New isolator

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- Boost switch and storage (split from Re: New isolator)

New isolator

August 06, 2016, 10:11:00 pm

See my thread about the dead alternator for the background on this.

Assuming that I need to replace the isolator, what is the preferred one, and a suggested source? My current one has four posts on it, with a heavy jumper running from post one to post three (looking at it left to right). Nothing else is on post three. I would assume that I could get one from Foretravel that would be pretty close, if not identical, to what I have, but is there a better choice?

Re: New isolator

Reply #1 – August 06, 2016, 11:09:59 pm

Would like some recommendations for a 270amp+ battery isolator

Re: New isolator

Reply #2 – August 06, 2016, 11:20:34 pm

Sterling ProSplitR

Sterling ProSplit-R – Zero Voltage Drop Battery Isolator

Re: New isolator

Reply #3 – August 06, 2016, 11:59:27 pm

If the isolator will be running a residential electric refrigerator in addition to everything else you should take that extra capacity into consideration when ordering the new isolator... and also the new alternator and new inverter when they fail ...and perhaps a heavier duty genset that can handle all the extra run hours... if you don't have an electric refrigerator someone else reading this is probably considering one and should take this stuff into consideration.

Re: New isolator

Reply #4 – August 07, 2016, 09:02:37 am

I think it is an inverter that runs the residektial refrigerator. The isolator separates two or more banks of batteries. Smarter ones begine to manage charge differentially. Smartest ones do multi stage charging.

Re: New isolator

Reply #5 – August 07, 2016, 01:31:42 pm

Roger, if you installed the Sterling relay-based isolator, did you reduce alternator output voltage to compensate for not having the diode-based isolator voltage drop? Your Sterling link sounds interesting.

Re: New isolator

Reply #6 – August 07, 2016, 03:26:04 pm

Barry,

It is a non-issue, as the sense wire is on the chassis battery side of the isolator.

All it means is that the alternator will not have to work as hard to overcome loss to heat in the diode-based isolator. Voltage to batteries will be exactly the same.

Re: New isolator

Reply #7 – August 07, 2016, 03:29:46 pm

And, for KISS theory guys, the SIMPLE answer is a marine ON-OFF switch.

Alternator output (B+) and chassis battery to one lug. House battery to the other.

Switch off: Chassis battery gets charged, house battery does not. A very good choice if at CG's every night. Why pay diesel to run the alternator extra hard to OVERcharge the house bank while driving.

Switch on: Both banks charged. Also, a 1000 amp manual battery combine switch.

It is idiot-proof. Switch on or off makes no difference to the alternator.

Re: New isolator

Reply #8 – August 07, 2016, 03:49:23 pm

Barry, with the LN alternator before the Sterling voltage was cranked up into the low 15 volts. With the Delco 240 amp brushless alternator that I installed with a properly wired start battery sense wire it adjusts the output voltage by itself. The Sterling ProSplitR works very well. The LN alternator rarely charged my batteries fully. The Delco is doing a much better job.

Sterling ProSplit-R – Zero Voltage Drop Battery Isolator

You have to read all this and see if it makes sense for your needs. Brett is correct a big switch may be just as effective for the isolation task. I am trying to improve the charging side of the equation on my coach which hasn't been up to par since we bought the coach.

Re: New isolator

Reply #9 – August 07, 2016, 04:04:14 pm

Quote from: wolfe10 – August 07, 2016, 03:29:46 pm

And, for KISS theory guys, the SIMPLE answer is a marine ON-OFF switch. It is idiot-proof. Switch on or off makes no difference to the alternator.

We have such a switch, never had to use it, but NICE to know we have it.

Re: New isolator

Reply #10 – August 07, 2016, 05:05:41 pm

Quote from: wolfe10 – August 07, 2016, 03:29:46 pm

And, for KISS theory guys, the SIMPLE answer is a marine ON-OFF switch.

Alternator output (B+) and chassis battery to one lug. House battery to the other.

Switch off: Chassis battery gets charged, house battery does not. A very good choice if at CG's every night. Why pay diesel to run the alternator extra hard to OVERcharge the house bank while driving.

Switch on: Both banks charged. Also, a 1000 amp manual battery combine switch.

It is idiot-proof. Switch on or off makes no difference to the alternator.

