KISS Dual Battery Upgrade
- Thread starter TeCKis300
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I'm going to add something modular as well. Prob more the home brew DIY though. Def won't be plug and play haha...All this is true. Also I just bought a lithium Goal Zero. Plug and play
For Mogwai and others (like me) contemplating a DIY battery build, I *HIGHLY* recommend this article.
LiFePo on boats
It seems to get referenced a lot on the various EV and solar forums. The main difference between the marine use case and ours is the size of the battery packs (e.g., 300Ah!), but the rest is a great explanation of the considerations.
I totally get the value of DIY. Cost per amp hour is much lower.
The goal of KISS is to make one large “bank” of nearly identical batteries and have them act as one. You split the pos and neg to force the current to flow through both batteries, otherwise the current will take the paths of least resistance.... which is through the factory cables located at the stock location (#1). Battery #2 is still technically part of the "bank", but it's only assisting #1.
By moving the negative, you force the current through the new cables routed along the firewall so both batteries are used equally.
Maybe someone can make a add more technical explanation?
I've done the DIY approach, and it's really not much (if any) lower. There are a ton of components, mounting brackets, electronics, terminals, etc. that all add up. Even not counting the time invested, I'd ballpark my setup had run within 80-90% of the cost of a GoalZero Lithium 1000, had less ah capacity, was not easily transferable out of the vehicle, and was generally less user friendly. I'd 100% get a GoalZero Lithium 1000 next time around.
No offense but you didn't do it right. I'm out and don't have time to reply in detail now but I'll send back some options later. For example, a 60aH Nissan Leaf Gen 2 module (single) is $80 used, 80% capacity and will cycle 2 or 3 times more over its life than a Goal Zero. Those goal zeros don't have a high cycle rate, are older Lithium tech, charge slower than advertised, and on the lithium versions it's not guaranteed you can replace the battery so plan to throw them out after 5 years.
If you have the time and the know-how, buying 8v leaf cells and making your own lithium pack sounds like a really interesting project.
The convenience of going to the store and buying something ready to use was worth it for me.
The convenience of going to the store and buying something ready to use was worth it for me.
These are a good option too, and I'm sure some will roll their eyes at Chinese/Alibaba but the reality is, for lithium batteries and solar components China leads the pack. Here's almost 200aH for less than $600. Good for 4000 cycles. Add a BMS (you can get one for $40) and an inverter and you got yourself a pretty nice setup. Double up those batts and add a larger inverter and now you're overlanding 
.
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Possible. I never considered lithium options at the time.
Two NorthStar batteries ran me about $650-700 CAD. An Off Grid Engineering battery mounting kit and BlueSea MLR ran another $500 CAD or so. 2 gauge wiring, terminals, shrink wrap, crimper, two circuit breakers, misc hardware, fuse boxes, various 12v ports, solar controller, at a least another $350-400 CAD. Very comparible price to the GoalZero 1000.
Could have probably gotten cheaper batteries, but the price would have still been up there.
Oh, yeah if you were doing this a while back there are more options out there now, and I wouldn't consider DIY that's not based on lithium tech.
potential that I overpaid, but I am putting a 100ah Lifepo4 in the rig tonight with a Redarc bcdc (yes the one with the lithium profile) .
Not horribly bad $ (more than that alibaba link though, I may need to look into those) and more ah than what I could have gotten in the same physical size otherwise (which was important to me).
I dont need it to be insanely portable, and a couple anderson plugs will go a long way for that.
Not horribly bad $ (more than that alibaba link though, I may need to look into those) and more ah than what I could have gotten in the same physical size otherwise (which was important to me).
I dont need it to be insanely portable, and a couple anderson plugs will go a long way for that.
That's awesome, looking forward to hearing how it goes. Which did you go with? Actually, let's move this convo to your build thread since this is neither KISS nor "tech", wouldn't want to upset those out there with sticks up their butt. 
I love the DIY approaches in general to almost everything. I heard a guy on a podcast put it into perspective well: "Everything has a cost, in either money, time, or frustration." Money to just buy a new widget; time to DIY your own widget, or the frustration of doing neither and having to use a POS widget that doesn't work well.
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- #117
For the same reason that banks should be built from batteries of a common type and bought at the same time. To ensure the batteries are as likely to be balanced as possible: distribute load, maximize charge, and minimize microcurrents between batteries as they try to balance each other, in order to maximize bank performance and life.
Over the life of a battery bank, wiring in the described fashion in the picture ensures continued cell balance under use, in draw and charge. This is not a lead acid battery thing, but any battery built from multiple components.
Wires are not perfect conductors and have resistance however minimal. Wiring with two grounds, and the positive lead to one, will cause the battery closest the the positive lead to bear the brunt of any load. Such that after the load, the primary battery will be discharged to a lower state of charge (SOC) than the secondary battery. It will then charge from the secondary battery in order to equalize. These microcurrents effectively are additional cycles on a battery that will cause the primary battery to wear harder and faster ultimately leading to premature failure compared to a system that is designed properly.
@DirtNap, I couldn't agree more!
I can’t wait to see your project and how it outperforms the lithium GZ 1000 for less than $800.
I'll let someone else respond to your dual-mount location question but I think it's been done. The problem w/ most of the lithium batteries is the max. discharge amperage - ie if your intent is to have it as a backup to "start" your truck it may/may not work. You could certainly trickle charge the dead starter battery and maybe connected the draw would be fine, but for example that Renogy shows a protection disconnect at 150A (max continuous draw 50A).