can deep cycle batteries do emergency start duty on bus?

[bevans6]

I am looking at getting 4 deep cycle 6 volt batteries for my house bank, wired series/parallel for 12 volt.  I can easily reconfigure them for 24 volt to start the bus in an emergency - but will that damage the batteries?  What I'm reading is that true deep cycle batteries (I'm thinking fork lift or golf cart type) have heavy plates that work better for deep cycle use, but conversely have a high internal resistance that doesn't support high current loads as well.  Any thoughts?

Brian

[Jerry W Campbell]

A friend of mine has an older WanderLodge. It has 4 Trojan 6 volt T145's. They are the house batteries and the starting batteries both. They are 5 years old. After 5 years of abuse ( dry cells etc. ) and not much use, a couple of days ago, He was in a gas station and it wouldn't start. Now he has 4 new batteries. So, I don't think it would shorten the life of your batteries by much to use them to start in an emergency, BUT If your motor doesn't start easily I would worry. EMERGENCY being the keyword here. I think it would be a nice option.
Jerry

[viento1]

Ahhh no worries, I have converted all my batteries to trojan 105. I fit 4 in the old battery tray and piled a bunch elswhere, run them all 24 volts,  use a 24volt inverter charger. Not sure if it will ruin the batteries but I am sure you would have no problems in an emergency.

ps. I do have a seperate battery to start the generator (to charge the house bank)

[FloridaCliff]

I have used my house batteries, tied together through a solenoid, to start the coach when I had one of my two 12VDC batteries die an unexpected death.

Worked great...and saved me waiting for help...

I set it up like that for just this reason.

Once I noticed my mains batteries had drawn down on some parasitic load and I switched both banks together to start.  No need to strain the starter.

I see no problems for an emergency start.

Cliff

[Don4107]

I had two banks of two batteries in my boat.  Bank 1 was two 12volt marine deep cycle/starting batteries.  Bank 2 was two Trojan T105s in series.  My normal routine was to run the day on one bank and at the end switch to the other bank keeping the most recently charged bank in reserve.  Monitored only by stock volt meter.  Of course I had more capacity in the Trojans and they worked fine for 7+ years until we stopped using the boat much.  Can't say the same for bank 1.

Anybody now what a golf cart draws in amps when working at max load?

[Frank @ TX]

Hi Bevans6 ,
I have a big relay that can ties the house bats to the start bats.
The switch that controls the relay is at the drivers area.
I have started the engine a few times with the bats tied together, really spins the engine fast.
I haven't had dead start bats to use the emerg start system for real.
I also have solar panels that charge the house house bats when dry camping.
Some times I activate the emerg start relay when dry camping to allow the solar to
  charge the start bats also.
9 years and no problems with the system.
Frank

[NJT 5573]

If you have enough deep cycles you should be OK. My understanding is the deeps don't release a large amp rush like regular cell batterys.

The starter needs alot of voltage and the deeps only allow a small amount of voltage at one time. If the starter is spinning fast, you should be OK. If it's spinning slow, better get the deep cycles some help soon, but it should still be good for a quick start without getting the starter to hot.

[gumpy]

I've done it. I have a crosstie relay.  I've also run jumper cables between the two banks when the coach batteries were too dead to power the
relay (bad start battery).

If you don't want to power the starter, just connect the two banks and let the start batts charge for awhile.

[gus]

I've done the same thing as Cliff a couple of times when I was having alternator problems and the starts were too weak. It started instantly each time so I don't see how it could have harmed the house bank, which is only two GP 31s.

I would only do it if the engine starts instantly, which my 671 does when it is warm, or in warm weather. Long cranking would probably damage deep cycles because of the large amp load.

[TomC]

My deep cycle batteries are 2-Lifeline 8D AGM's.  Since they are AGM, the internal resistance is much lower then a normal floaded battery.  Hence they work well to start the bus-of which I have done through my 300 amp solenoid when the starting batteries were dead, and also in cold weather when the engine had to be cranked more to start.  Good Luck, TomC