40 to 100 amps charging from tow vehicle

[CA_Tallguy]

Originally Posted by Jammer

Be careful. The alternator output stud can break off over time as a result of vibration stress from oversized cable, especially if the cable is not tied security in place at the alternator. Remember that there will be some relative motion from torque flex in the motor mounts, so leave a loop where you go from the engine to the body or frame, and be sure the cable is well secured. I use neoprene-covered steel strap tiedowns for cable this large. Having the output stud break off will end your trip early unless you carry a spare alternator around with you. You may be able to get a custom alternator with an oversize output stud.

Thanks... Good ideas. I hadn't thought of that added stress. Can I get the neoprene straps at Home Depot? I've wanted to pick some of those up for awhile but keep forgetting to look and/or have not come across them when shopping for other things.

I'm not 100% sure how the wiring to be alternator is going to work yet. It appears my alternator has a little black regulator box on the side and the positive and negative plus a few small wires run through it. Need to figure out if I should tie into the positive after the regulator or before (on the alternator stud). That's one question I was going to ask the maker. On one hand, the unit contemplates using the OEM regulator so I would think it might need to be in-line. On the other, seems like some directions say to wire directly to alternator post. The latter would mean the regulator wouldn't be sensing any amperage -- not sure it if needs so but since it is in-line I thought that might be a reasonable guess.

I have a few wiring plan alternatives I'm thinking over aside from that. One would be to pick up the charging line after the 140 amp OEM fuse, leaving the 4ga OEM wire run to there in place. The other would be to beef up the above run to 2/0 and still pick it up at the fuse block to go to the charging unit.

[CA_Tallguy]

Originally Posted by Wabbiteer

I think I found your vendor, or a similar one? A rare series of 140 piece auctions, and yes, copper-lust here bought one with the huge lugs they advertised swapped for smaller sizes – for 80¢ each! I’m not expecting much for those prices but may be perfect for a house battery bank in the future.

I bought several sets of lugs from different people and tried to get them at $1 on average. Seems like most sellers were wanting $3+ for decent brands etc. 95% of the stuff I got is name brand... I spent far too much time shopping for great deals on them to get an assortment to have on hand. I didn't want to end up going to napa auto parts for some random crappy lugs costing 3 to 5 each finding it I was missing something I needed during the install.

Originally Posted by Wabbiteer

Getting odd-lots of lugs is a compromise If the bolt holes are way oversized for the fasteners, the washers will cave in to the void, maybe all at once or maybe over time and loosening the connection....

Thanks for the notes on washers and caving in. Will be careful about that.

Some of my lugs are large holes but most are 3/8 or smaller. 1/2 is the max hole size. I think the holes on the charger were 5/16 and I set out to try to find some specifically for that. Tried to avoid 1/4 holes as I thought that to be too small for most needs I'll have (but there is the potential for drilling holes bigger). Many lots I got were of one type, and when I got an assorted set, I usually tried to make sure it had a few sizes I was looking for.

Originally Posted by Wabbiteer

Automotive/marine systems are usually in constrained spaces, those lugs are full size. If you need to round off a corner(s) do so but leave the lug flat greater than the diameter of the washer by as much as you can

GREAT idea! I also have been thinking some of these lugs have room to bend to right angle if needed.

[CA_Tallguy]

Doing a little bumper refurb and modification to add a mounted anderson connector. Getting close to wiring the system up! In the next few days.

Been distracted by some frame repairs on the trailer.

[CA_Tallguy]

The install now commences! Whew, took a long time to try to insert the 2awg welding cable into the thomas and betts #2 lugs. Didn't quite get all the strands in unfortunately.



My first task is to try doubling up the factory alternator wire to the factory 140 amp fuse. It looks like the positive and negative leads run through the external factory alternator regulator so I am unsure how this will work out. Not sure what the regulator is doing with those leads... Hopefully not much. As hey run through, that leads me to wonder if it is measuring current. Hope it doesn't or that it doesn't need accurate current measurement if it does.

Doubling up the wire was an idea I got from instructions for big output alternator installs. Many said to double the wire and leave all the factory wire/regulation alone.

I'll watch the Sterling charging unit control panel closely for any weirdness on how many amps it is getting.

[CA_Tallguy]

Whew. Probably a but more than half way done with the wiring. Ended up drilling a big fat hole in the truck cab over the transmission to run the 2/0 back to the bumper for the trailer connection. I was able to get the other wires in pretty good through an existing firewall hole.

After the fact, I realized the starter is right below the installation point with a big fat 2/0 or so positive cable. Maybe I should have tapped that for the charging line to the truck battery from the unit.

