Deep Cycle Battery Charging From Alternator

pianotuna wrote:
Hi,

For maintenance between trips 60 to 150 watts of solar per 100 amp-hours of storage.

For charging while trundling down the road, look at a DC to DC voltage boost device. Expect sticker shock.

Another route would be an inverter powered from the alternator that is sufficiently large enough to power the converter, or a stand alone battery charger.

I've spend more on generator maintenance than on my modest solar installation. My costs were $5.50 per watt in 2006. On a DIY it is possible to get to under $2 per watt.

Don - That was the first thing I did - was to check with AMAZON on how much the CTEK 250s cost... Definitely a sticker shock hehe... Sounds like an interesting thing to have for us OFF-GRID guys...

Roy Ken

Hi,

For maintenance between trips 60 to 150 watts of solar per 100 amp-hours of storage.

For charging while trundling down the road, look at a DC to DC voltage boost device. Expect sticker shock.

Another route would be an inverter powered from the alternator that is sufficiently large enough to power the converter, or a stand alone battery charger.

I've spend more on generator maintenance than on my modest solar installation. My costs were $5.50 per watt in 2006. On a DIY it is possible to get to under $2 per watt.

MEXICOWANDERER wrote:

Those batteries were perpetually undercharged. There are too many clues for this to not be fact.

Maybe not.

IF....they are being hit with 14.4 volts every day for an hour or more.....then they might be getting OVER CHARGED if they aren't used during that time.

Some resting voltage measurements need to be made.
You might be much better off disconnecting them from the alternator system during the "daily driver" periods.

THEN....there is the ridiculous drain from that blender.
Things can be mashed and shredded without electricity.

I suggest that you STOP using the blender....and any other high current device that may be present too, like a hair dryer maybe.

OR....that you keep doing what you are doing and buy new batteries every 2 years.

atp20 wrote:
Do I need to look into some sort of smart charger, alternator-to-battery charger, or inverter/charger setup? I'd like to keep things simple.

There's no way your vehicle's alternator is going to properly and fully charge your deep cycle batteries on it's own. The solution is a purpose designed DC > DC charger, one being the CTEK250SA that will ensure proper charging of those deep cycle batteries as you drive.

As Mex Says. ALL BATTERIES are sensitive to over (and I might add UNDER) charging. For best life they need PROPER charging.

AGM and other "Maintenance free" designs the issue is if you should boil them hard enough that they vent vapor. there is no way to replace the lost liquid.

Now they are designed to MINIMIZE this (not vent less they absolutely have to) to recombine the oxygen and hydrogen produced back into water and thus self water. But there is a limit to this ability.. IF they vent. it's lost and gone forever.

FLooded wet cells you can always add distilled water.

14.4V is not to high for AGMs.l and it sounds like yours never gets fully charged..:to small a charging wire from the alternator. How do you charge them when on shore power?

Even though I have a large 200A alternator on my DP, I do not use it to bulk charge my house batteries...150+ amps x 4+ hours cannot be good on the alternator without extra cooling. I run my generator before leaving and then let the alternator finish charging at 50 amps or less. Like the other posters I think you need a small generator or a better 129V charger. I get 10+ years out of my oversized AGM house battery bank.

Tough to beat a HF 2 cycle gen and 36 amp charger for the money 5 hours of charging for 2 dollars in fuel. 30+ amps of solar isn't cheap.

MEXICOWANDERER wrote:
Intermittent, The RV is used as a daily driver and for long distance trips, boondocking mostly. The coach battery is located under the rear floor, about 20' from the alternator. Not sure of the connecting wire size, which runs through an isolator and 50A breaker.

Those batteries were perpetually undercharged. There are too many clues for this to not be fact.

All batteries are sensitive to abuse.

This is my bet...abusing a different style of battery likely won't change the outcome.

atp20 wrote:
Hello,
The 120A(?) alternator charges at 14.4 volts when the battery is full.

Is you alternator the only charging source?

Pretty much impossible to get from 80% charged to 100% charged in less than 3.5 hours. Ideally if you were to drive this 3.5 hours, the vehicle's voltage regulator would ideally be holding voltage in the 14.4v range and this would also be reaching distant house battery, over thick copper cable/circuit between alternator and house battery.

BUt your vehicle is extremely unlikely to hold 14.4v after 3.5 hours driving, meaning they are not recharging as fast as they could/should.

Do not check voltage once after engine starting and expect this is the voltage the vehicle's voltage regulator always allows.

Intermittent use....Put a solar panel on the roof, it will have the time to get them full and keep them full between intermittent uses, but get a solar controller with a battery temp sensor for South Florida summers.

Getting the AGMs full between intermittent use is paramount to longevity. If you fully charge them from the grid, and then fully disconnect them from all loads, they should not self discharge much at all. as low as 1.5% and as high as 5% per month, but higher in hotter ambient temps.

If the only charging source continues to be only the alternator in intermittent use, 2 years is all you can expect from any lead acid battery no matter how high its perceived or actual retail value.

Flooded deep cycle 6v jars might wake back up some from an extended equalization charge upto 16.2v after such abuse. But perhaps not.

How you get your batteries full is up to you, but if you want more than 2 years from them you have to gt them full regularly, and hopefuly promptly after any significant discharge

Intermittent, The RV is used as a daily driver and for long distance trips, boondocking mostly. The coach battery is located under the rear floor, about 20' from the alternator. Not sure of the connecting wire size, which runs through an isolator and 50A breaker.

Those batteries were perpetually undercharged. There are too many clues for this to not be fact.

All batteries are sensitive to abuse.

First would be full one gauge AWG wire throughout the charging system. Eighty amp breakers to all batteries. A small generator and fixed voltage charger set for 14.4 volts that can run for 4 hours on a tank of fuel and deliver 40 amps.

My setup is larger. 4 L-16 batteries. A 400 amp 28 volt Niehoff Batteries 4/0 gauge to the L-16's and a 40 DC amp 120 volt 28 volt charger.

When your AGM batteries are finished charging they will automatically accept ONE HALF AMP EACH or one full amp both batteries. This is accurate and reliable indicator showing your batteries are full. If you shut down the charging before the amperage drops to one amp you are undercharging the batteries and the short lifespan screams proof of this. By getting a tiny generator and power supply then letting it run out of has finish charging every day you'll greatly improve battery life. That and spend the money for the wiring upgrade. What I just wrote is not guesswork :)