Battery combiners/isolators

[Maineah]

Here is some thing that maybe of interest to any one with the old battery isolators the type that looks like a Ford starter relay. It is a direct replacement no new wiring no dealing with your alternator or adding an isolator. It has a lot of pluses over the diode type isolators at about the same cost. This type is a "smart" relay it senses battery voltage unlike the other types of isolating devices. There is more then one manufacturer of this type they are also call ACR (automatic charge relay) or battery combiners. The Colehersse pdf gives a good description of their operation. www.colehersee.com/pdf/hot_feed/d-617_SmartBatteryIso.pdf

[ChairmanMeow7]

What happens when you truck battery goes dead ? Does it combine batteries so you can start ? Also , if it does combine batteries to start , how would you know your truck battery is bad ?

[Gulfstream Greg]

Here is some thing that maybe of interest to any one with the old battery isolators the type that looks like a Ford starter relay. It is a direct replacement no new wiring no dealing with your alternator or adding an isolator. It has a lot of pluses over the diode type isolators at about the same cost. This type is a "smart" relay it senses battery voltage unlike the other types of isolating devices. There is more then one manufacturer of this type they are also call ACR (automatic charge relay) or battery combiners. The Colehersse pdf gives a good description of their operation. www.colehersee.com/pdf/hot_feed/d-617_SmartBatteryIso.pdf

I can't get that link to work. I looked through the catalog but can't find it that way ether.

[sparky60]

Here is some thing that maybe of interest to any one with the old battery isolators the type that looks like a Ford starter relay. It is a direct replacement no new wiring no dealing with your alternator or adding an isolator. It has a lot of pluses over the diode type isolators at about the same cost. This type is a “smart” relay it senses battery voltage unlike the other types of isolating devices. There is more then one manufacturer of this type they are also call ACR (automatic charge relay) or battery combiners. The Colehersse pdf gives a good description of their operation. www.colehersee.com/pdf/hot_feed/d-617_SmartBatteryIso.pdf

Tried ur link ..but it dosen't seem to work ? I went to www.colehersee.com and they show 10 different isolators. Which one is the Smart Battery Isolator ?..........seems like a good idea ..tks

[Maineah]

Sorry guys copy and paste then it works. There are some differences in the makes but they will not let the truck battery go dead some are smarter then others the Cole Hersse is the neatest one I have seen it makes sure the truck battery is charged to 13.2 before it connects to the coach batteries I think it is bidirectional also so you can charge your truck battery with your charger. It does have a boast option so you can use the coach batteries to help crank. However you probably won’t get much help if you only are using a #8 wire.

[Gulfstream Greg]

I edited your post so the link works like a link now but I still get "File not found".

[Maineah]

http://www.colehersee.com/pdf/hot_feed/D-6...tBatteryIso.pdf Try this one I just copied directly from the url. All else fails it is a 48525 85 amp and a 48530 200 amp. I just copied it into a browser and it worked. It is a hard thing to find on the web I think it is a fairly new item. Blue Sea also makes them but I like the options of the 48525 better.

[Gulfstream Greg]

That link works. Looks like a good alternative with pluses and negatives. The plus side is no change in wiring if you presently have that type. Another plus that type has when new it does not have the small voltage drop across its terminals as does the solid state ones. On the negative side after time and many cycles the contacts can become carbon pitted and can develop a voltage drop across the contacts. That's speculation though. I like the idea of the battery boost operation but that's possible with the solid state by just jumping the terminals. Everything I have read and been told says not to hook two non alike batteries together in parallel and essentially that's what this isolator type does. I think the term "Smart Battery Isolator" is a bit misleading. Not in its smart sensing of the batteries but as a true isolator. Its only an isolator in its off state unlike a solid state diode type which is always an isolator. Anyhow running an expensive AGM battery in parallel with the starting battery while charging would be a concern for me. Lets cover some battery 101. Its advised by the battery experts that if you run two batteries in parallel that they are the same type and same age and if possible lot numbers and should be side by side with the cables as short as possible. The reason is whats called internal resistance. This resistance causes different charge rates for each battery. And the length of the interconnect cables can cause substantial voltage drops affecting the charge rates. So the coach battery is connected to a wire which might be 8 feet or more from the alternator and the starting battery is about two feet away from the alternator. The voltage drop in that 8 ft run can be considerable. The result is a possibility of the starting battery being consistently overcharged. I don't know how much of all that is actually something to worry about but that's what I have been told by several battery experts and Hams who deal with solar and emergency backup power systems. I do know that with the sunrader and the solid state isolator I had a volt meter in the cab and a double throw single pole switch where I could monitor both batteries and there were differences between the two with the engine running. The solid state isolator gives true isolation both in charging and in non charging use. My theory is that the mechanical solenoid type creates a bi directional connection, which in theory would create a balanced voltage on the line, possibly not reflecting the true charge state of each battery. Just my theory.

