Costco 6V battery charge rate

FWIW, I have one bank of two GC26V's, the Sam's club variety. My controller is set at 14.6 but with the temp sense wire, I'm seeing 14.9 in the Winter (MN) and 14.4 in the Summer. The SG of the 6's is bumping 1.30, last time I checked.

Good luck with the accountant, make sure you stay fiddling with it so she knows that it is keeping you busy. :B

Hi, Westend.

I already used temp sense wire from Morningstar. I plan on installing battery voltage sense wire this weekend so that the controller can have more accurate voltage measurement.

Yes, I agree. My vertical battery compartment is... how do I say a better word... lacking.

Been thinking of building a plywood box and put in the front storage compartment and run a 2" flexible corrugated plastic piping from the box to the outside area. But that is another topic. This topic I wanted to focus on is what is the optimal charge rate for this costco 6V batteries. I hear variation of 14.2V all the way up to 15V. For now, I'll stick with 14.6 or 14.8V since it is not easy to add water to these batteries.

For now I have connected both bank batteries through the red battery selector switch that lets me choose one or two or both at same time.

The main thing I need to do is... go have fun camping this weekend. No fireworks for me as it is plenty dry enough around here that if you stare at a dead grass long enuf, it would self combust! After camping I will know more where is my weak points would be. I am suspecting that I need 1 more 150V panel but I need to swing this cost by my chief accountant. Maybe after this one, she would be convinced to green light this expenditure.

I'd use the temp sense wire from the controller to batteries, it makes everything work well.

It sounds like you are due for a battery compartment upgrade.

Thanks Niner,

Sounds like I should install battery sense wiring from controller to the battery pack to realize the benefit of accurate calculations. The sun has gone down a bit so the controller has kicked off with solid green light on instead of flashing. I checked and it is 13.39V at the ring terminals (6.70 at lower #1, 6.69 at upper #2 and 13.39 at #3). As per paper manual, I assume it has entered "night" mode. Correct?

Perhaps I do need amp meter and volt meter...

By the way, it is not going to be easy to check water level in these 6V batteries because it is so tall and I have 1" or so clearance between top of the batteries and the ceiling of the battery compartment. I have to disconnect the conductors, tilt, and try to wiggle the battery out of the compartment without having the positive terminals touch the metal parts of the compartment.

I placed a heavy cloth on the positive post when I put the batteries in. I place a good size rectangle piece of rubber mudflap on top of the upper #2 6v battery so that it wont short out against the sheet metal when it bounce up if I hit a nasty bump. The lower #1 battery is OK because it is underneath a wood particle board that was supporting the #2 battery above.

Appreciate your feedbacks.

coldchuck wrote:

NinerBikes wrote:


I would do this, and I would verify the voltage of a fully 100% charged battery at the battery terminals to be 15.0V, not what the charge controller says it's set at, there are voltage losses from line and length of copper wire run.

Yes, I got digital multimeter to measure the voltage. Just that I am not quite familiar with 6V batteries and its charging characteristics. I am much more familiar with 12V batteries of various configurations. I calculated my voltage losses from the panel to the batteries at 0.7% using 4AWG cable 18 foot distance from roof to the batteries (one way). The controller is located next to the battery compartment using 2 foot length. I did not use battery voltage sense wire but I could put this on if any of you felt its value is warranted to use it. I am using the remote temperature sensor on the negative post of the last 6V battery in the series. I hope I am doing the optimal practice.

I do have Progressive Dynamics PD9260C with charge wizard pendant already. My 5ver is parked next to my house but I don't need to have this camper plugged in all the time if tristar does a better job.

Calculations are nice, and theoretical. Measure the actual voltage you are getting at the batteries, at the connections, while charging, once fully charged. You want 15.0V at those ring terminals on the battery. All else is irrelevant. Your CG2 batteries are 5% antimony lead plates. Keep on top of the electrolyte level and replace when low with distilled water.

Adjust charge controller for solar panel accordingly until you negate any voltage losses due to wire diameter and distances involved.

NinerBikes wrote:


I would do this, and I would verify the voltage of a fully 100% charged battery at the battery terminals to be 15.0V, not what the charge controller says it's set at, there are voltage losses from line and length of copper wire run.

Yes, I got digital multimeter to measure the voltage. Just that I am not quite familiar with 6V batteries and its charging characteristics. I am much more familiar with 12V batteries of various configurations. I calculated my voltage losses from the panel to the batteries at 0.7% using 4AWG cable 18 foot distance from roof to the batteries (one way). The controller is located next to the battery compartment using 2 foot length. I did not use battery voltage sense wire but I could put this on if any of you felt its value is warranted to use it. I am using the remote temperature sensor on the negative post of the last 6V battery in the series. I hope I am doing the optimal practice.

I do have Progressive Dynamics PD9260C with charge wizard pendant already. My 5ver is parked next to my house but I don't need to have this camper plugged in all the time if tristar does a better job.

Thanks, Ken.

I will have to dust off my old net book but I have to locate or buy serial cable and adaptors for the connection between netbook & tristar. I am using Mac computer. It doesn't make sense that we are still using old serial communication when USB is already out for years...

hmknightnc wrote:
You need to look up the manufactures recommended charge profile from their website but 14.8 volts with temperature compensation should work just fine for those batteries. Personally I would set equilize to 15 volts ( not higher to protect RV electronics) every 30 days and lose the bady 12 volt battery.

Opinions will vary

I would do this, and I would verify the voltage of a fully 100% charged battery at the battery terminals to be 15.0V, not what the charge controller says it's set at, there are voltage losses from line and length of copper wire run.

Update the firmware on the TS too if its needed...

smkettner wrote:
Serial to USB adapter on an old netbook computer.
No remote or unit display.

I might do the same thing. So far no gassing on any of three batteries. I will disconnect the 12V battery from circuit using selectable switch. I just dont like not using this perfectly good 12V battery just because I got 2 6V. I left the tristar at 14.6V to see how the battery do in long run.