KISS Dual Battery Upgrade

[ekolpack]

Point of clarification: Has anyone successfully installed 2 x group 31 batteries in a TLC 200? Since apparently fitting a second group 27 is already super tight, I'm guessing a second group 31 is out of the question, but it's been hinted at in this thread. Can anyone confirm either way?

 

[william571]

There’s been a lot of discussion on batteries and battery systems. Here’s my attempt to offer an easy button. The task of a battery first and foremost is to offer power and reserve capacity. There’s many battery setups and systems talked about. But perhaps some of those are solving a problem that really isn’t there, or need complexity to solve a fundamental shortcoming of an architecture as laid out. Some may judge this as not sophisticated, at least from a traditional expo POV. I’d say KISS, with reduction of complexity and dependencies to be its greatest advantages. That’s ultimately cheaper, easier, more effective, and reliable than anything out there.

1) 2x lead acid batts (matched batts, buy at same time)

AGMs are not the right solution here. Flooded lead acid is what’s fundamentally compatible with the alternator/regulator and underhood temps. As large or small as you like. Deep cycle (hybrid) batts preferably. I’d say that 2x group 27s are more than most people will ever stretch when setup like this. Most may not even need 2 batteries and can get away with one larger battery with the expo options below.

2) Wire these batts in parallel to make one big bank

Wire with heavy 0/2 gauge. One big bank has advantages to maximizing usable capacity and huge current draws. It also keeps cycle depth low, prolonging usable life (lasting potentially 8+ years, unless you live in super-hot places like Arizona which kills any battery/setup). “But, house and starter batt”…. I’ll get there in the expo section.

3) Wire the vehicle to the batteries in cross fashion. Positive to (+) terminal on one battery. Negative to (–) terminal on other battery.

This is a key optimization for long battery life. Move the chassis ground to the battery on the other side. This is important to keep the batteries balanced. Otherwise, there will be voltage offsets and micro-currents causing premature wear.
View attachment 1853542


That’s it. No fuss. Always charged. Maximizes the batt capacity possible for every device, with huge current capability.


Expo options

4) If one has continuous draw devices that operate after engine shut down (i.e. fridge, heavy lighting, house draws, etc.), they should be wired to a distribution point that is tied to the batt with a low voltage protection mechanism. This protects the batts and ensures starting reserves, which addresses the reason for house/starter batt setups.

5) If one wants to monitor voltage accurately in cab, add a USB cig lighter adapter with voltage readout ($10). Some even have low voltage alarm functions.

6) If one wants to support continuous draws for long parked durations, add a solar panel/charger tied directly to the bank. Something that makes enough output to support whatever particular draw. 50-100W can typically make the system last indefinitely, unless one has a particularly large draw.

7) Protection from battery bank failure. Carry a standalone lithium-ion jumper pack that typically doubles as a USB charger. It has the benefit of helping any expo friends in trouble, vs a built in battery jumper solution.

Helpful post

 

[NTV]

Point of clarification: Has anyone successfully installed 2 x group 31 batteries in a TLC 200? Since apparently fitting a second group 27 is already super tight, I'm guessing a second group 31 is out of the question, but it's been hinted at in this thread. Can anyone confirm either way?

I haven’t heard of anyone doing it. Heard of a few switching primary location of group 31 to be the aux and then using secondary location for starter with group 35. I like this idea but do not like the complexity that comes with moving your starting wiring around. We just need someone to come up with a lithium battery group 35 size that can handle the heat under the bonnet and give us around 100ah of capacity. That’s my hope in the long run.

 

[grinchy]

XS Power/Ioxus IX-3160 60Ah Lithium LTO Battery 10,000 RMS handling 14v

IX-3160 by XS Power An Audio Apex Exclusive! Max Amperage 500a Rated for 10-12k each Over 2500 cranking amps Rugged Group 31 casing Max recommended charge of 16.2 AGM Charger Compatible Internally Balanced 1 year warranty

caraudiobargain.com

Good with under hood temps. Good with cold. Group 31 size. Only 60ah. LTO isn’t energy dense.

 

[Bunga]

Grinchy, have you had a chance to try the XS battery?