Brett, for decades I have always read that directly connecting batteries of different sizes for charging is not good practice. House batteries and chassis batteries are almost always different sizes. 8D and Group 24, 27 for example.

If I'm reading your suggestion for an on-off switch correctly, that is the same as directly connecting an 8D and a Group 24 together and charging them (when the switch is in the ON position). I've always been under the impression that should be avoided.

In my old boating/cruising/sailing days, we used a manual switch that had OFF-Bank 1-Bank 2- Both Banks positions to direct the charge. Both was only used if the house batteries were needed to "jump" the start batteries.

Isolators were an improvement and then combiners did an even better job of keeping the batteries separate. I really like the new combiner that Roger installed. It automatically disconnects a battery bank from the charging source when no further charging is needed. It takes charging dissimilar batteries separately to the next level.

Re: New isolator

Reply #11 – August 07, 2016, 05:31:11 pm

Ed,

I suspect you may end up being disappointing in how isolators/combiners really work.

Most are pretty "stupid"-- isolators do charge both banks from the alternator, but charge a pretty "hefty penalty in terms of amps turned to HEAT". They have no means of charging different size/technology banks differently. Basically bank with lower voltage gets the amps.

Battery combiners do directly connect/charge both battery banks when voltage is above XX volts. Again, volts, not battery size or technology dictates

Not aware of any (insert reasonably priced/commercially available) device that allows for different voltages based on battery bank size/type.

Yes, on our sail boat, we do have a "smart regulator"/3 stage regulator to control alternator volt/amp output, but have not seen one installed on a motorhome. Not sure I could justify the cost for an RV.

All three (manual, isolator and combiner) do automatically put more amps into the battery bank with lower charge level-- just the nature of the beast.

Re: New isolator

Reply #12 – August 07, 2016, 06:16:09 pm

Heck, Brett, I was elated when Perko upgraded the battery switches to maintain contact between settings so we didn't need to shut the engine down to prevent frying the alternator/regulator when switching between battery banks. So all this new stuff since then is "gravy" to me.

Re: New isolator

Reply #13 – August 07, 2016, 11:06:17 pm

...what Brett said, except you can actually use your existing boost solenoid as long as you don't overload it ...this is what I'll probably do if my isolator ever dies, which it might not because I have a very low electric load, it's normally the people with residential electric refrigerators that burn out their isolator and inverter, then they start running their genset all the time and put huge hours on it ...so that's why I was saying to take the extra load of a residential refrigerator into account when replacing electrical components

Re: New isolator

Reply #14 – August 07, 2016, 11:36:10 pm

Residential refrigerator, 5 years. Isolator, origins am. Inverter, original.
Gen Set, 3100.00 hours because I bought it to use it. It's a generator, not a china doll or a museum piece. Well maintained, generator good for lots more hours.
I do like the quiet when not using it, but don't get overboard to avoid using it.

Re: New isolator

Reply #15 – August 08, 2016, 07:11:54 am

Yes, our generators have 20,000 hour design lives.

Re: New isolator

Reply #16 – August 08, 2016, 11:09:54 am

Scott. I use a separate smaller inverter for our fridge and it is fed off coach batteries OR shore power/ main inverter whichever I want thru a DTDP switch.
JohnH

Re: New isolator

Reply #17 – August 09, 2016, 10:40:57 pm

There have been several people on this forum who have lost one electrical component after another when they installed a residential refrigerator. They seem to lose their inverter, isolator, alternator first, then start running their genset all the time to take the stress off the other parts. At least one person on this forum told me he lost his genset after running it constantly. I think he lost the main bearings or something major like that and replaced the $10,000 genset. I'm not making this up, but whatever. This information won't benefit me because I don't have a residential refrigerator. I mentioned it hoping to help others because it hadn't been said yet in this thread.

Re: New isolator

Reply #18 – August 09, 2016, 11:24:33 pm

Most folks replacing their LP refrigerators with a residential are doing it because their LP refrigerator is failing or has burned up. At 15+ years of age alternators, inverters, isolators are all getting close to the age when they just fail. It is coincidence as much as anything when you do one thing and something else becomes a problem. i don't think there is a direct cause and effect here.

