk as this is the highest my Axpert can go?

Jip - as @plonkster so aptly described this is like travelling down the freeway in my own farm bakkie. You can travel at 120 km/h  but the bakkie can only do 110km/h. What this means you are going to go into absorb sooner and have to stay in absorb longer. I would on a day that you can monitor or by using  ICC work out how long your batteries are in absorb. The say minimum 2 hours expecting it to be 2-3 hours. (Do you have Coulomb's updated firmware? - if not and you have one of the  Axperts with newer firmware you can set the length of absorb (Program 32)

1 hour ago, GVC said:

And lastly is it normal that when the batteries reach the 58.4v charge they make bubbling sounds?

Yes you are above gassing voltage (55V @ 25°C). No problem though as you can replace the electrolyte. Just ensure that you have distilled water.  I have seen battery places get their battery water from the rainwater tank and that is not good enough. You can get distilled water from a mate at the university (if their is one near you) or from chemical supply companies. I use to have a 25l container that went to varsity with me and that is good for a year or so (obviously depends on the size of your bank).

The other thing that you need to add to your arsenal is a hydrometer as the spec sheet gives a full charge SG of 1.270.

1 hour ago, Chris Hobson said:

Jip - as @plonkster so aptly described this is like travelling down the freeway in my own farm bakkie. You can travel at 120 km/h  but the bakkie can only do 110km/h. What this means you are going to go into absorb sooner and have to stay in absorb longer

My analogy is sticking around? :-)

To use another extreme example: You can get a battery fully charged at the lower float voltage (typically 13.5V for a 12V battery). 13.5V is a "gassing" voltage, it is sufficiently high to charge the battery. The trouble is it will take the whole week.

Extending this argument to the 58.4V (vs the 59.2V a Trojan T105 bank wants), it is high enough to charge the battery, it's just going to take longer to get to 100%.

How much longer? Well that is the bit I don't know. My gut feeling is that the relationship is probably not linear, chances are the extra time will be proportional to the square of the voltage difference or something like that... it's after midnight and my last physics class was a decade ago.

17 hours ago, Chris Hobson said:

Yes you are above gassing voltage (55V @ 25°C). No problem though as you can replace the electrolyte. Just ensure that you have distilled water.  I have seen battery places get their battery water from the rainwater tank and that is not good enough. You can get distilled water from a mate at the university (if their is one near you) or from chemical supply companies. I use to have a 25l container that went to varsity with me and that is good for a year or so (obviously depends on the size of your bank).

The other thing that you need to add to your arsenal is a hydrometer as the spec sheet gives a full charge SG of 1.270.

Thanks,  that is a relief....I almost popped my hernia getting to the laptop to set the batteries to a lower voltage.

Still running 72:50, I do have Coulomb / Webber's new firmware....I will install it next week when I get back from the coast.

A hydrometer is definitely on my to-get list.

I must say that it is great to see normal PV production again using good batteries. One of my old ones was on its way out, so PV production fell be almost 40%.

With lead acid you are either above or below gassing voltage. Below it, you don't get any charge, the battery actually slowly discharges (around 13V). Above it, some of your charge current causes gas to be generated. With sealed batteries, the generated hydrogen is turned back into water (there is a safety release valve in case you overdo it). With the non-sealed ones you just add more water. You can charge faster, but it is less efficient and creates more gas... BUT... you can charge faster, hence this kind being so popular for golf carts.

I have setup the BMV702.....Can the knowledgeable gents on this forum please look at the ICC picture below and see if there are any funnies?

I have also stuck to the default settings for "Use SOC for control"

ie: 30 to Grid SOC and 90 to Solar SOC.....does not seem correct if i only want to go to 20% DOD?

Edited September 5, 20186 yr by GVC

Please ignore the request above. (It appears that I can not edit it)

I found some older threads that gave me the info that I needed.....Thanks