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Multi Stage Battery Charging Odd Application

cornbinder89

Registered
They take a little getting used to. It has a "soft start" built into it. When you first start the engine, it doesn't charge for 10-15 sec, almost enough time for me to think its dead, then ramps up the field current. My guess is these were designed for small pleasure craft gen-sets where you might not want to overpower the small engine when just started by hammering the field current all at once like a conventional reg does.
I've been working on other problems so still have no "road time" in it yet. So far tho it looks good.
 

cornbinder89

Registered
Had it out on the road today, after an hour it drops to float charge and you'd think the belt came off, as it show discharge on the ammeter for a about a minute until it pulls the surface charge off the battery down to float charge voltage, then it holds at that voltage. The real test is going to be when I overnight with the 'fridge" on.
 

cornbinder89

Registered
Well the longer term results have been less than stellar. While it did work as described in that it charged based on how long it took to reach bulk charge voltage, and did drop to float voltage, it shut down after an hr or so on float, completely turning off the charging system. No exactly useful on an over the road truck!
I could re-set the regulator by turning off the engine for 20 min or so. I'll have to do some more diagnosing to determine the fault, my guess is the regulator can handle "full fielding" the alternator but over heats when it has to limit the field current to low levels.
For the time being, I am going to try paralleling the regulators (I was only using the Sterling, in my initial install) with the internal reg set to float voltage.
Where I installed the reg is hard to get to when the truck is in service.
There are supposed to be led's to aid in diagnosing faults, but it appears that none are functioning except the one showing that there is power to the unit. The ones for overheat/over current are not active and when it malfunctions the one indicating battery type aren't showing what type battery is selected.
 

cornbinder89

Registered
well I thought it was time for an update.
The dealer thought it is shutting down because of high ambient temp. I went ahead and paralleled the regs with the internal reg was set to float level (13.7 volts)
Now that the weather has cooled, and I have a few nights in of running the heater all night. I can report that it works well. Before with a single set regulator, it wouldn't fully recharge in 11 hrs of running (almost but not complete). It took a night of no loads to fully charge the following day.
Now it stays on high charge for about 5 hrs and then drops to low for the rest of the day. The charge current drops to around 7 amps and is there for over an hr before switching to low (float) charge level.
I think it does a good job of keeping the battery bank up to max charge each day.
I think this water resistant reg should be installed away from engine heat. The problem with that is on the truck, there isn't a good place to mount that it still close to the engine. I don't imagine in the boats engine room would be much better either. The engine rooms I've been in are quite warm when the engines are running.
Paralleling works well and gives you a fail safe and would be my recommendation.
It does cut the charging time by well over 50% Last time I checked the water in the cells, it doesn't seam to use a lot.
All in all it was worth doing.
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
Does it need to be mounted near the engine? I would think you could put it a ways away (even in the cab?) so long as suitable wire is used. Glad to hear you got it working well though.
 

cornbinder89

Registered
They recommend keeping a few of the wires as short as possible, the field and alt hot feed are among those mentioned. Being installed on a cabover any wires to the cab have to go to the front thru the hinge area. Not sure why they say that however, if large enough gauge wire was used, voltage drop shouldn't be a issue.
My remote shunt ammeter uses 12 ga wire for a 20' run and it operates on mili volt signal, without a problem,
 

cornbinder89

Registered
A little more to add. I found that with the batteries being fully charged after each use, I find I could get by with a smaller battery bank. The instructions caution that the fast recharge is done at the expense of water useage. They recommend checking the water level at least monthly if not every few weeks. I have found water useage to be only slightly above what it was before the regulator was used. Today I added water for the 1st time in 5 months, and the four group 31 DC's together used 2 qts of water.
I never did figure out why when it was used alone, it would shut down. Since using it with the internal reg I have had no problems.
One reason why I may not be experiencing much water use is my max recharge current is limited to 75 amps. If I used a larger cap alternator I am sure it would dump a lot more current into the bank. Since I have no problem with the lower current I see no reason to change. The truck mostly runs for 10 or more hrs at a time, and that is well above what is needed to recharge, there is no gain for charging faster than 75 amp unit will.
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
One thing to consider is that a larger battery capacity results in longer battery life due to a lower depth of discharge. This may actually save money, and of course gives reserve capacity for when operating conditions are less than ideal or otherwise abnormal. Also means that the battery can still supply the load as it ages and decreases in capacity. Of course all of this at the expense of carrying around the extra weight...
 

cornbinder89

Registered
On this unit I am running 540 amp/hr pack and have no plans to change, on one of my other trucks I am running 465 amp/hr and don't yet have the multi stage reg, but think it would respond well to the multi stage reg.
In all cases I am discharging to less than 50% (that is to say there is more than 1/2 the charge remaining)
Another truck has 620 amp/hr and its batteries are the oldest, when they need replacement, I will replace with 540 amp/hr pack.
The difference is in the battery case, the 540 is std group 31 size while the other two are silghtly bigger and taller (floor scrubber) and the terminals are not as robust as the 31's stud terminals.
Most nights that I run the heater, I run my 'fridge (another energy hog) off LP, but for an experiment I ran both off the bank one cold night, and it didn't even trigger the low battery alarm on the inverter. That was deep a cycle as I have ever tried.
Without the multi stage reg, the bank would not fully recharge after a full day of running, so capacity would decrease as the week progressed.
 
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