On the truck end, I'm thinking about using the negative chassis ground quite a bit. The manufacturer said that would be fine. So, just after the anderson connector on the bumper, I'll likely just ground to the frame rail.

For the ground on the unit itself, there is a 2awg or so pigtail that needs to be extended. I am thinking I will stick with that size. I don't know dc current very well but I was thinking... That ground serves both incoming (from the alternator) and outgoing purposes (truck and trailer batteries). So, if anything is coming in or out, current wise, isn't it a wash or close to a wash for the ground? Just wondering for wire sizing reasons. Logically it would seem to have to be the case. So a big wire is probably not needed. (But hmmm.. Just testing the logic... That would seem to say that a #18 would work and that just seems out of the question. So still a but unsure.)

[CA_Tallguy]

I think that I've gained a couple tenths of a volt increase from doubling the alternator positive. So far so good. Everything seems to be behaving normally otherwise.

This has me second guessing my idea to use the factory 140 amp fuse on the incoming alternator cable. That fuse is pretty wimpy and is probably adding to voltage drop. I will file this away for now and circle back if the need arises. Or maybe I'll just keep that as a fuse on the truck batteries and put another fuse in place on the incoming alternator power.

One thing I've been reading on the boating forums is that those folks don't always fuse the alternator. Something about it being self limiting and that it doesn't have the stored energy that the batteries do. They point out that the alternator can only unleash the power it is generating so like 100 amps or whatever. Also that the diodes would blow in it. Seems like I'd rather try to have a fuse blow than something in the alternator... or this Sterling charge unit. Either way, some serious work would be needed while underway to have a functioning charging system again vs just replacing a fuse. That is assuming that a fuse would be functional in this capacity.

[CA_Tallguy]

A very helpful person in the boating community called "Maine Sail" explains...

"Even if the alt continued to work it can not exceed its rating. This is called a "self limiting device. The wire is sized to handle 140A continuously so the wire can handle all the alternators current safely and no fire. The max allowable ampacity of 2/0 wire, inside an engine space, and under ABYC E-11 is 420A @ 150% and 280A @ 100%. So the alt can't even touch with wires max ampacity with its 140A.

What the wires can not handle is the short circuit current that can be created by an AGM battery bank. With some AGM batteries this can approach 5000A of short circuit current for each parallel wired battery. As single group 31 AGM by Odyssey/Die Hard is capable of 5000A of current into a short. 5000A for just one battery!!!! If you have a bank of four, 400Ah, this is 20,000A. Your alt is still only 140A into a dead short........ The batteries are not self limiting and can easily exceed the capability if the wire, the alternator can not exceed this.."

http://forums.sbo.sailboatowners.com...d.php?t=154643

[CA_Tallguy]

Unexpectedly, the shunts took the most effort to install thus far. Trying to cram them behind the unit was part of it... Tried horizontal, then vertical, and finally diagonal - the cable needed plenty of room on each end. And then four big crimps were needed for the pair. Finally, attaching the small gauge voltage sense wires and then fumbling with the dozen TINY screws for attaching them along with the plexiglass covers. Ugh!

But I am excited to see it coming together. I believe I have all the cables and wires roughed in for hooking up the unit. A few more lugs to crimp in the cab, and the anderson connector on the bumper. Oh, and I have a three conductor wire to hook up back there too (one voltage sense for drop and two for the trailer battery temp). Voltage will be the positive lead in my seven way connector and I have a simple two pole rubber connector for the other two.

Then I still have to do the trailer side. Should be extremely simple compared to the truck... Just a pair of 2/0 into an anderson with lugs on the other side to fuse and battery bank. And of course the same three wires for voltage drop sense and temperature on the battery bank.

This thing better work! It will be a major bummer if there is any manufacturing defect requiring warranty repair before I can see it run.

[CA_Tallguy]

First Anderson crimp! The Anderson 2/0 connectors fit the wire a LOT better than the other standard lugs. I'm guessing that portable power cord is bigger than standard wire by a smidge. The 2/0 barely fit the hole for the sb175 connectors. They normally only take up to 1/0 but anderson has a terminal you can buy to make 2/0 work. The fit is so tight I worried the heat shrink would get in the way. I used smaller diameter heat shrink than I otherwise would have to reduce the bulk it would add.

[CA_Tallguy]

Bumper repainted and anderson connector installed permanently. Unfortunately I can't test it yet for clearance as the only other installed anderson connectors I have are blue, and they are not compatible with other colors. I did do a test fit with the blue and clearance was tight for the handle I am going to use to connect the trailer cables. So, still a bit anxious until I can confirm the final install.