 

[grinchy]

I’ve had it in a cart a couple times, but I’m probably going with an SLA next.
I want an LTO, was going to make one last summer but the cells got diverted by a package thief.

 

[Bunga]

Ugg. Good luck on the next order.

 

[TeCKis300]

XS Power/Ioxus IX-3160 60Ah Lithium LTO Battery 10,000 RMS handling 14v

IX-3160 by XS Power An Audio Apex Exclusive! Max Amperage 500a Rated for 10-12k each Over 2500 cranking amps Rugged Group 31 casing Max recommended charge of 16.2 AGM Charger Compatible Internally Balanced 1 year warranty

caraudiobargain.com

Good with under hood temps. Good with cold. Group 31 size. Only 60ah. LTO isn’t energy dense.

Any new thinking on how to address some of the challenges? Couple things stand out to me:
- At low states of charge, because of the high 2C recharge rates, could really tax the alternator potentially burning it out over the long term?
- Charge voltage mismatch as 6S config wants 16.2V for full charge? Alternator is well short of that and even if we assume a high 14.2V. Which will leave something less than 50-75% max charge / untapped capacity?

 

[grinchy]

Any new thinking on how to address some of the challenges? Couple things stand out to me:
- At low states of charge, because of the high 2C recharge rates, could really tax the alternator potentially burning it out over the long term?
- Charge voltage mismatch as 6S config wants 16.2V for full charge? Alternator is well short of that and even if we assume a high 14.2V. Which will leave something less than 50-75% max charge / untapped capacity?

- I was planning to run a 'resistor' in serial with the alternator charge input, no reason that wouldn't work for this. It would slow down the current draw max. I had done some calculations and had a stainless steel bolt, if I recall it was 4" long to create like a 25 ohm load. Or maybe it was a 1 ohm load. I'd have to go look at notes. Also had a fancy diode in parallel with the ground to handle potential alternator spikes if the battery decided to stop charging. Don't remember what kind it was but it was normally closed but would open on current spikes so the alt could dump its excess charge.
- Yeah, that's a problem. After watching the alternator voltages I figured I could get it charged near to 14v after driving a bit. But yeah, you'd want to plan capacity so that you only get 50-75% yield or there abouts.

**Alternatively you can get an appropriate DC DC charger, use the LTO as house battery, and get a bank of supercaps for starting duty, with the LTO serving as the battery buffer for the supercaps. I think this is probably the best way to go about dealing with the LTO charge issue. Of course this runs pretty solidly into a packaging issue under the hood, but it might be possible to put the supercaps back by the right firewall and the LTO house in the 'starter' location.

 

[ekolpack]

Point of clarification: Has anyone successfully installed 2 x group 31 batteries in a TLC 200? Since apparently fitting a second group 27 is already super tight, I'm guessing a second group 31 is out of the question, but it's been hinted at in this thread. Can anyone confirm either way?

I'll take the lack of confirmation as confirmation that this cannot be done. I think I'll go with 2 x deep cycle group 27's under the hood, wired as described in OP, which effectively creates one large battery. If I ever need more than 200aH (doubtful), I can add a lithium in the back as a "second" battery run off a BCDC1225.

Q: Will the BCDC1225 see the main battery bank (wired in parallel as described in OP) as a single battery? Will this cause issues with the batteries or charger since the charging profile will treat it as a single battery when technically it's two wired in parallel? I don't see why it would matter, but I also know that batteries are boxes of voodoo magic.

 

[ntdb]

Has anyone done a KISS dual-battery setup in a 60-series and have photos of their cable routing? There's a pretty good path below the condenser but an earlier post wisely advised against running them in a spot where a front-end collision could cause a bad short. Perhaps this is less of a concern with good cable insulation and some split loom tubing? Going to the firewall seems like a long trip for wiring batteries in parallel.

 

[NTV]

I'll take the lack of confirmation as confirmation that this cannot be done. I think I'll go with 2 x deep cycle group 27's under the hood, wired as described in OP, which effectively creates one large battery. If I ever need more than 200aH (doubtful), I can add a lithium in the back as a "second" battery run off a BCDC1225.

