Community Forums

**CountryFit** · 10-24-2016, 11:45 PM

Has anyone removed the chassis battery for good?

I am using a li pack for coach and just acquired another pack (un-planned though). Don't like to install it inside the coach, especially near the bedroom, as how it will affect the health is unknown (we don't know what we don't know, right?). My chassis battery occupies about 40% of the space in the battery bay, I am thinking to take it out and put the new pack there. Now two things I am not sure:

1) How to handle the chassis battery cables? Just individually wrap up and let them be idle?

2) I am aware of using the combiner switch on the transmission selector panel to start engine. The cranking current is huge I assume (the chassis battery indicates 1400 CCA). I tried to start the engine from my current li pack (700ah) today, it cranked once then the 350a fuse was blown. So what size/type of the fuse for the "super pack" should I go?

Anything else should I beware? TIA.

OLYLEN · 10-25-2016, 09:44 AM

The chassis battery/batteries do so much more than just start the coach. Did the grid heaters come on, on the failed test? Why screwup what works for what gain?

LEN

tmw188 · 10-25-2016, 10:04 AM

Yes why?

**CountryFit** · 10-25-2016, 10:38 AM

Quote:

Originally Posted by OLYLEN

The chassis battery/batteries do so much more than just start the coach. Did the grid heaters come on, on the failed test? Why screwup what works for what gain?

LEN

yes, the grid heater was on on my test. not sure if other things will be affected without chassis battery... (i remember i read on this board someone said to drop the chassis battery with house battery only).

i do so for three purposes:

1) run adsorption fridge on electric only. my fridge is a newer stainless steel model from dometic ndr1292; too new to throw away. it works great but has a slight waste air in the area whenever it burns propane. i have taped it up along the edge in front but still there. tried on 120v from inverter, perfect! my current li pack is 700ah, everything is good in sunny days but short in bad weather. bought additional 600ah to make a "super pack" at 1300ah, thinking that should make it "adequate".

2) charge plug-in hybrid car from solar. it's on my list to get a plug-in hybrid like c-max energi to replace my current 2010 honda fit sports, but may wait a little until "grand c-max" comes out (a longer body with 7 seats sold in europe already). for the time being, i have 1200w solar panels on the roof, will expand to 2000w+ as i have the space. when these are done, the car will be charged from inverter, hopefully making it real "green".

3) possibly run the front a/c occasionally. this is less important though; in summer time most likely i will be in nw coastal area, no a/c is needed.

keep coming... thanks.

twinboat · 10-25-2016, 10:42 AM

I would hook the chassis cables to the LI battery and then simply run a positive jumper to the other LI cell.

No other wiring needed. Doing what you proposed would leave you no power to the chassis when the combiner switch was turned off.

I don't know what the charging parameters of your LI batteries are, but most auto alternators may overcharge them, unless the voltage regulator is customised.

**CountryFit** · 10-25-2016, 11:01 AM

Quote:

Originally Posted by twinboat

I would hook the chassis cables to the LI battery and then simply run a positive jumper to the other LI cell.

No other wiring needed. Doing what you proposed would leave you no power to the chassis when the combiner switch was turned off.

I don't know what the charging parameters of your LI batteries are, but most auto alternators may overcharge them, unless the voltage regulator is customised.

or make 100ah to hook up with the chassis cables and rest goes to the super pack? this way at the worst cases i would lose 100ah only...

my li battery is charged at 14.0v and floats at 13.6v. max charge rate is 3c. the new one is the same.

my alternator outputs 13.6v at 160a; actually it's perfect. with my current setup, before starting the engine, i manually turn off the charge to the house battery. a few times i forgot to do it

, leaving the alternator to charge the house as well as the chassis batteries in a considerable distance (the longest was 200 miles). it seemed no harm to it.

this might work

.

**CountryFit** · 10-25-2016, 03:40 PM

oops, re-read my #4 and noticed a typo - i meant "absorption fridge". didn't spell check... fat fingers...

.

twinboat · 10-25-2016, 04:37 PM

You are aware that gas fridges running on 120 volts use 3 to 4 times the power that residental units do ?

**CountryFit** · 10-25-2016, 05:37 PM

i have tried, the power drawn from the house battery is about 39a on my fridge, vs. about 25a on a residential fridge like samsung f18, per my collections (cmiiaw). mine uses higher power but not too bad, the battery pack handles that ok.

in an extended cloudy or rainny period, i can still flip back to gas so i will be good

.

harryn · 10-31-2016, 01:34 PM

If you really want to ditch the starter battery, in theory you could wire in one of the larger size ultra capacitor setups. They are capable of starting up large semi trucks in the winter.

In case it self discharges from non use, you could wire a "charge up" cable (sort of like a jumper cable) from the house bank to the ultra cap. Most likely, you would want to have a fairly healthy in-line resistor to slowly charge that cap though, or it will melt everything when you hook it up.

Just as an example, suppose it was completely discharged and you wanted to limit the charge up current to 25 amps.

V = IR, so....... 12 volts = 25 amps x R, R = 0.5 ohm

Sizing the resistor wattage

Power = R x I x I, so... 0.5 x 25 x 25 = 150 watts or so, I would get a 200 watt rated resistor, which is not a light duty item.

Probably newark, mouser, or digikey have something like that.

vsheetz · 10-31-2016, 01:53 PM

Quote:

Originally Posted by CountryFit

i have tried, the power drawn from the house battery is about 39a on my fridge, vs. about 25a on a residential fridge like samsung f18, per my collections (cmiiaw). mine uses higher power but not too bad, the battery pack handles that ok.

in an extended cloudy or rainny period, i can still flip back to gas so i will be good

.

To better understand refrigerator power usage need to measure over time as its not constant draw. A Kill-a-Watt meter inline over a couple three days will provide actual usage data.

ByeTheWay · 11-04-2016, 04:12 PM

I have removed my starting batteries and replaced them with 6-6v agm's for a total of 672ah. In just over 2 years I have not had an issue.
FYI: Worse Case... According to a friend who has had several Diesel Trucks (18 wheelrs) you can start your engine by jumping from your toad. I keep a good quality jumper cable in the coach, which are still in the wrapper.

**CountryFit** · 11-04-2016, 10:54 PM

Quote:

Originally Posted by ByeTheWay

I have removed my starting batteries and replaced them with 6-6v agm's for a total of 672ah. In just over 2 years I have not had an issue.
FYI: Worse Case... According to a friend who has had several Diesel Trucks (18 wheelrs) you can start your engine by jumping from your toad. I keep a good quality jumper cable in the coach, which are still in the wrapper.

good to know... is this 672ah the house battery, or this 672ah as a starting battery and you have another set for house?

ByeTheWay · 11-05-2016, 05:10 PM

The 672ah is starting and house, total, that is it. I know several people doing this. I have enough solar to recharge quickly while boondocking. I prefer Life Line AGM's but they were on back order when I made the switch so ended up w/ FullRiver AGM's. 6-6's paired in series then parallel to the coach. 2 years and no problem.