Could this be a battery isolator problem, or???

[booster]

Originally Posted by peteco

Do you think the batteries will be damaged if the water level is always maintained above the plates?

I talked to Trojan about that quite a bit when we had wet cells, particularly because we had two GC six volt batteries and one 12v deep cycle (it turns out the 12v wasn't of the same durability, though). The 12v would always use more water than the much larger GC batteries.


They couldn't give any real guess as to how much it could shorten life, but said if the water use was from charging at absorption voltages in particular, it would shorten life some. They specifically mentioned their relatively new "daily charge" higher absorption voltage of 14.6/14.7v as being worse if if you don't have good charging control to prevent overcharging. The closer the voltage is to the float, the better, if the battery is full. It is interesting that the current specs on the Trojan site seem to indicate a 13.5v float voltage, but back a few years, I seem to remember them saying they preferred 1.32v forfloat over a time more than a couple of days.


They did say that wet cells will handle overcharging much, much, better than AGM or Gel batteries, and the GC batteries and industrial 6 volts have more reserve water capacity so can appear to use less water from that. They also do tend to actually use less water too, it appears.


So, I guess the bottom line is that overcharging wet cells will shorten the life some amount, I assume from plate oxidation or erosion, but will not kill them off nearly as quickly as overcharging and AGM would. Water use is a PITA, though, and can cause a lot of corrosion besides. The disclaimer, of course, is if the overcharging water loss exposes the plates, or the battery overheats and warps the plates from the overcharging.



We had the two GC batteries for about 5 years, starting with the Tripplite charger, then the Blue Sea. They also were in place with the Morningstar solar charger and uncontrolled alternator charging, so they saw quite a bit of poor charging, both over and under charged. Periodic equalization was needed, and the water watched closely while learning, but at 5 years they still tested like new for specific gravity and actual capacity. The 12v battery that was in just a bit longer than 5 years had started to show signs of wearing out.


As a point of reference, with full batteries leaving home and a 10 hour drive between the uncontrolled alternator charging and the Morningstar solar overhcarge, we used water at a rate that would require water in the 12v battery every two days, and the GC batteries about every 4-5 days, so you can go through a lot of water if you drive a lot with full batteries.

[markopolo]

I added the ground interrupt switch on mine (not Blue Sea). It's easy to do so might as well do it.

Test the system with a hot alternator and record the voltage. There may still be some voltage drop because of wiring and termination resistance. If you run the fridge heating element (absorption fridge) that load will also drop the system voltage a bit.

[booster]

Originally Posted by markopolo

I added the ground interrupt switch on mine (not Blue Sea). It's easy to do so might as well do it.

Test the system with a hot alternator and record the voltage. There may still be some voltage drop because of wiring and termination resistance. If you run the fridge heating element (absorption fridge) that load will also drop the system voltage a bit.

Good point on running the absorption frig, as the can have an affect depending on the alternator size and wiring. We have run across another case that I don't know is typical, or not, but running the frig was also able to take care of an issue with an added on stand alone engine generator setup on a Chevy. The system, because of the Bamar regulator, would not go to float on full batteries and just keep charging at full absorption. The owner had a marine tech look at it who talked to Balmar and got information from them that if the engine generator system is putting out enough current, I think it was 4 amps, the Balmar wouuldn't recognize it was charging and stay at high voltage. Their solution was to add a big resistor bank load on the system to get it to work, which it did. The resistors got very hot, though, and IMO were a fire hazard, so I had him have the resistors removed and just run the frig on DC while driving instead of propane as he was doing and it worked fine.


When checking the voltage drop for the situation of overcharge, it is very important to do it with the hot alternator, as mentioned, and also with the batteries full and normal load on in the coach. The current can be very low in those situations so the voltage drop will be very small. The isolators appear to always have the drop so those don't appear to vary with load.

[nicaland]

I didn't want to comment on the question as to if overcharging the house batteries, and as a result having to add more water to compensate when using (healthy) conventional flooded types, while using the Blue Sea ACR during long drives until I put quite a few miles on my Xplorer. Now, after over 3500 miles, I have yet to need to add any more water to them. My MH is powered by the Dodge 360 and has a 125A alternator. I typically see 14.1 to 14.2 volts going to both the house and chassis batteries initially, tapering down to 13.7 to 13.8 after a while, and have not attempted to compensate for this amount of voltage by running a DC load on the house batteries while underway. This backs up what I had been told by the Blue Sea techs five months ago. I realize that this might not be the case for those that are utilizing gel or AGM's, but I feel comfortable in saying that for those of you that are using flooded batteries for the house bank have little to worry about in terms of excessive water usage when using the Blue Sea ACR in lieu of a conventional old-tech battery isolator. The ability to keep the chassis battery charged when on shore or generator power automatically is a big plus that in my case at least has yet to show any downside, and the extra voltage when charging depleted house batteries via the engine's alternator definitely reduces fuel usage as well.