Q: Will the BCDC1225 see the main battery bank (wired in parallel as described in OP) as a single battery? Will this cause issues with the batteries or charger since the charging profile will treat it as a single battery when technically it's two wired in parallel? I don't see why it would matter, but I also know that batteries are boxes of voodoo magic.

I would think as long as the BCDC gets enough voltage from your parallel 27’s it should be fine but I dunno for sure. I too would be interested to know a good answer to this question.

 

[TeCKis300]

I'll take the lack of confirmation as confirmation that this cannot be done. I think I'll go with 2 x deep cycle group 27's under the hood, wired as described in OP, which effectively creates one large battery. If I ever need more than 200aH (doubtful), I can add a lithium in the back as a "second" battery run off a BCDC1225.

Q: Will the BCDC1225 see the main battery bank (wired in parallel as described in OP) as a single battery? Will this cause issues with the batteries or charger since the charging profile will treat it as a single battery when technically it's two wired in parallel? I don't see why it would matter, but I also know that batteries are boxes of voodoo magic.

The challenge to fitting a big battery in the passenger fender position is the power steering reservoir. It's not hard to move it for a group 27, but space gets tight quick. Here's an easy way to relocate the reservoir.

To answer your question, paralleling 2x batteries (or many more) into a bank with KISS, makes no difference to anything upstream. Other than it is a battery with much larger reserves. Chargers or devices will run the same. The bank configurations are used everywhere from solar installs to RVs and others, so it's a well understood strategy.

 

[lx200inAR]

Well, this just showed up from the Amazon man. Not sure if it was mistake or what, but a company who normally sells a battery powered fridge and other solar stuff had these on their store with a deal selling it for $150. It’s not branded by them (the one in the ad was), so not sure what’s going on. I fully expected my order to get cancelled, but it showed up. Now I need to figure out how to test it. There are other items that match what I received with limited but okay reviews.

 

[LTSR]

Well, this just showed up from the Amazon man. Not sure if it was mistake or what, but a company who normally sells a battery powered fridge and other solar stuff had these on their store with a deal selling it for $150. It’s not branded by them (the one in the ad was), so not sure what’s going on. I fully expected my order to get cancelled, but it showed up. Now I need to figure out how to test it. There are other items that match what I received with limited but okay reviews.

looking forward to hearing your feedback. i have a 5 year old agm 120ah that i’ve been thinking of replacing due to sheer weight.

 

[lx200inAR]

Well, this just showed up from the Amazon man. Not sure if it was mistake or what, but a company who normally sells a battery powered fridge and other solar stuff had these on their store with a deal selling it for $150. It’s not branded by them (the one in the ad was), so not sure what’s going on. I fully expected my order to get cancelled, but it showed up. Now I need to figure out how to test it. There are other items that match what I received with limited but okay reviews.

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Seems to be working fine. “Bench” testing along with my Auxbeam switch I picked up recently.

I’ve been dumping 240 watts into it for about an hour now and it hasn’t blown up yet.

Ran a 100w load off it to make sure the battery monitor and everything was working properly.

After adjusting settings on the monitor. Got a $50 18Amp charger specific for LiFePo4 off Amazon and the monitor is from AliExpress for $50. Battery project at $250 so far. The monitor is Bluetooth enabled and has an app to show all the same stuff that’s on the screen.

 

[FrazzledHunter]

Seems to be working fine. “Bench” testing along with my Auxbeam switch I picked up recently.

I’ve been dumping 240 watts into it for about an hour now and it hasn’t blown up yet.

Ran a 100w load off it to make sure the battery monitor and everything was working properly.

View attachment 3053916

View attachment 3053917

After adjusting settings on the monitor. Got a $50 18Amp charger specific for LiFePo4 off Amazon and the monitor is from AliExpress for $50. Battery project at $250 so far. The monitor is Bluetooth enabled and has an app to show all the same stuff that’s on the screen.

View attachment 3053928

Nice! Looks like you're on you way to making your own secondary battery system. Curious as to the details of the shunt and the other two modules you have there.

