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Old 07-22-2019, 06:58 PM   #1
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Another question re electrical upgrade: DC-DC, or alternator>inverter>converter

In trying to retrofit my electrical system with new batteries (BTW, Northern AZ Wind & Sun has a 10% off on Battle Born Lithiums this week, July 22-26, 2019, use code JULY10).

I have the old school isolator, with the alternator cable detached from van battery and to the isolator, then two cables to van and house batteries.

And an old Intellipower 9140 40A converter for AC to DC charging (can be used with the Battle Born lithiums, but not ideal). And I have a solar controller but it has no means for changing the profile from AGM to LFP.

I was pretty set on going with the Kisae for solar and alternator charging, omit the SurePower and add the ignition activated relay, and just attach alternator and van batteries wires back together (rather than back to the van battery itself). And maybe upgrade the converter. Might throw in a new switch, but fuses and wiring basically set.

But then I re-read Mike's alternator to inverter to converter description, and remembered that (doh) I had wired in an alternator, big gauge wire and fuses, when I installed a winch. But I hardly ever use the inverter, 600W anymore. It attaches in cabin near the passenger seat via Anderson power poles. Sheesh, I just take the converter's plug out of the AC outlet (shorepower) and plug in my extension cord, plug in the inverter, and bingo, charging at 40A. That's really close to the inverter max of 600W, so I might need to upgrade. And the solar? geez...I hadn't realized that MPPT controllers had dropped so far in price, like about $150 for one big enough for my panel plus a bluetooth dongle. All that's less than the Kisae set up.

So now I'm wondering about a more automatic connection for the inverter. I know Mike's description is pretty old. I've seen transfer relays of the fancier type designed for inverter, shore, and gennie input. The idea is shorepower fails, and it can switch to inverter or gennie (some have autostart, all have delays for generator input, which would seem to work well for alternator input as well). Has anyone ever wired up one of those?

Or is that too fancy and too automatic? I don't see a scenario where I have both shore power and the van running, so a simple relay that could sense when the inverter/alternator came on and then paused for say 30 seconds before sending power to the converter would work.

2001 Ford E250 Sportsmobile with Salem-Kroger 4x4 conversion
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Old 07-23-2019, 09:13 AM   #2
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You can make just about anything work, but first you need to ask if it is the best way to go. While Battleborn says you can use an Intellipower 9140 40A converter, but it's not ideal. What does that really mean? In someway you are paying the price for not being ideal. In most cases that would come in the life cycles of the battery. So I guess I would ask what they mean by not ideal. It might not be ideal but limited negative effect, if you only use on occasion.

Now you are looking to have your non ideal charging solution as your primary solutions. Sure you may save some money, but there may be some unintended consequences in your path. One of the features of KISAE is that it periodically checks the status of the start battery to determine if it needs to derate its output. While some of these features don't sound glamorous, they are the things that keep things running. You would also be generally using about the same amount of power to get 40 amp charge into your new battleborn's as you would to get with the KISAE's 50 amp charge. Part of the reason of going to lithium is the fast recharge, which only happens with more current.

So yes, it could be done, but should it be.


2004 E350 EB V10 E/PH 2WD
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Old 07-23-2019, 10:09 AM   #3
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Thanks. Indeed, you're right; if I was to go to an alt-inverter-1940 it would be stupid to not upgrade that to a lithium model, which Progressive Dynamics makes and Battle Born sells. Since I do far more driving than sitting on shore power it makes sense. Duh, really.

It looks like the costs would be about the same, since I do need the new inverter. I do appreciate that the 9140L would be designed for charging under perhaps more constant input from shorepower. Not sure if the Kisae would do much better, but it does have some nicer features built in, and is more flexible in that I can change more of the parameters. And its solar controller is quite robust. And it has a way to monitor vehicle and solar charging, which in my experience in troubleshooting on the road is quite nice to have.

I'd be going with the 30A Kisae, largely because my existing wiring and fusing is set up for that (and has worked with my existing alternator and other loads), and I can live with a somewhat slower charge. I do think I am leaning back in that direction again.
2001 Ford E250 Sportsmobile with Salem-Kroger 4x4 conversion
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