Battery-Charging Voltages

[Rick]

The missing piece is a good monitor. You can read the manuals for your charger(s) to discover just how to vary the voltge(s) to suit your needs yet you need a good battery monitor which also monitors just what your sources are doing. By reading other threads under Electrical: Batteries by using your monitor you can determine how the internal resistance of your bank is doing and how the charge acceptance is changing (if at all).

Once you become comfortable with the concepts and methodology you will establish a charge/discharge cycle and just what should be done by you and what gets done automatically. You will discover that if your charge sources deliver the correct voltages for the correct times then you will be able to merely keep track of what is going on and relax.

[BlueSovereign]

Thanks for that.

Any opions on my equipment choices which I mentioned?what

[Rick]

Be careful to check (if you have not yet bought) that your shore charger or alternator regulator can allow the user to set the upper voltage range well above 14.4V. 14.6V is a minimum, in my opinion. Check to see just how easy it is to make such changes.

Usually you can "lie" to the charger by telling it to use flooded-cell settings and very low temperatures in order to get the acceptance settings up. It depends upon what the manufacturer allows the user to do. One then might (when entering float) have to revert to the AGM or a gel setting to get a good 13.7-13.9V foat value. Even then it is O.K. to float at a flooded-cell setting around 13.3 with AGMs or gel-cells as long as you periodically re-enter an acceptance cycle to check for how much charge acceptance current the battery exhibits. If a previous charge cycle properly recovered lost capacity then the battery will not charge accept much current.

The two revealing factors here are to check for the internal resistance of the battery (delta-V divided by delta-I) for both charge acceptance as well as heavy inverter load discharges. It is difficult for most people to understand that a full battery just will not charge accept much current when you subject it momentarily to a high voltage. The difference between a sulphated (like a dead AGM) battery that will not charge accept current and a good one is that the dead one will not deliver heavy load current...easy to check with an inverter heating up a cup of water.

[hellosailor]

Rick, have you seen:
Large Pulse Resistance

Aside from the drawback of needing to be affixed up close to the battery...an interesting concept?

[quidam]

Rick, I have not yet purchased an external regulator and was hoping you could tell me what you think is the best one. My alternator is a large case electrodyne that is rated at 125 amps @ 24 volts, and it is setup for an external regulator.

[bobfnbw]

Rick,
Going with a 600ah bank of odyssey batteries at 100ah each.
Will increase to 800 at some time in the future, maybe next time batteries are changed out.
Need to replace my alternator, inverter charger, and batteries due to a flood in the boat. All are shot.

What I would like to know is what equipment is best to MAXIMIZE these types of batteries. Currently I have balmar 100 amp alternator, and a prosine 75amp charger.
Was going to change to the victron multiplus 120 amp inverter/charger, and as large of a alternator as I can, probably a 160 or 210 amp balmar or electrodyne.
The goal of course would be to recharge at the most rate these batteries are capaple of, reducing run time on engine.

If I understand you correctly, with these types of batteries, I could charge at 33% of battery bank, which would equal ~ 200 amps. How do I get this type of charging current into the batteries. Not much out there that delivers that kind of current.
What would you use ?
Any input is appreciated.
Thanks
bob

[Extemporaneous]

Originally Posted by bobfnbw

Rick,
The goal of course would be to recharge at the most rate these batteries are capaple of, reducing run time on engine.

If I understand you correctly, with these types of batteries, I could charge at 33% of battery bank, which would equal ~ 200 amps. How do I get this type of charging current into the batteries. Not much out there that delivers that kind of current.
What would you use ?
Any input is appreciated.
Thanks
bob

I think Rick's got you covered already. Post 1 through 16 of this thread will get you there.

Extemp.

[hellosailor]

"How do I get this type of charging current into the batteries. "
A whopping big alternator. Or, two 100+ Amp alternators, belted up on opposite sides of the engine so they also even out the load on the shaft bearing. If you have the space for it--there's a lot to be said for dual alternators. In any case, make sure they are rated for continuous output at the power you intend to draw from them.

[Rick]

Hellosailor, yes I've looked into such technology and rejected the concept due to the inherent problem of generating EMI and RFI that would wipe out SSB reception on a cruising boat. In other applications there is still the problem of not being able to ever meet agency requirements in EU or other countries for EMI and RFI. In addition, short term resistance values do not match up with longer time measurements due to electrolyte starvation near the plates at high currents and long times which do not show up with short pulse measurements.

With a good battery monitor one can better determine resistance for your application by measuring delta V and delta I when using a microwave/inverter, for example. This could be done automatically yet such development was stopped when I was working at Xantrex. Boo-hoo1

Regarding high output alternators, keep in mind that two small frame high output alternators (90-100A) will not be as reliable or efficient as one 190A large frame alternator. The large frame alternators have much more volume with which to accommodate magnetic flux saturation of the field, better cooling and bearings that are about 4 times "stronger" than those of small frame alternators. All this with only 1 inch increase in diameter. Small frame alternators that put out 120-150A are way overstressed in my opinion.

[hellosailor]

Rick, I appreciate that large frame alternators, or simply higher capacity alternators, have their advantages. The problem is that on a retrofit, let's face it, there are limits of space and of course limits of the single v-belt. Dual belts are a nice way to guarantee permanent employment at the alternator shop or garage, and ribbed belts can mean changing the flywheel and visiting a machinist.

What I really want is to get Reddy Kilowatt in a dark alley one night and ask him why the pint-sized nuke he promised me in the 50's hasn't come onto the home market yet. (Well, aside from some thousand or so small strontium piles that seem to have disappeared from the old USSR.)

[Beausoleil]

Originally Posted by hellosailor

What I really want is to get Reddy Kilowatt in a dark alley one night and ask him why the pint-sized nuke he promised me in the 50's hasn't come onto the home market yet. (Well, aside from some thousand or so small strontium piles that seem to have disappeared from the old USSR.)

Reddy Kilowatt went green and is now working for Panasonic... And Toshiba will have something, but it's a bit larger than just a single-home unit.

I want one on my boat.

[hellosailor]

Me too!

Now I've found a reason to buy "too much boat" so there will be room for that powerplant.

Interesting that it is made by Toshiba, since the Japanese wouldn't let you sail into the country if you had one on your boat!