For the ground behind the bumper, I sanded down to bare metal on an area of the frame for the crimped lug to contact. Then I buttered it up with antioxidant and bolted it together with stainless 1/2 inch hardware. Then I covered it with vulkem. That should do the trick!

[CA_Tallguy]

It works! At least the first test without the trailer hooked up. I still need to make an umbilical to wire the trailer batteries up. But it fires up and the control panel is putting out useful info about the alternator and truck batteries.

The unit said the truck batteries were getting about 30 amps at first but that quickly dropped to about 20-22. All this is just at idle. I suspect the batteries don't need much at the moment, just a quick boost to recover from starting. Turning on the headlights caused a 10 to 12 amp increase in both alternator output and amps going into the truck electrical system.

Now the real test will be with the trailer hooked up. I'm very curious what I will get at idle back to the trailer bank. This charging system is supposed to put a load on the alternator, so just like turning on the headlights, it should have no problem pulling a decent amount of amps back to the trailer even at idle.

That's kind of one of my ultimate scenario for doing this -- being able to idle at rest stops or whatever to juice up the batteries if I need power to watch satellite! Currently, I keep one eye on the tv and one eye on my voltage meter and there are times I have to shut it down if I haven't collected enough solar power during the day. Especially if I have to run the furnace.

With this system, I should never be at a loss for power. Well, except in the case of the AC.

[CA_Tallguy]

Back from a test drive... Couple of surprising things watching the control panel and data from the shunts.

One, there was absolutely NO discernible difference in alternator output based on speed of the vehicle. Of course, this may (probably) change if the alternator was being taxed. Basically, as the specs on alternators show, the capacity depends on higher rpms. But I was surprised that there wasn't any difference from idle for normal loads. The only impact to the amps was based in loads, which brings me to my second point...

These little alternator devices are pretty remarkable! I was shocked at how it seemed to almost instantly react to any load put on it! Brake lights, windows, etc all nearly instantly showed up in current crossing the shunts! In fact, I could see a difference between rolling the windows down vs up! It was so fast that I'm almost surprised I didn't see vacillation in blinkers.

Well so far, so good. Tomorrow I should have a chance to finish trailer wiring so we'll see what it does with that connected. I'm hoping for at least 25 amps at idle, and based on what I've seen so far, I don't think that will be a hard target to beat. I figure headlights and trailer lights alone must pull 20 amps, which the alternator certainly handles at idle just fine. So that capacity (and hopefully much more) should be available for trailer charging when at idle and those systems off.

[CA_Tallguy]

HOLY cow! 96 amps at IDLE!!!! Yes, that's right! NINETY SIX amps at IDLE!

(DOM is for "domestic" which is what the unit calls the trailer battery bank)

Just like the unit advertised, it pulled down the truck battery voltage to 12.9 or something and that made the alternator work close to capacity. I just was surprised to see the full effect even at idle.

[Kyle401]

Have you had a chance to measure the voltage delivered to the battery bank? That appears to be outstanding performance. How long does output stay high before the current begins to taper?

[CA_Tallguy]

I have not measured at the bank in the trailer yet but it is supposed to compensate for voltage drop. There is a sense wire running back to the unit so it knows how much the drop is, then it boosts to compensate. I did press the "full/empty" voltmeter button on my 70s control panel and the needle went all the way to the right like it does when the regular charger/converter is working.

Today I just started the truck and let it idle for 30 minutes or so. It has a routine it goes through -- I think the first 5 minutes of run time are focused on making sure the truck/starter batteries get what they need, then it switches over to focus in trailer batteries. I think it was about 60 amps to the trailer for the first 5 min then it went to 96. The first 5 minute think can be overridden if desired to immediately go I to trailer charging.

Every 20 mins it is supposed to pause and check the starter batteries to make sure they are full. It also has temp sensors on the alternator and trailer batteries so it can adjust what it is doing if either seems to be getting too much action.

The charger runs a multistage charging program to take good care of the batteries. I think towards the start of the tread I posted a marketing graph from the company. I don't think the detail level is great on it, however. It didn't show the 20 minute pauses for example.

[CA_Tallguy]

Well I may need a bigger alternator! I made an assumption when buying the 210 amp charger vs the smaller 160 amp charger that it would work fine with my smaller alternator for the time being, and I would just have extra capacity if I decided to upgrade the alternator later. Well, the system is VERY effective in milking amps from the system so today when I hooked up the trailer to do more testing I decided to rev the engine (the trailer is up on blocks in my workshop at the moment). The amps jumped up (140 to the trailer!) and it seemed like the alternator was working AT capacity. The temp probe on it soon showed it was overheated.

