AMP-L-START compatible with Battleborn lithium batteries?

[jeegro]

I'm looking at the AMP-L-START to maintain my starting batteries. I'll be running a Redarc BCDC and a Battleborn lithium.

The AMP-L-START specs say that the unit is 'on' when voltage is >= 13.2. Correct me if I'm wrong, but isn't the Battleborn fully charged resting voltage 13.5+V? I don't want the AMP-L-START to turn on unless there is adequate solar coming in.




AMP-L-START: http://www.lslproducts.net/ALS_Overview_Page.html

From the page: "...compatible with all battery types - Gell-Cell, AGM, "Maintenance-Free" and conventional flooded-cell."

Lithium not mentioned.

 

[LivinDaDream]

I have been using a Battleborn 100Ah battery for a while now and I see about 13.32V when fully charged with no or very minimal load.

When my solar system is charging the BB battery, I'll see voltages up to just below 14.5V just before the solar charge controller curtails charging. From the sound of it, the unit you're looking at will try to draw power from the BB until the pretty far down the discharge curve...which is more of a flat line than a curve.

Seems like you might have to put a manual switch or V sensing relay to control power to AMP-L-START if you only want it to operate when you have solar operating.

 

[DiploStrat]

This is the major conundrum with all voltage sensing devices intended for use with lead acid batteries; the resting voltage of a lithium battery is higher.

Most VSR devices work on numbers like these:

Full Charge: 12.7 - 13v
Charge source present: 13 - 14.xv.

So they disconnect at around 13v to prevent the discharge of the source battery and connect at 13+v on the assumption that the source battery will only be over 13v when there is a real charge source connected. (The exact numbers vary a bit and some add a time delay.)

Real world? For your main connection to your start battery, these voltages probably won't work., This is why Victron sell their own VSR with higher voltages and some folks go back to a key controlled relay. Of course, with a B2B (Sterling, REDARC, etc.) this is not a problem.

For a trickle charger? Probably not a real problem as the actual amp draw is very limited and remember, in a camper, the batteries are rarely "resting." You probably have background draws, e.g. your refrigerator, running all the time, so even with a lithium battery, the actual voltage may be down a bit. (Danger Will Robinson! NO personal experience.)

Another option is the Magnum Smart Battery Combiner. I used one of these on my last truck and you can set the combine voltage to well above 13v and the disconnect voltage any where you want. It passes up to 25A natively and can be used to control a relay if you need to pass more. Also offers a remote voltage sense option. Not cheap, but may do what you want. http://www.magnum-dimensions.com/si.../SBC_smartbatterycombiner_data_sheet_revb.pdf

I certainly would not run a VSR or a manual switch with the AMP-L-START - No point in paying twice for gear to do the same thing.

 

[jeegro]

I have been using a Battleborn 100Ah battery for a while now and I see about 13.32V when fully charged with no or very minimal load.

When my solar system is charging the BB battery, I'll see voltages up to just below 14.5V just before the solar charge controller curtails charging. From the sound of it, the unit you're looking at will try to draw power from the BB until the pretty far down the discharge curve...which is more of a flat line than a curve.

Yes, this is my concern

Seems like you might have to put a manual switch or V sensing relay to control power to AMP-L-START if you only want it to operate when you have solar operating.

Too complicated, but I understand the logic.

This is the major conundrum with all voltage sensing devices intended for use with lead acid batteries; the resting voltage of a lithium battery is higher.

Most VSR devices work on numbers like these:

Full Charge: 12.7 - 13v
Charge source present: 13 - 14.xv.

So they disconnect at around 13v to prevent the discharge of the source battery and connect at 13+v on the assumption that the source battery will only be over 13v when there is a real charge source connected. (The exact numbers vary a bit and some add a time delay.)

Real world? For your main connection to your start battery, these voltages probably won't work., This is why Victron sell their own VSR with higher voltages and some folks go back to a key controlled relay. Of course, with a B2B (Sterling, REDARC, etc.) this is not a problem.

For a trickle charger? Probably not a real problem as the actual amp draw is very limited and remember, in a camper, the batteries are rarely "resting." You probably have background draws, e.g. your refrigerator, running all the time, so even with a lithium battery, the actual voltage may be down a bit. (Danger Will Robinson! NO personal experience.)