 

[lx200inAR]

Here’s a sort of brain dump from the few hours I spent researching these things. My interests currently are in a house battery in the rear of my 200, but also doing some of the pre research for a DIY home solar array/battery backup. I think In DIY form we are getting close to the point where these are viable as a cost savings (6-7 years before break over point) and becoming less grid dependent.

The battery monitor/shunt is an all in one kit. It is available on eBay and Amazon from multiple brands, but I’ll link here who I think is the original manufacturer on AliExpress.
Junctek KG140F

(Someone should tell them “Junk-Tech” isn’t the best name for the US market)

Comes in 100/400/600 amp versions. Seems well made and worked as expected out of the box. The key reasons I went with this unit were price, temperature sensor, and a built in relay that can be triggered by an array of conditions. There are also recovery timers for the relay to reattempt connection after a failure automatically.

Less important to me features are, The unit can function without the screen plugged in over Bluetooth (in fact you can buy the monitor and shunt without the screen for a few bucks less). Can also be powered by the battery it’s monitoring or by external power supply in case you want it to function even in battery failure scenario.

I bought the 400a version, only for an instance where I may want to repurpose it to a solar array or something. It’s capable of monitoring 120v/400a.

I looked at the Renogy RBM500 monitor that you can get for about same price from their eBay store ($60). I like it, but couldn’t justify not getting the battery protection relay. It also isnt bluetooth and the temperature monitor is part of the shunt. This may not matter since the shunt should be pretty close to your battery, but the Junctek has a probe rather than built in.

Third option I looked at was this:

AiLi Voltmeter Ammeter Voltage Current Meter Voltmeter Ammeter 100V 350A Caravan RV Motorhome 999 AH

It was best price ($45 on Amazon, less on AliExpress). Has bidirectional monitoring, probably everything most people need.

The common complaint with the cheapest monitors on Amazon was that the <$25 models usually didn’t distinguish between watts in and watts out. I also assume the percent used meters were probably rudimentary at best. The nicer monitors probably give a much more accurate idea of percent used because they don’t rely on an instantaneous voltage reading to guess. The one I bought bases the available battery capacity by tracking how much battery you use and subtracting that from a configurable battery capacity. I assume the other 2 I linked work the same.

 

[lx200inAR]

Unless I can find something more interesting, I’m thinking of going with the Renogy DC-DC with MPPT (DCC50S 50a or DCC30S 30a) chargers. These allow simultaneous DC and solar charging, as well as can be configured to trickle charge the DC feed (starter battery in this case) when not charging. I believe it can sense when alternator is running (even with “smart” alternator) to only charge the house battery while active and to trickle charge starter from solar when not active.

The 30amp is all I need but is only slightly cheaper than the 50amp. I’d need to do some research to see if the max charge rate is configurable. My battery says it’s max charge rate is .5c (50amp) so it would be okay either way. But for longer battery life a 20-30amp charge rate would be ideal.

A charger like this is a bit pricey, but its also pretty much covers all the features that the battery monitors mentioned above cover (especially all the protections). Assuming it’s reliable it should be a nice setup. This might be a big assumption though as in general the internet isn’t too favorable of Renogy.

Currently the market for all in one mppt/inverter/chargers is booming for home market. I’m surprised this isn’t much similar in the RV market. I guess if you have an RV you can fit one of the large home boxes, but that’s tough to adapt to an overlanding rig.

The ideal overland all in one box would actually be a DC-DC/MPPT/Inverter. I can’t imagine there wouldn’t be some market for it, since what we are asking for is all the makings of a larger Jackery/ecoflow “solar generator” just without the battery, so we can provide our own battery bank. I’d love a 1250-1500w box that did that.

I guess a 1000-1500W inverter and the Renogy charger listed above isnt a bad compromise.

 

[Julian73]

Well, this just showed up from the Amazon man. Not sure if it was mistake or what, but a company who normally sells a battery powered fridge and other solar stuff had these on their store with a deal selling it for $150. It’s not branded by them (the one in the ad was), so not sure what’s going on. I fully expected my order to get cancelled, but it showed up. Now I need to figure out how to test it. There are other items that match what I received with limited but okay reviews.

View attachment 3048467
View attachment 3048465

What are the dimensions?