Now, I think there is a workaround for now so it isn't the end of the world. The system also kicked in and disengaged as it is supposed to.

Also, keep in mind my batteries are far lower than they normally would ever be while underway, so this situation may not present itself very often anyway. Glad they were low for this testing, however, so I can understand this better.

And, consider that this was revving at idle, so there was no extra airflow through the engine compartment like there would be underway. I don't think it is going to overheat the alternator at normal idle and 100 amps or so charging to the trailer (it started off today at 110).

One thing that surprised me is that when the system disengaged, the trailer was still drawing like 60-70 amps! I thought system disengaged meant that the batteries would be disconnected and the truck would revert to only handling it's own needs. My theory, which I need to confirm with the maker, is that it acts as a combiner when it isn't doing the voltage boost thing in normal operation. And the high amps going back was a result of the beefy wiring I've done.

That gets back to the point of the system anyway -- it's really designed to speed up charging to get the max benefit when the engine is running. And, to be able to fully charge the batteries with the voltage boost whereas you can never fully charge with an alternator and long wiring run otherwise. It seems there is still plenty of charging that can happen without the boost when you have this extra big wiring and low battery levels.

So my workaround for the undersized alternator may be to just turn off the system when batteries are very low like this to let them come up with some bulk charging and equalizing with the truck batteries. That will hopefully keep the alternator working at no more than 60-65% capacity. This may ONLY be needed while underway and when batteries are at an exceptionally low state of charge. Then I can turn on the system to charge beyond where this workaround is effective and the batteries won't need to suck as many amps. Again, I think the normal boost will be fine with my alt capacity for charging at idle.

I had been counting on a disconnect function, however, for times such as climbing mountains when I didn't want any extra load on the system. Well, I guess I can always manually unplug if I really really am desperate.

[slowmover]

Probably mentioned and likely already known by the PO is that some OEM's offer dual alternator packages for some light duty and medium duty trucks (4500 -5500 series) and not just an oversized alternator. I've bookmarked the "ambulance package" single alternator for my pickup R&R at some point. The aftermarket offers some dual alternator packages as well, but I'd sure prefer an engineered approach (as I'd be as worried about bracketry as about alternator quality). This thread will help determine my path.

LEECE-NEVILLE was part of the DODGE Police Pursuit Package in the late 1960's and forward. I recall some RV'ers wanting that just for this kind of purpose . . but the price can be daunting, now as then (and another reason big engines [440, 454 & 460 cid] were popular with the trailering crowd: could easily run air-conditioning and had the biggest alternator. Which back then was the mind-blowing 60A configuration, ha!)

Great thread, good work, and look forward to more.

.

[CA_Tallguy]

Thanks Slowmover - good to hear your thoughts on Leece-Neville. I had come across a DIY on how to install one of those into a Dodge Cummins but I have not learned a whole lot more about them.

I've been meaning to come back to post some follow up about the system now that I have about 1500 miles experience with it. This was pretty much a "lets get there" trip scenario with overnights in rest stops and walmarts so there are certainly many other scenarios still to be tested.

The unit performed quite nicely and provided the quick charging of the battery while parked on those nights. The weather was quite cold (you may have heard about the texas ice storms) so it was nice not to have to worry about 12v power. The furnace was blasting and I had my TV on many hours, even leaving the Dish Hopper DVR on overnight to collect some recordings. I did go out and run the truck engine for about 30 minutes to recharge the batteries before bed and while out walking the pooch.

That was the main scenario I was envisioning when going all out to setup this crazy system. It was clear to me, watching the control panel numbers, that the system capacity is FAR above what someone would need to get good charging of batteries over slightly longer periods -- or with a smaller battery bank. My large battery bank was getting fully charged in about 2 to 3 hours of driving in the morning. I'd say maybe 90 to 95% charged in the first hour alone.

I'd also estimate that probably 90% of the improvement I've seen is from the beefy wiring I've done. Inserting the charge controller into the mix really only benefits the setup in very specific scenarios like being able to top up the batteries in those rest stops as quickly as possible. If you are like me and have reasonably long driving days when the trailer can get long periods of charging, there isn't as much need for super ultra fast charging (just the complete charging that these types of units can provide).