I certainly would not run a VSR or a manual switch with the AMP-L-START - No point in paying twice for gear to do the same thing.

Agreed on not running a VSR + amp-l-start.. too much

I don't have any constant loads really other than the fridge. I get by okay right now with a 68ah AGM house battery, so I'm thinking I'll be above 70% SoC most of the time with the lithium, and do not want the AMP-L-Start pulling the lithium down to 70% on its own.

My concern is according to the BattleBorn specs, 13.2v is around 70% SoC. so 13.2 sounds like too low of a number to use for the trickle charger.

I sent an email to them last night, and received a quick reply, but it doesn't really address my concern:

Yes, the AMP-L-START is compatible with LiFePO4 house batteries.

BattleBorn recommends a fully-charged "float" voltage of around 13.6
volts - which is real close to the ideal 13.5 "float" voltage of
conventional lead-acid starting batteries.

When operating on solar, your BattleBorn house battery will get priority
for recharge. The AMP-L-START will not begin to maintain your starting
battery until late in the recharge process - which is fine, because your
house battery is the one that usually gets deeply discharged while
dry-camping.

Another option is the Magnum Smart Battery Combiner. I used one of these on my last truck and you can set the combine voltage to well above 13v and the disconnect voltage any where you want. It passes up to 25A natively and can be used to control a relay if you need to pass more. Also offers a remote voltage sense option. Not cheap, but may do what you want. http://www.magnum-dimensions.com/si.../SBC_smartbatterycombiner_data_sheet_revb.pdf

This looks like a better solution. The adjustable voltage setting seems like the key. Only 40 bucks more than the AMP-L-START. The 25 amps is a bit overkill though. Installation looks the same as the AMP-L-START. Though I'd prefer the simplicity and lower amp draw of the AMP-L-START.

My truck has a 'superlock' security feature which electrically deadbolts all doors. So if the battery is dead, I can't even get in the truck to flip the ML-ACR combine switch. Plus my land rover has some electronics that are always on. Purpose of the trickle charger is peace of mind to make sure the vehicle electronics can never die

With either units, in theory the REDARC will take green priority of the solar so it doesn't create an endless charging loop with the trickle charger, but who knows, this setup might confuse the REDARC?

 

[DiploStrat]

You are, to a degree, trying to over think this.

The folks at Battle Born have a good reputation of telling the truth about their products. The AMP-L-START and the TRKL-L-START are just solid state voltage sensing relays. The TRK-L-START just passes less amperage and thus might be perfect for your use.

Similarly, the Magnum SBC is simply a user adjustable VSR. I used one for a couple of years on my Tiger, controlling a 200A relay. Without a relay it can only pass 25A through its solid state relay, so this would be perfect for what you want to do. The actual amperage that passes will depend on the state of charge of the target battery, limited by the capacity of the relay. In any case, the AMP-L-START will open before your lithium camper battery is fully discharged.

Remember, a refrigerator is a serious load, so the voltage on your camper battery is always going to be down a bit. And, by extension, the REDARC always tries to keep the voltage up as long as the engine is running or this is sunlight. People worry that a lithium battery doesn't need a float. It doesn't for the battery, but a good solar controller will try to keep the voltage up a bit so as to cover your loads without discharging the battery.

I is possible that you might create a feedback loop with the AMP-L-START, but I doubt it - you are unlikely to pass enough amperage to worry about. (This is a doubt, I have no proof.) If you are REALLY worried, I can send you a wiring diagram of how I use two REDARC BCDC's with a pair of relays to turn off the feed to the starter battery when the engine is running. (AKA the "Twisted Sister" (tm) wiring diagram.)

 

[LivinDaDream]

This is the major conundrum with all voltage sensing devices intended for use with lead acid batteries; the resting voltage of a lithium battery is higher.

For a trickle charger? Probably not a real problem as the actual amp draw is very limited and remember, in a camper, the batteries are rarely "resting." You probably have background draws, e.g. your refrigerator, running all the time, so even with a lithium battery, the actual voltage may be down a bit. (Danger Will Robinson! NO personal experience.)

