Battery charging abuse by the numbers

[Nasdaqsam]

Not to burst any bubbles but all the spec and charging data is mute as no two vehicles these batteries are being used in are the same. So there is no controlled environment to draw data from. Where as the manufacturers are using ideal conditions for temps, charges being used and being administered by highly paid engineers. I know very little about batteries and can think of half a dozen things that can and will effect charging off the top of my head.

Another point is the 6 volt batteries we use were designed for golf carts not RV's. The abuse they see in that environment is brutal that is why they work so well for our use. If you think we put them through their paces imagine a whole fleet of batteries that get just about completely discharged daily and put on high output rapid charges all night every single day.

With all that said I just changed out all my 6 volt batteries and added the easy water system but now wish I had just ponied up the funds for the sealed ones. It's not a big deal it's just one more thing I would prefer not to think about.

[PbdBlue]

Originally Posted by gpounder

One source gave me the numbers I posted, I called the factory and gave me new numbers, bulk and absorption to be the same. I have had batteries blow up when I have not been diligent or watering them and that happened at a much lower charge rate so it does happen.

I'll give you that but a battery in good health should not blow up. Also AFIK on the Magnum inverter\charger you can only set the adsorb, float and equalization voltages. There's no setting for bulk. Bulk is constant current mode not voltage driven. When the voltage reaches the adsorb setting and the current drops the charger will switch to adsorb and maintain the preset voltage. Once the adsorb time\current parameters are met it will drop down to the float setting.

[twinboat]

Originally Posted by PbdBlue

I'll give you that but a battery in good health should not blow up. Also AFIK on the Magnum inverter\charger you can only set the adsorb, float and equalization voltages. There's no setting for bulk. Bulk is constant current mode not voltage driven. When the voltage reaches the adsorb setting and the current drops the charger will switch to adsorb and maintain the preset voltage. Once the adsorb time\current parameters are met it will drop down to the float setting.

Magnum and other inverter/charges do have setting to cut back the maximum amp output of their units.

If its a 100 Amp charger and you set it to 80% output, you get 80 Amps max.

[c_oneil]

Originally Posted by twinboat

Trojan says 10% to 13% of total AH capacity, that will make your 45 amp charging a bit lower the max.

They also say to use the TOTAL AH of the combined batteries. No mention of series or parallel.

Does that mean the total of 4, 225 AH batteries, equaling 900 AH ?

OR is it the 450 AH at 12 volts, that you use the bank at ?

twinboat,
I called Trojan and asked the engineer this very question and this is what I learned. If you have for example 2ea 6v T105 batteries in series then the capacity of each battery is 225ah at 6 volts. However the capacity of the entire bank is also 225ah but at 12 volts. The capacity of the batteries in series remains the same but the voltage is increased. My entire house bank is 4 in series pairs of 6v batteries for a 12v system but the total bank of 8 batteries has a capacity of 4 x 225ah = 900ah at 12v.
My inverter has a max output of 150amps and I set if at 70% = 105a (about 11.5% of the 900ah total battery bank capacity)

[twinboat]

Originally Posted by Quincy

I am no expert on batteries, or anything else for that matter but that wont stop me from posting

Batteries are charged with voltage, not amps. The alternator charges at 14.8 volts until the battery is at 12.8 volts then shuts off. The only amps involved are what ever the wire size provides in Ohms which are resistance to the voltage.

One Ohm resisting One Volt creates One Amp of current. You dont charge at 100 amps or at any amps, just volts. The battery wires are large and provide minimum resistance to the voltage (in the case of an alternator, 14.4 volts)

Float chargers will charge to full battery voltage, about 12.8 volts then shuts off for a while, say a week or two then starts and brings the battery voltage up to proper voltage again. Modern motorhomes should have virtually a worry free maintenance system.

Of course this is JMHO based on experience and forms like this.

Alternators keep a constant 13.5 to 13.7 volt output going to the battery. They never stop outputting.

Float charging is holding the house battery voltage above 13 volts for a 12 volt battery bank.
The chassis battery may be switched on and off at 12.6 volts, with some new isolator systems, but the house is held at float voltage as long as the house charger is working.

[RVPioneer]

Originally Posted by gpounder

That's a huge system. L16 batteries I am guessing, have those for the house solar off grid system. They would take all day to recharge from a 2K charger.

GC6. Ah rating is actually 675. I would imagine that your off grid system is at 48V with an appropriate charger.

Upon review of your first post, the 2000w rating for your inverter is for AC output, 16.6A at 120V. I’m not certain of the charging specs for your Magnum, but would suspect it has a maximum charge rate of 100A.

With 4, 6V 225Ah batteries, the options are a 6V battery at 900Ah, a 12V battery with 450Ah or a 24V battery at 225Ah. Only one will play well with your coach and inverter/charger.