One thing I ponder is how the system would have worked with less beefy wiring and a less beefy charge controller. For anyone else considering stuff like this, you might look at the Balmar Duo Charge (30 amp rating), Xantrex Echo Charge (15 amps), the CTEK D250S (20 amps base but they have an expansion module) -- and of course, I recommend people check out the Sterling products (also sold under ProMariner brand). Sterling has units at 40, 130 and 210 amps.

You could probably insert one of the smaller units into your 7 way connector to get faster and more complete charging of your trailer batteries. The larger units should be run through a separate connector. The main problem to solve would be setting it up to limit the amount of current that can be pulled by the trailer at once as appropriate for the size wire you want to use.

One thing I also wonder is how its possible that these 7 way connectors are not melting when people have them hooked up to directly connect a big battery bank in a trailer to the tow vehicle charging system. I was SHOCKED by how many amps were being pulled through my fat cabling even when my charging system was deactivated. I know the wiring does limit how fast the current can move, but wow, my batteries wanted to suck many, many amps down my fat wire and it would seem that any big battery bank would still want to pull those amps over a 7 way! So if you have a big battery bank, you might want to think about this.

I know that some of the smaller units I mentioned, in particular the Balmar, have ways to hook up a solenoid so if a big battery bank wants a lot of amps at the start, that just activates to parallel the truck/trailer batteries. Then the Balmar unit kicks in once the amp draw comes down to handle the tail end charging. I could see how that could work pretty well. Still wouldn't have the fast charging I get with the 220 amp sterling unit, but I'd think it would work pretty well (but I'd think you would still need pretty big wiring unless you can limit the current draw somehow). And Sterling does have smaller capacity units as well but I can't tell you how they handle that scenario.

Anyway, just wanted to get some of that info dumped out of my head in case anyone was wondering how it was going. Feel free to ask questions in this thread and I should be around to answer them now and into the future.

[Jammer]

Originally Posted by CA_Tallguy

I'd also estimate that probably 90% of the improvement I've seen is from the beefy wiring I've done.

+1

One thing I also wonder is how its possible that these 7 way connectors are not melting when people have them hooked up to directly connect a big battery bank in a trailer to the tow vehicle charging system. I was SHOCKED by how many amps were being pulled through my fat cabling even when my charging system was deactivated. I know the wiring does limit how fast the current can move, but wow, my batteries wanted to suck many, many amps down my fat wire and it would seem that any big battery bank would still want to pull those amps over a 7 way!

The 7 way connectors are rated for 30 amps.

Typically, the alternator delivers 14.4 volts and the battery charges at around 12.5 volts. When enough current flows that the voltage drop in the charge circuit wiring (tow vehicle and trailer combined) reaches 2.1 volts, the system is in a state of equilibrium. With stock wiring that will usually occur at less than 30 amps with some occasional brief excursions up to higher currents that don't last long enough to cause the connector to overheat. The exact voltages involved vary based on a whole bunch of things but the overall effect is usually the same.

When you upsize the wiring, there is a greater risk of overheating the connector. I have 6 gauge wire on my main tow vehicle and have switched from a 7 way to a 6 way connector because of the slightly higher current rating. The 6 way connectors have their own problems and I don't recommend them, and will switch to a 7 way pin type (the kind used for semis) when it fails.

[CA_Tallguy]

Well folks, looks like I may dismantle this system and sadly I didn't get all that much use out of it over the last few years. Some health issues (now behind me) along with building a man cave type thing at Texas Airstream Harbor have kept me off the road. I just purchased a Mercedes GL350 and am looking to set it up as my new tow vehicle and I don't think that I want to try to modify that electrical system to the extent I did for the system described prior to this post in my Dodge truck.

Instead I may go for a "battery to battery" type charging system with the goal of getting maybe 60 to 100 amps back to the trailer over smaller wiring. The HUGE amperage of my prior system is too much. I do have a 220 amp alternator in the Mercedes vs 140 in the old Dodge but I just feel like it would be good to max out at drawing around 100 amps from that. Maybe 120/140 for the first few minutes of bulk charging. But in any case, a far more reasonably sized system.

I do want to be able to top off my batteries quickly by idling the engine for short periods. So still some hefty amps, but not insane. One nice thing is I can start the Mercedes with an app on my phone so I'll be able to kick off charging without even leaving the trailer. Hmmm.... I wonder if I can kill the engine though? I have not yet tried this app so will have to find out. Guessing that they probably didn't implement killing the engine because I can see how that might present safety issues if someone on an app tried killing the engine of a vehicle that someone else was using.

Anyway, I'll likely be updating this thread with some new info in the coming weeks/months... depending on how soon I decide on what I want to do.