Re: New isolator

Reply #19 – August 10, 2016, 01:02:40 am

Quote from: RRadio – August 09, 2016, 10:40:57 pm

There have been several people on this forum who have lost one electrical component after another when they installed a residential refrigerator. They seem to lose their inverter, isolator, alternator first, then start running their genset all the time to take the stress off the other parts. At least one person on this forum told me he lost his genset after running it constantly. I think he lost the main bearings or something major like that and replaced the $10,000 genset. I'm not making this up, but whatever. This information won't benefit me because I don't have a residential refrigerator. I mentioned it hoping to help others because it hadn't been said yet in this thread.

Don't want to get too far off topic, but this is my take on RRadio's concern

My 1981 Foretravel came with a residential refrigerator from the factory. I bought it in 1994 and used it for 18 years. The only thing that wore out was the first refrigerator which I replaced it 1995. The original generator is working fine including the 21 year old Kenmore refrigerator and the invertor I installed in 2000, the alternator is original also. I keep the coach as a back-up in case of an earthquake here in Los Angeles. The '81 is what spoiled the DW and she doesn't want to ever go back to a propane refrigerator like we had in the Vogue. When we bought the 1996 Monaco the first thing I did was put in a Samsung and everything is still working on it and I have it up for sale.

Re: New isolator

Reply #20 – August 10, 2016, 11:04:38 am

Scott, I think you are over-estimating the electric loads residential fridges put on motorhomes. Fridges use a small additional amount of current and do not take much additional management if the original system has the battery and inverter is sound.

Re: New isolator

Reply #21 – August 10, 2016, 11:22:51 am

Agree with Barry. Good discussion (below) on actual documented electrical load produced by a residential fridge:

Residential fridge energy use (split from Yacht Fridge VS Residential Fridge)

Re: New isolator

Reply #22 – August 10, 2016, 08:36:23 pm

I think there is no question that some coach owners lose their inverter, isolator, alternator & genset including some who had to replace the whole expensive backend pumpkin from damage caused by a broken generator-end bearing.

These repairs happen from a lot of use, poor maintenance, and bad luck. Too little use can also contribute to bearing failures from lack of lubrication.

But none of the problems are caused by adding an electric refrigerator. Electric refrigerator's fans, compressors and defrost heaters do consume relatively low amounts of electricity, but the loads are spread out over the day, which will require a new management when dry-camping.

Driving the coach and on shore power does not need any new attention because house battery bank is not being used to power the fridge. There are advantages and disadvantages of converting to electric fridges, but one that stands out is the lack of concern about propane refrigerator fires.

Re: New isolator

Reply #23 – August 10, 2016, 10:06:44 pm

To get back on topic, is there any preference between the Sterling and the Sure Power? I see that Sterling has several models. I have a single alternator (probably the original) and two battery banks (2 8-D AGM house batteries and three standard engine batteries). Do I need the PSR252 or the PSR 253? I think I need the PSR252.

The existing isolator has (had) four lugs. The third from the left has only one cable on it, going to terminal one (from left). Each of the other three lugs has at least two wires attached, some heavier and some lighter. The Sterling looks like it has more terminals, all of which are labeled, so I'm assuming that some of those "extra" smaller wires go on those smaller terminals. I have drawing B-2126, but I'm not sure that the wires on the isolator actually match the drawing. I'll see if I can't figure the "extra" wires out this weekend. I do know that two of them (the really little ones in the picture) are for the trik-l-charger (sp?) that is supposed to keep the engine batteries charged while parked. Looks like all of the "extra" wires are on terminal four.

Fairly easy upgrade?

Re: New isolator

Reply #24 – August 10, 2016, 11:05:26 pm

I am not sure what the differences are between the Sterling and the Sure Power isolators are. I chose the Sterling because it had enough capacity to handle a bigger alternator and three outputs to allow for the start battery and two sets of house batteries. Wit h this one if you only have one house set of batteries you simply run a jumper wire from the second house terminal post to the first terminal post. It was almost an exact replacement. It fit right where my old isolator was and if you don't want to change any wires they can be used with the Sterling. In your coach the location is different but the Sterling should work where yours is as well. It has an IP66 waterproof rating.

Alan at Bay Marine Supply is a Forum Member and if you call him there may be a Forum discount as well.

I am sure there are several capable products out there. This on fit my current and future needs, supports a Forum Member, was priced OK and comes with great support from Alan. That is worth a lot to me.

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