[RVPioneer]

Originally Posted by c_oneil

twinboat,
I called Trojan and asked the engineer this very question and this is what I learned. If you have for example 2ea 6v T105 batteries in series then the capacity of each battery is 225ah at 6 volts. However the capacity of the entire bank is also 225ah but at 12 volts. The capacity of the batteries in series remains the same but the voltage is increased. My entire house bank is 4 in series pairs of 6v batteries for a 12v system but the total bank of 8 batteries has a capacity of 4 x 225ah = 900ah at 12v.
My inverter has a max output of 150amps and I set if at 70% = 105a (about 11.5% of the 900ah total capacity)

Carter,

Do you still have 2 chassis batteries in the bay as well? I’ve got 6 house and 2 chassis. I’d be interested to see how 8 fit.

Bob

[c_oneil]

Looks like this.

[PbdBlue]

Originally Posted by twinboat

Magnum and other inverter/charges do have setting to cut back the maximum amp output of their units.

If its a 100 Amp charger and you set it to 80% output, you get 80 Amps max.

That is correct. Max current can be set for bulk. Not voltage.

[gpounder]

The comment about voltage is correct. In general a charger will provide a voltage and the current will be dependent on the internal resistance or the state of charge. A very dead battery will suck of the current available. The Magmun charger is able to limit the current and that is a big point of my post to limit that charging current. At the point of limiting, the voltage will lower and rise with time until either the voltage hits it limits or some timer says to stop.

I found no literature for any brand that supports charging above 10% of the AH rating for a flooded battery.

If the Magmun is a 100Amp charger than it is still needs to be set to limit my battery bank to 45 amps in any condition.

While the coach systems may be different battery 101 still rules the day. Under charging or overcharging will cost you you useful life or limit your ability to the power you need.

[RVPioneer]

Originally Posted by Quincy

I am no expert on batteries, or anything else for that matter but that wont stop me from posting

Batteries are charged with voltage, not amps. The alternator charges at 14.8 volts until the battery is at 12.8 volts then shuts off. The only amps involved are what ever the wire size provides in Ohms which are resistance to the voltage.

One Ohm resisting One Volt creates One Amp of current. You dont charge at 100 amps or at any amps, just volts. The battery wires are large and provide minimum resistance to the voltage (in the case of an alternator, 14.4 volts)

Float chargers will charge to full battery voltage, about 12.8 volts then shuts off for a while, say a week or two then starts and brings the battery voltage up to proper voltage again. Modern motorhomes should have virtually a worry free maintenance system.

Of course this is JMHO based on experience and forms like this.

The volts won’t go in the battery without amps to push ‘em along. They’re not like old folks at a Cracker Barrel that rush through the door under their own power.

[oscarvan]

Not going to respond to specifics above other than.... like heck Amps don't matter! They are the ONLY measure of current and batteries know the difference between a LARGE and a small current. Watch em boil.

System: (Several write ups on these systems and mods/upgrades on my blog, see below)

2 sealed chassis batteries, size unknown. Guessing they're 31's... doesn't really matter. Engine starts fine.

Precision Circuits smart Battery Isolation Manager rated for 225A

4x6v lead acid....."World Wide" which is a brand I can find NO data on. Closest I can figure is they're re-labeled Trojan T-105's. This is what came NEW from Forest River. 2 pair in series paralleled total 12V/450Ah

Magnum MSH 3012M Inverter Charger
Magnum remote and BMK. (Battery Monitoring Kit)

Current (haha) usage profile:

Never discharge below 50%, in fact a night in a Wallmart parking lot with temps in the 40's and furnace for heat and inverter for fridge and miscellaneous takes us to about 60-65%.then drive at least 6 hours and get SOC back to 100%, or drive and plug in. Max charge rate for Magnum set to 50%. (50A)

Water regularly, equalize once a year. (Two months use a year).

So far so good, 2-1/2 years and batteries appear quite healthy.

That said.... I used to be in the sailing hobby, where off shore we didn't have the fuel to run engine or generator for 6 hours and get to absorption/float. So we ran the batteries between 50% and 80%. This was the most bang for the charge buck.

Batteries lasted for many years.

[RVPioneer]

Originally Posted by c_oneil

Looks like this.
Attachment 238634

Hadn’t though of moving the chassis batteries under the Vansco. Quite a difference between the 2 bays.

[twinboat]

Originally Posted by gpounder

The comment about voltage is correct. In general a charger will provide a voltage and the current will be dependent on the internal resistance or the state of charge. A very dead battery will suck of the current available. The Magmun charger is able to limit the current and that is a big point of my post to limit that charging current. At the point of limiting, the voltage will lower and rise with time until either the voltage hits it limits or some timer says to stop.

I found no literature for any brand that supports charging above 10% of the AH rating for a flooded battery.

If the Magmun is a 100Amp charger than it is still needs to be set to limit my battery bank to 45 amps in any condition.

While the coach systems may be different battery 101 still rules the day. Under charging or overcharging will cost you you useful life or limit your ability to the power you need.

From Trojan battery;