Battery maintenance

JimM68 wrote:
Depending on how long or often they run, the furnace blowers, on a cold night, can put a serious hurt on the batteries.

I'll charge them until I go to bed and hope they make it until morning.

On a recent trip it was chilly & windy with a morning temp of 27F. I knew it was time to get up because I could hear the furnace blower click but not blow. A minute or so later it would repeat. Batteries were at 7.3V (2 6V cells). Thank God for that jumper switch to crank up the generator!

A typical "at rest" voltage would be 12.4V a few hours after charging, and that's from the dash meter, which might not be accurate. Is there any wisdom for when it's time for a bank of batteries to hit the trail? I have a DVM and ball tester but that only indicates current (no pun) state of charge.

Winter is the biggest draw. Now I have 8 months to put it off!

Best,
- bob

Yes. Each pair of 6 volts (wired in series to produce 12 v) provides 220 a/h.
Since we can only use half the power, that = reality = 110 a/h.

Each series pair we add to that will increase the power 110 a/h...

4 batteries = 220 a/h useable.
6 = 330
8 = 440

More batteries = more time or more current draw (Ampere / Hours) before you use all the power.

We have 4 T105's. We can charge while cooking the evening meal, run on battery during the evening, and have enough power left to run the coffee machine and microwave and hair dryer in the morning (on the inverter)

Depending on how long or often they run, the furnace blowers, on a cold night, can put a serious hurt on the batteries.

I went to the store fully intending to purchase 4 Trojans for my trailer. I do some camping/fishing where there are no hook-ups.
It was the worker bringing them to my truck who said : "You need need FOUR batteries for your rv???"
That was enough to mak me go back in and change my purchase. Now I'm wondering if I should just go ahead and get two more while mine are new.
More batteries means less discharge means longer life. RIGHT?

Any comments?

4 220 amp-hr 6 VDC batteries wired in series/parallel= 440 amp-hrs @12 VDC.

And, you are correct, that high voltage would only be reasonable during equalization, not in bulk, absorption or float mode.

chastho wrote:
I think you may be over charging the batteries, are you sure your 4 Trojans are 600 ah? Mine are 220 each which is 440 ah. Have you checked the water level in the batteries?

4, 220's are ? my battery pack is 2 six volt 220 amp batteries in series for 12 volts, in parallel with two more, for a total of 4 batteries delivering 12 volts to the inverter, with an amp hour capacity of 220 X 4 = 880 total AMP capacity.

Yes on the water levels.

Charging at 15.5 volts will cause the batteries to gas profusely, and they did, but they did not loose any water.

Tom/Barb wrote:

wolfe10 wrote:
Tom,

Just verify that the inverter/charger is properly programmed. That includes battery technology, battery size (in amp-hrs) and ambient temperature.

Now that you have done the equalization charge, use a hydrometer and check the cells for variance.

Done, the inverter charger is set by the book, for wet cell size of 600 AH, and voltage was checked by both methods.

We start tomorrow by disconnecting the coach and see how long it requires for normal usage to draw the pack down. then a timed charge to see if the whole pack is delivering

I think you may be over charging the batteries, are you sure your 4 Trojans are 600 ah? Mine are 220 each which is 440 ah. Have you checked the water level in the batteries?

wolfe10 wrote:
Tom,

Just verify that the inverter/charger is properly programmed. That includes battery technology, battery size (in amp-hrs) and ambient temperature.

Now that you have done the equalization charge, use a hydrometer and check the cells for variance.

Done, the inverter charger is set by the book, for wet cell size of 600 AH, and voltage was checked by both methods.

We start tomorrow by disconnecting the coach and see how long it requires for normal usage to draw the pack down. then a timed charge to see if the whole pack is delivering

On my motorhome, I can just flip 2 switches the wrong way, and have the fridge running off the inverter. Huge loss for the batteries, of course.

I have a similar 4x6v pack for my remote mountain place, and we can watch satellite tv, run a hair dryer, and leave the inverter on after we go to sleep, and have the batteries charged up every day, easily on 600w approx. panels.

We also had the 458, but went to the ProSine 2000 after I couldn't quite get my microwave going. The 458 is a very good modified sine wave, but the microwave and well pump like the Prosine full sine better. The 458 has a built in transfer switch and charger, which is perfect for what you need, in those respects, and even has user settable battery charging voltages, if I remember correctly.

If you have any amp meter reading on the inverter remote, check the output while turning off breakers, see if you can find the big loss. Some of the very knowledgeable guys on this forum have noted a pretty big draw for some CO2 monitors, and control circuits for fridge, (12v draws). But make sure you're not heating the fridge gas with the inverter A.C. juice.

It would be good to get some voltage readings from each battery during various phases, mainly looking for differences. Reading the specific gravity of each cell is the correct way, again, looking for differences, since the cheap specific gravity readers aren't calibrated very finely. One bad cell can take down your pack, but is easy to find with voltage readings on the individual battery.

These are just things to try, sort of guessing with the info in your post. One more thing is that you can put the inverter into 'search' mode where it sends just a tiny signal to see if there's a load, then when there is, it starts 'inverting', saving the draw of staying on all the time (about 2ah @ 12v by memory). But, you need to have an inductive load like a light bulb to draw enough to get the inverter to start if the threshold is not set just right for that operation. But it saves juice if A.C. is not used constantly, and you can put the inverter in that 'standby' or 'search' mode using much less amperage. But you should have 220ah at 12v easily, before you're even at 50% discharge, with your pack. But 5 minutes of toaster, microwave, or hair dryer can take 15-20 ah from your battery each use. And leaving inverter on all the time (with nothing else on) can take 40+ ah/day without the power saving feature in use.

Solar! There are some folks on the forum that have really figured out how to do that well, and would give you much more cushion once you get your big draw figured out.

Tom,

Just verify that the inverter/charger is properly programmed. That includes battery technology, battery size (in amp-hrs) and ambient temperature.

Now that you have done the equalization charge, use a hydrometer and check the cells for variance.

olfarmer wrote:
Sounds like you have a pretty high quality inverter, but I know some inverters will over charge the batteries if left on too long with out a draw on the batteries. I never leave mine plugged in for long periods if we are not using it. The batteries are usually fine when I get it out, but if I want to be sure I use a battery maintainer to keep them up. They just keep them charged and will not over charge them.
Good luck, hope they are OK now.

That is what a float charge does, maintains the batteries at a certain voltage. I can shut it off by clicking the remote panel's button marked "Charger"