Want to make sure I’m not destroying my new battery pack

[jkredman]

We’ll, you may remember, my battery saga started with a bad 48 volt side cable. Being too lazy to eliminate some easy stuff, I bought a remanufactured charger. That got me about another month, or so.

Then last weekend the 4.5 year old 4 - 12 volt pack went from full charge to half charge / reserve in 4 holes in high 50, almost 60, degree weather.

OK, I bit the bullet and did my 4 - 12 volt to 6 - 8 volt conversion I’d been planning.

Also put a brand new from shop.txtsv.com charger receptacle on the cart.

Today I changed out the battery tray and installed 6 brand new Trojan T-875’s. According to my DVM pack charge is 52.2. If I’m reading the specs correctly fully charged that pack should be at 55.8 volts. So some simple math says that pack should be about 93% charged.

When I plug in the charger it goes to < 80% charge mode and the batteries start boiling. After several minutes it will go to > 80% mode, but the battery boiling doesn’t sound, or smell, like it’s slowing down. Unplugged the charger to be on the safe side.

We are having a cold snap. My garage is heated and air conditioned. Realistically it just tempers the outside conditions. I can heat about 20 degrees above the outside which means, today, it’s between 45 & 50 in the garage.

So before I try to charge further, I’m going to wait for this cold snap to break and get back to our normal 40 to 50 degrees, where my garage will warm to 60 to 70 degrees.

My question is this - since I’ve never been able to find any specs or a schematic on the wavy 48 volt charger:

Is this a case where the cold temp is throwing off the temp sensor? Or do I still have a charger issue?

Not wanting to damage a brand new pack of Trojan T-875s. Bob, Scotty, CGTech; please chime in. The math says I should be fine. What I hear & smell has me wondering.




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[Mooncarter]

I would let it run and finish charging now.

[JohnnieB]

Sounds like it might be a bit late, but new batteries ought to be fully charged before each use and after each use.

Trojan suggests the operating temperature range for their cart batteries is from -4°F to +122°F. They also mention that charging a battery whose temperature is above 122°F should be avoid and charging a battery whose electrolyte is frozen shouldn't be attempted.

The SG of the electrolyte in a fully charged Trojan battery is 1.277, which freezes at about -78°F and its SG at 50% SoC is 1.172, which freezes at about -5°F, so if you don't discharge the batteries more than 50% and it is above -5°F in your garage, there is no technical reason not to charge the battery.

The at-rest voltage for a T-875 is typically 50.93V, but may be a bit higher when new. At-rest means after sitting 12 hours without any charging or discharging. (I'm not sure where you got the 55.8V from, The on charge voltage ought to reach a minimum of 60V.)

Please give a better description of the charger. Make/model and picture if possible.

[jkredman]

This the charger. I have it mounted on the wall.

Batteries have NOT been used to power the cart. I installed them, then plugged in the charger.

I'm confused why the charger thinks their less than 80% charged. I get their not fully charged, but why the boiling?


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[cgtech]

They don't "boil", that would require temps above 200 degrees, so that concept can be thrown out the window. What they can do is reach "gassing voltage", which is what you are seeing. That is the voltage at which electrolysis occurs readily. Have no fear, gassing voltage is not a bad thing, and is normal and desirable to stir fluids up in the batteries. New batteries will off-gas and smell more at the very beginning. Don't worry, charge them till the charger shuts off, and do several shorter-than-usual uses before going for the marathon runs. From what I can tell, you are just fine.

[Mooncarter]

Originally Posted by cgtech

They don't "boil", that would require temps above 200 degrees, so that concept can be thrown out the window. What they can do is reach "gassing voltage", which is what you are seeing. That is the voltage at which electrolysis occurs readily. Have no fear, gassing voltage is not a bad thing, and is normal and desirable to stir fluids up in the batteries. New batteries will off-gas and smell more at the very beginning. Don't worry, charge them till the charger shuts off, and do several shorter-than-usual uses before going for the marathon runs. From what I can tell, you are just fine.

[jkredman]

thanks. that’s what I wanted to confirm.


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[rib33024]

When you buy new batteries they are usually around 70% charged off the shelf. That is why they need to be fully charged before you drive the cart with the new batteries

[jkredman]

I let the charger run a full cycle today. The gas smell dispated very quickly. All good.

Because the first issue was a charger issue, and I have no specs or schematic for the charger to be able to understand how it senses the condition of the batteries, I just wanted some input from the full time folks.

Thanks for the help.


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