[ChairmanMeow7]

So Greg... You seem pretty knowledgeable on this subject of isolators and batteries. What do you think of the Blue Sea automatic charge relays ?

I am thinking about one of these , as I went to an RV repair place and the repair guy was attempting to hook up my 3 post solid state isolator I installed under the hood (but it is not hooked up). He seemed oblivious to the fact that some vehicles require a 3 post and some (as from my understanding , our Toyota's) require the 4 post. He was the 2nd place that told me my alternator was bad , and thus didn't finnish hooking up the isolator.

I'm wondering if the Blue Sea is a good alternative ? It appears as though it only has TWO posts (unless I am missing something) and thus should be pretty straight forward as far as wiring. I was just wondering about IT'S plusses and minusses ?

[Maineah]

Your isolator guys description really nailed it for me I had all ways labored under the impression that they had some type of electronics ie. could turn on and off and sense voltage. I have never used one or for that matter installed one so I was in the dark. It’s nothing more then a pair of blocking diodes and if it has a “e” terminal there is one more diode. The alternator gets its voltage sense from the truck battery because it can’t read coach voltage so it will not over charge the truck battery if any thing it would have a tendency to undercharge the coach battery because as the truck battery reaches its full charge it will drop the charge rate to both batteries even if the coach battery is low because the diode blocks any return voltage. Most of what I have read particularly from marine data sheets say different batteries are not an issue you often see all kinds of batteries on boats. With the common relay type it can read the coach battery and could over charge the truck battery if the coach battery was low, plus the inrush to equalize the voltage so the relays are lacking. I believe the data sheet for the combiner relays are rated 100,000 cycles. The Cole Hersse ones seem to have an off the shelf relay with add on electronics.

[Maineah]

So Greg... You seem pretty knowledgeable on this subject of isolators and batteries. What do you think of the Blue Sea automatic charge relays ?

I am thinking about one of these , as I went to an RV repair place and the repair guy was attempting to hook up my 3 post solid state isolator I installed under the hood (but it is not hooked up). He seemed oblivious to the fact that some vehicles require a 3 post and some (as from my understanding , our Toyota's) require the 4 post. He was the 2nd place that told me my alternator was bad , and thus didn't finnish hooking up the isolator.

I'm wondering if the Blue Sea is a good alternative ? It appears as though it only has TWO posts (unless I am missing something) and thus should be pretty straight forward as far as wiring. I was just wondering about IT'S plusses and minusses ?

Blue Sea makes nice marine stuff but the bottom line you need to have a 4 wire isolator to make your alternator charge your batteries and you have to patch into your alternator wiring to supply voltage to your 4th terminal on the isolator. This is why they can't get your alternator charge on the MH. The "ign" terminal on your alternator must go to both the alternator and the "E" terminal on the isolator. You can find the "ign" terminal pretty easy it will have power when you turn the key on and go off when you turn it off.

[Gulfstream Greg]

So Greg... You seem pretty knowledgeable on this subject of isolators and batteries. What do you think of the Blue Sea automatic charge relays ?

I am thinking about one of these , as I went to an RV repair place and the repair guy was attempting to hook up my 3 post solid state isolator I installed under the hood (but it is not hooked up). He seemed oblivious to the fact that some vehicles require a 3 post and some (as from my understanding , our Toyota's) require the 4 post. He was the 2nd place that told me my alternator was bad , and thus didn't finnish hooking up the isolator.