A data point with regards to background draw in my particular camper (Lance 815). In my case, background draw is 1.2 watts...that's with the refrigerator off and no 12V DC devices plugged in, other than things that are hard-wired as part of the camper, ie, monitor panel, wireless jack control, etc. There are also two hard-wired, dual USB charging outlets that I added and I know those draw a few milliamps each. I don't have a radio or other entertainment devices installed that can have some background consumption, so nothing there. My older Norcold refrigerator drew about 10-11A constantly...100% duty cycle, but the new Vitrifrigo draws an average of 3.8A on a 25%-33% duty cycle, depending on temp and time of day.

For the last couple weeks, with the camper sitting where I park it, I've been logging my system parameters to get a feel for how it performs overall...both from a solar charging standpoint with various conditions and how much power is consumed by lighting, fan, charging devices and operating a fairly high performance laptop for photo and video editing. The last 24 hours (11am to 11am) saw a total power consumption of 198Wh with 169 of that being the refrigerator and 29 for "other" background loads. Granted, it was a cool night, but that's my absolute minimum baseline usage...and it being a totally clear day here, the two 100W solar panels had it topped off before I took readings at 11am.

To the OP's original question, I don't leave my truck batteries and the house battery connected when I'm not driving...no reason to do so, though the camper does have a built-in LVD that disconnects the camper from the truck when voltage gets below 12.8V and reconnects when above 13.2V. Though I haven't monitored how much power will flow into the starting batteries when they're fully charged, at rest they'll certainly be well below the Lithium battery until it would get near the end of it's discharge curve and I'd guess substantial current would flow into them. Given that when connected, the voltage the LVD reads is going to be the voltage of the Lithium battery, minus any voltage loss due to current flow in wiring between the Lithium battery and the LVD, the LVD will not disconnect until the Lithium battery is a good ways down the discharge curve.

So yes, devices that take this situation into account seem like a solution...but what is the problem? Is your starting battery weak...will it not start your truck after sitting a few days or weeks? Seems like a lot of expense and additional points of drama/failure to solve a non-existent problem...unless you see yourself relying on the starter battery to meet some of your power needs while camping.

 

[jeegro]

You are, to a degree, trying to over think this.

The folks at Battle Born have a good reputation of telling the truth about their products. The AMP-L-START and the TRKL-L-START are just solid state voltage sensing relays. The TRK-L-START just passes less amperage and thus might be perfect for your use.

Similarly, the Magnum SBC is simply a user adjustable VSR. I used one for a couple of years on my Tiger, controlling a 200A relay. Without a relay it can only pass 25A through its solid state relay, so this would be perfect for what you want to do. The actual amperage that passes will depend on the state of charge of the target battery, limited by the capacity of the relay. In any case, the AMP-L-START will open before your lithium camper battery is fully discharged.

Remember, a refrigerator is a serious load, so the voltage on your camper battery is always going to be down a bit. And, by extension, the REDARC always tries to keep the voltage up as long as the engine is running or this is sunlight. People worry that a lithium battery doesn't need a float. It doesn't for the battery, but a good solar controller will try to keep the voltage up a bit so as to cover your loads without discharging the battery.

I is possible that you might create a feedback loop with the AMP-L-START, but I doubt it - you are unlikely to pass enough amperage to worry about. (This is a doubt, I have no proof.) If you are REALLY worried, I can send you a wiring diagram of how I use two REDARC BCDC's with a pair of relays to turn off the feed to the starter battery when the engine is running. (AKA the "Twisted Sister" (tm) wiring diagram.)

Thanks for the insight.

I think the way to go is the TRIK-L-START - worth trying anyway, for its simplicity. All I need it to do, is guarantee enough juice to unlock the doors. I'll take out my CTEK 25 amp permanent install, and use it as a traditional portable charger to top up the AGMs every now and then at home.

So yes, devices that take this situation into account seem like a solution...but what is the problem? Is your starting battery weak...will it not start your truck after sitting a few days or weeks? Seems like a lot of expense and additional points of drama/failure to solve a non-existent problem...unless you see yourself relying on the starter battery to meet some of your power needs while camping.

Like I mentioned above, my truck has a 'superlock' mode, which electronically deadbolts the doors. If the battery is dead, you can't open the doors, even with the key. I also have an OwlCam security camera that runs 24/7, draws about 0.5-1amp, and runs off the OBD port. Yes I could make an adapter and power that off my lithium instead, but rather not mess with the warranty and the TRIK-L-START will - hopefully - kill both birds.

