Battery break in

[andy.]

Scotty's site says to run down to 75% and charge, is it ok to do that over a couple days? Or should I just charge it every night even if on run it down to 90%. Trojan t-125's and dpi charger.

[bigstik40]

I'm also interestd in the answer to this one !! I think it came up before and the answer was daily charging regardless how much was used, but not 100% sure. - RAY

[scottyb]

The 75% is more of a maximum than a minimum discharge. The idea is several shallow discharge cycles. So drive a little and plug her in.....hope this helps

[andy.]

Thanks Scotty!!!!

[JohnnieB]

Sounds like you situation is the opposite to most.
That being, most people tend to over-discharge new batteries due to wanting to test their cart's new-found performance and endurance.

You have to exercise the batteries to break them in, but you shouldn't take them below 70% SoC or so during the first dozen, or so, discharge/recharge cycles.
However, you do want to take them down to around 75% several times, preferably in the same day and recharge that night.

Taking them down to 90% one day and an additional 10% to 80% SoC the next before recharging probably wouldn't hurt them any, since major sulfating of the plates while partially discharged is minimal when the charge level is above about 70% SoC.

Other than taking longer to break in, I don't believe there would be any adverse effects from only discharging them down to 90% SoC, but I would intentionally take some longer trips when possible.

Fortunately, you have a DPI charger, which goes into a float charge mode when the regular charge cycle ends. Float charging more or less puts the new batteries in a state of suspended animation, so they get broken in when they get broken in.

---------------
My seven new Exide GC-145 batteries are sitting on large piece of cardboard on the garage floor at the moment.
They have received an initial charge and are now on float charge until they get installed. (42V DPI)
The old batteries are still in the cart, but also on float charge. (36V DPI)
After the new batteries are installed, if there are some days warn enough to ride far enough to take them down to 75%, I'll do it, but otherwise they will stay floating until next spring.

Hope this helps more than confuses.

[andy.]

Helps a bunch Johnny. Thanks. Gonna ride it a good bit tomorrow. Problem is with the dpi floating around 39.8v is it takes a long time to get to 75%. Lol

[Dela]

Someone needs to post Scotty's chart. 75% on a 36v system is not 27 volts as many would assume (including myself before dissecting Scotty and Johnny's advice)

Be sure you know your percentages, or just always plug in...

[scottyb]

Here it is...

[JohnnieB]

Everybody should have such "problems".

The run-time difference between starting at 39.8V and 38.2V is only a couple of minutes since it's a surface charge once the charger is disconnected.

Basically, float charging is maintaining the "on-charge" voltage above the "at-rest" voltage and below the on-charge voltage where significant gassing occurs. Essentially, a float charger is a voltage regulated current source that keeps the on-charge voltage at a predetermined level while the current flow (Amps) is allow to float to whatever rate is needed to maintain that voltage.

If you want to keep track how your batteries are doing, and don't want to let them rest for half a day before measuring the voltages, take a short trip around the yard or down the road to a specific landmark and back that takes less than 5 minutes, or so, and then let them rest for about 10 minutes.

That will put you on the State of Charge charts, or just off the top of them with new batteries.
If you make the same trip every time, you will get accurate data.