I'm wondering if the Blue Sea is a good alternative ? It appears as though it only has TWO posts (unless I am missing something) and thus should be pretty straight forward as far as wiring. I was just wondering about IT'S plusses and minusses ?

I am not familiar with the "Blue Sea" but if it just has 2 posts my guess it only isolates the battery that's connected to it from the alternator or charging circuit and the other battery is basically connected directly to the alternator.

Your isolator guys description really nailed it for me I had all ways labored under the impression that they had some type of electronics ie. could turn on and off and sense voltage. I have never used one or for that matter installed one so I was in the dark. It's nothing more then a pair of blocking diodes and if it has a "e" terminal there is one more diode. The alternator gets its voltage sense from the truck battery because it can't read coach voltage so it will not over charge the truck battery if any thing it would have a tendency to undercharge the coach battery because as the truck battery reaches its full charge it will drop the charge rate to both batteries even if the coach battery is low because the diode blocks any return voltage. Most of what I have read particularly from marine data sheets say different batteries are not an issue you often see all kinds of batteries on boats. With the common relay type it can read the coach battery and could over charge the truck battery if the coach battery was low, plus the inrush to equalize the voltage so the relays are lacking. I believe the data sheet for the combiner relays are rated 100,000 cycles. The Cole Hersse ones seem to have an off the shelf relay with add on electronics.

I don't understand completely how you can have two sense wires to the alternator. Almost seems like the original ignition wire should have a diode on it also. I have my new 4 pole isolator sitting here on the bench and will be installing it maybe tomorrow. I will take some volt readings at various locations.

[Maineah]

That is the beauty of the little combiner it reads both voltages. With the 4 terminal isolator the diode is built in and goes from "E" to "A" and passes voltage from E to A and blocks from A to E. The "E" terminal recieves power from the "ign" wire at the alternator when you turn the key on. What this does is provides a 12 volt signal to the alternator battery lead other wise it would not energize the field through the regulator it has to see battery voltage at the alternator output terminal. With both terminals 1 and 2 blocking return voltage there would be no voltage at the alt. output terminal. This could be accomplished by adding a diode to the alt. between the regulator "ign" lead and the output terminal and would achieve the same results with a 3 post isolator as a 4 post. So with the two diodes on the isolator battery leads the only voltage the alternator sees for regulation is through the battery sense wire from the truck wiring. Try your ohm meter between 1 and 2 and A then A and E and I think you'll see what I mean. There are some alternators that self energize and they do not require the "E" terminal.

[ChairmanMeow7]

Although there is some concern about connecting to non alike batteries , as Greg mentioned , I think I am going to give this one a try. Especially seeing I am not exactly sure how to wire the 4 post solid state isolator , and no one I had look at it seems too sure either. This one seems pretty straight forward as far as wiring

As I mentioned , even the guy at the RV repair shop was trying to hook up my 3 post solid state islolator , even though I mentioned to him that this vehicle may indeed need a 4 post isolator. He seemed oblivious to this , and it still cost me over $100 for labor and the isolator didn't even get hooked up (he just told me alternator was not charging) ! I should have just got one of these for what I paid him in labor and it would be hooked up !!

I see the Cole-Hersee has 5 wires connected to it. One to each battery , a ground , a monitor (led) and boost switch. If I do get this , can I NOT hook up the led indicator and boost switch (at least for the time being) and will it still work properly ? I'm just a little concerned as to exactly where I should drill a hole trhough the firewall to bring the boost and indicator wires into the cab.

I tried looking on the Cole-Hersee site , but could not find this part #. Do you know where it is on the site ?

[Gulfstream Greg]

Although there is some concern about connecting to non alike batteries , as Greg mentioned , I think I am going to give this one a try. Especially seeing I am not exactly sure how to wire the 4 post solid state isolator , and no one I had look at it seems too sure either. This one seems pretty straight forward as far as wiring

As I mentioned , even the guy at the RV repair shop was trying to hook up my 3 post solid state islolator , even though I mentioned to him that this vehicle may indeed need a 4 post isolator. He seemed oblivious to this , and it still cost me over $100 for labor and the isolator didn't even get hooked up (he just told me alternator was not charging) ! I should have just got one of these for what I paid him in labor and it would be hooked up !!