Even with dual AGMs and ML-ACR up front, there's no way I can solve this problem. I have one agm hooked up the starter, and the other connects to the vehicle fuse box. I need to guarantee that both batteries cannot die, and the TRIK-L-START is the only way I can think of.

Another idea I suppose would be to install a hidden ML-ACR combine switch accessible from outside the vehicle. I might eventually get rid of the ML-ACR though, we'll see. Nice feature to have, but makes less sense with the lithium now.

An adjustable TRIK-L-START would be ideal. The magnum is kind of overkill.

 

[DiploStrat]

...
Another idea I suppose would be to install a hidden ML-ACR combine switch accessible from outside the vehicle. I might eventually get rid of the ML-ACR though, we'll see. Nice feature to have, but makes less sense with the lithium now.
...

Again, WAY overkill to use an ACR when a simple switch will work. If you can't use jumper cables to bypass the REDARC, then a length of wire, say 10 AWG, with a simple toggle switch would give you a quick and dirty bypass.

But, as noted above, how long will your truck sit without running? Might it simply be easier to attach a shore or solar power trickle charger? If you are driving at least once a month, your starter battery should be fine.

 

[jeegro]

Again, WAY overkill to use an ACR when a simple switch will work. If you can't use jumper cables to bypass the REDARC, then a length of wire, say 10 AWG, with a simple toggle switch would give you a quick and dirty bypass.

But, as noted above, how long will your truck sit without running? Might it simply be easier to attach a shore or solar power trickle charger? If you are driving at least once a month, your starter battery should be fine.

I think we're talking about the same thing. I meant adding another switch in parallel with the existing ML-ACR switch I installed, not adding another ML-ACR. But good point, the switch can be connected directly to the batteries. However, it's nice to keep the battery terminals clean from small wires.

Or are you saying I should get rid of the ML-ACR altogether? I'll probably replace these Odysseys when they die with regular FLA... but I want to retain optimal winching power, so maybe not. The ACR is mounted on top of the batteries - that wouldn't work with FLA's, correct? I'm rather fond of the ACR with my fancy switch in the dash, haha.

Attaching a shore charger isn't an option, I park in an exposed alley with no power. I have 200w fixed solar on the roof, on a slide, that I pull out when parked, so the idea is to use an amp or two from that to maintain the starter batteries and keep the security camera on. The security camera claims it shuts off after 72 hours, but I found that it doesn't - it stays on forever with solar - which suggests it actually senses voltage, and is not a timer.

 

[DiploStrat]

...
Or are you saying I should get rid of the ML-ACR altogether? I'll probably replace these Odysseys when they die with regular FLA... but I want to retain optimal winching power, so maybe not. The ACR is mounted on top of the batteries - that wouldn't work with FLA's, correct? I'm rather fond of the ACR with my fancy switch in the dash, haha.
...

The ACR and the REDARC BCDC perform the same function - you use one or the other. The REDARC, like all B2B units, merely adds a new voltage regulator for the camper battery.

Do you have the ACR between the two AGM batteries under the hood? If you move your camper loads to the lithium battery, then I would simply wire the under hood batteries in parallel. In any case, if you use the REDARC for your lithium, wire it according to the instructions - connected to the starter battery.

 

[jeegro]

The ACR is wired between the two AGM batteries, so completely separate from the proposed AGM to Lithium connection (which will be managed by the BCDC). The idea is to have just that extra level of protection -- and mostly since it's already there. Agreed that it's unnecessary... especially if I have the Trik/Amp start to keep the AGM's alive. I do like that combining switch on my dash panel though! I'll have to think over taking it out

 

[DiploStrat]

Probably no need. Just make sure that the REDARC is wired to the primary starter battery, not the secondary one.

 

[jeegro]

Probably no need. Just make sure that the REDARC is wired to the primary starter battery, not the secondary one.

Yes, but to be exact.. it should be wired to the battery that the alternator is wired to. They're usually one and the same.

 

[john61ct]

Some ACRs have a higher close setpoint, look for 13.8V or so, but a little lower is fine, you don't want an LFP bank to sit long at Full anyway.

Some have an adjustable setpoint, even better

 

[jeegro]

Some ACRs have a higher close setpoint, look for 13.8V or so, but a little lower is fine, you don't want an LFP bank to sit long at Full anyway.

Some have an adjustable setpoint, even better

I'm using a B2B charger, and getting rid of the ACR