Yet another battery thread

[luvrbus]

Clifford said above.
You know the Delco 42 starter on your bus is a 900 amp 10 hp motor and they will draw those amps on a cold day I have seen higher, that is why lead batteries have cold cranking amps to turn that baby,The part I don't get is drawing a 100 amps from a 100 amp battery you only get maybe 30 seconds then drawing the same amps from a 100 amp battery would be like shorting one out I guess.

Don doesn't have a 42 he has a 39 like mine.

Still takes the same toque the 39 does it through the reduction gears to achieve the magic 60 rpms with less amps and those are 7-1/2 hp 

[luvrbus]

I understand Don sizing now I looked at a factory setup the largest cable on the system was AWG 2 with 6 LifePo4 , the Delco starter would do the AWG 2 in fast I doubt the AWG 2 would carry a 100 amps ,then the BMS looks like a weak link,the unit did not a boost switch either tying the banks together 

[windtrader]

There's a simpler solution!

Just keep your start batteries always topped off by using a solar charge controller that has it's solar input hooked to your 48V house battery pack.

All solar charge controllers know how to correctly charge a lead acid battery.

This works because most solar panels are between 36-72V when they are producing power. Doesn't have to be a high power solar charge controller.

Here's a inexpensive one with blue tooth that you can control from your phone.

https://www.amazon.com/Victron-SmartSolar-Charge-Controller-Bluetooth/dp/B075NQQRPD/ref=sr_1_1_sspa?crid=32QDJCHHGN14G&dchild=1&keywords=victron%2Bmppt%2B75%2F15&qid=1634487075&sprefix=victron%2Bmppt%2Caps%2C218&sr=8-1-spons&smid=A2VHGGOHXF24LJ&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEySldONjAwU1RVTFZDJmVuY3J5cHRlZElkPUEwNzQyNTAxMVNHQkpZSFU4TTZaSyZlbmNyeXB0ZWRBZElkPUEwMzk4NjQyUDRYMFBZWVlQRjRaJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1

Did not want to mention the idea of keeping start batteries ready to start the bus, what a concept. lol What I do is simply have a plain old AC powered battery charger charge the starts if needed. Yes, using the solar powered lithium battery to charge the bus battery. Just plug it in like a house plug!

[luvrbus]

Can you use a Echo charger for the chassis battery when charging with solar ? my RV has a echo charger that charges the chassis batteries from the inverter and the banks are separated

[Jim Blackwood]

Yeah but you guys are just dodging the question. Hey, what if a battery bandit snuck in overnight and stole your start batteries?  What if an Outlaw put a bullet through them? What if they fell out just as you made camp? What if they got struck by lightning? What if a quad-runner ran into them and shorted them out? How about then huh? Is there a way you could start your engine off the house batteries? A good old fashioned carbon pile could limit the voltage and current to the starter but how about the batteries? Are you guys saying there's a reason the lithium batteries couldn't be made to run the starter? I mean it sounds like that's what I'm hearing and I'd like to know why.

Jim

[windtrader]

I'm advocating that with proper sizing of battery and connectors, there is no reason that a lithium house battery can't start the bus. The main consideration is peak current draw while cranking, that's it. I have jumped my starts from the house battery and it works but the jumper cables were not up to the current so got warm. Like I said as long as all specs are met, then no issue.


The other hillbilly method I have done in the past with fading starts was to start the generator to charge up the starts. Many ways to get sick starts well enough to crank the bus.


The easiest way is to just plug in a regular AC battery charger, take a nap, then start the bus and go. Not rocket science guys.

[dtcerrato]

We can easily start the bus with either our two chassis start 8D hybrid wet lead acid or the house bank five group 31s wet lead acid. No lithium here - don't have those kinds of Benjamin's... The house bank is supported by 400W solar & the starts supported by 100W solar. The start & house banks can be switched to either or combined by blue sea RBSs for starting, house camping needs, &/or feed to the inverter. While OTR the house bank is dropped out & the starts power the roof air with 1/2 load on the engine 200A alternator. We're just all wet...
A total replacement of the entire seven batteries mentioned above is little more than the purchase of one 100AH Battle Born Lifepo. Serves us very well.

[luvrbus]

It would take a lot of Battle Born at 100 amp each to replace 1-8D starting battery with 1100 to 1400 amps, cost would be killer for the Battle Born used as starting batteries like 200 bucks for the 8D and 10 grand for the Battle Born.HWH hydraulic slides must use a lot of power Zach told me he needs to start the engine to extend his 4 slides or it cuts off after 2 times with his LifePo4 battery pack,I have not tried to extend or retract the slides on mine without the engine running it may do the same with my four Lifeline AGM 8D's  (1200 amp ) don't know

[dtcerrato]

All our wet lead acid batteries were replaced a few months ago. We went with NAPA hybrids which gives great option to use either bank as start or deep cycle and they are all totally compatible with each other. The NAPA's have the highest AH/Cranking amps in comparison to similar competitors - NAPA group 31s are 105AH each & the 8Ds are 1700 cranking amps each. Prior to our current 4 stage smart charging these batteries were real close to 7 years old before weakening - we're good with that but will increase with the increased TLC they receive now. Yup, we're all wet...

[luvrbus]

All our wet lead acid batteries were replaced a few months ago. We went with NAPA hybrids which gives great option to use either bank as start or deep cycle and they are all totally compatible with each other. The NAPA's have the highest AH/Cranking amps in comparison to similar competitors - NAPA group 31s are 105AH each & the 8Ds are 1700 cranking amps each. Prior to our current 4 stage smart charging these batteries were real close to 7 years old before weakening - we're good with that but will increase with the increased TLC they receive now. Yup, we're all wet...

Don was DIY he probably has a 1/4 or less of the cost if he went out and bought Battle Borns

[dtcerrato]

I followed Don's build. He spearheaded a unique design and has a primary off grid system. We just went for supplemental solar - that & the added inverter instead of genny power otr has decreased our dependency on the genny exponentially.

[lostagain]

On the 5C, I tied the starts and house batts together as one bank. 8 6V Trojan golf cart batts. Works good.

[luvrbus]

LOL I guess I will tough it out because I am not going to install solar on the roof of my RV ,heck I dislike  the in motion satellite on the roof so much I am removing it   

[epretot]

Does the max charge rate of a battery increase when wired in series?

[luvrbus]

No when wired in series the voltage will increase but not the amps