I see the Cole-Hersee has 5 wires connected to it. One to each battery , a ground , a monitor (led) and boost switch. If I do get this , can I NOT hook up the led indicator and boost switch (at least for the time being) and will it still work properly ? I'm just a little concerned as to exactly where I should drill a hole trhough the firewall to bring the boost and indicator wires into the cab.

I tried looking on the Cole-Hersee site , but could not find this part #. Do you know where it is on the site ?

The main output lug (terminal) on the alternator which is attached directly to your starting battery by a cable actually supplies voltage to that alternator output lug. The alternator needs voltage to be seen there which tells it that a battery is there and it can put out a charge (current). When you move that cable from the battery to the solid state isolator that voltage to the alternators output lug is no longer there because the isolator blocks it. IE isolator!. The work around is the 4th (E) terminal on the isolator. It supplies that required voltage to the alternators via the A terminal. The A terminal is connected to the output lug (terminal) of the alternator. And thus the alternator will put out a charge (current).

That's why a 3 terminal isolator will not work. The alternators output lug (terminal) sees no voltage and will not output current.

Here is the wiring diagram for a 4 pole isolator http://www.toyotamotorhomes.com/technicald...eingDiagram.pdf

[ChairmanMeow7]

Greg , I see you still feel the 4 post solid state isolator is the way to go. I'm still a bit confused (sorry).

There are only 2 wires currently connected to the positive post of the battery. It IS charging. There is one heavy gauge wire to the starter , and one (a 8-12 gauge ??) wire that come out of the fuse box under the hood. It appears as though this wire is leading from an 80 amp fuse in the fuse box. This MUST b3e supplying the charge , correct ?

Now , would I unhook that wire and hook it to the alternator post of the 4 post isolator ? If not , I guess I would need to find where the charging wire leads INTO the fuse box and tap into that and hook it to the charging post of the isolator ?

If that's the case , what would prevent the (starting) battery from receiving a charge from the EXISTING wire that is charging it now ? I mean it seems like I would then have TWO wires supplying a charge to the (starting) battery , unless I need find and cut the alternator wire leading INTO the fuse box and route that to the charging post of the isolator). But then , would I still need to leave the wire coming out of the fusebox (80 amp) hooked up to the positive post of the battery and what does this wire do ?

Sorry for all the questions , but this is a little confusing to me. And as I said , I attempted to have a mechanic and a RV reapair place hook this up without much success.

[Gulfstream Greg]

There is a big wire that will come off the alternator, its the biggest one. That is the output wire. I am not 100% sure if that goes directly to the battery or if it runs through the fuse box as you say. Also what engine and year do you have? I will be starting my isolator install this weekend on our 92 V6 but will take a look at the wires tonight when I get home. Anyhow a 3 pole isolator will not work. Toyota alternators have to use the 4 pole. I will get back to you tonight with a better answer on the wires.

[Maineah]

Greg , I see you still feel the 4 post solid state isolator is the way to go. I'm still a bit confused (sorry).

There are only 2 wires currently connected to the positive post of the battery. It IS charging. There is one heavy gauge wire to the starter , and one (a 8-12 gauge ??) wire that come out of the fuse box under the hood. It appears as though this wire is leading from an 80 amp fuse in the fuse box. This MUST b3e supplying the charge , correct ?

Now , would I unhook that wire and hook it to the alternator post of the 4 post isolator ? If not , I guess I would need to find where the charging wire leads INTO the fuse box and tap into that and hook it to the charging post of the isolator ?

If that's the case , what would prevent the (starting) battery from receiving a charge from the EXISTING wire that is charging it now ? I mean it seems like I would then have TWO wires supplying a charge to the (starting) battery , unless I need find and cut the alternator wire leading INTO the fuse box and route that to the charging post of the isolator). But then , would I still need to leave the wire coming out of the fusebox (80 amp) hooked up to the positive post of the battery and what does this wire do ?