[booster]

Originally Posted by nicaland

I didn't want to comment on the question as to if overcharging the house batteries, and as a result having to add more water to compensate when using (healthy) conventional flooded types, while using the Blue Sea ACR during long drives until I put quite a few miles on my Xplorer. Now, after over 3500 miles, I have yet to need to add any more water to them. My MH is powered by the Dodge 360 and has a 125A alternator. I typically see 14.1 to 14.2 volts going to both the house and chassis batteries initially, tapering down to 13.7 to 13.8 after a while, and have not attempted to compensate for this amount of voltage by running a DC load on the house batteries while underway. This backs up what I had been told by the Blue Sea techs five months ago. I realize that this might not be the case for those that are utilizing gel or AGM's, but I feel comfortable in saying that for those of you that are using flooded batteries for the house bank have little to worry about in terms of excessive water usage when using the Blue Sea ACR in lieu of a conventional old-tech battery isolator. The ability to keep the chassis battery charged when on shore or generator power automatically is a big plus that in my case at least has yet to show any downside, and the extra voltage when charging depleted house batteries via the engine's alternator definitely reduces fuel usage as well.

The voltages you are seeing would back up exactly what you say, I think. The gassing voltage is normally around 14.1v and varies with temp some. Some gassing is good when at absorption charge, so no issue at all there. With the alternator turning down to 13.7v or so, you are below gassing so water use would drop way down. While that is still a bit high for most wet cells if they are on continuous float, it is probably good for driving time frames and will help top off the batteries.


Most of the vans that have had issues with overcharge were later models, mostly Chevies as there were lots used. We have a 2007 and it would run 14.5+ volts most of the time and rarely turn down below 14.3v. When we had wet cells with those voltage we would have add a lot of water after a long drive of 8-10 hours.


Sounds like you hit the sweet spot!

[nicaland]

Well I can certainly see how running that high a voltage continuously while underway could result in requiring water addition, and frankly wonder how the chassis battery can stand this sort of charge over time! I'm guessing that more current vehicles than mine (a '9, as a result of having substantially more computing power require this sort of voltage output from the alternator to keep running properly. I would think that running an appropriate load, like perhaps an absorption fridge on DC or perhaps something smaller would remedy this situation. By the way, I do keep my van plugged in most all of the time when not in use, and the PD 4635 is keeping it at a 13.2 float voltage with timed 'equalization" input of 14.2V or so (can't remember exactly) happening from time to time.

[nicaland]

Don't know where that cool smiley face came from. Meant to say mine is a '98!

[booster]

Originally Posted by nicaland

Well I can certainly see how running that high a voltage continuously while underway could result in requiring water addition, and frankly wonder how the chassis battery can stand this sort of charge over time! I'm guessing that more current vehicles than mine (a '9, as a result of having substantially more computing power require this sort of voltage output from the alternator to keep running properly. I would think that running an appropriate load, like perhaps an absorption fridge on DC or perhaps something smaller would remedy this situation. By the way, I do keep my van plugged in most all of the time when not in use, and the PD 4635 is keeping it at a 13.2 float voltage with timed 'equalization" input of 14.2V or so (can't remember exactly) happening from time to time.

At least according to what I have been able to find out about the higher voltage on the newer vehicles, it appears to be very intentional, and the starting battery designs are designed to be able to handle it much better than the deep cycle types we use in the coaches.


What I was told by the Cadilac dealer tech that I ran into at a car show is that the new cars have so many high current using accessories that there are real issues with the batteries going dead even if the cars would get driven regularly, but not very far. Cold weather makes it much worse. Figure a cold start, heater fan on full, headlights on, rear defogger on, seat heaters on and only a 10 minute drive to work or the store, plus the battery is cold and resistant to taking charge. You have an almost certain loss of charge. Do that for a week in row twice a day and all of sudden the battery is dead. They counter it by turning up the voltage to force more into the battery and warm it up while still being able to run all the accessories. It also used to be that a 60 amp alternator was considered large and heavy duty and now it would be nearly useless. It all boils down to doing whatever they can to recover as much power as they can in as short a time as they can. Not an easy task at -20*F.

[nicaland]

Makes sense to me.

[avanti]

My new Volvo XC60 has a second small battery specifically to handle the stresses of restarting the engine after it has turned itself off at stoplights.