Sorry for all the questions , but this is a little confusing to me. And as I said , I attempted to have a mechanic and a RV reapair place hook this up without much success.

It's not wired right wait until Greg gets his wired with pictures.

[Gulfstream Greg]

The alternator wire definitely does go to the fuse box. I think on my rig its the big white one but will not know for sure until I can unbolt the fuse box, disconnect the battery and disconnect the alternator wire from the alternator. I will be able to trace the wire then. Here are some images. The alternator output post, and the old style solenoid and breaker (to the left). More to come but dinner duties are upon me.

[ChairmanMeow7]

Greg , that definately looks like my (old) setup , right down to the gold battery post ! But I currently only have 2 wires connected to the positive post. The one from the 80 amp fuse and the starter cable. The new isolator I installed under the hood is NOT hooked up (and I guess is useless anyway seeing it's a 3 post isolator). And there was only 3 wires hooked to the poitive terminal when I got it (including the isolator wire). I see you have a 4th wire hooked to the positive post. What is this wire , and what does it do ?

[Gulfstream Greg]

We bought this Gulfstream about 2 months ago so I am just now tracing all the added wireing. On the positive post there are 4 wires. The one from the 80 amp fuse is sorta under all the others (red and black). The large red goes to the isolator solenoid. The black wire I just traced and it runs to a added cigarette lighter outlet at the cab over bunk, I might add it was not fused. The smaller red wire, I don't know. I am just now putting in my solid state isolator and will trace the red wire some time today. Its added in, not a toyota original wire.

I am just about 100% wired, just have to tap into an ignition circuit for the "E" post on the isolator. I won't go into details just yet as how I have done it all. I have taken pictures all the way through so far. Some modifications to the inside of the fuse box (on the 92 V6) are needed to do this correctly. It will take awhile to put the story all together with the photos and its doubtful I will get to that today. Maineah has written an excellent write up on the solid state isolator and so we are going to join together. I will post here what I have done so far but we will eventually create a new thread which will become a sticky in the "Tech Issues" forum.

Lunch is over - back to work!

[Gulfstream Greg]

I can now verify that if everything is wired correctly you must use the 4 pole isolator. I did a test with out hooking up the 4th "E" pole to the ignition, there is no output from the alternator with the engine running and the "No Charge Battery Icon" on the dash is on. With the 4th "E" pole connected to the ignition on circuit the alternator then has output and the charge icon on the dash is off.

I am off to a Birthday party. Check back tomorrow for a photographic update!

[ChairmanMeow7]

I thought the small blue wire to the center post of the old mechanical isolator WAS the ignition wire (on mine it's white) ? From what I am reading , you say you needed to tap into the ignition wire. So what is the 3rd wire that went to the old mechanical isolator , and if I do opt for the 4 post solid state one , I assume this wire will not be used or taped off ?

[Gulfstream Greg]

I thought the small blue wire to the center post of the old mechanical isolator WAS the ignition wire (on mine it's white) ? From what I am reading , you say you needed to tap into the ignition wire. So what is the 3rd wire that went to the old mechanical isolator , and if I do opt for the 4 post solid state one , I assume this wire will not be used or taped off ?

The 3rd wire is your ignition on circuit. The color of the wire is just what ever the coach manufacture used when they installed the solenoid. You will be able to use that wire on the 4 pole isolator, it will go to the "E" pole. I did not think my 3rd wire to the solenoid was working but it turns out it is so I have used that blue wire for my ignition to the "E" pole.

I just uploaded several images from the project into the gallery, click here to see ISOLATOR. Note though that the wire labels will be some what cryptic to you until I put together the text for it all.

[ChairmanMeow7]

Greg , would the pics and instructions ONLY apply to a V-6 ? Or would the wiring 22-RE be the same ?

[Gulfstream Greg]

Greg , would the pics and instructions ONLY apply to a V-6 ? Or would the wiring 22-RE be the same ?

I don't know. The 4 cyl fuse box might be the same or similar. I have been overwhelmed with projects right now so I have not been able to sit down and complete the blow by blow instructions.